Does a truma need water for central blown heating? (1 Viewer)

Aug 16, 2014
73
43
Worcestershire
Funster No
32,844
MH
Auto-Trail GF70
Exp
since 1993
Hi, just wondering if I drain the water system if the blown heating will still work or does it need a tank of water to heat and then blow air passed???

Thanks in advance!
 
Feb 9, 2008
4,086
5,902
SW Scotland
Funster No
1,453
MH
LP Coachbuilt
Exp
Since 2008 after caravanning for 20 years
As above, just select the correct setting on the controls. First time I used this function I was a bit dubious but it works fine. We us it quite a bit when running on gas only, just flick the water heating on for the washing up.

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Feb 18, 2009
573
247
Guisborough North Yorkshi
Funster No
5,677
MH
Malibu T410
Exp
Since August 2008
As above, just select the correct setting on the controls. First time I used this function I was a bit dubious but it works fine. We us it quite a bit when running on gas only, just flick the water heating on for the washing up.
Am i missing something?
Asking if he drains down water ......................................
So putting water heater on = will not do the washing up
Tank and hot water tank will be empty?
I would Not put electric water heater on if no water water in system - Boil a kettle.
Heating will work fine as said above
Unless I am missing something obvious??
 
Feb 9, 2008
4,086
5,902
SW Scotland
Funster No
1,453
MH
LP Coachbuilt
Exp
Since 2008 after caravanning for 20 years
Oops, forgot to say that sometimes we do have water in the system but don't heat it. It does work fine with no water but nothing comes out the taps!
 
Feb 2, 2015
2,283
7,264
Shropshire, UK
Funster No
34,975
MH
A motorhome!
Exp
we are still learning
Am i missing something?
Asking if he drains down water ......................................
So putting water heater on = will not do the washing up
Tank and hot water tank will be empty?
I would Not put electric water heater on if no water water in system - Boil a kettle.
Heating will work fine as said above
Unless I am missing something obvious??
I thought you could not use the heating when winterised? As above..No water ...no heating

Kev

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Coolcats

LIFE MEMBER
Jan 24, 2019
5,892
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HymerCar Ayres Rock
Just editing to say (to be honest it seems sensible that it does as it is a boiler) however page 17 makes me wonder if it is mandatory?

  1. In heating mode the appliance automatically selects the re- quired operating level according to the temperature difference between the temperature set on the control panel and the cur- rent room temperature. If the boiler has been filled, the water is automatically heated as well. The water temperature de- pends on the selected operating mode and the heater output.

, so I am now left doubting the view it 'Must Be' filled with water.

But what ever its a good question and I could not find a clear answer.
 
Last edited:
Aug 6, 2013
11,941
16,527
Kendal, Cumbria
Funster No
27,352
MH
Le-Voyageur RX958 Pl
Exp
since 1999
It can be operated without water. from the manual:

"In heating mode the appliance automatically selects the required operating level according to the temperature difference between the temperature set on the control panel and the current room temperature. If the boiler has been filled, the water is automatically heated as well. The water temperature depends on the selected operating mode and the heater output."

And further in the manual:

"When the temperature at FrostControl is below approx. 7 °C, first switch on the heater to warm the installation compartment and FrostControl. After several minutes, when the temperature at FrostControl is above 7 °C, the safety/drain valve can be closed."

(My bold emphasis)
 

Coolcats

LIFE MEMBER
Jan 24, 2019
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Funster No
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HymerCar Ayres Rock
It can be operated without water. from the manual:

"In heating mode the appliance automatically selects the required operating level according to the temperature difference between the temperature set on the control panel and the current room temperature. If the boiler has been filled, the water is automatically heated as well. The water temperature depends on the selected operating mode and the heater output."

And further in the manual:

"When the temperature at FrostControl is below approx. 7 °C, first switch on the heater to warm the installation compartment and FrostControl. After several minutes, when the temperature at FrostControl is above 7 °C, the safety/drain valve can be closed."

(My bold emphasis)
Nice one although I think it could be written with a little more clarity.....but what a brilliant unit

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OP
OP
hadders
Aug 16, 2014
73
43
Worcestershire
Funster No
32,844
MH
Auto-Trail GF70
Exp
since 1993
Thanks for the responses, so are we saying no water it will still work for heating??? Still confused lol
 
Feb 18, 2009
573
247
Guisborough North Yorkshi
Funster No
5,677
MH
Malibu T410
Exp
Since August 2008
If it is a blown air heating system with also electric element- then we have had 2 of these systems - and unequivaically (big word that - is there such a word?) we have used them with no water in them - absolutely - definitely, but you only put the Electric Boiler part of heating on when the system is full of water and you are sure and ran it through - otherwise just blown air heating on.
It is possible that your system is different but I very much doubt it- You should be able to drain down for the winter and use your heating.
 

pappajohn

LIFE MEMBER
Aug 26, 2007
43,202
48,792
Dark side of the moon
Funster No
172
Exp
Since 2005
Follow the flow....
Red = combustion heat
Orange = warm air flow
Blue = water
Blue arrow = cold air inlet/flow

The combustion chamber and water jacket are separated by the warm air chamber.
So yes, it can be run without water as there's no direct contact between combustion chamber and water jacket, it relies on heat transfer via warm air chamber alone to heat water.

Screenshot_20191128_191034_com.android.chrome.jpg
 
Last edited:

BillandHelen

LIFE MEMBER
Nov 17, 2013
846
2,126
Edinburgh United Kingdom
Funster No
29,056
MH
Wildax Elara
Exp
since 2004
I asked this before and got great advice. For a Combi 4, make sure water is at zero/off on the control, you can then use the heating on gas or electric. All worked fine for me when my filter in the water system cracked over winter as I had forgotten to drain and remove it! Saved my bacon on a weekend trip, just used the site tap and a kettle for hot water!
Bill

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romany

Free Member
Jul 3, 2018
714
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Oxfordshire
Funster No
54,729
MH
Wildax aurura xl
Exp
since 2014 camping since1968
well I clarified this with a dealer after truma set me to them yes you can run blown air heating without and this is the important bit the water heating switched on but you need water in the tank or as I did you will get over heat errors I find after a lot of trial and errors that I can run blown air on electric 1 setting with fan set on full but will still get an occasional overheat message forget any other electric setting without water ( combi 4 )
 

Loveshack

Free Member
Feb 16, 2019
135
128
Funster No
58,570
I’ve drained my Combi for frost protection, and installer tells me ok to use space heating say at 5 deg on electric.
Better than sticking an oil rad inside.
 
6

63720

Deleted User
On most systems you can use the heating as long as the water heater is switched to Off. Otherwise, off hookup, how else can you raise the temperature in the van to a level when the auto drain valve can be closed allowing the tank to be filled.
 

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