Combi boiler - any ideas what's wrong?

[Madmog]

We have an Ideal Response 100 combi (not jokes please!). This morning put heating on and after about a minute a gurgling sound could be heard in pipes from boiler and the pressure gauge shot up. There was no heat in radiators, but boiler was warm. Have also noticed that when hot water tap is switched off, you no longer hear a whoosh of water in the radiators and the open radiator is cold when it would normally be slightly warm. There's no air in radiators as I've aired them since. Has anyone any ideas what could be wrong and if it's likely to be expensive as I'm wondering if it's worth getting a new boiler given the number of problems with Ideal Response.

 

[doitall]

Sounds like the expansion vessel has gone.

Best and cheapest plan would be to fit an external vessel into the heating return pipe.

 

[kevplumb]

stuck pump

 

[Agile]

Bleeding rads is not a good idea if you dont repressurise afterwards.

Set to about 1.5 Bar.

It may still show a low pressure light inside if the sensor has become bunged up with dirt.

Tony

 

[Madmog]

We normally keep our pressure at 1.2bar when cold and it's still on this after airing radiators and going cold again.

 

[doitall]

if it's working ok now, then it may been a slug of air in the system, or as Kev said a sticky pump.

 

[Agile]

Is it working now?

Tony

 

[bengasman]

If you can afford replacing it properly with a good boiler, go for it. Failing that, get boiler breakdown cover, it will save you a lot of money.

 

[Madmog]

Tony, the boiler is still the same as above - we have hot water and central heating is causing problems. Our engineer will call out later - reckons expansion vessel needs pumping up. The vessel is only two years old so reluctant to replace it again if there is a hole.

 

[Agile]

I am now starting to be able to diagnose what you have written.

The boiler is working fine but the EXV has failed.

It may be possible to repressurise it but if not then an external one can be added.

Tony