Help! My Truma heating system is not working properly
So I have a Truma combi boiler and recently it’s not been working the same. The front two blowers that are at the front of the van get very hot, as they always have. The rear two blowers are tepid at best. Closing the front blowers makes no difference to the temperature of the rear blowers. Also the hot water comes to temperature on the Truma display, and holds that temperature, unless the blowers kick in. As soon as the blowers kick in the hot water immediately tries to come back up to temperature. I’ve spent hours troubleshooting and I’ve reset the boiler and panel multiple times, fuse on the boiler also checked and is fine. I’m starting to think one of the heating elements has gone with only the left side of the boiler blowing heat . Any other thoughts on what the issue could be before I spend a fortune trying to getting this fixed? I’m going to try on the gas only to see if that works then I’m fairly certain it’s the element. Thanks everyone
Best Answer
-
@Ziggy - unfortunately, I am one of those to whom @DavidKlyne refers! - and have quite a lot of experience of the problems associated with the Truma Combi 6e. I have had the elements changed twice in the 7 years we have had the Knaus Starclass and finally - just over a year ago, I had the whole boiler replaced. We have used the van extensively during that period - all year round - so the heating system has had some stick.
It is well documented on the internet that the elements only last a couple of thousand hours or so - which in our case, equates to about two year's use. Unless you have a very unusual installation, changing the elements means removing the whole boiler assembly and it's time consuming and expensive - it cost me £350 the first time, but £750 the second - since, because of widespread installation problems, Truma now only offer a complete kit comprising of both elements and the heat exchanger combined. (On the other hand, a new boiler is 'only'!! £1600 and can be fitted in a fraction of the time it takes to change the elements so, because of time pressures, that's why I went down that route, last time).
However, I'm somewhat confused by the symptoms you describe and I'm not yet convinced it is the element(s) that is/are at fault. The only sure way is to measure the current draw when on Eco (1 element) or Hot (2 elements). With both elements operating, the current drawn should be about 7.5 amps. If, when on Hot the current drawn is somewhere around 3 amps, then one element has failed. I am fortunate in that I fitted a power meter in the van, so I can see at a glance whether both elements are working or not.
Something doesn't sound right about your hot water. Are you saying that the water gets hot even if you haven't selected to heat the water? That shouldn't be happening - although if you run the heating on gas, you will find that, over a protracted period, the water will get hot regardless of whether or not hot water is selected. As far as the fan is concerned, that should only kick in when the temperature in the van has dropped below that demanded and it shouldn't have any effect on the water temperature.
It could be a fault on the PCB although the Chief Tech at ALV has always said that PCBs either work or they don't!
If it runs normally on gas, then it does point to an element having failed but the only sure way is to use an ammeter on the supply coming into the van. However, bear in mind that the heat output when on gas is far greater than when on electricity, so the issue with not enough heat coming out of the rear vents will be solved anyway.
Hope I haven't confused you even more. Good luck!
4
Answers
-
@Ziggy I have heard that others have had issues with the heating elements. Perhaps check out Youtube as there might be some videos onthis subject.
David
0 -
cheers for this, really appreciated. In relation to the hot water no, i turn the water to hot, it flashes as it comes to temperature and then will hold that temperature as it always has. If we turn on the blow heaters the hot water immediately starts flashing which leads me to think it is one of the elements as it cant hold the temperature of the hot water which it has always done, whilst the blowers are on. I’m going to try the gas bottle route first as this seems the least costly for now. It just very strange that the front 2 blowers work fine without issues and reach and hold their temperature no problem. I’ve seen in some forums people talking about a butterfly switch thats at the rear of the boiler which can be adjusted to direct the heat, cant find that anywhere. Weirdly when we have the hot water on boost and it finishes the boost ‘cycle’ (if that makes sense) the second the blowers then kick back in we have full heat from all blowers, front and back which im guessing its pulling the heat for the blowers from the heated water, which they starts to instantly cool down kicking in the boiler again to try and reach temperature. This tends to only last for a few minutes before the back runs cold again. Anyway thanks for the reply, onward to further testing!!!
0 -
There are defiantly some really good videos on YouTube. I’ve found some that walk you through a heating elements change which i reckon i could do. I love tinkering and repairing things on the van myself so im seriously thinking of doing the element change myself if thats what is gone.
0 -
@Ziggy - a couple of points. Firstly - what you describe about having the hot water on boost is exactly how it should work. When on boost - it overrides the heating and the fan will shut down until the water has reached temperature and then, when it has, the fan will come back on again. That's all normal.
Just bear in mind that you can no longer change just the heating elements. There was a problem up until about 4 years ago whereby, apparently, they were supplying the elements separately and people (including professional technicians) were putting them in and not ensuring the heat exchanger was crimped properly around the fins on the element. Not having done it myself, I'm not certain about the details, but that's how it was described.
As a consequence, Truma decided to cease supply of the elements alone and replaced them with a kit in which both elements were supplied already fitted to the heat exchanger. Again, I'm just relaying what was described to me, although I saw what went into my boiler the last time they were changed. It looked like about half the boiler was being replaced - a big lump of intricately machined aluminium! I suppose that accounts for the almost doubling of the cost. There were also some changes to the various gaskets. There's no way that could be done with the boiler in situ - even if you had room to change the elements that way.
As a consequence of my experience, I now tend to run the heating on gas if I can. It's a more efficient and effective heating source anyway - plus I use Safefill - so it's cheap as well. However, because of the current crisis, I'm having to re-think that because I anticipate that LPG will be in short supply before long.
1
