dropping pressure in my gas linea 24 boiler
- Thread starter tu_pence
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tu_pence said:
Are you saying you have to repressurise the system once the heating has been off or that the pressure drops then returns when heating is on?
'Safety Valve replaced and no leaks found'. Did a Pro replace the valve and if so was it the pro who checked for leaks?
You may have a leak beneath the downstairs floors which is VERY difficult to identify as the water leaks straight into the ground below.
A bit more info and background needed.
The pressure drops but returns once the heating comes back on. however, if heating is off for more than 3 hours i have to repressurise the system.
A pro replaced the valve. should i check the outside copper pipe to see if it is still leaking water?
A friend from the building trade check for leaks. He did pull up the floor board to check for leaks under the house (there is a bit of a basement). He has recommended a pro to check the pipes under the house properly.
could it just be a problem with the boiler.
I've even had a man out from the water service to check water pressure and it's 4.5 bars and 20 gallons a minute, which he said is very good. Before my boiler problems the pressure gauge would only sit as 1.5 pressure. Is that normal? could is possibly be the boilers connection to the water mains?
A pro replaced the valve. should i check the outside copper pipe to see if it is still leaking water?
A friend from the building trade check for leaks. He did pull up the floor board to check for leaks under the house (there is a bit of a basement). He has recommended a pro to check the pipes under the house properly.
could it just be a problem with the boiler.
I've even had a man out from the water service to check water pressure and it's 4.5 bars and 20 gallons a minute, which he said is very good. Before my boiler problems the pressure gauge would only sit as 1.5 pressure. Is that normal? could is possibly be the boilers connection to the water mains?
The pressure on the gauge on the boiler is NOT the same as the mains water pressure. You use mains pressure to refill the heating system (and therefore 're-pressurise' the boiler) but once you close the filling valve, the two pressures are completely unrelated. That's the way it's supposed to be! If you're losing pressure in the heating system, then either it's because water is going down the wall outside due to a boiler fault or you have a leak in a heating pipe somewhere else. The 'design pressure' for most heating systems is about 1 Bar. Working pressure should not exceed 2 Bar. The Pressure Relief Valve should open at 3 Bar (and water runs down the wall).
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tu_pence said:
I assume from what you are saying that the 'Pro' replaced the PRV (pressure Relief Valve) due to the system losing pressure out of the Blow Off pipe. Yes you should check if the copper pipe (blow off pipe) outside is still leaking water. If it is get the 'Pro'
back and tell him there is still a problem. I'm curious, did the 'Pro' cure the problem and it has subsequently returned or has the problem been a continuous one?Yeah 1.5 is right for the pressure. Are you filling it up higher than that? If so, when the system heats up its possible the PRV is blowing off due to the fact you are pressurising too high.
Time for a new pressure vessel methinks
The problem has been a continous one. I would repressurise the boiler to about 2.5.
Were, what how much is a pressure vessel?
also, when the heating comes on my radiators would make a whistling noise but his stops if i move the valve. could this be related?
Were, what how much is a pressure vessel?
also, when the heating comes on my radiators would make a whistling noise but his stops if i move the valve. could this be related?
Dont re pressurise to more than 1.5 with the system cold. Run it on that, take note of how far the pressure goes up and down when you use it. keep an eye on the PRV to see if it leaks and report back
Taking it to 2.5 hammers your PRV as Blasphemous has said
Taking it to 2.5 hammers your PRV as Blasphemous has said
FINALLY, got someone out to check for leaks. None found. he put a bung on the outside copper pipe. he told me to keep an eye on the pressure. (he had left the boiler at 1.5 pressure) within 30 mins pressure was up to 3 bar (he told me if this happend to turn heating off), I turned the boiler off and then water started coming out of a copper pipe in the boiler. It stopped once pressure was at 1.5 bar.
dont bung up the pipe outside, it is from the safety valve and is there to relieve pressure if things go wrong.
water coming from inside the boiler means you may have damaged something else by blocking the saftey valve pipe with that bung.
I'd let all pressure off completely so there no pressure on the gauge, leave the SRV open for another 30 seconds so air can be heard gurgling into the boiler.
on the top of the Linea at the back below the flue pipe (if it exits just above the boiler) there is a small valve cap (like what you have on your car tyre). check it has 1.5 bar in there and if not pump it up with a bike or car tyre pump. once it's up to pressure add water through the fill line as normal to bring the pressure on the gauge up to 1.5 bar.
I had no end of bother with mine until I discovered my pressure vessel was empty.
see how it goes once youve done this
if it drips out of SRV then it's probably best to get a new one although I have taken my leaky one off and dismantled it and cleaned it and it now is ok. seems to be that if they have activated then crud can get into the seat and they leak all the time. if it leaks then clean it or replace.
also as you look at the boiler behind the pump there is another tyre valve cap, this is the auto air bleed. make sure it is 1 full turn open or loose so that it lets air out of the system. once you refill it you will here it fizz as air is let off.
good luck
Webbie
water coming from inside the boiler means you may have damaged something else by blocking the saftey valve pipe with that bung.
I'd let all pressure off completely so there no pressure on the gauge, leave the SRV open for another 30 seconds so air can be heard gurgling into the boiler.
on the top of the Linea at the back below the flue pipe (if it exits just above the boiler) there is a small valve cap (like what you have on your car tyre). check it has 1.5 bar in there and if not pump it up with a bike or car tyre pump. once it's up to pressure add water through the fill line as normal to bring the pressure on the gauge up to 1.5 bar.
I had no end of bother with mine until I discovered my pressure vessel was empty.
see how it goes once youve done this
if it drips out of SRV then it's probably best to get a new one although I have taken my leaky one off and dismantled it and cleaned it and it now is ok. seems to be that if they have activated then crud can get into the seat and they leak all the time. if it leaks then clean it or replace.
also as you look at the boiler behind the pump there is another tyre valve cap, this is the auto air bleed. make sure it is 1 full turn open or loose so that it lets air out of the system. once you refill it you will here it fizz as air is let off.
good luck
Webbie
I bleed the boiler and then pumped 1.5 bar air pressure into valve as suggested. however this pressure also showed on my boiler gauge but to my mind it should only show water pressure not air pressure. So I put water in the boiler until it read 2 bar. but after the heating was on 5 mins the pressure was up to 3 bar so I realised some air pressure. should this have happened?
The boiler repair man has said I prob need a new expansion vessel. does that sound right?
The boiler repair man has said I prob need a new expansion vessel. does that sound right?
once youve pumped up expansion vessel try and see if more water comes out.
the gauge might show pressure but your only interested in the expansion vessel pressure for now (which is just air)
try leaving the SRV open (or whatever you have open to let the water out) whilst pumping up the expansion vessel.
once your happy with your expansion vessel pressure you should then start adding water and the gauge should rise.
make sure you disconnect the fill pipe afterwards as the fill valve could pass and add water slowly without you knowing.
it sounds like you have the same problem I had going by your last reply. my problem was a knackered heat exchanger which kept adding tap water to the central heating circuit. If you keep having to drain the system pressure then it's probably the heat exchanger thats gone especially if after a few days you drain everything and check that your expansion vesssel is still at 1.5 bar.
remember to disconnect the fill line as it could pass.
you have to figure out if the pressure keeps rising where the water is coming from.
good luck
Webbie
the gauge might show pressure but your only interested in the expansion vessel pressure for now (which is just air)
try leaving the SRV open (or whatever you have open to let the water out) whilst pumping up the expansion vessel.
once your happy with your expansion vessel pressure you should then start adding water and the gauge should rise.
make sure you disconnect the fill pipe afterwards as the fill valve could pass and add water slowly without you knowing.
it sounds like you have the same problem I had going by your last reply. my problem was a knackered heat exchanger which kept adding tap water to the central heating circuit. If you keep having to drain the system pressure then it's probably the heat exchanger thats gone especially if after a few days you drain everything and check that your expansion vesssel is still at 1.5 bar.
remember to disconnect the fill line as it could pass.
you have to figure out if the pressure keeps rising where the water is coming from.
good luck
Webbie
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tu_pence said:
Diaphragm is gooshed me thinks. New Expansion Vessel needed.
The person you got out to 'check for leaks' and subsequently decided to Bung the PRV (Copper Pipe Outside) needs to learn one or two things before he starts sticking Bungs in pipes! Blocking that pipe could cause damage to your boiler. The PRV is there for a reason and if Pressure gets too high that's when the PRV comes into action... to relieve the pressure before it causes any damage.
I feel my knowledge of the Gas Industry is low compared to someone like Slugbaby but reading things like Bungs being stuck in PRV pipes gives me more confidence everyday that at least I'm not at the bottom of the pile... hopefully!
This set my alarm bells ringingtu_pence said:
Pressure vessel definitely gone
This turned my alarm bells off or at least quietened them down. Not the way I would recommend doing it but it at least indicated that this was only while things were being monitored and a reasonably safe procedure was being followed
In a later post I saw
You already said the leak is coming out of a pipe in your boiler
Ok heres some of what you missed when you nicked off from school all them years ago
A liquid cannot be compressed. Water does expand and contract between 4ºC and freezing as I recall it expands about another tenth of its original volume. We are concerned with the expansion between 4ºC and its gaseous state which is 100ºC at normal atmospheric pressure and 143.6ºC at 3 bar. This expansion is as I recall a 20th of its original volume. ie 20 litres becomes 21 litres.
The liquid needs somewhere to expand to, so by having a compressible gas [air] in a pressure vessel separated by a rubber diaphragm a provision is made for this expansion.
The short version of this is that your guage shows the air pressure exerted on the water in the system
Depletion of the gas in the pressure vessel results in excessive pressure readings on your guage when the water is heated.
When you followed the instructions given by we88ie
and pumped up the pressure vessel. It was nearly full of water. If you didnt leave some way for the water to get out then all you did was increase the volume of air by a small amount.we88ie said:
Explain this more if you can. I'll try my take on what you said here.
Valve = Pressure relief valve = PRV or as we88ie calls it an SRV
So with the 'valve' open you pump air in. Yes?
If it pumps out then where is it pumping out to?
My interpretation is that you either just need to do more pumping or that the air you are pumping in is just going into the system through the knackered diaphragm.
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