new caravan ?

[robf1234]

hi i am thinking about another caravan i would like a one a bit longer 24 ft i have 21ft now ,,should i be looking for the wet heating ,,or stick to the hot air that i have now ,,thanks ,,

 

[WoodlandsCamper]

You're asking if people like Marmite.

I prefer blown warm air.

 

[ProfJohnL]

I think Woodlands sums it up quite well

I have used both systems in different circumstances, I have also done work on comparing systems, there are some differences which may or may not affect your decision.

In summary Both wet and dry systems are capable of creating adequate heat inside a caravan when they are installed to their best advantage

Water is great transporter of heat, and as such a wet system can deliver useful heat to teh extremities of a long caravan, However to make that heat usable, it requires an radiator in the best position. Sometimes caravan design does not allow a radiator to be placed in an ideal position. Also as the system only relies on convection to release the heat teh hot air rises quickly and pools at the top of teh caravan, taking a longtime to get back to floor level. This can lead to hot head cold feet syndrome. I should point out that some people do not mind this effect as much as others - so it may or may not be an issue for you.

By comparison Dry blown Air systems, use a forced fan which mixes the air in the caravan far more effectively reducing the hot head cold feet problem. Over long distances blown air systems are less effective as the duct add significant resistance to the air movement, but in a well set up system, there is still useful heat available at the extremities of medium sized vans, and the forced air mixing keeps the temperature differentials to a minimum. Unfortunately some caravan manufactures do not pay full attention to teh design of their blown air systems, and this can compromise the performance especially in longer vans.

Have I stirred up the mud enough? :huh:

 

[Martin24]

hi i am thinking about another caravan i would like a one a bit longer 24 ft i have 21ft now ,,should i be looking for the wet heating ,,or stick to the hot air that i have now ,,thanks ,,

Yes

 

[xtrailman]

Wet or dry they can both work well if installed correctly.
Wet may be the better choice for winter caravanning as it controls the temperature a little better, blown air can heat up quicker and may be the choice for summer given the option.

I've got wet at present and just ordered another with wet, standard for both so no choice really.

 

[ProfJohnL]

....
Wet may be the better choice for winter caravanning as it controls the temperature a little better,.....

Can you clarify that statement please?

 

[oldagetraveller1]

May sound like a daft question (I've no experience of wet systems), but can they be used 'off grid'?
I like to use minimal facility sites. My current (older) van has the old faithful gas fire which works well and I have no need of an EHU. I assume a wet system would use quite a bit of 12V power? And would I have to charge the water system each time I wanted heat??

 

[Mel]

A wet system can be heated just by gas, but they need electricity to work the pump to send the wet stuff around ( I think). Not sure how power hungry the pump is.
Mel

 

[oldagetraveller1]

Thanks, Mel.
I know nothing about electronics but I suspect that a pump running full time will quickly drain the battery.
On that score, it seems that a wet system is not really practical for 'off grid' camping.

 

[xtrailman]

Using gas also requires the fan to run, its around 1 amp for the boiler mounted pump, depending on what speed setting you're on.

 

[oldagetraveller1]

Thanks, Trailman.
To reduce it to terms I can understand, how long will my battery last if I am using the pump?
I have an 110 amp hour battery.
What do other 'off grid' caravanners do if they have a wet system but no EHU?

 

[xtrailman]

I don't know enough about battery technology to answer that accurately.

But a 110AH battery fully charged in new condition although it will not give 1 amp for 110 hours, i would expect say 40 hours at a guess assuming no solar panel is fitted.

You could conduct your own test by running the system until the battery approaches 12 volts.

Alde have advised in the past that the system will still run on pump speed one, which takes the least current, it also gives the longest pump life.

 

[WoodlandsCamper]

But a 110AH battery fully charged in new condition although it will not give 1 amp for 110 hours, i would expect say 40 hours at a guess assuming no solar panel is fitted.

Don't forget that other items will also be using 12v, not just the wet heating. eg water pump, toilet, lights, fridge control panel, heating control panel, etc.

 

[oldagetraveller1]

So, it seems to me that a wet system is something I should avoid if I want to continue to use basic facilities sites.
That is if the old , simple gas heater is still fitted to new vans!

 

[xtrailman]

Most new caravans with blown air appear to require a fan, replacing the old trusty convection heater with blown air as an option.

 

[ProfJohnL]

Hi
In the context of running off grid, then the the most sensible choice would be a Tuma style convector heater. These used to be totally independent of the 12V system, but I'm not so sure about that these days. If it has the blown air ducts fitted ( and most caravans would have them these days) it is optional if you want to run the fan or not.

Just be sure it's a convector style heater, becasue there are an increasing number of combined units with no convection option.

Just a point about battery life, no one can give you a specific answer, becasue it depends on what 12V appliances and lights you have running, and for how long.... there have been several quite extensive threads on the subject so a search should throw up lots of information. but to put the Truma fan into perspective, it will use about 1A when it's running, that is 12Watts. Many of the 12V filament and fluorescent bulbs used in caravans until recently would also pull about 1A each, so on balance its very similar to a light bulb. It surprises many to learn that probably the biggest user of 12v electrical power is lighting and TV's over the course of a holiday, and things like caravan movers are by comparison actually use quite small amounts of power.

 

[oldagetraveller1]

Thanks for all the useful information/advice.

 

[Dustydog]

The Trumatic S 3004 kicks out 3.5kw of convected heat on gas only. The S5004
manages a hefty 6kw on gas.
Most new caravans using a non wet system will have one of these heaters. They will invariably be fitted with a blower for the warm air blown option.you don't need to use the blower. Even in a large caravan leaving the toilet door open the convected heat will reach the extremities.
The add on is the Ultraheat bit which is an electric element.

 

[Gabsgrandad]

Does anyone fit them now?

 

[Dustydog]

I haven't seen a gas only one in 25 years :woohoo:

 

[Raywood]

As far as I know you cannot turn off the fan on our Truma system. The instructions say you can adjust it but I have never seen the point, but as the heater is hidden under a seat without something forcing the heat out I cannot see how it could work efficiently. I cannot think that any caravan now has the old wall mounted heaters so some use of electricity seems inevitable.

 

[ProfJohnL]

Hello Gabs, Dusty, and Ray

I didn't say the heater was gas only, what I said a "convector heater". The Truma S type heaters (which include the Ultrheat option) consist of A convection gas heater, a convection electric heater (if fitted) and the blown air fan on the back.

The truma web page
https://www.truma.com/uk/en/heating/overview-heating-systems.php

states
"Truma S heaters have always been legendary trend setters regarding reliability and comfort. Just turn it on and feel the warmth immediately - even without electricity"

You do not have to use the fan all the time, which means the heat produced by either the by the gas or the electric elements can simply convect out of the top of teh heater.

And Ray,
I am not familiar with the details of your particular heater but I suspect it's the type I referred to when I wrote "becasue there are an increasing number of combined units with no convection option." On checking the Truma web pages I guess you have one of the "combi" heaters which are fully enclosed and would require a constant electrical supply to run on either gas or mains heating power.

 

[Hutch]

When I have had my Truma Combie running in our Coachman, once its up to the set temperature, We never notice the fan running, I suppose it must, but maybe just at a tickover, I have gone for two days with a 110 amp battery, but running the fridge and heating on gas, with no problems, but normally go to EHUs as wife needs to dry her hair using the hair dryer, rather than Kneel infront of the oven.

 

[Raywood]

When I have had my Truma Combie running in our Coachman, once its up to the set temperature, We never notice the fan running, I suppose it must, but maybe just at a tickover, I have gone for two days with a 110 amp battery, but running the fridge and heating on gas, with no problems, but normally go to EHUs as wife needs to dry her hair using the hair dryer, rather than Kneel infront of the oven.

I agree the fan is usually only noticeable when you switch the heater on or turn the heat up. In practice I cannot see a fan uses very much power so it should not run down the battery but a solar panel should sort it if need be.

 

[ProfJohnL]

.............. I cannot see a fan uses very much power so it should not run down the battery but a solar panel should sort it if need be.

Ray Ray Ray,
what an illogical statement. hmy:

Anything that uses battery power at all will eventually run a battery down. :woohoo:

The Truma web site implies that at idle the heater will be using around 0.4A which granted isn't very much but its almost roughly the equivalent to a 5W side light bulb on continuously. Yes it is trivial, and a smallish solar 15W panel would probably cover the deficit over a day.