Boiler Flame Fault

Are any other appliances in the house affected? for example,when the boiler is running,do the cooker burners dip also? if so you may have a supply problem. Which model of netaheat is it? If the flames can be seen visibly reducing in this way then its a bit of an unusual fault as normally its either on (ok) or off (faulty) and no inbetween!

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On 7 Jun 2006 08:45:08 -0700, "Dekkaxx" wrote: There are a couple of variations of netaheats as they were a very popular (and good!) boiler and were made for quite a while. The most popular version,and the one you probably have, is fitted with a control commonly called a white rogers valve. Mainly becuase thats the name of the makers!.

The sequence of events is

boiler turned on/called for heat

fan runs

pressure switch makes

power supplied to pilot solenoid of the WR valve and the spark gen

pilot lights

pilot heats the tip of a vapour pressure sensing switch

about 30 secs to 1 min later vapour pressure switch makes and provides power to the second main solenoid in the white rogers valve

As i say,it is rather unusual to have an "in between" main burner stage,its usually on or off. If you have little or no knowledge then its probably best left to someone with specialist knowledge as you could have an accident!

You would need to do electrical testing to ensure that the air pressure switch is operating

then check that power is supplied to the pilot SV AND that there is gas available at the pilot burner

If that bits ok you would then have to check the operation of the vapour pressure switch ie is it operating? is it switching power to the main SV?

A full working knowledge of the correct sequence of operation and electrical testing procedures is required.

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Since this actually works first time it suggets that most of the components are more or less right.

I would certainly want to monitor the main burner pressure. Initally it is probably within spec (as specified on the boiler rating plate) but for some reason goes down after a few minutes. Once down it then can't relight until something cools? or resets? I suspect that the gas valve is playing up - you _might_ be able to get a replacement but I would leave actually doing so to a pro.

Seen this in two boilers before, including mine. Basically boiler sucking in its own fumes. Both cases the inner tube of the concentric vent pipes had seperated allowing the exhaust to mix with the incoming air. In one case fault visible easily as inner piper seperated at external vent but at my mates house a joint in inner vent pipe in the wall had come apart which was not visible until the whole vent pipe was removed.

Basically I think the flames lifted off the burners, the flame detect cut the gas, the flames returned to the burners, flame detected applied gas and sequence contined.

Might not be your boiler fault but worth knowing.

Somehow I doubt these were Neatheats the Neatheat is just about unique (for boilers [1]) in that the flame failure mechanism is a mercury vapour bulb and capilliary unit. This acts directly on the gas valve to control the main burner.

If flue gases were recirculating into the supply air then the flames would enlarge, impinge and even become yellow and sooty. The OP stated the flames went smaller and darker which means that the gas suply pressure coming out of the valve was reducing for some reason.