Boiler problems 2
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Discussion

jbswagger

Original Poster:

965 posts

231 months

Friday 24th October 2008
quotequote all
Prompted by another thread about plumbing I was hoping the PH massive might be able to help with my boiler and pressure problem

I have an Ideal Mini C24 Combi boiler (no idea if these are any good, it was here when we moved in) and have the opposite problem to the other thread, I have too much pressure. It started when we turned the heating back on about two months ago, I noticed that the pressure was a bit low so topped the system up to about 1 bar when cold with water. When the heating was on the pressure would rise to 4 bar and (off the scale sometimes) and water would come out of an overflow type pipe outside. Whenever the pressure got above 3 bar I would drain off water from the system to get the pressure down to 2.0 bar quickly. Only problem was the pressure would go back up over time (faster when the heating was on) although eventually it settled down after about a week down to 1 bar cold and 1.5 – 2 bar hot.

About three weeks ago I had to drain the system down to take a radiator off and the same problem came back only this time it’s still happening (although it is getting better). I put this down to the fact that I had added central heating treatment this time and this might take a while to “settle down” (I’m no heating expert!). I’ve bled all the rads (never any air coming out) but I’m concerned that I’ve drained off so much water over time to get the pressure down that there will be little water left in the system.

After reading the other thread it would appear my expansion vessel may need pressuring (how do you do that). Also after searching the net the heat exchanger may me broken (would this explain why the hot water isn’t as hot as it used to be)?

Apologies for the long post but anyone have any idea what is going on as it’s doing my head in!

Orb the Impaler

1,881 posts

220 months

Friday 24th October 2008
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i thought this was going to be a thread about Mrs Orb(s) biggrin

jbswagger

Original Poster:

965 posts

231 months

Friday 24th October 2008
quotequote all
Up.

Big Al.

69,336 posts

288 months

Friday 24th October 2008
quotequote all
Just had a similar problem, pressures all over the place Hi then Low then Hi, turned out to be a knackered pressure vessel, had it replaced this week and all is back to normal thank God. Pressure fluctuates by about a bar around 1.5 to 2.5 depending on what's running.

dangerousB

1,701 posts

220 months

Friday 24th October 2008
quotequote all
Sorry, thought this was another "relationship trouble" thread

jbswagger said:
it would appear my expansion vessel may need pressuring
. . . hang on wink

Pigeon

18,535 posts

276 months

Friday 24th October 2008
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If the episodes of rising pressure follow you having to put more water into the system then it makes me wonder if the fill valve is leaking a bit and gradually oozing more water into the system.

In theory one is supposed to take the fill loop off after using it but nobody-obody ever ever does.

Ferg

15,242 posts

287 months

Friday 24th October 2008
quotequote all
As Pigeon says, it may be the filling loop valve leaking. They are crappy plastic things and often the plastic turns leaving the actual valve partially open.

If the vessel is fked, the pressure will rise alarmingly when heat is applied to the heat exchanger. This will inevitably result in water being discharged out of the safety relief which will blow at 3Bar. On cooling the pressure will drop well below te 1Bar we tend to recommend.



jbswagger

Original Poster:

965 posts

231 months

Friday 24th October 2008
quotequote all
Pigeon said:
If the episodes of rising pressure follow you having to put more water into the system then it makes me wonder if the fill valve is leaking a bit and gradually oozing more water into the system.

In theory one is supposed to take the fill loop off after using it but nobody-obody ever ever does.
Thanks for the reply

I haven't added any water since filling it up three weeks ago, only had to drain it off.

jbswagger

Original Poster:

965 posts

231 months

Friday 24th October 2008
quotequote all
Ferg said:
As Pigeon says, it may be the filling loop valve leaking. They are crappy plastic things and often the plastic turns leaving the actual valve partially open.

If the vessel is fked, the pressure will rise alarmingly when heat is applied to the heat exchanger. This will inevitably result in water being discharged out of the safety relief which will blow at 3Bar. On cooling the pressure will drop well below te 1Bar we tend to recommend.
Cheers I'll disconnect the loop to check. How do I check if the vessel is gone?

Ferg

15,242 posts

287 months

Friday 24th October 2008
quotequote all
If you try to let a little air out of the valve on the vessel (this may well be almost impossible to get to smile ) you'll get a spurt of water.