Truma Ultraheat Remote Sensor

[Christhecaravanner84]

On my trial run in the van a few weeks ago, I had the usual issue with the Truma heating on electric which folks seem to talk about. Heat was cutting out on setting 5 on the stat at about the right temperature, but not coming back on. Higher settings resulted in a sauna. I resorted to having it tick over on gas a couple of time despite EHU as I found the temp more manageable. Anyway, I found a couple of posts on this forum about about it and plenty of info on other forums about it. I'm pretty confident about doing the job. One question is that on the Caravantalk forum they mention a sensor / kit from a bloke called Gary which is meant to be better than the Truma part. Does anyone have know where I can get this "Gary" sensor. Maybe Gary is also on this forum? Has anyone installed one of these sensors, "Gary" or otherwise?

 

[ProfJohnL]

THey are probably referring to Gary of

Arcsystems.biz

 

[Buckman]

We had them on previous caravans. What happens is the standard sensor is high up and records that temperature as hot air rises and thinks it is still at the correct temperature. Another sensor needs to be near floor level where it is the coldest. I think the sensors were supplied by the dealer who also fitted them in all our previous caravans with air blown heating.

 

[ProfJohnL]

The problem in some caravans was the sensor was fitted on a wardrobe wall which was always warmer than the caravan becasue the heaters was inside at the bottom of the wardrobe. This was contrary to the heater manufacturers instructions, but it where the caravan manufacturer decided to put it!

The sensor needs to be relocated to a position where it will follow the room temperature. It doesn't actually need to be lower in the caravan just where it can sense the caravans real temperature.

 

[Christhecaravanner84]

I'm not sure where it is currently located on mine, but somewhere daft I suspect. It always seems quick to go off and slow to come back on, unless you have it on at least 7, then it gets too hot. I suspect it's in a position where it's being directly influenced by the heat.

General consensus seems to be at the bottom of the fire front for the remote sensors. If it was a proper stat with temperatures on it, I'd be more inclined to have it somewhere else. But I think it just needs to be somewhere where it isn't being directly influenced by the heat source.

Anyhow, I've ordered a sensor off eBay. Got more or less an idea of how / where to plug it in.

 

[Jaydug]

Different caravan builders put the temperature sensors in different spots. On my own caravan, it was originally fitted below the overhead lockers on the curtain pelmet. But wherever they are fitted, on the Truma Ultraheat, they are all plugged into the control box which is on the floor right at the back of the rear back-plate. Truma's recommended spot for the electric temperature sender is to ride piggy-back on the gas temperature bulb.

This was my original room temperature sender:



Below is the control box. The red arrow shows where the electric temperature sender plugs in. The top of the box is removed here. The plug is similar to a stereo miniature jack plug.:-



And here is the electric temperature bulb sitting alongside the gas temperature bulb.

 

[Buckman]

Anyhow, I've ordered a sensor off eBay. Got more or less an idea of how / where to plug it in.

Place it at floor level at the coldest place i.e. doorway.

 

[Christhecaravanner84]

Well as often is the case with these little jobs, it raises even more questions.

There was already a sensor clipped to the gas sensor. After a lot of confusion and head scratching, I found the control board by disconnecting the blown air duct and using my phone as a “periscope” of sorts and found the socket just inside the hole for the duct. Interestingly the jack was laid on the ground next to it. It’s quite possible that I managed to disturb it whilst ferreting around for the end of the lead. I’ll never know for certain. Perhaps the previous owner gave up looking for the connection so just left it there to pick up another day. If it WAS indeed connected, it wasn’t doing it’s job. So was it a faulty sensor? Nonetheless, I installed the new one. According to the EBay listing it’s the “new red wire type” whatever that means. Not sure what’s “better” about it other than fancy coloured wires. I ran it up on 1KW using my generator and it seemed to cut out at a reasonable temperature set to 5. True test will be at night when I go to Stonehenge at Easter.

 

[Jaydug]

After a lot of confusion and head scratching, I found the control board by disconnecting the blown air duct and using my phone as a “periscope”

Well, I did say the control box was in a difficult position. In my case it means using a light and a mirror through the drawer opening. To do work on it really requires the removal of the complete fire. But well done. ⭐

 

[Christhecaravanner84]

Hardest part was getting the front mounted again.

 

[Christhecaravanner84]

Well, I did say the control box was in a difficult position. In my case it means using a light and a mirror through the drawer opening. To do work on it really requires the removal of the complete fire. But well done. ⭐

View attachment 3055

Mine was easy in comparison, not meaning to rub it in!





Control box seen with iPhone camera poked through hole. Although I did have to remove shelf above to get an idea of where to look.

 

[Jaydug]

Hardest part was getting the front mounted again.

The design for the front fixing on the S2003 is "Heath-Robinson". It troubles many owners, some of which resort to putting a screw through the front to stop it from falling off. Fortunately, I fitted a new S2004 model in which Truma have re-designed the fixing. Now it's much more secure.

 

[otherclive]

The design for the front fixing on the S2003 is "Heath-Robinson". It troubles many owners, some of which resort to putting a screw through the front to stop it from falling off. Fortunately, I fitted a new S2004 model in which Truma have re-designed the fixing. Now it's much more secure.

View attachment 3058

I recall once trying to remove the front without realising a screw had been fitted. Of course I went by the Owners Manual and previous caravan. After I frustrating few minutes I eventually found the “added” screw.

 

[bertieboy1]

On my trial run in the van a few weeks ago, I had the usual issue with the Truma heating on electric which folks seem to talk about. Heat was cutting out on setting 5 on the stat at about the right temperature, but not coming back on. Higher settings resulted in a sauna. I resorted to having it tick over on gas a couple of time despite EHU as I found the temp more manageable. Anyway, I found a couple of posts on this forum about about it and plenty of info on other forums about it. I'm pretty confident about doing the job. One question is that on the Caravantalk forum they mention a sensor / kit from a bloke called Gary which is meant to be better than the Truma part. Does anyone have know where I can get this "Gary" sensor. Maybe Gary is also on this forum? Has anyone installed one of these sensors, "Gary" or otherwise?

On my trial run in the van a few weeks ago, I had the usual issue with the Truma heating on electric which folks seem to talk about. Heat was cutting out on setting 5 on the stat at about the right temperature, but not coming back on. Higher settings resulted in a sauna. I resorted to having it tick over on gas a couple of time despite EHU as I found the temp more manageable. Anyway, I found a couple of posts on this forum about about it and plenty of info on other forums about it. I'm pretty confident about doing the job. One question is that on the Caravantalk forum they mention a sensor / kit from a bloke called Gary which is meant to be better than the Truma part. Does anyone have know where I can get this "Gary" sensor. Maybe Gary is also on this forum? Has anyone installed one of these sensors, "Gary" or otherwise?

I've the temperature differential ( difference between thermostat switch off and switch on temperatures ) rather high, pity there's no adjustment of differential available

 

[NorthernMarty]

The problem in some caravans was the sensor was fitted on a wardrobe wall which was always warmer than the caravan becasue the heaters was inside at the bottom of the wardrobe. This was contrary to the heater manufacturers instructions, but it where the caravan manufacturer decided to put it!

The sensor needs to be relocated to a position where it will follow the room temperature. It doesn't actually need to be lower in the caravan just where it can sense the caravans real temperature.

Installtion instructions for the Truma sensor recommends above the front door horizontal. That’s where I put it, hope it will work m😃

 

[Jaydug]

Installtion instructions for the Truma sensor recommends above the front door horizontal. That’s where I put it, hope it will work m😃

I would be interested to see the Truma sheet that gives that advice. Our friend Gary who is a Truma trained specialist has been advising us for years that the ideal position for a remote Ultraheat sensor was to fit it alongside the gas sensor. ie:- at the bottom of the fire. On this forum, Gary wrote in 2010, "At or just above floor level is best then, problem is where, answer to that is where it is not affected by other than the actual lowest temperature. My experience says the very best place is attached to the gas fires temperature sensor, this ensures the air flow over it is what either source of heating is pulling in to reheat".

 

[Buckman]

Installtion instructions for the Truma sensor recommends above the front door horizontal. That’s where I put it, hope it will work m😃

Hot air rises so you will get a false reading. At floor level it will be a lot cooler.

 

[Christhecaravanner84]

Update... New sensor appears to have done it's job. On recent Easter trip the Truma maintained a very pleasant temperature in the van at night, had to make a couple of adjustments initially, then it was just "set and forget".