I don't know a hell of a lot about heating, because I generally negate the need for it by travelling north. We also have a full size gas oven in our caravan and roof top extractors. If we ever are in the unfortunate position of being where the temperature drops below 20 C, we can heat the van up fairly promptly by lighting said oven. The extractors remove carbon dioxide and provided that there's a small window partly open, oxygen flow into the caravan is ample. There are people however, who don't mind punishing themselves through travel in cooler climes. Again and again I meet people who own both rooftop reverse cycle units, which heat and cool, as well as diesel heaters. We're talking around $4,000 worth of appliances, after installation costs. Throw in a generator powerful enough the run the rooftop unit off grid and we could be talking as much as $7,000.
 |
| Carframo Ecofan Belair stove top fan |
I'm not here to start a war over what type of appliances people should have, but I will say that's a hell of a lot of money and way out of reach of low income earners. I hear a lot of good things about diesel heaters. They're quiet, efficient and cheap to run, but at over $1,000 a pop plus installation costs, that's a lot of money just to heat a small space. As previously mentioned a gas oven or stove in a caravan can provide a fair bit of heat, but admittedly it's quite inefficient given that you have virtually no control over the flow of warm air. If you have around $250 to spare, you can turn a very low burning gas stove hob into a very efficient directional heater. The Canadian made Caframo Belair is a stove top fan that uses conduction to not only to provide heat, but also to generate electricity to drive a small fan that blows that heat in whichever direction you wish. It works very efficiently with a small flame. The smaller the flame, the smaller the amount of carbon dioxide that's produced as a result. some ventilation is obviously required, but personally I wouldn't run a diesel heater without ventilation in such a small space either.
The stove top heater probably isn't as convenient as a diesel heater. Despite being small, it still needs to be stored away for travel. At around $800 to $1,200 less than a diesel heater after installation, it's most likely worth the slight inconvenience for those who don't have money to burn - excuse the pun. If you're not off grid and have a source of 240v electricity, there are a number of very compact and cost effective options for heating. Caframo's True North is designed for the marine market and is therefore extremely rugged. It has 600 and 900 Watt settings, which means that it can run off a small generator if so desired. They cost around $200.
With a somewhat higher price tag at around $330, Nobo's 750 Watt wall mounted electric convection heater is also an excellent option for caravans and RVs. At only 630mm wide by 400mm high and 55mm deep, it should fit on a wall somewhere. They're highly efficient and can be run by a 1 KVA generator. Given that you can pick up a fairly decent 1 KVA generator for under $300, for between $550 and $750, you can heat your caravan / RV and get yourself a small generator that'll be extremely useful for general off grid living.
For $250, you have the convection fan option and for the cost of a bit of gas, you can just use you're oven or stove and some blankets.
Whichever option you take, I don't really think diesel heaters are for the low income earner, or anyone who cares about how much they spend. It's another one of those things that "you have to have." I've seen a number of forums and Facebook posts where people have asked about low cost heating solutions. Oh look, here comes 60 plus bearded Akubra wearing man. "You have to have a diesel heater. I have a diesel heater. You can't camp here without one. It's Un-Australian!"
I'm not hanging shit on diesel heaters, they do the job extremely well, but do the sums. Is it really worth over $1,000 to heat spaces that on average are around 140 sq ft? That's a hell of a lot of money. I'll be so bold as to say it's a bloody extravagance. When someone is asking for advice on a low cost heating solution, I couldn't think of worse advice than a diesel heater. It might sound like i'm on an anti-diesel heater crusade, but that's not the case. I'm on a crusade against online forums that are dominated by advice from people who don't have to survive on a low income. Sure they're entitled to give whatever advice they like, but it's relentless. I often witness people expressing despair because they think they'll never be able to afford to live on the road. Every time they ask for advice about anything, they're told that they'll need to spend immense amounts of cash and that anything else 'just won't do.' It infuriates me, because it's such bullshit.
Air conditioning can be an even bigger expense than heating, but doesn't necessarily need to be an exorbitant cost. Getting warm is considerably easier than staying cool, therefore mechanics are somewhat more vital. Whilst air conditioning most definitely isn't essential, it can prevent significant discomfort in the hotter months and in the hotter regions of Australia. I suppose air conditioning could be regarded as a luxury, but sometimes when I come back from a long, hot fishing trip, it feels quite essential. A cool caravan is indeed very welcoming. We also enjoy good food and often entertain. We make the most of our kitchen setup, including the oven. A lot of people are happy to limit themselves to cooking outside on a gas grill, but we're not. The caravan is our home and we wish to enjoy it's full benefits. Air conditioning is absolutely essential if you want to run an oven inside, during warm weather.
Roof top air conditioners are a pretty standard appliance on caravans these days. There are under bench type air conditioners that vent out of the side of caravans, but they are significantly less popular than the roof top types, which take up less space inside the van. Whether dedicated caravan air conditioners are the roof top or under bench type, they are exceedingly expensive. Considerably more expensive than comparable domestic split systems that are commonly found in houses. Roof top units cost on average around $2,000. Their installation is a major exercise and one can expect to pay a minimum of $1,000. An average area of 140 sq ft. $3,000 is an obscene amount of money to cool such a small space.
Unlike diesel heaters, online forums aren't quite as full of over enthusiastic roof top air conditioner owners. In fact most owners seem to complain about them. People usually acquire them when they purchase their caravans. There doesn't seem to be a huge market for fitting new roof top systems to caravans that don't already have them. Most everyone I've spoken to who does own one, seems to have had problems with their unit, often costing them big money in repairs, only to be left disappointed with the results. They're often noisy, they under perform in extreme temperatures, they're notoriously inefficient and they add a large amount of weight (up to 50kg) at the highest point of a caravan or RV. That's not great for stability. When it comes to free camping, most roof top units require a 3 KVA generator run them off grid. Three KVA generators are big, heavy and obviously noisier than 1 KVA generators. A smaller generator, such as a 1 KVA is sufficient for most needs such as charging and running lights, a television, computers, mobile phones etc. A 3 KVA generator seems like a considerable expense, weight and size consideration just for running an air conditioner that isn't that great anyway.
Generators are a big issue. they seem to be a little like air conditioners; everyone has one, but nobody's game to use one. I rarely witness roof top units running in caravan parks on power and am yet to see anyone running one in a free camp from a generator. It doesn't matter how ridiculously hot it is and how likely you are to expire as a result, you'll be the devil incarnate if you actually dare to run your generator.
Domestic split systems are often installed as an alternative to rooftop systems, but they have their issues too. Whilst Split systems can be considerably cheaper than rooftop units, they aren't designed for installation in caravans and RVs, thus they're far from ideal. The compressor units are big and heavy. They can be installed either on a reinforced extension from the chassis at the rear of an RV or caravan, or on the draw bar at the front of a caravan. I don't recommend either. Rear weight distribution in caravans is detrimental to stability. Too much weight at the rear will result in fish tailing. Whilst weight distribution that favours the front results in a more stable caravan, you run the risk of increasing the tow ball weight beyond what's acceptable, which can have a detrimental effect on the tow vehicle's front wheel traction. I've also seen examples of draw bars actually buckling under the weight of split system compressor units.
So far it's not looking good for air conditioners, but every time there's a ridiculously hot day, I'm incredibly thankful that we took the least popular option; the old fashioned window rattler or wall unit. Our unit is far quieter, drastically more efficient, substantially lighter and much more capable of cooling in extreme conditions than any rooftop unit that I've had experience of. It cost us $300. It was a fully warrantied, "factory second," which meant the box was missing. It cost me less than $50 to install. It runs very well for 7 hours on one fuel fill, from our light and compact 1 KVA generator, which is so quiet that people can hardly hear it, so we never get complaints from generator Nazis. The other interesting point as far as free camps go; most grey Nomads are either off the road or way down south in the warmer months. The rest are in caravan parks so they can power their rooftop units from 240v. The net result is that the free camps, particularly in Queensland are virtually deserted. If we want to run our very small generator on an extremely hot night, we can hardly hear it inside and there's nobody around to complain. We haven't looked back.
The southern grey nomad migration in late August, amuses me somewhat. They rush like lemmings because they're inherently convinced that 'summer' is unbearable up here in Far North Queensland. It might get a bit soggy on occasions and I admit the occasional cyclone is problematic, but if heat is a problem for someone, they really don't need to be in temperate or sub-tropical Australia during Summer. South Australia for instance, is the hottest place on the planet during February. Victoria isn't far behind, with temperatures occasionally exceeding 45 C in Melbourne. By September FNQ is deserted, the short mid-year rains have stopped, there's generally an off shore breeze and temperatures rarely exceed 32. September to December at Mission beach is glorious. Just this last summer, I was visiting my family in southern NSW. There was a particular 10 day period when the maximum temperature was no lower than 38 C. It got up to 43 on a couple of occasions. I was looking at Mission Beach on the weather app; 30 and sunny. Those lucky bastards, I thought.
Our wall unit does one thing and it does it well; it cools. It's not a particularly powerful unit at between 800 - 900 Watts, but it's supremely efficient. Our van is 20' x 8' and it gets very cool in there with the air conditioner on, in full sun on a typical day in the tropics. Even in the extreme heat of southern NSW during the summer, we have managed to keep the caravan internal temperature to below 28 C, in full sun, in shade temperatures of up to 43 C. Most importantly the unit kept going. One of the main complaints I hear about rooftop units is that some simply shut down in extreme conditions. One of the huge benefits of our little rear mounted wall unit, is that I can erect temporary shade over it, if necessary. That's pretty tricky with a rooftop unit.
I suppose the $6.40 question is 'why do we see so many rooftop units on caravans?' I think it's simply a case that we see a lot of later model caravans and they tend to come with them installed by default. It's the easiest place for manufacturers to put them and when it comes down to it, if they don't work so well, the warranty is covered by the air conditioner manufacturer / supplier, not the caravan manufacturer. It's fair to assume that most people who survive on the road on low incomes, don't have flash new caravans, so much consideration should be given to a wall unit.
Our Kelvinator ???? is a fairly light unit at under 30kg. We intentionally limit the weight in the rear of the caravan, so there was enough leeway to handle it. Originally the caravan had a large back window, which was actually the only area with a serious leak issue. It wasn't a hard decision to rip it out, given the endless frustration caused by it's leakiness. We were considering a new window anyway, which would have cost more than our air conditioner. Upon removing the back window and the surrounding timber, we found a significant amount of rot, so we were glad that we started the job when we did.
Once the back end was ripped out I built what is essentially a stud wall on top of the existing window sill, which is a very strong structural point that can take considerable weight. I left apertures the size of the air conditioner and one big enough to take a small window in the future. The stud wall takes the bulk of the unit's weight, with 2 very compact brackets supporting it from the sill on the outside. We left the window frame in place and filled it with the sheet of aluminium that was in the shutter that formerly covered the window. It might not look a million bucks and I doubt it would be up to the aesthetic standards of the "Mr and Mrs Bucket" type caravaners, of whom there are many, but it serves us extremely well.
I see some dreadful Jerry built meas of supporting wall units, particularly on older vans. It's not uncommon to see frames welded to chassis with long upright supports. I think this is due to a combination of older units being quite heavy and a tendency to sacrifice the weight balance of the unit in favour of getting the inside control panel as flush as possible with the wall through which it's mounted. Our unit protrudes some 20cm on the inside, but not only is it fairly unobtrusive, it's how the unit is meant to be installed in terms of balancing the weight in order that the bulk of the resulting downward force is on the wall as opposed to hanging out of the back of the caravan. With just 2 small brackets to hold it in place, I can literally hang off the unit without even the slightest chance of anything giving way and I'm a very big bloke. So far the unit has travelled some 30,000 kms without shifting a millimetre.
On of the most significant issues facing air conditioning in caravans, is that people expect magic defiant of the laws of physics. There's only so much an air conditioner can do as far as an aluminium box in the Australian sun is concerned. Even some of the most modern and expensive caravans and RVs are insufficiently insulated. Getting behind roof and wall skins to improve insulation is a very major, very costly task, but there is much that can be done to make a caravan or RV solar passive. Shade over windows is a good start. It's cheap and easy to run some sail track along the roof line, on the opposite side to the awning. You can run a piece of shade cloth along that and peg it down in the ground in order to keep the sun off the windows. That's simple. The roof is a less surmountable problem, but tackling it can virtually make the difference between being in the shade or full sun, no matter where you are parked.
There are all sorts of expensive caravan roof membranes designed to waterproof joints and reflect heat. They're very expensive and they're very good at sealing joints. As far as the reflection of heat is concerned, any good gloss white enamel spray paint will do just as good a job. Up-market membranes cost between $500 and $800 to cover the average caravan roof. A tube of butyl rubber for the joints and a few cans of gloss enamel spray paint, is only going to set you back around fifty bucks. There are also other far more effective steps that you can take. About a third of our roof space is covered with solar panels. They each have a 20mm air gap between them and the roof. The heat that they absorb is converted into energy, so they actually work quite effectively to provide shade. Solar panels are also expensive and heavy. Whilst I'd like to cover the entire roof, there is a downside to that. That's why I have come up with solar passive panels, which are extremely light and very, very cheap to make.
My solar passive panels consist simply of a layer of foil backed, air pocketed insulation, sandwiched in between two layers of corflute plastic sheet. Simply cut the corflute and insulation to squares of equal dimensions and sandwich them together using contact adhesive, then fill the edges with a 2 part epoxy builder's bog, to prevent fraying in the wind. Stick them to the roof with at least five points of super strong construction adhesive, such as Sikaflex. If you wish, you can stick a piece of plastic angle along the front edge and stick that to the roof. That will create greater wind resistance and lessen the chances of them coming off. The difference the panels can make is substantial. It means being able to park in full sun for the benefit of solar power generation and enjoy the comfort of partial shade.
Other very important factors affecting the efficiency of air conditioners in caravans and RVs is internal airflow and ensuring that there are no points of radiation in the roof. By points of radiation, I refer to weak points in the roof insulation. Hatches can be notoriously problematic in this regard, particularly in older caravans from an era when hatch construction involved the use of a significant amount of aluminium.
In our 1975 Frankilin Arrow, we soon discovered that the standard Four Seasons roof hatches literally worked like radiating heaters on hot days. The square roof in the centre of the hatches consisted of 2 very thin sheets of aluminium with nothing but a sheet of cardboard in between them. The aluminium angle at the base of the hatch was totally un-insulated, the same went for the thin aluminium hatch flaps. The flaps were not such a problem if the hatches were open as they provided some shade and there was air between them an the fly screens. However, when running an air conditioner, they had to be shut, which meant that the hatch openings were covered by nothing but a thin sheet of aluminium in direct sunlight. on hot days, most of each hatch was actually too hot to touch, they worked literally like convection heaters, especially when closed with the air conditioner running. It was like running an air conditioner and 2 heaters simultaneously.
The solution was very simple, reasonably cheap and extremely effective. The first job was to insulate the roof of the hatch. I cut a sheet of foil backed, air pocketed insulation to size then covered that with a sheet of 5mm plywood, mounted on four timber spigots, using construction adhesive. The reduction in internal heat convection was immediate and significant, despite the fact that hot air rises. I then removed the the fly screens, which were an absolute pain. Not only did they block light through the openings, but also gathered a massive quantity of dust, which exacerbated the light problem. I cut some pieces of good quality perspex to fit the openings and fitted them permanently with contact adhesive and putty. They now work as skylights, letting in more that 50% more light than the fly screens. Best of all, the hatch covers can remain open whilst the air conditioner is operating. Light still gets in and the perspex windows are shaded by the open hatch covers. I covered the aluminium angle on the base of the hatches with insulation from the outside. The hatches are now as cool to touch as the rest of the ceiling, which is well insulated. The air conditioner is significantly more efficient.
Even with such huge improvements, even more was possible by tackling air flow. Whilst hot air rises, it still needs to escape. That issue was tackled very easily by fitting small extractors into the roof of the hatches. I used solar powered units that have their own solar panel fitted on top. If going down this path, be sure to install the "night and day" models. These utilise a lithium battery that is charged by the mini solar panel and thus they can operate when not in full sun. They cost around $120 each. They extract a surprisingly high volume of warm air and are absolutely silent. They're also extremely effective in keeping a caravan cool whilst under tow. Since fitting the extractors, we have noticed how much cooler it is inside the van when we make roadside stops. The extractors are another marine product. We have found that products sourced from the world of yachting are not only cheaper, but more robust and effective than products designed specifically for caravans and RVs.
Our airflow was further improved by the installation of wall mounted cabin fans. They can also assist with the efficiency of the air conditioner. Being mounted at the rear of the caravan the air conditioner outlet provides a flow of air through the rear sleeping cabin, through to the front. The laws of physics determine that as air is blown further from the unit, it gets warmer, expands and rises. We use the bedroom fan to combat some of this effect. We simply run the fan across the flow of air at 90 degrees, angled upwards at about 35 degrees. This functions as an air curtain, keeping the flow of air from the air conditioner cool and preventing it from expanding and rising before it reaches the main cabin / kitchen area. It works very well indeed.
On the subject of fans, since installing wall mounted cabin fans, we have used the air conditioner more than 70% less than we previously did. This is where I turn into the 60 Plus Bearded Akubra Wearing man! "Don't buy anything other than Caframo fans. I've got Caframo fans. You can't camp here without Caframo fans. It's un-Australian!" Fuck it! If you can't beat 'em, join 'em.
I have to say, I haven't found a product that comes near to the Caframo fans. They are freakishly good. Their super lightweight blade design, not only makes them extremely efficient in terms of power, but also makes the absolute most of wind chill factor, generating a flow of cool air that generally negates the need for air conditioning except for in the most extreme conditions. What's particularly great about them is that they draw only 0.5 amps and can be run from even the smallest 12v house battery setup.
Carframo fans were originally designed for marine use and are used in yachts the world over. They're a very high quality product, fully manufactured in Canada, right down to the super efficient motors. As far as electric fans go, they're not particularly cheap, probably double the price of a cheap Chinese wall mounted fan, but 5 times more efficient, substantially quieter and significantly smaller. Where I do disagree with a lot of caravan and RV owners, is on the model. There are several models. The most popular by far is the Sirocco, which is also by far the most expensive, clocking in at around $180. When I researched the range extensively, I set out to buy the best model, regardless of price. I ended up buying the Ultimate, which clocks in at only $80.
OK, so here's the run down. The Ultimate is more powerful than the Sirocco, but the high setting is a bit noisier than the Sirocco's highest setting. We generally use the ultimate on the lower setting, which is very quiet. We don't use it on the low setting because it's quiet, but because it's usually powerful enough when it's very hot, we use the high setting, but the noise doesn't bother us. The Sirocco has 3 speed settings, the ultimate has 2 - big deal. The Sirocco features a timer. I'm still attempting to work out what the benefits of that feature are. The Sirocco fan is mounted on a "gimball," which means it sits inside a moving ring and can be rotated in any direction. Seeing as you can buy 2 Ultimate fans for a fair bit less than 1 Sirocco (there are pair deals), that doesn't sell me on it. Finally the Sirocco has a protective cage around the blade, whereas the Ultimate doesn't. Given that the ultimate's blade weighs little more than a similarly sized piece of card board and the motor is clutched, the open blade is not a problem. If you are stupid enough to walk into it, something I do frequently, it doesn't hurt at all, but causes you to yell "oh fuck!" and give everyone else a bloody good laugh.
Obviously from my perspective, given my penchant for tropical climes, cooling is a much bigger deal than heating. Cooling also presents greater mechanical challenges. However, as I have outlined, the mechanics of cooling can take various forms, however none of them are as efficient as they can be without first addressing the issues of shade and insulation. Not all caravans, particularly the more modern ones, have good front to rear airflow, which can work wonders in even the slightest breeze. for anyone who's attempting any kind of temperature control in an RV or caravan, it's important to establish where it's weak points are, our hatches being a classic example. If you can reduce the ambient temperature of your van or RVs interior prior to using appliances, the efficiency of the appliances that you use, will be that much better.
With a somewhat higher price tag at around $330, Nobo's 750 Watt wall mounted electric convection heater is also an excellent option for caravans and RVs. At only 630mm wide by 400mm high and 55mm deep, it should fit on a wall somewhere. They're highly efficient and can be run by a 1 KVA generator. Given that you can pick up a fairly decent 1 KVA generator for under $300, for between $550 and $750, you can heat your caravan / RV and get yourself a small generator that'll be extremely useful for general off grid living.
For $250, you have the convection fan option and for the cost of a bit of gas, you can just use you're oven or stove and some blankets.
Whichever option you take, I don't really think diesel heaters are for the low income earner, or anyone who cares about how much they spend. It's another one of those things that "you have to have." I've seen a number of forums and Facebook posts where people have asked about low cost heating solutions. Oh look, here comes 60 plus bearded Akubra wearing man. "You have to have a diesel heater. I have a diesel heater. You can't camp here without one. It's Un-Australian!"
I'm not hanging shit on diesel heaters, they do the job extremely well, but do the sums. Is it really worth over $1,000 to heat spaces that on average are around 140 sq ft? That's a hell of a lot of money. I'll be so bold as to say it's a bloody extravagance. When someone is asking for advice on a low cost heating solution, I couldn't think of worse advice than a diesel heater. It might sound like i'm on an anti-diesel heater crusade, but that's not the case. I'm on a crusade against online forums that are dominated by advice from people who don't have to survive on a low income. Sure they're entitled to give whatever advice they like, but it's relentless. I often witness people expressing despair because they think they'll never be able to afford to live on the road. Every time they ask for advice about anything, they're told that they'll need to spend immense amounts of cash and that anything else 'just won't do.' It infuriates me, because it's such bullshit.
Air conditioning can be an even bigger expense than heating, but doesn't necessarily need to be an exorbitant cost. Getting warm is considerably easier than staying cool, therefore mechanics are somewhat more vital. Whilst air conditioning most definitely isn't essential, it can prevent significant discomfort in the hotter months and in the hotter regions of Australia. I suppose air conditioning could be regarded as a luxury, but sometimes when I come back from a long, hot fishing trip, it feels quite essential. A cool caravan is indeed very welcoming. We also enjoy good food and often entertain. We make the most of our kitchen setup, including the oven. A lot of people are happy to limit themselves to cooking outside on a gas grill, but we're not. The caravan is our home and we wish to enjoy it's full benefits. Air conditioning is absolutely essential if you want to run an oven inside, during warm weather.
 |
| Small, efficient wall unit - back window replaced by a wall and porthole. |
Roof top air conditioners are a pretty standard appliance on caravans these days. There are under bench type air conditioners that vent out of the side of caravans, but they are significantly less popular than the roof top types, which take up less space inside the van. Whether dedicated caravan air conditioners are the roof top or under bench type, they are exceedingly expensive. Considerably more expensive than comparable domestic split systems that are commonly found in houses. Roof top units cost on average around $2,000. Their installation is a major exercise and one can expect to pay a minimum of $1,000. An average area of 140 sq ft. $3,000 is an obscene amount of money to cool such a small space.
Unlike diesel heaters, online forums aren't quite as full of over enthusiastic roof top air conditioner owners. In fact most owners seem to complain about them. People usually acquire them when they purchase their caravans. There doesn't seem to be a huge market for fitting new roof top systems to caravans that don't already have them. Most everyone I've spoken to who does own one, seems to have had problems with their unit, often costing them big money in repairs, only to be left disappointed with the results. They're often noisy, they under perform in extreme temperatures, they're notoriously inefficient and they add a large amount of weight (up to 50kg) at the highest point of a caravan or RV. That's not great for stability. When it comes to free camping, most roof top units require a 3 KVA generator run them off grid. Three KVA generators are big, heavy and obviously noisier than 1 KVA generators. A smaller generator, such as a 1 KVA is sufficient for most needs such as charging and running lights, a television, computers, mobile phones etc. A 3 KVA generator seems like a considerable expense, weight and size consideration just for running an air conditioner that isn't that great anyway.
Generators are a big issue. they seem to be a little like air conditioners; everyone has one, but nobody's game to use one. I rarely witness roof top units running in caravan parks on power and am yet to see anyone running one in a free camp from a generator. It doesn't matter how ridiculously hot it is and how likely you are to expire as a result, you'll be the devil incarnate if you actually dare to run your generator.
Domestic split systems are often installed as an alternative to rooftop systems, but they have their issues too. Whilst Split systems can be considerably cheaper than rooftop units, they aren't designed for installation in caravans and RVs, thus they're far from ideal. The compressor units are big and heavy. They can be installed either on a reinforced extension from the chassis at the rear of an RV or caravan, or on the draw bar at the front of a caravan. I don't recommend either. Rear weight distribution in caravans is detrimental to stability. Too much weight at the rear will result in fish tailing. Whilst weight distribution that favours the front results in a more stable caravan, you run the risk of increasing the tow ball weight beyond what's acceptable, which can have a detrimental effect on the tow vehicle's front wheel traction. I've also seen examples of draw bars actually buckling under the weight of split system compressor units.
So far it's not looking good for air conditioners, but every time there's a ridiculously hot day, I'm incredibly thankful that we took the least popular option; the old fashioned window rattler or wall unit. Our unit is far quieter, drastically more efficient, substantially lighter and much more capable of cooling in extreme conditions than any rooftop unit that I've had experience of. It cost us $300. It was a fully warrantied, "factory second," which meant the box was missing. It cost me less than $50 to install. It runs very well for 7 hours on one fuel fill, from our light and compact 1 KVA generator, which is so quiet that people can hardly hear it, so we never get complaints from generator Nazis. The other interesting point as far as free camps go; most grey Nomads are either off the road or way down south in the warmer months. The rest are in caravan parks so they can power their rooftop units from 240v. The net result is that the free camps, particularly in Queensland are virtually deserted. If we want to run our very small generator on an extremely hot night, we can hardly hear it inside and there's nobody around to complain. We haven't looked back.
The southern grey nomad migration in late August, amuses me somewhat. They rush like lemmings because they're inherently convinced that 'summer' is unbearable up here in Far North Queensland. It might get a bit soggy on occasions and I admit the occasional cyclone is problematic, but if heat is a problem for someone, they really don't need to be in temperate or sub-tropical Australia during Summer. South Australia for instance, is the hottest place on the planet during February. Victoria isn't far behind, with temperatures occasionally exceeding 45 C in Melbourne. By September FNQ is deserted, the short mid-year rains have stopped, there's generally an off shore breeze and temperatures rarely exceed 32. September to December at Mission beach is glorious. Just this last summer, I was visiting my family in southern NSW. There was a particular 10 day period when the maximum temperature was no lower than 38 C. It got up to 43 on a couple of occasions. I was looking at Mission Beach on the weather app; 30 and sunny. Those lucky bastards, I thought.
Our wall unit does one thing and it does it well; it cools. It's not a particularly powerful unit at between 800 - 900 Watts, but it's supremely efficient. Our van is 20' x 8' and it gets very cool in there with the air conditioner on, in full sun on a typical day in the tropics. Even in the extreme heat of southern NSW during the summer, we have managed to keep the caravan internal temperature to below 28 C, in full sun, in shade temperatures of up to 43 C. Most importantly the unit kept going. One of the main complaints I hear about rooftop units is that some simply shut down in extreme conditions. One of the huge benefits of our little rear mounted wall unit, is that I can erect temporary shade over it, if necessary. That's pretty tricky with a rooftop unit.
I suppose the $6.40 question is 'why do we see so many rooftop units on caravans?' I think it's simply a case that we see a lot of later model caravans and they tend to come with them installed by default. It's the easiest place for manufacturers to put them and when it comes down to it, if they don't work so well, the warranty is covered by the air conditioner manufacturer / supplier, not the caravan manufacturer. It's fair to assume that most people who survive on the road on low incomes, don't have flash new caravans, so much consideration should be given to a wall unit.
Our Kelvinator ???? is a fairly light unit at under 30kg. We intentionally limit the weight in the rear of the caravan, so there was enough leeway to handle it. Originally the caravan had a large back window, which was actually the only area with a serious leak issue. It wasn't a hard decision to rip it out, given the endless frustration caused by it's leakiness. We were considering a new window anyway, which would have cost more than our air conditioner. Upon removing the back window and the surrounding timber, we found a significant amount of rot, so we were glad that we started the job when we did.
 |
Stud wall supporting a wall unit air conditioner |
Once the back end was ripped out I built what is essentially a stud wall on top of the existing window sill, which is a very strong structural point that can take considerable weight. I left apertures the size of the air conditioner and one big enough to take a small window in the future. The stud wall takes the bulk of the unit's weight, with 2 very compact brackets supporting it from the sill on the outside. We left the window frame in place and filled it with the sheet of aluminium that was in the shutter that formerly covered the window. It might not look a million bucks and I doubt it would be up to the aesthetic standards of the "Mr and Mrs Bucket" type caravaners, of whom there are many, but it serves us extremely well.
I see some dreadful Jerry built meas of supporting wall units, particularly on older vans. It's not uncommon to see frames welded to chassis with long upright supports. I think this is due to a combination of older units being quite heavy and a tendency to sacrifice the weight balance of the unit in favour of getting the inside control panel as flush as possible with the wall through which it's mounted. Our unit protrudes some 20cm on the inside, but not only is it fairly unobtrusive, it's how the unit is meant to be installed in terms of balancing the weight in order that the bulk of the resulting downward force is on the wall as opposed to hanging out of the back of the caravan. With just 2 small brackets to hold it in place, I can literally hang off the unit without even the slightest chance of anything giving way and I'm a very big bloke. So far the unit has travelled some 30,000 kms without shifting a millimetre.
 |
| Rear mounted aircon - Rear window replaced, overhead gutter and flashing fitted to prevent leaks - Sorry it's not clean |
On of the most significant issues facing air conditioning in caravans, is that people expect magic defiant of the laws of physics. There's only so much an air conditioner can do as far as an aluminium box in the Australian sun is concerned. Even some of the most modern and expensive caravans and RVs are insufficiently insulated. Getting behind roof and wall skins to improve insulation is a very major, very costly task, but there is much that can be done to make a caravan or RV solar passive. Shade over windows is a good start. It's cheap and easy to run some sail track along the roof line, on the opposite side to the awning. You can run a piece of shade cloth along that and peg it down in the ground in order to keep the sun off the windows. That's simple. The roof is a less surmountable problem, but tackling it can virtually make the difference between being in the shade or full sun, no matter where you are parked.
There are all sorts of expensive caravan roof membranes designed to waterproof joints and reflect heat. They're very expensive and they're very good at sealing joints. As far as the reflection of heat is concerned, any good gloss white enamel spray paint will do just as good a job. Up-market membranes cost between $500 and $800 to cover the average caravan roof. A tube of butyl rubber for the joints and a few cans of gloss enamel spray paint, is only going to set you back around fifty bucks. There are also other far more effective steps that you can take. About a third of our roof space is covered with solar panels. They each have a 20mm air gap between them and the roof. The heat that they absorb is converted into energy, so they actually work quite effectively to provide shade. Solar panels are also expensive and heavy. Whilst I'd like to cover the entire roof, there is a downside to that. That's why I have come up with solar passive panels, which are extremely light and very, very cheap to make.
My solar passive panels consist simply of a layer of foil backed, air pocketed insulation, sandwiched in between two layers of corflute plastic sheet. Simply cut the corflute and insulation to squares of equal dimensions and sandwich them together using contact adhesive, then fill the edges with a 2 part epoxy builder's bog, to prevent fraying in the wind. Stick them to the roof with at least five points of super strong construction adhesive, such as Sikaflex. If you wish, you can stick a piece of plastic angle along the front edge and stick that to the roof. That will create greater wind resistance and lessen the chances of them coming off. The difference the panels can make is substantial. It means being able to park in full sun for the benefit of solar power generation and enjoy the comfort of partial shade.
Other very important factors affecting the efficiency of air conditioners in caravans and RVs is internal airflow and ensuring that there are no points of radiation in the roof. By points of radiation, I refer to weak points in the roof insulation. Hatches can be notoriously problematic in this regard, particularly in older caravans from an era when hatch construction involved the use of a significant amount of aluminium.
 |
| Re-modeled 4 Seasons hatch with skylights and solar extractor |
In our 1975 Frankilin Arrow, we soon discovered that the standard Four Seasons roof hatches literally worked like radiating heaters on hot days. The square roof in the centre of the hatches consisted of 2 very thin sheets of aluminium with nothing but a sheet of cardboard in between them. The aluminium angle at the base of the hatch was totally un-insulated, the same went for the thin aluminium hatch flaps. The flaps were not such a problem if the hatches were open as they provided some shade and there was air between them an the fly screens. However, when running an air conditioner, they had to be shut, which meant that the hatch openings were covered by nothing but a thin sheet of aluminium in direct sunlight. on hot days, most of each hatch was actually too hot to touch, they worked literally like convection heaters, especially when closed with the air conditioner running. It was like running an air conditioner and 2 heaters simultaneously.
The solution was very simple, reasonably cheap and extremely effective. The first job was to insulate the roof of the hatch. I cut a sheet of foil backed, air pocketed insulation to size then covered that with a sheet of 5mm plywood, mounted on four timber spigots, using construction adhesive. The reduction in internal heat convection was immediate and significant, despite the fact that hot air rises. I then removed the the fly screens, which were an absolute pain. Not only did they block light through the openings, but also gathered a massive quantity of dust, which exacerbated the light problem. I cut some pieces of good quality perspex to fit the openings and fitted them permanently with contact adhesive and putty. They now work as skylights, letting in more that 50% more light than the fly screens. Best of all, the hatch covers can remain open whilst the air conditioner is operating. Light still gets in and the perspex windows are shaded by the open hatch covers. I covered the aluminium angle on the base of the hatches with insulation from the outside. The hatches are now as cool to touch as the rest of the ceiling, which is well insulated. The air conditioner is significantly more efficient.
Even with such huge improvements, even more was possible by tackling air flow. Whilst hot air rises, it still needs to escape. That issue was tackled very easily by fitting small extractors into the roof of the hatches. I used solar powered units that have their own solar panel fitted on top. If going down this path, be sure to install the "night and day" models. These utilise a lithium battery that is charged by the mini solar panel and thus they can operate when not in full sun. They cost around $120 each. They extract a surprisingly high volume of warm air and are absolutely silent. They're also extremely effective in keeping a caravan cool whilst under tow. Since fitting the extractors, we have noticed how much cooler it is inside the van when we make roadside stops. The extractors are another marine product. We have found that products sourced from the world of yachting are not only cheaper, but more robust and effective than products designed specifically for caravans and RVs.
Our airflow was further improved by the installation of wall mounted cabin fans. They can also assist with the efficiency of the air conditioner. Being mounted at the rear of the caravan the air conditioner outlet provides a flow of air through the rear sleeping cabin, through to the front. The laws of physics determine that as air is blown further from the unit, it gets warmer, expands and rises. We use the bedroom fan to combat some of this effect. We simply run the fan across the flow of air at 90 degrees, angled upwards at about 35 degrees. This functions as an air curtain, keeping the flow of air from the air conditioner cool and preventing it from expanding and rising before it reaches the main cabin / kitchen area. It works very well indeed.
On the subject of fans, since installing wall mounted cabin fans, we have used the air conditioner more than 70% less than we previously did. This is where I turn into the 60 Plus Bearded Akubra Wearing man! "Don't buy anything other than Caframo fans. I've got Caframo fans. You can't camp here without Caframo fans. It's un-Australian!" Fuck it! If you can't beat 'em, join 'em.
I have to say, I haven't found a product that comes near to the Caframo fans. They are freakishly good. Their super lightweight blade design, not only makes them extremely efficient in terms of power, but also makes the absolute most of wind chill factor, generating a flow of cool air that generally negates the need for air conditioning except for in the most extreme conditions. What's particularly great about them is that they draw only 0.5 amps and can be run from even the smallest 12v house battery setup.
 |
| Caframo Ultimate cabin fan |
Carframo fans were originally designed for marine use and are used in yachts the world over. They're a very high quality product, fully manufactured in Canada, right down to the super efficient motors. As far as electric fans go, they're not particularly cheap, probably double the price of a cheap Chinese wall mounted fan, but 5 times more efficient, substantially quieter and significantly smaller. Where I do disagree with a lot of caravan and RV owners, is on the model. There are several models. The most popular by far is the Sirocco, which is also by far the most expensive, clocking in at around $180. When I researched the range extensively, I set out to buy the best model, regardless of price. I ended up buying the Ultimate, which clocks in at only $80.
OK, so here's the run down. The Ultimate is more powerful than the Sirocco, but the high setting is a bit noisier than the Sirocco's highest setting. We generally use the ultimate on the lower setting, which is very quiet. We don't use it on the low setting because it's quiet, but because it's usually powerful enough when it's very hot, we use the high setting, but the noise doesn't bother us. The Sirocco has 3 speed settings, the ultimate has 2 - big deal. The Sirocco features a timer. I'm still attempting to work out what the benefits of that feature are. The Sirocco fan is mounted on a "gimball," which means it sits inside a moving ring and can be rotated in any direction. Seeing as you can buy 2 Ultimate fans for a fair bit less than 1 Sirocco (there are pair deals), that doesn't sell me on it. Finally the Sirocco has a protective cage around the blade, whereas the Ultimate doesn't. Given that the ultimate's blade weighs little more than a similarly sized piece of card board and the motor is clutched, the open blade is not a problem. If you are stupid enough to walk into it, something I do frequently, it doesn't hurt at all, but causes you to yell "oh fuck!" and give everyone else a bloody good laugh.
Obviously from my perspective, given my penchant for tropical climes, cooling is a much bigger deal than heating. Cooling also presents greater mechanical challenges. However, as I have outlined, the mechanics of cooling can take various forms, however none of them are as efficient as they can be without first addressing the issues of shade and insulation. Not all caravans, particularly the more modern ones, have good front to rear airflow, which can work wonders in even the slightest breeze. for anyone who's attempting any kind of temperature control in an RV or caravan, it's important to establish where it's weak points are, our hatches being a classic example. If you can reduce the ambient temperature of your van or RVs interior prior to using appliances, the efficiency of the appliances that you use, will be that much better.
No comments:
Post a Comment