Air Con

[timbo67]

Hi
Has anyone seen or got the "cool my camper" air con unit from www.coolmycamper.com,we were thinking of buying for our trip to Italy in August
We bought a free standing unit from B & Q last year it worked well but was heavy and took up valuable space in the caravan
Any info would be appreciated

Thanks

Tim

 

[ProfJohnL]

Hello Tim,

I haven't used one of these, but I have looked closely at AC in caravans for a manufacture in the past.

One of the persistent problems with most AC units in caravans, including your mobile unit is the fact that both the evaporator and the condenser coils share the same box, and thus the exterior air has to be ducted in and out. This always compromises performance and leads to an increase in the noise the unit produces inside the caravan.

The the "cool my camper" gets round those two issues by mounting each coil with its own fan in two separate boxes. This is good for the occupants, but it may cause an increased annoyance to other site users as there is one fan completely external to the caravan. How much annoyance I cannot say as the web site does not mention noise figures.

As to how effective it will be :-

In essence AC cools the volume of air inside the space. So in simple terms the power consumption of the AC unit should be divided by volume of air it is expected to cool.
This gives a figure of Watts per cubic Metre (W/m3) this will enable rough comparisons to be made with other systems you may be familiar with.

Many modern cars also have air conditioning. This is a compressor driven system with mechanical power being taken from the engine. There is also some electrical power needed to operate the cabin blower, and the external condenser coil fan. The power needed for these systems varies depending on the model of the car, and can range from 5 to 10 horse power, Typically close to about 7Hp or about 5kW (1hp = 746W =0.746kW)
a typical saloon car has an occupancy space of about 4 cubic metres, so the watts per cubic meter is about 5000/4 = 1250W/m3

The "cool my camper" also uses a compressor driven system with two fans for moving air, but in this case the whole appliance is electrically driven. It specification claims a consumption of 350W.
The volume of a 3.6m (12ft) caravan will be typically 13 cubic metres, so the watts per cubic meter is about 350/13 = 26.9W/m3 (obviously larger caravans will see even lower W/m3 results)
So comparing a small caravan to a typical saloon car you can see based on power consumption figure the "cool my camper" is 26.9/1250 = 0.02 or only 2% as powerful!

Now a minor miracal seems to have been performed beacuse they claim that the 350W actually becomes 700W of cooling! even allowing for their miraculous gain that only makes it 4%, still a long way off the cars system.

It is difficult to be absolutely fair as there are lots of unknowns and vairaibles, but the margin of difference is so large that it is fair to say that the performance of the "cool my camper" unit in cooling a caravan will be vastly inferior to that of an AC system in a car.

However, it is clearly unreasonable to expect the "cool my camper" to cool an entire caravan, but most people are actually find that having air movement over their face or exposed skin is quite refreshing. Consequently if the unit is used so it directs its cooled air onto your face you will certainly find it better than nothing, But you might find you get the same effect by simply using an oscillating fan to move the air around in the caravan.

If you decide to go ahead and buy a "cool my camper" unit make it absolutely clear to the seller what purpose your expect it to perform, what volume of caravan it is expected to work in and how much you expect it cool it down – actually write it down in detail and send it to them before you purchase. This make your requirement an expressed term of your order and contract with the seller. If the seller feels the unit cannot meet your requirements they will not supply it.

On the other hand if they do supply it, it means they guarantee it will do what you want. However if it doesn’t meet your expressed requirements, then they are in breech of contact for supply a product that is not fit for purpose, and they are legally obliged to either supply a unit that does perform to your specification or make a full refund including P&P.

 

[timbo67]

Hi Prof John L

Thank you for such a long and informative answer. I think all things considered we may well give this a miss!

Tim

 

[DianeLily]

Prof John L you are wrong on so many levels it makes my head hurt!

Why would you compare in-car Refrigerant Air Conditioning with something used in a leisure vehicle? I don't lounge, socialise or sleep in my car, that would be daft as my car is surrounded on four sides by glass and the car roof is not white and full of insulation?

Why would you justify your theory with assumed values and bunkum mathematics? The coefficient in a cooling system is found by dividing the refrigeration effect by the compressor work work and that the energy efficiency ratio is found by dividing the cooling capacity by the total input power. 350 watts of input power does not become 0.7kw cooling by a miracle - it's just fact using the formula given above and the laws of enthalpy. You must be confusing units of specific heat capacity with something else.

I am so disappointed that you did not call our office and tell us that you had reviewed air conditioning units for a caravan manufacturer as we would have happily delivered a unit to you and you could have undertaken real testing at your leisure rather sticking a thumb in the air and putting off heaven knows how many potential customers with your guesswork.

So does it work? Or is a fan just as good? We have lots of satisfied customers who think it works and they have used them in a caravan!

Lastly as John is no legal beagle I'd point out that anyone buying items online or on the telephone from Cool My Camper is protected by EU Distance Selling regulations that allows a customer to change their mind for ANY REASON and obtain a full refund within 7 days. But anyone who purchases a unit from us and quotes "Professor John's Wrong" will be given a one month period for them to try the unit out on their caravan to ensure they are perfectly happy and we'll increase the warranty from one year to 18 months with our pleasure.

Prof John please consider you comments in the future.

Hello Tim,

I haven't used one of these, but I have looked closely at AC in caravans for a manufacture in the past.

One of the persistent problems with most AC units in caravans, including your mobile unit is the fact that both the evaporator and the condenser coils share the same box, and thus the exterior air has to be ducted in and out. This always compromises performance and leads to an increase in the noise the unit produces inside the caravan.

The the "cool my camper" gets round those two issues by mounting each coil with its own fan in two separate boxes. This is good for the occupants, but it may cause an increased annoyance to other site users as there is one fan completely external to the caravan. How much annoyance I cannot say as the web site does not mention noise figures.

As to how effective it will be :-

In essence AC cools the volume of air inside the space. So in simple terms the power consumption of the AC unit should be divided by volume of air it is expected to cool.
This gives a figure of Watts per cubic Metre (W/m3) this will enable rough comparisons to be made with other systems you may be familiar with.

Many modern cars also have air conditioning. This is a compressor driven system with mechanical power being taken from the engine. There is also some electrical power needed to operate the cabin blower, and the external condenser coil fan. The power needed for these systems varies depending on the model of the car, and can range from 5 to 10 horse power, Typically close to about 7Hp or about 5kW (1hp = 746W =0.746kW)
a typical saloon car has an occupancy space of about 4 cubic metres, so the watts per cubic meter is about 5000/4 = 1250W/m3

The "cool my camper" also uses a compressor driven system with two fans for moving air, but in this case the whole appliance is electrically driven. It specification claims a consumption of 350W.
The volume of a 3.6m (12ft) caravan will be typically 13 cubic metres, so the watts per cubic meter is about 350/13 = 26.9W/m3 (obviously larger caravans will see even lower W/m3 results)
So comparing a small caravan to a typical saloon car you can see based on power consumption figure the "cool my camper" is 26.9/1250 = 0.02 or only 2% as powerful!

Now a minor miracal seems to have been performed beacuse they claim that the 350W actually becomes 700W of cooling! even allowing for their miraculous gain that only makes it 4%, still a long way off the cars system.

It is difficult to be absolutely fair as there are lots of unknowns and vairaibles, but the margin of difference is so large that it is fair to say that the performance of the "cool my camper" unit in cooling a caravan will be vastly inferior to that of an AC system in a car.

However, it is clearly unreasonable to expect the "cool my camper" to cool an entire caravan, but most people are actually find that having air movement over their face or exposed skin is quite refreshing. Consequently if the unit is used so it directs its cooled air onto your face you will certainly find it better than nothing, But you might find you get the same effect by simply using an oscillating fan to move the air around in the caravan.

If you decide to go ahead and buy a "cool my camper" unit make it absolutely clear to the seller what purpose your expect it to perform, what volume of caravan it is expected to work in and how much you expect it cool it down – actually write it down in detail and send it to them before you purchase. This make your requirement an expressed term of your order and contract with the seller. If the seller feels the unit cannot meet your requirements they will not supply it.

On the other hand if they do supply it, it means they guarantee it will do what you want. However if it doesn’t meet your expressed requirements, then they are in breech of contact for supply a product that is not fit for purpose, and they are legally obliged to either supply a unit that does perform to your specification or make a full refund including P&P.

 

[ProfJohnL]

I can assure DianeLily my comments are very seriously considered. and I stand by my 2011 comments regarding the relative effectiveness of small AC units.

I must make it clear that I have no commercial interests past or present with businesses that sell AC to the caravan market. (Edit added) - And I did not write I reviewed AC units for a caravan manufacturer)

It is only fair 'Cool My Camper' have an opportunity to put their position forward. And caravanners must welcome the chance to see more information about their products.

And it is in everyone's best interests when the goods supplied may not be used in anger until after the automatic right to return has expired, to ensure the consumer knows what they are buying and how to protect themselves when products do not meet expectations, which is why simply relying on the distance selling regulations is not enough, Setting out what a customer expects as part of the purchase contract (SoGA Fit for Purpose)is both their right and recommended.

 

[Dustydog]

Hi John

Do you know how loud these units are compared to our Omnivent?

I have a cheap fan driven cool box which works very well 24/7 and fairly quiet.
Are these ACs very noisy?
Does anyone know how much they cost?

 

[RogerL]

According to the Cool My Camper website http://www.coolmycamper.com :-
Price for the two sizes are £465 or £575, incl delivery
Under specifications, they give noise in dB but don't specify distance which I thought was crucial for noise measurement - nor do they state which of the two units the ratings apply to.

Noise:

The unit is not noisy and our customers confirm that it is a lot quieter than any roof mounted equipment.

Indoor unit:

Low speed RPM: 950, ≤ 42dB,

High speed RPM: 1,250, ≤ 45.8dB.

Outdoor unit:

Low speed RPM: 600, ≤48dB.

High speed RPM: 900, ≤55

In layman's terms - it makes less noise than a dishwasher operating in the next room

 

[ProfJohnL]

Hello Dusty,

I do not know how loud the Cool my Camper or the Omnivent or any other AC unit is as I haven't measured them. What I can say is that I am often aware the noise of roof mounted AC units when they are switched on in neighboring caravans - that not to say I'm complaining only that I am aware of them. I haven't experienced the Cool My Camper models so I can't make any quantitative comment.

Roger is perfectly correct, quoting a number of deciBells (dB) has no meaning on its own. The measurement distance from the source is vital as the Sound Pressure Level (SPL) increases by a factor of 4 (6dB) for every halving of the distance.

In essence manufacturers who want to suggest their products are quiet will use a long measurement distance (Many generator manufactures use 6M) whereas manufacture who want their products to appear loud will use small distances (Loudspeaker manufacturers use 1M on axis for both volume and frequency response)

if you google "relative noise levels" you will find many articles that may help to demonstrate sound levels measurements values and distance.

See the list at the bottom of the web page at
http://en.wikipedia.org/wiki/Sound_pressure

or in a slightly simpler form

http://www.weset.org/uploads/worksheets/Noise Volume - relative levels.pdf
I could go on and get involved with equal volume and A & C weighting curves, noise perception from point and line sources, transient/impact vs constant level, frequency band limited, RMS peak, noise vs signal etc .

 

[Gafferbill]

........like a lot of potentially desirable caravan equipment a major concern is the weight as the OP points out.
On any outfit there is a finite limit......my observations of fellow caravaners would suggest most are at that weight without Air con!
Air con in the UK?......yea right

My cunning plan is to get in the swimming pool

 

[RogerL]

Air con in the UK?......yea right

Yet the vast majority of new cars sold in the UK get aircon.
Have you noticed that some Brits actually take their caravans abroad in summer ?

 

[Dustydog]

Thanks John

I can't stand the constant monotone buzzing so armed with your info I too will give it a miss.

 

[ProfJohnL]

I'm not saying don't buy an AC unit but I hope I've provided food for thought so potential customer can make a better infomed desision, and to take steps to get their money back if the product fails to meet contractural expectations.

Incidentally I encourage every one who deceideds they want to have AC to consider the CMC unit, and advantagous extension to the distance selling regulations and warranty I have some how manged to create, But don't forget to set out in writing exactly what you want the unit to do and make it a critical term in your contract to buy.

 

[Gafferbill]

Have you noticed that some Brits actually take their caravans abroad in summer ?

........well if they have done that and towed to somewhere hot and then need air con, I would suggest they need to make there mind up!
By the way it wasn't hot when I towed to the Arctic Circle in summer .... I was really glad I had not lugged air con all the way up there

Both my cars have air con which is rarely used in the UK.........really useful though when spending all day driving abroad on a hot day ........by definition trapped behind the wheel.
I would suggest no one is trapped in a hot sited caravan.

Of course air con is a personal choice.....but there is a weight penalty.

 

[JonnyG]

'I would suggest no one is trapped in a hot sited caravan.'
Gafferbill, that is nonsense, if one travels to the southern parts france or any southern part of Europe in the summer months its quite possble day temps in a caravan will hit 30 plus degrees C easily. and indeed one does not have to stay inside but with night time temps staying in the 20's outside could have an indoor temp in a caravan in the high 20s or more.. normal fans will do nothing to help bring down that heat. Frankly in a car 'trapped behind the wheel' opening the windown will do more to cool you down, then having to sleep in a caravan still burning in the high 20s. with no wind or daft to mention....

 

[Gafferbill]

'I would suggest no one is trapped in a hot sited caravan.'
Gafferbill, that is nonsense, if one travels to the southern parts france or any southern part of Europe in the summer months its quite possble day temps in a caravan will hit 30 plus degrees C easily.

.......I am sorry you find my point of view to be nonsense.

To simplify my point of view for you...... if you find by towing your caravan all the way to the southern parts of Europe in the summer months to be too hot for you.......then why go there at that time.
You are not trapped in a hot caravan because you have to be there.....you could have gone to a cooler destination.
If you get round your perceived problem by investing in air con you will use up valuable caravan payload if you intend to stay legal.

I tow to southern Spain every year....but in February.....their weather then is equivalent to a UK June and you do not need air con.

Everybody is of course free to make their own choices ......if you have air con fitted and want to go to southern Europe in the height of summer then that's great.

This is a public forum and there is room for all points of view even nonsensical ones!

 

[Brum1]

Have a look at this link to a similar question asked on the Pracital Motorhome forum

http://www.practicalmotorhome.com/forum/tech/air-conditioning-living-area-advice-sought

 

[Georg1o]

We have the same in the trailer and to tell the truth when traveling this thing is irreplaceable but the only problem that it often breaks down and account for often turn in aircon service company for mending or recharging freon and that's the problem with all portable air conditioners and without it in travel especially in the summer it is simply impossible. Will, have to put up with it

 

[JezzerB]

Personally I use the aircon in the car a heck of a lot given how hot this summer was we would have used it in our van too-our dog esp gets very hot very easily. It'll come to vans as it has to cars as a matter of time I think as things get lighter and more efficient but not for us at the mo!

 

[ProfJohnL]

Personally I use the aircon in the car a heck of a lot given how hot this summer was we would have used it in our van too-our dog esp gets very hot very easily. It'll come to vans as it has to cars as a matter of time I think as things get lighter and more efficient but not for us at the mo!

It has already arrived for caravans, and has been available for over twenty years, but it has not taken off for a number of reasons. Cost is one, weight is another. Some units are designed to be fitted to teh roof, but the roof needs to be strong enough to take theh weight and the extra loads when travelling.

Another often misunderstood problem, is the amount of power they need to operate. In a car AC units can often absorbe 10 to 20HP of engine power , but the electrical power available for a caravan on site will be no more than about 3.6kW or about 5HP. you will never achieve the same ferocity of cooling in a caravan as you experience in a car because the power is so much less, and the caravans volume is so many times bigger than the cabin of a car.

They can make a localised area of a caravan more tolerable, but as soon as someone opens a door or window, the benefit is vastly reduced.

I see AC in caravanas as an very expensive luxury of limited benefit.

 

[JezzerB]

Yes am aware it is available-was an option on ours but we didn't spec it for your very reasons-weight,power consumption and of course price-quite expensive we felt! By come to I meant in terms of weight power and price reducing-when I was a lad, a heated rear window was an option on a car I got really excited about-how things have changed-even basic cars now come with aircon.

 

[ProfJohnL]

Until there's a radical new way of cooling air, AC will always have a significant weight and size penalty for caravans. I worked for a company who was looking at AC, and apart from the constitution of the refrigerant fluid, there was no hint of any radical developments to change the way AC could be achieved on a practical level.

So the points I made are very likely to remain the main stumbling block to widespread touring caravan usage.

 

[otherclive]

By its very nature aircon will be used when its hot. The user will have their windows closed in order to aid its effectiveness. Neighbours without aircon will most likely have their windows open to help cool their caravans. Whlist the user might not find the aircon noise intrusive, those with windows open may find it disturbing. I have been on some sites in Europe when there was a "switch off" time for aircon units.

It can sometimes be difficult to estimate if you are causing nuisance to an adjoining neighbour(s), but once i got a complaint when in southern France my very small fan (computer fan sized) kept cutting in on its thermostat. This fan was behind the fridge and used to aid cooling air flow in very hot weather. So not wishing to be hit with a divorce, or empty wine bottle I obeyed my wife's request to switch it off. Which meant going outside at night in jammies and removing the side vents to access it.

 

[ProfJohnL]

....So not wishing to be hit with a divorce, or empty wine bottle I obeyed my wife's request to switch it off. Which meant going outside at night in jammies and removing the side vents to access it.

:cheer: There is a solution... keep all the wine bottles full, so if an argument does arise you have to both drink the content before using the bottles as clubs!

 

[Perry525]

Because cold air drops, homes, offices factories, caravans have their air con units on high, but cars do not. Cars usually have theirs at waist height and the air is blown from vents in he dash board and at floor level.
Would it not be more logical to have caravan air con under the double bed, thereby having the weight low down, avoiding the need for a heavier roof and have it in the space where it is most needed.

 

[Hutch]

That doesn't get away from the fact the units are heavy, noisey and use a lot of power. A wet air humidifier uses a lot less power And is much lighter, and cools very well.