ENGLAND, UK. DOMESTIC HOUSE CENTRAL HEATING. Baxi Bermuda

I would try Baxi or one of their agents.
If in the UK, this MUST be installed by a Gas Safe Registered engineer.

possibles are thermostat or circulator

needs tune up change filter and nozzle and check electrodes are clean with no build up and clean out chambers

http://www.baxi.co.uk/products/bermuda-back-boiler-unit.htm?view=download , i hope that will help

Try;http://www.baxi.co.uk/about/products.htm "Product Literature" on left side of page and supply needed info. Failing that, I generally type the manufacturer's name into a google search then space, then .pdf.

Go to this link.Bottom of page 15 on the manual
http://www.aroundtownflats.com/manuals/Boilers/Baxi/BAXI%20BERMUDA%20SP3%20GCNo.37-077-63.pdf

Basically it says (turn on the power first) Turn the knob to the the star/flame marking. Push the knob in, hold it for approximately 10 seconds. Release and check the small flame is lit. Now turn it to your desired heat setting.

After you pressure system do you bleed the rads then top up again .

Your boiler is overdue for a service.

Combi boilers are unlike regular boilers in that they have quite a few moving parts, it's vital that these are serviced annually if you want the boiler to remain reliable and to avoid expensive failures.

In your case, the diverter valve has most likely failed. Normally, when the heating is on this senses when there's a demand for hot water and temporarily diverts the primary hot water circuit to feed the domestic hot water heat exchanger. When the demand for hot water ceases the primary hot water circuit is diverted back to the central heating heat exchanger. The valve has a number of moving parts including a rubber diaphragm which can wear out and split and moving shafts which can seize.

When the valve fails it can leak and also can divert hot water to the central heating heat exchanger when hot water is used. The reason that only the highest radiators in the system are affected is probably because the failed valve does not necessarily cause the central heating pump to activate and circulate the hot water throughout the system (it does on some boilers though). If hot water is introduced into a cold heating system it will rise via convection to the highest points in the system like an old fashioned gravity circulation system which was unpumped.

Call a heating engineer out as soon as possible; I'm not going to advise how to do the repair yourself as gas appliances MUST be serviced by qualified persons only for reasons of safety. If you're lucky then the valve simply needs cleaning up and a few new diaphragms plus other minor seals and rings. If it's gone too far then the valve and possibly the manifold it's attached to will need to be replaced.

In the UK the part alone typically costs between £100 to £200 depending on whether it's just the valve or the manifold as well. The diaphragm kit typically costs up to around £15 and is routinely fitted when the boiler is annually serviced, and a new valve will already have new diaphragms fitted. For a routine service expect to pay for up to two hours labour (many can be done in one hour), but if the valve/manifold have failed it will be longer as one failure often causes other parts to need further inspection/repair.

I hope that I've helped you today, if so please return the favour by rating my answer.

Hi. we have a baxi bermuda. I know that you need to hold in the silver button on the left while repeatedly pressing red/ignighter button until pilot is lit. Hold in the silver button for at least another 30 seconds.
Good luck, ours wont light anymore so was on here looking for advice.
Cheryl

is this a baxi 105? chances are you diaphragm has gone on your diverter valve. Or your diverter valve.
Do you will initially get a liitle hot water if your heating is on?