Why's my boiler gone over-pressure?
Alpha Combi boiler. Working fine, or so I thought.
A bit chilly this evening, so put the heating on for the first time in 3 weeks or so. Pressure was a little low, so fill up to the recommended 1 bar. Tap is shut off. Heating comes on fine. 20 minutes later, I'm outside and hear water running - the pressure relief/overflow from the boiler is spewing out a bit more than a trickle, but less than a hosepipe, of hot water. Back inside, turn off heating. Notice pressure guage now at 4 bar, hence the pressure relief. First thought, air in system, though bleeding all the rads doesnt produce much air - typical of what I'd expect after not being done for 6 months. Pressure now down to 2 bar when it is cool. So, why has this happened? The pressure relief has never opened, to my knowledge, in the 8 years we've had the boiler. All rads were warm, though not hot. Thanks Alan. -- To reply by e-mail, change the ' + ' to 'plus'. |
Why's my boiler gone over-pressure?
So, why has this happened?
Could be a faulty pressure vessel... |
Why's my boiler gone over-pressure?
On Wed, 28 May 2008 21:48:56 +0100, A.Lee wrote:
First thought, air in system, though bleeding all the rads doesnt produce much air - typical of what I'd expect after not being done for 6 months. Shouldn't produce any "air" at all after a system has been in use for a while. Routine bleeding of radiators is indicative of either lack of a inhibitor (thus the "air" is hydrogen from corrosion of the steel rads) or there is fresh water being introduced on a regular basis. Pressure now down to 2 bar when it is cool. Pressure gauge was lying initially, did you give it a little tap? -- Cheers Dave. |
Why's my boiler gone over-pressure?
On Wed, 28 May 2008 21:48:56 +0100, A.Lee wrote:
Pressure was a little low, so fill up to the recommended 1 bar. Tap is shut off. Heating comes on fine. 20 minutes later, I'm outside and hear water running - the pressure relief/overflow from the boiler is spewing out a bit more than a trickle, but less than a hosepipe, of hot water. Back inside, turn off heating. Notice pressure guage now at 4 bar, hence the pressure relief. First thought, air in system, though bleeding all the rads doesnt produce much air - typical of what I'd expect after not being done for 6 months. Pressure now down to 2 bar when it is cool. http://wiki.diyfaq.org.uk/index.php?... sure_dropping (or go to http://wiki.diyfaq.org.uk/index.php?...Heating_Repair and navigate to section "system pressure dropping") -- John Stumbles I used to think the brain was the most interesting part of the body - until I realised what was telling me that |
Why's my boiler gone over-pressure?
"A.Lee" wrote in message ... Alpha Combi boiler. Working fine, or so I thought. A bit chilly this evening, so put the heating on for the first time in 3 weeks or so. Pressure was a little low, so fill up to the recommended 1 bar. Tap is shut off. Heating comes on fine. 20 minutes later, I'm outside and hear water running - the pressure relief/overflow from the boiler is spewing out a bit more than a trickle, but less than a hosepipe, of hot water. Back inside, turn off heating. Notice pressure guage now at 4 bar, hence the pressure relief. First thought, air in system, though bleeding all the rads doesnt produce much air - typical of what I'd expect after not being done for 6 months. Pressure now down to 2 bar when it is cool. So, why has this happened? The pressure relief has never opened, to my knowledge, in the 8 years we've had the boiler. All rads were warm, though not hot. Thanks Alan. -- To reply by e-mail, change the ' + ' to 'plus'. Did you remove the filler pipe after topping up the pressure? If not tap may not have been properly closed Tony |
Why's my boiler gone over-pressure?
In an earlier contribution to this discussion,
A.Lee wrote: Alpha Combi boiler. Working fine, or so I thought. A bit chilly this evening, so put the heating on for the first time in 3 weeks or so. Pressure was a little low, so fill up to the recommended 1 bar. Tap is shut off. Heating comes on fine. 20 minutes later, I'm outside and hear water running - the pressure relief/overflow from the boiler is spewing out a bit more than a trickle, but less than a hosepipe, of hot water. Back inside, turn off heating. Notice pressure guage now at 4 bar, hence the pressure relief. First thought, air in system, though bleeding all the rads doesnt produce much air - typical of what I'd expect after not being done for 6 months. Pressure now down to 2 bar when it is cool. So, why has this happened? The pressure relief has never opened, to my knowledge, in the 8 years we've had the boiler. All rads were warm, though not hot. Thanks Alan. Chances are that the pressure vessel is shot [1]. That would certainly explain the symptoms because (a) it would cause the pressure to drop (prompting you to top it up) and then (b) it would have no resilience to absorb the expansion volume when the system gets hot - causing the pressure to build up to the point where it triggers the pressure relief valve. [1] There are degrees of shottedness - some of which are fixable just by topping up the air through the schrader valve, and some of which are not without replacing the whole thing -- Cheers, Roger ______ Email address maintained for newsgroup use only, and not regularly monitored.. Messages sent to it may not be read for several weeks. PLEASE REPLY TO NEWSGROUP! |
Why's my boiler gone over-pressure?
On Thu, 29 May 2008 14:28:04 +0100, Roger Mills wrote:
[1] There are degrees of shottedness - some of which are fixable just by topping up the air through the schrader valve, and some of which are not without replacing the whole thing Or more practicably by adding a new one externally, in the many cases where you'd have to virtually dismantle the boiler to get at the one built-in. -- John Stumbles Bob the builder / it'll cost 'yer Bob the builder / loadsa dosh |
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