Boiler problem

[AMO]

I have a problem with my boiler.

It heats the water up for general use just fine.

However, every year it gets hard and harder to get it to heat up the cental heating.

Basically, on the front of the boiler there is a dial from 1-5 and then Max.

Three years ago, when it was on the 3 setting, it would heat up the radiators.

Two years ago, I needed to increase this to 4.

Last year I needed to increase this to 5.

This year, even at Max it won't pump hot water to my radiators. The boiler works fine for hot water.

Unfortunately this setting I believe controls the temperature at which the water is boiled to, so I don't want to leave it on Max.

Is it because of air pressure in the boiler thats causing this problem?

Is it something I can fix myself?

Can anyone recommend a newsgroup or website to ask about these things?

I had a similar problem at my parents house a couple of years ago. Got a cental heating engineer to come out. He had something that looked like an aerosol can and he connected it to the boiler and said he was depressurising something. After that, the boiler was fine. Having said that, the problem at my parents house was that the boiler would start and then stop within a couple of seconds and not heat the water.

Anyway, I don't want to call someone out for £50+ just for them to press a few times on some kind of aerosol can - I figured I could do that if I can buy the equipment.

Any suggestions?

AMO

[a_mcbride]

Good site here to ask boiler questions =

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[Set Square]

It would help more than somewhat if you were to tell us the type of boiler you have - conventional (heating a tankful of hot water + radiators) or combi (providing instant but not stored hot water + radiators) - and also the make and model. Any further information you can give about programmers, room and/or cylinder thermostats, zone or diverter valves etc. would also be useful - plus whether the water flowing round the radiators is vented (open to atmosphere, with a small header tank) or pressurised (with a pressure/expansion vessel, filling loop and pressure gauge).

If you are to fix your own system, it is important to understand how it works. If you are unable to supply the information listed above, I would respectfully suggest that you probably shouldn't be messing with your system.