I have had the above boiler for about 2 yrs now. But in the last 4 weeks, it has not been working perfectly.

Whether heating on or off, when I turn hot water on, it gives me sometimes hot or cold water. As the pilot light goes on and off when the heater and/or hot water on, the plumber changed the sensor, but still not working.

In the last few days, the heater seems having problem too because it doesn't give the heat what it is supposed to do. When I touched plumbing (bronzed) pipes, they are not hot at all, not even warm. They used to be quite hot to be tocuhed.

And this morning I noticed that when I put the heater on manually, it didn't start its function immediately. It waited for few minutes before it started, which I think this was wrong because normally it is on immediately after I pressed the on manually.

When the heating is on, I am hearing noises and sometimes they are cracking noises. These noises sometimes on for few seconds and then off again. It does this on and off all the time when the heater is supposed to be on or when I turn the hot water tap on.

I have undefloor heating throughout the house.

Can you please help me what is wrong with my boiler and how to fix it?

Thank you very much.

Lisa Kilvington, January 2007

my boilor if just hot water on the Central Heating comes on, may be the switch control is not working

nadim, September 2010

i had this problem also, was told to change timer, and hey presto worked straight away

roly, December 2008

I am having exactly the same problem and have changed both thermistors, I am a plumber and I am completely baffled

Dave Mason, February 2007

There are 2 thermistors on these boilers, one which is simply for hot water and one that has a triple roll (High Limit, Frost Protection and Central Heating), it is this second one that causes most problems, like the ones you are describing, ask your plumber to change both thermistors.

Ex Ravenheat engineer, January 2007

The "cracking" noise you suggest sounds like the ignition which is quite normal.

Without seeing the appliance in the flesh to perform fault diagnosis I would've gone with the thermistor which it seems you have had change.

There's not much I can suggest you do; apart from get your plumber to check the gas rate of the appliance to see if it's getting onto full rate when it does fire.

GasAid.co.uk, January 2007