Heating a caravan

[ProfJohnL]

Over the years there have been several discussions about what is the best heating systems for a caravan, and it usually focuses on the differences between blown hot air and wet radiator systems. Both options have their strengths and weaknesses, and it's not my intention to reignite that particular debate.

I spent several years working for a company that had test facilities which had a large environmental chamber that was from time to time used to take a whole caravan and test the effectiveness of different heating systems. and one of the effects we noted was the perceived comfort in a caravan very much depended on the temperature range from floor to ceiling inside the caravan or motorhome.

Most of us know that hot air rises, and conversely cool air falls, so if relying on convection only heating was used the ceiling would heat up much faster than the floor level, and even after an extended period there could still be a significant floor to ceiling temperature difference. If an occupant was in the caravan, they would often report not feeling comfortable becasue their feet were cold and their head was hot.

By introducing some means of mechanically stirring the air, the temperature differentials can be reduced, which adds more warmth at foot level and reduces the temperature higher in the caravan, producing a far more comfortable temperature regime for occupants.

I have revisited this subject becasue I have found this video, which touches on the physiological perceptions of temperature comfort from 7minutes into the video

It not only reinforces the results we had all those years ago but It also raises the idea that different lighting to help make occupants feel warmer and use less fuel.

View: https://www.youtube.com/watch?v=5rVJDwBoBnM

 

[JohnW250]

Very interesting. So, does that indicate that a blown air system, with blowers at floor level, is likely to provide a better level of “comfort” than a wet system with radiators?

 

[Raywood]

Personally I think so, certainly with smaller caravans. With larger ones though the caravans tend to have the heater at the front and with blown air it be a problem getting the back end heated, whereas a wet system tends to be better for getting an even temperature for the full length, so it may just be horses for courses.
Some blown air installations do have the piping under the floor which can result in the air being cooled and reduce the efficiency in cold weather.

 

[Hutch]

We have the Truma blown air on our Coachman and it is fairly long , no real problem heating the rear bathroom, our friends Unicorn same size and layout, is with the alde radiators and complained about the pump noise at time, but as we have found out now maybe the speed needed to be turned down.
Both vans nice and warm in the winter.

 

[Dustydog]

Our TA is blown air. Years ago we found the bedroom area and bathroom very cold. It turned out the air distribution lever was totally biased to the front. No complaints now. When cold we do start up on convection with both gas and 230v. Then switch to pure electric blown air

 

[ProfJohnL]

Very interesting. So, does that indicate that a blown air system, with blowers at floor level, is likely to provide a better level of “comfort” than a wet system with radiators?

As you will no doubt find there will be strong recommendations from owners of both wet and dry systems, but both types of systems have strengths and weaknesses some of which have already been mentioned. With both systems its important to ensure they have been set up correctly, but once the caravan is fully warmed, the differences between wet and dry heating diminish.

The biggest differences are how quickly each type of system warms the caravan. and the way it does it.

Blown hot air provides warmed air quicker than wet convector units.

 

[Jcloughie]

Blown hot air provides warmed air quicker than wet convector units.

I agree. Both systems do the job and do need to be understood to work to there best advantage. It must be remembered that heating a van is very different than heating a home. Vans have much less volume, permanent ventilation, poor insulation and almost no thermal capacity. Wet systems are definitively slower to get going simply because they need to heat the system and the structure before real convection can begin. Whereas. Blown air is near instantaneous. When in use, I find the wet system less prone to fluctuations.

With Alde. If we go away in very cold weather, I get the van initially warm with a fan heater while the Alde is warmed up with gas.

John