Fitting out your motorhome: All the trades
 #99721  by Coast2Coast
 Mon Sep 14, 2015 11:50 am
One morning this week our Truma hot water heater stopped working. Normal click about 30 secs after turning on the switch and which usually ignites the gas (warm air coming out the outside vent is the 'OK' symptom). Now about 30 secs later a red light comes on at about 8 o'clock on the dial and no warm air coming out the vent. Any thoughts please as to where to start looking for gas/electrical/mechanical issues?
 #99722  by Roamnz
 Mon Sep 14, 2015 11:57 am
If you type Truma into the search facility above -next to the Home emblem, you will find a number of helpful threads and posts relating to Truma systems not working and a number of remedies. That should give you somewhere to start. ;)
 #99732  by 96coaster
 Mon Sep 14, 2015 3:26 pm
If possible, try and get hold of a replacement circuit board to "try out". (maybe if you know another camper friend who has same heater, offer a "koha" and borrow theirs ??) The PCB is very easy to replace (about 2 minute job if heater is readily accessible, undo two screws on plastic triangular cover were wires enter unit, gently undo the two plastic plug connectors and gently lift PCB up and out. Installation is same, ensuring PCB pushes into socket at bottom of heater (this is where the wires to the igniter goes) ) and if heater works ok, fault is more than likely with PCB.

These are not cheap ($399 or so - total rip off). There is one on Trademe at present for this price. We had similar problem, i.e. turn on, click and red light would come on after about 8 seconds. Sometimes it would light after several attempts, but problem got worse. The red LED indicates gas burner has not lit (or overheat temperature has been reached).

When I got frustrated and did not wait for several minutes before re-light attempt, there were frequent gas explosions, best to avoid these.

To see if ignitor is working you could try listening very close to outlet grill (on outside of van) while somebody operates heater switch). You may be able to hear clicking as this is the igniter working, which may indicate no gas or overheat sensor fault. Keep ear to one side in case it goes bang.

Another fault may be leaking tank and water drowning burner (but with this problem you may see water dribbling out of drain on exterior vent. The 30 seconds before hearing "click" seems a long while, ours clicks 2-3 seconds after turning on.

Could be other faults apart from PCB (no gas supply, overheat sensor gone bung etc - there is a fuse on the PCB but I don't know what this protects - whole PCB or parts of it).

After parting with $390 for another PCB, I (as a long shot) replaced two small relays on PCB (at cost of about $2.50 each !!) and PCB seems ok, although I wouldn't guarantee long term, but it will do as a spare.

However, as mentioned, do a search for truma on this forum, and Google "Truma Ultrastore", you can find a spare parts diagram which shows PCB and all other bits.

Lets us know how you get on.

 #99734  by Coast2Coast
 Mon Sep 14, 2015 3:50 pm
Many thanks for those responses. I have checked the fuses and all OK and the igniter sounds as though it is working OK. I can hear the gas ignite for a while before it goes out I have now downloaded the Truma Manual and it suggests an issue in the gas/air supply system rather than the electrical system. I have now managed to get the heater to work twice this pm, after 3 attempts the first time and on the first attempt the second time. Since then I removed the grill on the outside and found a spiders web in the exhaust duct. Will try the system again over the next couple of days to see if it behaves (it has worked first time over the past 3.5 years) before delving deeper.
 #99745  by Copout
 Mon Sep 14, 2015 6:57 pm
Another thing to check is to make sure that there is not a very small leak in the tank which allows water to drip into the gas ring and puts the flame out. The water only drops into the ring after it is lit and the heat opens up the crack, which is sometimes only just a small crease in the tank.
 #99773  by kiwigold
 Tue Sep 15, 2015 1:55 pm
Hi All

My advice is take it to a qualified Truma technician. Playing with gas powered appliances is fraught with danger. One poster here mentioned we had explosions. Well they are damm lucky it wasn't a big one. I had a friend and his friend come down to Westport one day. Parked at the Buller Club. One had a Nissan civilian and the other a Bedford Bus Conversion. Well the lads were in the club having a quiet beer. The girls were in the Bedford, chatting and having a coffee. Next minute there was a mighty explosion. It was the Bedford. Somewhere there was a gas leak, when the gas reached the gas fridge burner, yep she ignited. All the ladies received burns to their legs, one needing to be hospitalized. The front windscreen of the Bedford blew out. Need I say more. Take it to an expert.

Cheers Trev
 #99774  by kiwigold
 Tue Sep 15, 2015 2:04 pm
Hi All Again.

I might add my interior gas heater started to malfunction. The dreaded Red, light. Not igniting. And then shutting down the ignition process.
I rang the British Company that manufactures that brand of heater. They sent me out a new PCB board and new sensors etc. Do you think I am going to have a go myself at fitting them. Na mate, ya gotta be joking. It will be a certified gas fitter who has knowledge of that brand of heater. I have no wish to go kaboom and no longer be an active member of this forum.

Cheers Trev
 #99928  by Coast2Coast
 Fri Sep 18, 2015 9:01 am
As an update, it has started first time over the past couple of days so perhaps the spider's web was the issue.
With reference to Copout's comment about the moisture leak from a crack in the tank, this did occur a couple of years ago and was noticeable by water dripping from external small drain pipe below the exhaust vent. I have noticed a small amount of moisture there again and as yet haven't found out for sure whether this is normal or not (it may be a condensate drain?) but will keep an eye on it.
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