Vaillant Turbomax on Calor

[John]

At the Scout Hut we have a Turbomax converted to Calor - every time we go down it is invariably on "lock out", although it relights when you press the flame out button.

Any thoughts?

[Andy Hall]

Because of the application, it's expecting to be ignited by the rubbing together of two sticks.

You are doing that aren't you? ;-)

Realistically...... it needs to be serviced....

[Guy King]

The message from Andy Hall contains these words:

If you really want hot water, rub two boy scouts together. You'll get all the hot water you need from Baden Powell House.

[Andy Hall]

I thought that was hot air.....

[Ed Sirett]

Using the manual you can find out how to ask the boiler why it keeps locking out. What's the fault code? F.28 maybe? I.e. failed to light after repeated attempts. Which if the boiler is really otherwise OK probably means someone is switching off the gas ?!?!

[John]

Yup it is code F.28.

It works okay when we are there - it will turn on and off as the thermostat requires. However, it appears to be when it has not had a demand (due to the timeswitch being off) for a considerable period - then it locks out.

The feed pipe is quite long, but large bore and (apart from a few occasions where the local yobs have turned it off) it is always on.

One problem is that we never actually see it trying before it fails (and some weeks we go in and it is working). Any suggestions gratefully received (and yes we did get an engineer to look at it, but he couldn't find anything amiss).

[Ed Sirett]

You really need to catch it "inflagrante". You'll get lucky sometime. Here are some ideas:

1) Gas valve sticks closed when off for a long time. Work around: use 7 day timer to put hetaing on once a week for a minute or two. 2) Damp gets into the unit when not in frequent use. These lead to HT ignition shorts.

[John]

Thanks for that - I will go down and reprogram the time clock to warm the place every day for an hour and more when the Scouts, Beavers, Cubs and Guides are expected!

I think I will need to put it on twice a day at least - I "rebooted" it last night at Cubs and it had failed again at Beavers tonight - 22 hours later.

[Ed Sirett]

OK so it's not a sticking gas valve or other sort of "atrophy" problem.

I've not got any LPG qualifications - but what sort of gas bottle are you running it from? It occured to me that if the bottle was rather too small you might get too little pressure after the boiler had been in use a while. The bottle would cool down till there is not enough gas pressure. Perhaps enough to not reliably light _and_ be detected as lit.

[John]

Large tank (about 1.5m high and 3.5m long) outside with 22mm (or thereabouts) feed pipe - the tank has a leak detector cutoff (or so I was told). Tank is outside the hut.