Truma 4e combi question

[Elfit]

Hi all. We have a truma 4e combi and all seems to be working fine. However I have a question about keeping a constant temperature. I can't seem to find an answer in the manual.
If I set the heater away at, say, 15 degrees all goes well. The heater fires up and we are warm. Once the thermostat registers that 15 degrees is reached the heater turns off. That's great. I was expecting it to fire up again once it detected a drop of a certain number of degrees. It doesn't.
Am I doing something wrong or does it not work like this?
Cheers, Tim

 

[quilkin]

That's interesting. I have the same boiler. The control is done by the CP plus box rather than in the boiler itself.
My heater works as expected, i.e. turns on and off automatically as the temperature falls and rises. But the water temp (if on 'economy') doesn't; once it's got warm the first time it doesn't come on again until I reset the controller (by turning it off).
Are you sure the sensor has indeed cooled down enough to make the system restart heating? Try putting something cold (from the fridge) up against it and see what happens.

 

[Elfit]

Thanks. Yes I'll pop some ice cubes on the sensor and see what happens.

 

[Harryw]

Depends on the system I suppose, there will be a hysteresis for on and off, on my PVC I have a Whale complete heat thingymyBob I recorded it at various settings to understand what illuminated bar equated to a temperature as they are not numbered. See attached picture which I took of it on the frost setting, you can see the off and on cycles, it heats to 5c then drops to about 3c before cutting back in again.…

 

[Elfit]

Are you sure the sensor has indeed cooled down enough to make the system restart heating? Try putting something cold (from the fridge) up against it and see what happens.

I have now had a chance to test and mess around. I've been getting van up to temperature then opening doors/ windows and putting ice on the sensor.
The heating does come back on!
I'm now wondering if I have put the sensor in a bad place. It's sort of tucked away in a corner and may not get the drop in temperature that can be felt elsewhere in the van ( e.g, by feet)
There was no guidance as to where it is best placed. Where is yours ? what is considered to be a good place to install it?

 

[molly 2]

On the controle panel in settings their is a temp offset settings it goes from 5 pos to 5 neg , it controls the temp sencer range , adjusting it controls temp sensor on off range .ie off 15 degrees back on 13 degrees experiment with setting until it suits you .

 

[colinm]

Our Truma 4 (non E) seems a bit slow to react to temperature changes sometimes, but your heater doesn't sound right. As for temperature sensor, like any thermostat it should be placed where it can best sense the general temperature.