High pressure in heating system and constantly filling

[Si_99]

Hello,

Around 3-4 weeks ago I noticed the TPV overflow pipe at the back of the house was dripping and the system pressure had increased to 3 bar. I bled the radiators (no trapped air) and then ran off some water from a downstairs radiator. Initially this did the trick and the pressure dropped to 1.5 bar, but within 10-15 minutes the pressure was back-up to 3 bar. More recently the dripping from the overflow pipe has increased to a steady pour. Also, I can hear two downstairs radiators constantly filling-up.

The filling loop in the airing cupboard is disconnected and the red expansion vessel next to the cylinder seems to be OK.

If the filling loop is disconnected, why does the pressure stay high at 3 bar?

I've spent several hours trawling the internet for advice (should have come here first!) and one theory is the heating coil in the cylinder might have a leak. How can I check for this?

Any other theories???

Any advice gratefully appreciated.

Cheers.

 

[SimonG]

Couple of theories. Best get a heating engineer.

 

[Si_99]

I spent 2 hours this week with two heating engineers from a local plumbing company and they failed to solve the problem. Before I pay more money for someone else to look at the problem I thought i'd get myself up to speed on the topic on this forum. I'm not looking to put the local heating engineers out of business, merely trying to educate myself so I can better understand the problem and likely fixes.

 

[Howsie]

Firstly don't pay anybody who doesn't fix the problem.

It's a simple fix for a qualified engineer but it will require you taking the case off your boiler which you should be qualified to do as it often serves as a seal against products of combustion.

 

[ShaunCorbs]

turn the water mains off and open a hot tap does the pressure gauge drop?

 

[Si_99]

Turned off mains water and pressure dropped to 0 bar. Didn't need to open the hot tap?

 

[Si_99]

Also, as soon as mains water back on, can hear the two downstairs rads filling-up.

 

[ShaunCorbs]

Turned off mains water and pressure dropped to 0 bar. Didn't need to open the hot tap?

Did it all go out via your blow off out side ? And turn water back on does the pressure rise ?

 

[Si_99]

Yes, pressure went straight back up when water mains back on. Blow off still leaking outside....

 

[Si_99]

A bit more information for you. The boiler is an oil fired Worcester Greenstar 32/50. We ran out of fuel a while back and had an engineer out to clear air block in fuel line. Not sure if this is connected to current problem?

 

[ShaunCorbs]

No not related problem is with the boiler best get and oftec eng out

 

[Si_99]

OK, will do. What do you think the problem is?

 

[ShaunCorbs]

OK, will do. What do you think the problem is?

Can't give that info as your not trained and might try and fix your self but it's faily simple to figure out and any decent eng should know

 

[Si_99]

That's fair enough. At least I can point next engineers in the right direction. Previous lot didn't even look at the boiler! Thanks for your help.

 

[ShaunCorbs]

That's fair enough. At least I can point next engineers in the right direction. Previous lot didn't even look at the boiler! Thanks for your help.

Also get the blow off changed as they never seal right again and always leak after

 

[Si_99]

Will do. Thanks again!