Truma Ultraheat Fire - Heater Element Replacement

[shelleyp]

Hello

I have stripped down the fire to replace the heater element. Does anyone know how I remove the wires from the connector connected to the PCB board please.

Many thanks
Shelley

 

[Beachball]

Welcome to the forum Shelley (Why dont you google Truma Ultraheat they have downloads for instalation and instructions ..

 

[Dustydog]

Does this diagram help you? The elements are very expensive , nearly £300. Hope you get the wiring correct. Having gone as far as you have may I suggest you also change the two TODs.

 

[Damian]

One question I have is how have you decided that the elements are at fault?
It is very unusual for them to fail (although they can do).
The usual suspects for the heater not working are the TOD's (one or both), or the PCB .

 

[shelleyp]

Thank you for your replies. I have managed to get the wires off. It was an auto electrician who my husband uses at his garage who has diagnosed it as been the possible fault!

 

[Damian]

Thank you for your replies. I have managed to get the wires off. It was an auto electrician who my husband uses at his garage who has diagnosed it as been the possible fault!

Thank you for that info.
I hope all goes well and that you cure the problem.

 

[shelleyp]

Thank you for that info.
I hope all goes well and that you cure the problem.

TODs is that the temperature sensors located at the front? Will replace them as well and hopefully fingers crossed that will fix the problem. If not it looks like it could be the PCB.
Many thanks

 

[Dustydog]

There are two. Known as Thermal Overload Devices. One cuts out at 175deg c, and does not reset. the other cuts out at 125 deg c but as it cools resets.
Apuljack sell them at good prices. See the diagram I posted , parts noted as 21 &22. It is unusual for both main elements to fail simultaneously. Did the garage chap check the continuity of both elements? Hope you get it working.

 

[shelleyp]

There are two. Known as Thermal Overload Devices. One cuts out at 175deg c, and does not reset. the other cuts out at 125 deg c but as it cools resets.
Apuljack sell them at good prices. See the diagram I posted , parts noted as 21 &22. It is unusual for both main elements to fail simultaneously. Did the garage chap check the continuity of both elements? Hope you get it working.

No he didn't! Could be £80 wasted for the part. For what the TODs cost will replace them as well. Could end up been cheaper buying a new fire lol.

Many thanks for your help.

 

[Dustydog]

Shelley,
I have to ask, before the Prof does, have you removed the entire fire from the caravan including the flue and gas connection? Both are safety critical connections one requiring a new seal on each disconnection. Incorrect fitting wi cause a potential gas explosion and or carbon monoxide entering the caravan!

 

[shelleyp]

Hi yes and new seal purchased already.

Thank you

 

[stuwoolland]

There are two. Known as Thermal Overload Devices. One cuts out at 175deg c, and does not reset. the other cuts out at 125 deg c but as it cools resets.
Apuljack sell them at good prices. See the diagram I posted , parts noted as 21 &22. It is unusual for both main elements to fail simultaneously. Did the garage chap check the continuity of both elements? Hope you get it working.

Hi. Sorry this is an old thread but joined the group. I have the same problem with no heat at any setting. I have power coming out the board so I'm guessing it will be the TOD,s. These are situated behind the gas section. How do you get to them or do you need to remove the gas section?
Thanks
Stu

 

[Dustydog]

Hi. Sorry this is an old thread but joined the group. I have the same problem with no heat at any setting. I have power coming out the board so I'm guessing it will be the TOD,s. These are situated behind the gas section. How do you get to them or do you need to remove the gas section?
Thanks
Stu

Depending on make and model you may be able to access the rear of the heater. Otherwise the while unit, section by section needs removing . It involves gas and flue joints and is not something to be attempted by an unqualified person. Note the flue gasket MUST be replaced with new.

 

[stuwoolland]

Depending on make and model you may be able to access the rear of the heater. Otherwise the while unit, section by section needs removing . It involves gas and flue joints and is not something to be attempted by an unqualified person. Note the flue gasket MUST be replaced with new.

Thanks for reply. I thought that might be the case. Think I will get them changed on the service to be on the safe side.

 

[trevormonty]

Before replacing elements measure their resistance NB they are just one big resistor that runs hot. I'm going guess resistance is 100s ohms. If open circuit >1Mohm then probably faulty. Just make sure there aren't any thermal fuses in circuit that your've overlooked, should be obvious once you've remove element.
Measure element again once it is out as other components in circuit can affect resistance reading.

 

[Dustydog]

Before replacing elements measure their resistance NB they are just one big resistor that runs hot. I'm going guess resistance is 100s ohms. If open circuit >1Mohm then probably faulty. Just make sure there aren't any thermal fuses in circuit that your've overlooked, should be obvious once you've remove element.
Measure element again once it is out as other components in circuit can affect resistance reading.

The TODs are the thermal overload fuses!

 

[trevormonty]

Before replacing elements measure their resistance NB they are just one big resistor that runs hot. I'm going guess resistance is 100s ohms. If open circuit >1Mohm then probably faulty. Just make sure there aren't any thermal fuses in circuit that your've overlooked, should be obvious once you've remove element.
Measure element again once it is out as other components in circuit can affect resistance reading.

The TODs are the thermal overload fuses!

These will be close to elements blow if temperature gets to high. Typically because heater outlet is blocked or fan has stopped in case if forced air heater.

 

[Dustydog]

These will be close to elements blow if temperature gets to high. Typically because heater outlet is blocked or fan has stopped in case if forced air heater.

The two TODs are different. One cuts out at 125deg C cools and resets. The other permanently cuts out at 175degs C. It does not reset

 

[gary]

The two TODs are different. One cuts out at 125deg C cools and resets. The other permanently cuts out at 175degs C. It does not reset

175deg stat does reset but its what's known as a 'self hold', when it trips it has an internal element that is connected that keeps it off until 240v is disconnected from heater, the stat itself can then cool down and resets automatically.

 

[Dustydog]

175deg stat does reset but its what's known as a 'self hold', when it trips it has an internal element that is connected that keeps it off until 240v is disconnected from heater, the stat itself can then cool down and resets automatically.

Didn’t know that Gary. Amazing what we get taught word of mouth! Thankyou👏👏

 

[gary]

The other point I should have made is the 175deg is actually a fail safe, so the need to operate means the 125deg didn't and therefore it's that one that's faulty.
Overall though neither should be required to operate but using gas and electric together without enough fan speed to disperse the extra heat effectively is common reason. So it's essential while using gas with electric, that fan control is set at 'A' (auto) with maximum speed set on dial.

 

[ProfJohnL]

The other point I should have made is the 175deg is actually a fail safe, so the need to operate means the 125deg didn't and therefore it's that one that's faulty.
Overall though neither should be required to operate but using gas and electric together without enough fan speed to disperse the extra heat effectively is common reason. So it's essential while using gas with electric, that fan control is set at 'A' (auto) with maximum speed set on dial.

Also problems can arise if the fan has become clogged with dust and hairs, or if the hot air outlets are closed or blocked.