worcester bosch greenstar 18i - over pressure

[delstevens]

Morning all

Just had my central heating system over-pressure with a massive release of air and a dump of several gallons of hot water out through an overflow. I was sort of expecting some escaping air as I've been trying to get air out of the system for a couple of days, but this completely drained the pressurised system - now reading 0 bar.

I'd like to reset the system.

The T&P release valves didn't appear to be where the water was released from, but the air pressure definitely released through the valve to the side of the tank as the water flowed through the relief line to the U shaped outflow pipe outside.

Boiler is off and system is now cool but my first attempt to use the filling loop failed to show any increase in pressure in the system - so I think there must be a valve open somewhere that I can't see / don't know about.

Grateful for any help you can provide.

Cheers

Del

 

[Simon F]

hello Del and welcome to the forum.
short answer is that you need to get someone in to check why you have had the issues in the first place.

as to putting pressure back in, what is the problem with the fill loop, is it not opening?
does it have 2 taps, are you only opening one of them?

 

[delstevens]

as to putting pressure back in, what is the problem with the fill loop, is it not opening?
does it have 2 taps, are you only opening one of them?[/QUOTE]

thanks for the reply. Problem isolated - I was looking at T&P valves on the cylinder (4.5 Bar) but the 3 bar valve on the back of the boiler is the one that went.

And it was almost certainly my fault.... For anyone reading this who has a similar system.....

Cylinder in the loft with a local pressure gauge where expansion tank and filling loop are.

Boiler - ground floor in the kitchen with it's own pressure gauge.

Gauge in loft registers one pressure (i.e. 1.5 bar) but GRAVITY invcreases the pressure at the boiler to be >2bar.
Once the water get's hot, boiler pressure exceeds three bar and the valve blows (exactly as it should).

Valve wouldn't re-seat and so the filling loop was just pouring water straight through the system and out into the back garden!!!

A replacement valve now fitted on the boiler (£90) and all is well once more!!

 

[Rob Sale]

Thats an unvented cylinder don't play with that get a pro in bud, who has unvented cylinder tickets. 1 you could damage the cylinder if pressure not balanced right. 2. or a serious incident.

I'm a qualified gas engineer and i don't mess with these things cuase i don't have the ticket and 2. don't know awful lot about it. turn everything off and call someone out.