glowworm betacom-24

[joorange]

our newish (4 yrs) boiler loses pressure when the CH is on but not when we are just using hot water.

We've checked the rads and the connectors under the boiler for water leaks and haven't found any so we're at a loss as to why it needs repressuring whenever we've had the heating on for a few hours.

This is a problem that's got gradually worse over 12 months, from needing repressurising after a few months to every day.

We have two underfloor heating systems and I'm concerned that they could be the problem.

Any suggestions as to what the problem could be please?

 

[misterdubya]

You have had it serviced, haven't you?

 

[dcawkwell]

Expansion vessel.
Is pressure going up and up when you turn the heating on and then dripping from the pressure relief valve outside?

 

[misterdubya]

Expansion vessel.
Is pressure going up and up when you turn the heating on and then dripping from the pressure relief valve outside?

An annual service would include a check of the EV Pre-Charge. Why have a boiler serviced? Its not as if it a potentially lethal appliance - running on fossil fuels and fixed inside your house is it?

How is a 4 year old boiler 'newish'?

How old is your car OP, and when was that last serviced?

 

[Agile]

Virtually NO servicing engineers check the pre charge pressure ( with the system at zero pressure ).

I dont do it either but I do check the efficiency of the EV by watching the pressure increase as the CH is warmed up. That has the advantage of also checking that the communication pipe is not blocked as well as an adequate air charge.

 

[joorange]

thanks for all the responses - its given me a useful starting point.

I have to admit to considering a 4 year old boiler still relatively new or rather 'not old' - the boiler in my old house was about 30 years old and ran like a dream! I stand corrected.