Truma Ultrastore flameout

[farmerbob]

Hi all
I've had my caravan (2005 Magnum Compass) for about 4 years. When I got it the Truma Ultrastore (10L) worked without issue on gas or electric. I keep it on a friends farm near the coast and its fairly static, occasionally it gets moved to a different field depending upon cropping. About 2 years ago it got moved to its current location and since then the Ultrastore has given problems, some times it will work perfectly, but mostly I get ignition followed by the 5 second piezo click followed by the red light. This can happend totally randomly it seems.
I have had the circuitboard checked and returned as working correctly. I have fitted a new gas safety valve because I found the copper gas pipe was full of the sticky liquid often mentioned on here. It has a new flexible hose pipe from the gas bottle (propane) to the regulator. The Truma gas caravan heater and the gas oven all work fine, and you can turn them all on without a drop in flame height which leads me to think the problem is not gas pressure.

I had initially assumed the problem was gas pressure until I found a video on Youtube recently which showed a similar problem, but the answer was that the exhaust gas wasn't exhausting properly and leading to a flameout caused by lack of oxygen. I took the white 'grille' off the outside of my caravan and tried blowing gently into the lower air intake every time the piezo started clicking, and it works every time. The flame reignites! The problem is the exhaust gas isn't drawing properly. In the Youtube video the gentleman explains (not very well) that his Ultrastore wasn't mounted at the correct angle, that it should be off horizontal to get the flue (the white grille) to draw the exhaust gas correctly. I have read the Truma installation instructions and nowhere does it mention this, and that does not explain why it worked flawlessly for two or more years. Equally if you didn't level the caravan up correctly when siting it, this would throw the angle out anyhow.

I have taken the Ultrastore apart and reassembled it (I have a friend who is a gas engineer who helped), the burner is perfect and clean , there is no evidence of water corrosion, or debris blocking the vents etc etc. The piezo and flame electorde all look perfect, and must be because occasionally it will work wothout issue.

The only issue I can think is that the current location of the caravan is causing airflow issues...? The caravan has always been situated on a field edge against a hedge with the Ultrastore vent on the hedge side. There has usually been at least a 6ft gap between the caravan and the hedge so plenty of space, at the moment that is maybe 4ft since it was last moved. Could this be the problem? Does there need to be a larger gap between caravan and neighbouring object (hedge) for the flue to draw properly?

The problem has become so infuriating that I am considering fitting a computer fan or similar to the outside of the grille on the intake side to gently push a bit of airflow into the Ultrastore.....

Anybody have any similar issues or suggestions?
TIA
Bob

 

[ProfJohnL]

From your description, the combination of reluctance to ignite, and finding waxy oily residue in the gas supply pipe, does strongly suggest there is a restriction in the gas flow into the heaters burner. This would result in a smaller flame which might not have the gas flow to fully circumnavigate the burner or be big enough to reach the flame detector probe. A small flame would also be more prone to windage problems.

I suspect the residue may be the culprit. For it to have reached the water heater it must have travelled all the way from the gas bottle, through the regulator and along all the pipework. It may not have affected other appliances so badly because of the greater gas flow they have or the height of thier pipe runs.

If you have found the residue, then all the pipework and fittings needs to be either replaced or cleaned, the regulator changed, and all the appliances checked for gas way obstructions and correct operation.

Static gas pressure checks will not show restrictions caused by residue only dynamic pressure on demand at the appliance or a flow rate check will reveal if there is a restriction, or problem with the regulator .

I'm not sure what use the caravan is being put to, but If it's for workers accomodation, then by law all work on the gas system must be carried out only by a qualified fitter with the LPG authorisations as required by the gas regulations and the Heath & Safety executive.

 

[farmerbob]

From your description, the combination of reluctance to ignite, and finding waxy oily residue in the gas supply pipe, does strongly suggest there is a restriction in the gas flow into the heaters burner. This would result in a smaller flame which might not have the gas flow to fully circumnavigate the burner or be big enough to reach the flame detector probe. A small flame would also be more prone to windage problems.

I suspect the residue may be the culprit. For it to have reached the water heater it must have travelled all the way from the gas bottle, through the regulator and along all the pipework. It may not have affected other appliances so badly because of the greater gas flow they have or the height of thier pipe runs.

If you have found the residue, then all the pipework and fittings needs to be either replaced or cleaned, the regulator changed, and all the appliances checked for gas way obstructions and correct operation.

Static gas pressure checks will not show restrictions caused by residue only dynamic pressure on demand at the appliance or a flow rate check will reveal if there is a restriction, or problem with the regulator .

I'm not sure what use the caravan is being put to, but If it's for workers accomodation, then by law all work on the gas system must be carried out only by a qualified fitter with the LPG authorisations as required by the gas regulations and the Heath & Safety executive.

There is no reluctance to ignite initially, or after the red light comes on. By the time you turn the Ultrastore off, wait a couple of seconds and turn it on again it reignites straight away, it may then work perfectly for a day, a couple of minutes, or if may only work for 15 seconds, it is totally random. What I do now know is that if I hear the piezo clicking, if I blow gently into the air intake it will re-ignite, everytime, without fail. I do take your point about the poor gas flow maybe leading to poor heat generation and therefore poor exhaust expultion. Perhaps I'll replace the copper pipe from the joint to the isolation tap for the Ultrastore.
On gas how long would you expect it to take to heat the water to 70 degree's? When working correctly this one takes 12-15 minutes I would say.

The caravan is used for personal use, it's brilliant for regular seaside getaways at weekends. Pile the family into the car on a friday afternoon, 2.5 hours later arrive at the caravan. Much cheaper and more socially acceptable than a second home IMHO.

 

[ProfJohnL]

You clearly do not understand what I have advised you.

The residue from the gas comes from the gas bottle pigtails and as you found some at the water heater it must have contaminated ALL the pipework to the water heater and very possibly other branches to other appliances. It will have affected the regulator, and might compromise its ability to safely limit the pressure in the caravan. Items with low gas consumption such as the fridge and water heater have very small gas injector bores and a small amount of residue will affect their ability to pas the required gas flow. The Trumastore has an electrical solenoid gas valve, and its shut off function might be compromised by residue.

Obviously I cannot see your caravan, but having had to deal with such matters professionally previously I know that partial cleaning often results in future contamination. You will at least need a new regulator and tails fitted in accordance with the manufacturer's instructions.

For the safety of everyone don't skimp on these matters. Even though specifically as a privately owned touring caravan solely for your own use (i.e. not loaned or hired or owned by or used for a business) you are allowed to undertake the work as long as your are competent, the work still has to conform to the codes of practice for design and implementation which unless you have access to the required test equipment it's unlikely you can verify conformance.

 

[farmerbob]

You clearly do not what I have advised you.

Thanks for your reply. Much appreciated. What do you mean in the sentance above?

 

[ProfJohnL]

Sorry missed out "understand"

 

[farmerbob]

Sorry missed out "understand"

Charming. Why do you say that?

 

[ProfJohnL]

Charming. Why do you say that?

I'm sorry if you think my response was unwelcome. But I never make light of gas safety issues, and sometimes it needs a forceful reply to make a point.

In one of my earlier replies I had advised you need to consider the whole pipework system, after which you only indicated you might clean one section.

Your reluctance to tackle the whole system means you did not understand the implications of what you had found and the reason for my advice.