Gas and Oil Home Heating Furnaces - combi boiler heating

My combi boiler is heating the water alright but not the central heating. When the central heating is switched on the boiler flares up for about two seconds and then goes off. The radiators remain cold.

Help

What fuel type do you have? Gas or Oil?

This just started acting up this way?

Is Combi a brand name of your boiler?? I honeslty not heard of it.. Give us more detals. and are you zoned?

Gas is the fuel and the Brand Make is Saunier Duval.
Tried everything with it!!!!!!!!

I never heard of that brand or been around one here in the US..

I did a search, and looks like it's a UK style system...


I am sure someone will stop in here soon when they are home from work, and maybe give you some tips.. I have a feeling you may not have luck with us, so you may have to call in your local dealer to service your boiler.

Combi is the common term in Europe for what is known as tankless in the US - another name for instantaneous heaters.

Suggest you check your central heating pump to start with. If this is not working the heat exchanges will rapidly overheat and the boiler will shut down. Also check the thermostat - if it is faulty the boiler will not work. You may be able to bypass it to check.

The fact that the boiler is heating the domestic water makes me think the pump is working but there is always a possibility that it is not all the same. The little pumps in these things are so loow powered and gutless that they sometimes need a bit of help at the begining of the season. First try giving the pump a good thump on the end this shakes the rotor and can start a pump, or take the end cap of and take the big screw out of the end of the pump you may get a bit of water coming out but its usually easily caught then put a screw driver in to the rotor and give it a turn you'll soon know if it's going or not. Just watch the water could be hot too, The pumps usually have speed adjustment on them 3speed or 4 speed.
However it sounds more like the thermostat could be faulty, I had one were the boiler would not go over 35 degrees Cent. These are usually a thermistor type and not easy to short out to try and it's a possibility you may damage the circuit board if you short it out .
1) Make sure the pump is running first.
2) Make sure there is no other stats stopping it from going.Is there a room stat some were?
3) Subsitute the thermostat/Thermistor.
4) oh yes make sure any valves down stream of the pump are able to allow the water from the pump to circulate. ie the pump is not deadheaded.