Under Pressure! From the Combi!

jspireite · 15 Dec 2006

When my CH not operating for several hours, say, overnight, the operating pressure drops to zero and won't function unless I top the system up from the tap. It, then, seems to run fine until the next time. I have done this procedure some 10 times now. There are no obvious system leaks as far as I can see and all the radiators are bled. The hot water seems to create more pressure in the system and seems uneffected.

Appreciate any advice, or is this an engineer call out prob.?

Thanks!

weareleeds · 15 Dec 2006

When system is cold put pressure to about 1 bar & then switch on htg. After about 10 mins observe pressure gauge if it is going very high your pressure is being lost out of prv so exp vessel will need pumping up

Alfredo · 15 Dec 2006

What the make and model of combi, sometimes this is relevant, sometimes not when this sort of thing happens, but its always useful to know what we are dealing with.

Alfredo

jspireite · 16 Dec 2006

weareleeds said:
When system is cold put pressure to about 1 bar & then switch on htg.After about 10 misn observe pressure guage if it is going very high your pressure is being lost out of prv so exp vessel will need pumping up

Thanks. I'll give it a try.

ChrisR · 16 Dec 2006

See Boiler Pressure Problems in the FAQs

jspireite · 16 Dec 2006

Alfredo said:
What the make and model of combi, sometimes this is relevant, sometimes not when this sort of thing happens, but its always useful to know what we are dealing with.

Alfredo

Boiler is Baxi 105E.

Thanks

jspireite · 16 Dec 2006

ChrisR said:
See Boiler Pressure Problems in the FAQs

Cheers!

m.900 · 16 Dec 2006

Hi, did you sort out the problem as I am having exactly the same on my baxi 80 eco.

jspireite · 17 Dec 2006

m.900 said:
Hi, did you sort out the problem as I am having exactly the same on my baxi 80 eco.

Not tried suggestion of cranking pressure up to 1 whilst cold, then running for 10 mins, yet. To see if prob with press relief valve. Has been suggested a system leak may occur there. Busy browsing useful FAQs. Let you know if sort it.

System seems to work ok thro day. Just gradual topping up seems to sort it. Or do I need to look at PRV or EXP. My main concern is I have a system leak I don't know about! Can't get 2 PRV??!!

I hate these uncertainties!

HELP!

Novice

System seems to work ok. JUst gradual topping

jspireite · 17 Dec 2006

weareleeds said:
When system is cold put pressure to about 1 bar & then switch on htg.After about 10 misn observe pressure guage if it is going very high your pressure is being lost out of prv so exp vessel will need pumping up

Tried that Wlds. Pressure didn't go up. Fine. System operating fine. Only goes down (pressure) if left for long time. (Quite slowly).

Any ideas?

Cheers!

Softus · 17 Dec 2006

jspireite said:
Only goes down (pressure) if left for long time. (Quite slowly).

You have a leak.

In case the FAQs don't mention it, strap a plastic bag under the end of the PRV exit tube (outside) until the pressure drops. It if collects water then the leak is caused by a faulty PRV, which you can replace.

Wherever the leak is you need to find it, not just top up every time you need to use the central heating, otherwise the system will corrode quite quickly and cost you a lot of unnecessary money in the long term.

jspireite · 17 Dec 2006

jspireite said:
m.900 said:

Hi, did you sort out the problem as I am having exactly the same on my baxi 80 eco.

Click to expand...

Not tried suggestion of cranking pressure up to 1 whilst cold, then running for 10 mins, yet. To see if prob with press relief valve. Has been suggested a system leak may occur there. Busy browsing useful FAQs. Let you know if sort it.

Go to FAQ They tell you hoe to access PVV.

System seems to work ok thro day. Just gradual topping up seems to sort it. Or do I need to look at PRV or EXP. My main concern is I have a system leak I don't know about! Can't get 2 PRV??!!

I hate these uncertainties!

HELP!

Novice

System seems to work ok. JUst gradual topping

jspireite · 29 Dec 2006

Softus said:
jspireite said:

Only goes down (pressure) if left for long time. (Quite slowly).

Click to expand...

You have a leak.

In case the FAQs don't mention it, strap a plastic bag under the end of the PRV exit tube (outside) until the pressure drops. It if collects water then the leak is caused by a faulty PRV, which you can replace.

Wherever the leak is you need to find it, not just top up every time you need to use the central heating, otherwise the system will corrode quite quickly and cost you a lot of unnecessary money in the long term.

Done that. No noticeable water.

Pressure loss only very slight now. Is this common with PRV leak?

Thanks

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Under Pressure! From the Combi!

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