Viessmann LPG ignition problems

[google_groups]

I recently installed a Viessmann LPG boiler along with their solar panels to run central heating, under floor heating and hot water. However during the recent cold spell if the boiler goes off for any length of time it will not restart (shows an ignition problem). I strongly suspect it is to do with the low temperature casuing the gas not to vapourise properly and therefore the boiler cannot ignite it. If I blow hot air into the boiler intake when it tries to ignite it solves the problem - I just don't want to strip the boiler down every mornign to start it up again. Anybody else found this problem?

Having said that the boiler is really well put together and I am pretty pleased with the performance of it when it is running. The solar panels are awesome with it currently heating up a 500 litre tank to 55 degrees at the end of the day on it's own. However it will take sometime to recover the cost of the boiler which was considerably more than any other boilers out there.

[Mike]

Uh - how big are these panels ? That's a lot of Joules/ergs/whatever needed to heat that much water through forty-five degrees or so.

[Doctor Evil]

Nothing to do with cold weather. The ignition is at fault. If it is new get the engineer around for free.

It sounds as it the electrodes are damp and the hot air dries them out. You will find that if it fails and you retry it will work as the fan dries out the contacts. There is usually baked on soot that holds moisture that causes this problem.

The panels are not cheap either. Evacuated tube I believe. Nothing Viessmann makes is cheap. You could use the solar heated hot water to heat the underfloor heating as it only requires low temperatures. It may be worth your while looking into getting another panel and fitting a plate heat exchanger and bronze pump to supply the UFH from the cylinder.

What were the panels performing like a few weeks back when it was freezing point?

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[Cappy]

The panels are about 3m2 (collector area) and are the Vitosol 300 evacuated tubes ones (from memory).

I'll give the ignition replacement a try - purely going on my greenhouse LPG heater which if the temperature drops below 5 or 6 can prove a real bitch to start. The boiler is in an unheated barn whcih I assumed was not helping with the problem.

Be interested in running the UFH from the cylinder as it is currently run from the boiler alongside the radiator circuits (all a big viessmann control panel) - have to look into that.

The temperature does not seem to affect the panels performance at all (it was hitting -10 in the morning on the collector panels). However they didn't work until I cleared the snow off them (duh) but were still getting the temperature up to about 25 ish on light but overcast days. They are on a south facing roof at just the right inclination so I guess that helps a lot. Throughly recommend them if the capital can be found.

Doctor Evil wrote:

[John]

If you are in the uk and your lpg is Propane (not Butane) then you can discount failure to vaporise. Of course Butane will not vaporise at freezing temperatures which is why it is not used for external storage installations. Blowing hot air into the burner may indicate dampness tracking the ignition spark to earth. Have you stripped out the electrode assembly and checked the porcelain/leads are/is clean and gaps are correct? You may also have an issue if there is water in a fuel line which has frozen and formed a plug of ice

[Cappy]

It is actual in Mid-France (2500 ft altitude) and is "called" propane but I assume it is a mix of sorts. The stove/oven works fine so I guess I have to assume that it is not a vapourisation problem. Have not stripped down the ignition system (it is new so I assumed it was fine) but will ask for a raplcement ignition unit and see if that helps. I can hear the gas going in and the sparks going - just does not catch. I might try dis-connecting the fuel lines and drying them all out properly.

thanks for helping.

[fred]

In article , google [e-mail] writes

Another possibility is that you may have mixture problems. When I installed my boiler (not a Viessmann) I had serious ignition problems until I set it up with CO probe, it had been running very weak. Could you borrow a flue gas analyser for a day? The test & measurement side of HSS has them on hire but I think it is about 40quid for a day.