Hi everyone,

I was thinking the other day after reading some comments about caravan airconditioners, that I must be one of the lucky ones that got a unit that works and is not too noisy. You do see many topics where people are saying they don't work very well if at all.

Then while wandering around a few caravan parks we have been staying in on this trip north I noticed not one but many caravans with the aircon running and all the WINDOWS AND HATCHES OPEN as well as the door.

Now I do have the technical qualifications and experience that enable me to install and service refrigeration and airconditioning equipment so I have a bit of an idea how it all works.

If you want your caravan aircon to cool the inside of the van/mh/camper then you MUST close the windows/hatches/doors so the recirculating air can be cooled. There is no way a caravan aircon will cool the inside of an RV with the heat load it is getting from all those open apertures.

I do hope I have made myself quite clear on how this is supposed to work.

Any of the other members who are similarly qualified would like to reinforce my comments please feel free to join in. I am really not interested in adverse arguments because they are of no value here.

regards

Frank

I agree with you 100% Frank, I think there must be a lot of people around who think that an air-con works on the same principle as an evaporative system, which in fact is the exact opposite.

After years in the Caravan industry working as a Service Tech, I have heard many complaints about air-cons not working as they should, nine times out of ten, the reason is exactly what you described, the other 1% is because the air-con fitted to the caravan is so small, it just can't handle the volume of air inside the caravan and although it is working flat out the out-put is inadequate to be effective,

Many people make the mistake of buying a nice low profile air-con thinking it will be safer when going under trees etc, not thinking, will the air-con be big enough for the job, there are some very poor machines on the market, I would advise anyone to get good reliable advice before purchasing, and the first thing to do is work out the area to be cooled, then look for a machine that has the capacity to adequately do the job.

One last thing, make sure the filters in the system are regularly cleaned, a small amount of dust can have a large negative effect on it's operation.

K.J.      

As a current holder of a refrigeration/air conditioning contractors license you have opened a can of worms.

I agree with you that all windows, doors and vents should be closed to obtain max cooling and heating capacity.

See this section from the Dometic B3000 plus user manual:

1.4. How to use the air conditioner
The air conditioner performance can be improved by taking some simple measures.
Improve the thermal insulation of the vehicle by closing any opening and by covering any glassed surfaces with reflecting curtains.
Avoid opening doors and windows unnecessarily.
Select the most suitable temperature and speed.
Properly direct the air flaps.
To prevent troubles and minimise risks for people, take the following
precautions:
Do not obstruct the air inlets and outlets with cloths, paper or other
objects;
Do not introduce your hands or other objects into the openings;
Do not spray the air conditioner with water;
Keep inflammable substances away from the air conditioner.

But there are a number of issues I have with the selection of air conditioning product being installed in caravans and mobile homes.....I won't list all the issues but I would like to make some comment.

1. I agree in principle with rooftop air conditioners are noisy. I have a Dometic B3000 plus series installed in my caravan (the air conditioner was already installed prior to purchase) and from day one this unit was noisy (a) from the vibration of the compressor (b) the indoor fan above low speed fan. The cooling and heating performance was not up to my expectations and I complained to Dometic for 12 months before they agreed to remove the unit and replace it with an exchange unit. this was done however the unit was placed in storage for a couple of months and on removal of the caravan from storage the unit was switched on and the internal fan would not operate, so they had to change the indoor PCB. (total hours run 2hrs and distance van traveled 23K's).

2. I requested the capacity test conditions of the unit.......they could not supply the information

3. The Dometic specifications state the the B3000 plus has a capacity of 3.2Kw (I assume this is for both cooling and heating) and is suitable for a vehicle of internal space of 30 cubic meters with insulated walls. NO WHERE does it state what the indoor/outdoor design conditions were used to select this air conditioner for the vehicle volume.

4. I requested the information on the selection of this unit to this van...........answer was that is what they supply.

5. I asked for the design indoor and outdoor design conditions for the capacity selection of the unit for this caravan....they could not advised.

6. I asked for the expanded temperature/capacity data for selection of the unit ......they could not supplied.

7.  I asked for the indoor fan NC curves and indoor fan speed curves.....they could not supply.

8. Question if the air conditioner is a reverse cycle or element heat...do not accept the sales person comment that it cools and heats.

9. I have phoned Dometic service 2 weeks ago and left a message for a return call, as of today still no reply.

10. When did any caravan company ask the client what was their indoor DBC/WBC temperature expectation at what DBC outdoor temperature.

From what I understand most people do not run the air conditioner for a length of time when they pick up their van to test the operation it is only when you go on the trip you may run it over a couple of hours.

I would be interested if anyone can tell me under what indoor and outdoor operating conditions was their air conditioner selected for their caravan.

Await with interest.

The Dometic manual states:

1.7. Ordinary maintenance
Cleaning; periodically clean the air conditioner and remove dust with a dump cloth. When necessary, use a mild detergent. Do not use petrol or solvents.
Checks; regularly check the air conditioner and make sure that the water outlet holes are not clogged.
Filters cleaning (1): periodically carry out this operation; wash the filters with a detergent solution and allow to dry before refi tting.
Active carbon filter (2): Its recommended to change the active carbon filters every year.

There are no filters in the outdoor unit however an inspection of the outdoor coil should be done in my opinion every 12 months. the coil can get blocked with leaves, bugs and dust/dirt.

Frank, Do you know of a unit that would work in northwest cooling 30 cubic Metres and run off a 1KVA Honda genset?

G'day again everyone,

Migra, I understand where you are coming from, they are similar specs I was looking for but have yet to find any. A service agent may have something in the service manuals and may or may not give you a look. My opinion is the RV aircon industry is way behind everyone else in the HVAC business. The RV units you see today are little more than cut down window rattlers from 25 years ago.

haha thanks Bruce, I do agree some people may relate any cooling unit to be similar to an Evap cooler in operation or they may simply not care about power consumption.
Re the outdoor unit the only service item I can remember about these is to blow the dust out of the condensor and if the provision exists to lube the fan bearings.

TommyG, If I was doing a caravan build all over again I would be insisting on a domestic inverter split unit. They are about the only machine that will provide the cooling/heating you are looking for from a 1kVa genny. They are almost silent running too.

thanks for your insights and opinions

frank

Doug I knew you would be doing the right thing with your A/C

and you know as this is my topic I cannot be

Frank

I have been to the service agent for Dometic and yes he did give me a copy of the "service Manual" but what the caravan industry call a Service Manual is only the users manual with an electrical circuit diagram and exploded spare parts section. The technical page only give dimensions and weight it does not shown what refrigerant is used. I had to explain to the service agent that the noise complaint was not out of balance fans but the compressor.

I have spoken to the Service Manager of Dometic Queensland and raised the questions with him and he can't answer the questions, he also advised these are now being made in China...I requested them to supply me a copy of the service manual in Chinese but he was unable to supply me a Chinese version.

It is interesting that caravan air conditioners are also excluded from the MEPS process. (see AS/NZ 3823.2.2013 section 1.2 (f).

So what capacity at what temperatures are you getting from these appliances and at what outdoor temperatures.

If you have the space for a residential split system (inverter type) that's fine but a lot of vans fit these and the outdoor units hanging off the back...I understand that many manufacturers will not cover warranty...DO NOT rely on the sales person selling the air conditioner ALWAYS request a copy of the warranty card before any purchase....some sales people have short memories and selective hearing, also it's not a problem until you have a problem and you try to claim warranty.....REMEMBER if is not in writing it has not been said.

Tommy G

The question you have asked is the reason for my detailed comment.

they can tell you anything about what is suitable....in my case the unit supplied has a cooling/heating capacity of 3.2Kw.

With regards to what size genie.....find out the max starting current is of the air conditioner.

Bruce

Evap air conditioners are not rated with cooling capacity (Kw), they are selected based on temperature difference/air flow and number of air changes for the area to be conditioned.

When we fitted the Fujitsu split on the back of our van, we were well aware that Fujitsu would not cover it with warranty. But when you buy it for $500, and a roof top is over $3,000, I figure we can afford to loose a couple and still be ahead.

Plendo wrote:

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When we fitted the Fujitsu split on the back of our van, we were well aware that Fujitsu would not cover it with warranty. But when you buy it for $500, and a roof top is over $3,000, I figure we can afford to loose a couple and still be ahead.

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 Good point Plendo and nice and cool and quiet too.

frank

migra wrote:

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Tommy G

The question you have asked is the reason for my detailed comment.

they can tell you anything about what is suitable....in my case the unit supplied has a cooling/heating capacity of 3.2Kw.

With regards to what size genie.....find out the max starting current is of the air conditioner.

---

Thanks for that, I was hoping that someone with experience might know with the details I offered.

I am able to work out the Watts needed and Watts supplied by a 1KVA but do not have the knowledge of the units available, ex fitters may know that.  

Frank to TommyG, "If I was doing a caravan build all over again I would be insisting on a domestic inverter split unit. They are about the only machine that will provide the cooling/heating you are looking for from a 1kVa genny. They are almost silent running too."

Thanks for that. I have a motorhome with an inbuilt through the window type air con, professionally installed in one side, it fits over the top of the wardrobe and position and capabilities are just about perfect. although I think it's starting to need attention 10 years. It's Inclined to be a bit noisy but not too bad. Limited space means having to carry a 2 KVA Honda is difficult and of course the 1KVA won't run the air con. I will do some measuring up to see if I can put a split system in but it doesn't look good. I was just hoping someone may have had an easy answer. Dreaming, one might say.

Thanks. TommyG.   

tommyG

As previously stated my air conditioner fitted is a Dometic B3000 Plus and Dometic state it has a capacity of 3.2Kw with a power consumption on cooling of 1.2Kw and heating of 1.3Kw however they do not state the starting current...this unit is non inverter type.

The starting current is not stated however I use a Honda 2i pure sine wave genie to operate if no power is available.

so, if your van is say 6M (L) x 1.5M (W) x 1.7M (H) = 15M3, so Dometic say this capacity aircon is suitable for volume of 30M3.

TommyG, I do not know if this will help or not, but out Fujitsu Inverter Split system appears to take up to 900 watts initially, but quickly settles down to operate on a base of 300W surging to 600W occasionally. I have run it on my inverter for five hours after the

 sun has gone down.

On the surface it looks as if a 1kva could run it, but since the usage I am seeing is averaged, there may be some above average spike sin the early running which may bring it unstuck. Assumes of course that the 1kva, was a real 1kva, which most are not.