Urgent Central Heating System Pressure Problem

[Nigel B]

Good evening everyone,
New to the forum, hopefully someone can help with a problem which has just developed with our central heating system.

We have a sealed / pressurised system which has been working pretty much perfectly for many years. Aside from needing to increase the pressure a couple of times a year from say 1bar upto 1.5bar, nothing else has needed attention.

This evening I came home to find our kitchen ceiling looking damp, so a quick run up the stairs to the airing cupboard revealed some issues. The CH pressure gauge was reading 3.4bar, and therefore the PRV had opened and was releasing water down the drainage pipe via the tundish. Unforutnately the tundish didnt line up very well with the pipework and so most of the water was on the floor, and subsequently on the kitchen ceiling.

First thing for me to confirm is that my filling loop is NOT connected!

My next thought was to try and reduce the CH pressure by bleeding some radiators and letting some water out. This had no effect on the pressure.

Next i turned off the cold water supply to the house to see what effect this had. Nothing immediately. I then ran a hot tap, and noticed the pressure on the CH gauge beginning to drop. However as soon as i turn the cold water mains supply on again, the pressure shoots back up to 3+ bar.

I've turned the boiler off of course whilst all this is going on, however obviously this means no heating and no hot water, so i'm desperate for your help!! :confused5::confused5:

Hope someone can reply soon.
Many thanks,
Nigel

 

[SimonG]

Urgently call a gas safe engineer. Sounds like somethings split.

 

[lame plumber]

difficult to say, as you tell us its your ch system blowing off, but from the airing cupboard which means it could be an unvented cylinder issue. Your best and only safe option is to isolate the boiler and call an unvented qualified gas technician first thing in the morning, to carry out a fairly simple fix for most of us. But as it is a safety issue, we wont be advising you on how to do it at present.

 

[Dotty]

Agreed, unfortunately this isn't a diy repair.

Whereabouts are you, we might have someone nearby who can help.

 

[Nigel B]

Hello Simon,
Thank you for your reply.

For what its worth, its an oil fuelled system boiler setup....

Because of the way the cold water pressure appears to be directly affecting the CH system pressure, i agree that i think something has split.

I didnt want to comment further as I was hoping someone would tell me their thoughts and confirm my own diagnosis, but i think the coil within the hot water cylinder has split, allowing the cold mains pressure to mix with the central heating system primary circuit....

Any further thoughts?

Thank you
Nigel

 

[lame plumber]

turn off the cold supply to the cylinder in the airing cupboard overnight. just wondering why your central heating pressure gauge is in the airing cupboard and not on the boiler, are you sure its not the hot water vessel pressure gauge your looking at?

 

[SimonG]

Aye, could have given all info in first post. Never mind.

Any chance of some pics of the airing cupboard Nigel?

 

[Nigel B]

Thank you lame plumber and croppie for your replies!

I think the coil within the cylinder has split - would you agree?

 

[lame plumber]

Thank you lame plumber and croppie for your replies!

I think the coil within the cylinder has split - would you agree?

could be a simpler problem but I am not sure whether your talking ch system pressure or unvented cyl pressure

just isolate cold feed to hw cyl, to prevent feeding possible split and another problem and turn off your boiler overnight till techie gets to have a look. turn on hot tap to remove excess pressure and off again to check pressure is no longer an issue overnight.

 

[Nigel B]

Photos coming in just a second....

 

[lame plumber]

doh, was going to bed....

 

[Dotty]

Cheers Nigel, but either or.

You will need a qualified person. OFTEC guy with g3.

Whereabouts are you?

 

[Dotty]

doh, was going to bed....

Have you had your horlicks then, gramps......

 

[lame plumber]

Have you had your horlicks then, gramps......

got my second little one due on 1st of March, just cancelled the wrist op on the 29th of Feb, so I can be around and useful (not an invitation for abuse folks), going for a single malt and looking for a 12 bore to blow away a certain bird!!!!!!!!!!!1

 

[Nigel B]

 

[Dotty]

You really need a g3 in. Sharpish.

 

[Rickster123]

Is that a coke bottle cut in half to make a tundish?! Or is it just my eyes?!

 

[SimonG]

The water is the least of your worries. You will need a g3 engineer (unvented cylinder) to have a look. Kill the mains cold to the cylinder. Should be able to run your heating as a very short term stop gap.

Wouldnt mind seeing the rest of the cylinder.

 

[Nigel B]

Is that a coke bottle cut in half to make a tundish?! Or is it just my eyes?!

Its a bottle cut in half, sat in the proper tundish, in order to try and capture any escaping water better than the tundish alone managed originally!

 

[Nigel B]

 

[lame plumber]

3 port on an unvented, your missing some essential safety features, as Mr Cropp states, get someone in to sort out that set up asap.

 

[Nigel B]

3 port on an unvented, your missing some essential safety features, as Mr Cropp states, get someone in to sort out that set up asap.

Whilst I don't understand the issues, that sounds worrying. This setup is as new when the house was built 12 years ago.... i'm surprised that something would be incorrect?

Thank you for any input

 

[Dotty]

3 port on an unvented, your missing some essential safety features, as Mr Cropp states, get someone in to sort out that set up asap.

Thought I was the only one who spotted that!

 

[lame plumber]

Thought I was the only one who spotted that!

I borrowed you stool to see it............

 

[lame plumber]

Whilst I don't understand the issues, that sounds worrying. This setup is as new when the house was built 12 years ago.... i'm surprised that something would be incorrect?

Thank you for any input

To be honest, so are we...