Water Too Hot & Bolier Overheating

[JustDoItY]

Hi

I hope someone can help me.... We have a Biasi combi boiler - not sure of the model.

CH works well alone but as soon as a water appliance goes on ie dishwasher the temperature creeps up to over 90 degrees which then overheats making the overheat button pop out. The water coming out of the taps is constantly too hot too (scalding).

We have recently had a new pump put in & the bolier is about 7/8 years old. We have had various engineers round but they seem to tell us different things.

So far on hear it sounds like maybe the gas valve?

 

[Agile]

This is a very simple fault for any competent engineer to diagnose.

Nothing to do with the gas valve unless it has been misadjusted in whcih case it would need setting but not changing.

Have you really had CORGI registered boiler engineers or just some kind of "plumber"? Its very sad if anyone is pretending to fix boilers when they obviously dont have a clue.

The first thing to check with the boiler cold is the resistance of both temperature sensors.

Next is to run 9 litres per minute from a hot tap and measure the inlet and outlet temperatures of the hot water.

Tony

 

[Aquaheat]

Has anybody checked the temperature sensors as this is most likely to be the cause. Very doubtful that it will relate to the gas valve.

 

[JustDoItY]

Thanks for getting back to me, how do I check the following that you suggested-

"The first thing to check with the boiler cold is the resistance of both temperature sensors. "

"Next is to run 9 litres per minute from a hot tap and measure the inlet and outlet temperatures of the hot water. "

This will be done by someone alot more competent than I am but I just want to relay the instructions clearly!!

 

[Aquaheat]

To check for resistance you will need a multimeter all good engineers will carry them.

To check inlet temperature you can run the mcw tap and use a probe, again any good engineer will have one.

To check flow rate then you can use a weir gauge or a bucket with graduations marked on it.

To check outlet temperature use the same probe and use it on the hot tap as apposed to the cold.

Simplezz