Discuss Losing pressure on a new worcester boiler, but there have been times it has been (temporarily) fixed in the Plumbing Jobs | The Job-board area at PlumbersForums.net

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Hi,
I would love to get some expert thoughts on my pressure loss problem.
I have just replaced my boiler and radiators to fix a raft of problems with the heating system mostly caused by old radiators filled with sludge. Unfortunately the loss of pressure hasn't been fixed.
There are no signs of leaks any where and most of the house is over a studio flat in the basement, so we would be likely to see signs of leaks in our ceilings or in the flat below.
At the moment I have to refill the system every 1 to 2 days. However there have been a couple of circumstances that seem to have fixed the problem for a couple of weeks, which makes me wonder if it is a leak.
The first was when the water board decided to change my meter - this was when the old boiler was still in place. After they had finished our water supply was shot. Pressure was down. Toilet flushes would endlessly refill etc. It seems that dirt got into the system, so they sent a contractor out with a compressor to clear the dirt out of the system. This not only cleared the problem but for about two weeks the pressure gauge sat happily on the same bar, before slowly over about a week starting to lose pressure increasingly quickly until I was back to topping up the old boiler at least once a day. One engineer said it must have been coincidence, but I don't really buy that. I am sure that that process did something to stop the problem for a bit.
A similar thing happened after the new install. I thought everything was great for the first week. The second week was still okish but I started to see a slight drop in pressure, now after 3-4 weeks I am back to topping up regularly, though it is still a bit better than the old boiler.
The other thing I notice is that when I turn on the kitchen tap which is right by the boiler I can often see the pressure drop quite noticeably - about 1/4 bar. When I turn the tap of the pressure does go back up a bit but usually not to where it was. The tap does have a bit of a drip. I understand that taps shouldn't effect the pressure but that is what I see pretty much every time I run the tap.
Obviously I will go back to my installers and maybe to Worcester, but both have had a look at it in the past, so I thought I would though it open to the web to see if anyone had any advice.
All suggestions would be gratefully received.
Thank you,
James
 
The water board changing your meter and flushing the pipes out would have had no effect on your heating system as they are 2 separate systems so was purely coincidental. The gauge moving when you operate a tap is likely just vibrations though the pipe causing the needle to move because again they are separate systems so should have no impact on the pressure within your heating.

When do you notice the most amount of pressure loss? You may find when the heating isn't on you may lose more pressure and when the heating is on and everything expands the leak is plugging itself and allowing any wet patches to dry up. Also the size of your system may be making it harder to spot, if your system is small it won't take that much water loss to actually drop the pressure so you may think your looking for a bigger leak than you have.
You could try thermal imaging, get everything nice and hot and then starting at the boiler you'll be able to trace where your heating runs are which will show up as 2 orange lines, if you see an orange pool then this would indicate a leak.
 
If his filling loop was passing surely he would have the opposite issue of his pressure constantly increasing as the mains water would over power that of the heating system.
No, op states when tap turned on adjacent to boiler the pressure drops and then reverts. The whole system is obviously at low pressure anyway. I would disconnect filling loop and see if the pressure changes, if will probably go down over time as there is a leak but not vary in a short time ....centralheatking
 
If your losing pressure then you have a leak somewhere a dripping tap won't make a difference to the heating a hot dripping tap could be a nuisance, we would only be guessing where the problem is check all your radiator valves and obvious joints . Kop
 
Thanks for you replies.
I would say that the system loses pressure faster when the heating is off. Though it doesn't appear to be clear cut.
With the old boiler however I think the pressure dropped slowest if I turned the boiler of completely by pulling the plug out.
As for the water board action and the temporary fix being a coincidence, as I said, I find that hard to believe, The system had lost pressure consistently for about 3 years maybe longer as that is when we moved in. Then suddenly we have taken these measures and suddenly everything works fine for a bit. I think something happened. Presumably the two systems meet somewhere, Could that valve or whatever it may be be the problem.
I shall certainly share your thoughts with the installers.
Any suggestions how to go about getting the thermal imaging done? Is it something you would expect the intallation company to do, or is it usually a specialist thing?
Thanks again.
 
No, op states when tap turned on adjacent to boiler the pressure drops and then reverts. The whole system is obviously at low pressure anyway. I would disconnect filling loop and see if the pressure changes, if will probably go down over time as there is a leak but not vary in a short time ..centralheatking

Pump starting and pump stopping
 
Maybe the PRV is letting by sometimes? Could be an expansion vessel undersized or failing issue. Cut the finger off a rubber glove and attach it to the end of the D2 discharge (Blow off/Pressure relief pipe) with a rubber band. If that is where the water is escaping you'll be able to tell.
 
Maybe the PRV is letting by sometimes? Could be an expansion vessel undersized or failing issue. Cut the finger off a rubber glove and attach it to the end of the D2 discharge (Blow off/Pressure relief pipe) with a rubber band. If that is where the water is escaping you'll be able to tell.
Doubtful, he had pressure loss on the old system before the new one was fitted and it's unlikely the expansion is undsized on a studio flat.
 
Doubtful, he had pressure loss on the old system before the new one was fitted and it's unlikely the expansion is undsized on a studio flat.

Fair enough but it is an easy thing to eliminate and doesn't cost anything to investigate. Still worth a look I'd say.
 
But last resort, sealing solutions can block air vents and similar within the boiler
 
Isolate boiler on flow and return underneath boiler. See if drop is from boiler or system. Then go from there.

As for drop when opening kitchen tap, is it the hot tap, if so it's just as the boiler switches modes.
 
If you’re loosing pressure on a sealed system, you have a leak, simple as that.
Probably a radiator valve, could be the PRV discharge pipe (put party balloon over discharge pipe end outside).
The only other possibility is that the oxygenated water you keep on adding to system is speeding up corrosion within system. Thus produces Iton Oxide and Nitrogen. The Nitrogen escapes through the auto air vent causing a pressure drop. This is not that common and can be solved by adding chemical inhibitor.
 
Hi,
I would love to get some expert thoughts on my pressure loss problem.
I have just replaced my boiler and radiators to fix a raft of problems with the heating system mostly caused by old radiators filled with sludge. Unfortunately the loss of pressure hasn't been fixed.
There are no signs of leaks any where and most of the house is over a studio flat in the basement, so we would be likely to see signs of leaks in our ceilings or in the flat below.
At the moment I have to refill the system every 1 to 2 days. However there have been a couple of circumstances that seem to have fixed the problem for a couple of weeks, which makes me wonder if it is a leak.
The first was when the water board decided to change my meter - this was when the old boiler was still in place. After they had finished our water supply was shot. Pressure was down. Toilet flushes would endlessly refill etc. It seems that dirt got into the system, so they sent a contractor out with a compressor to clear the dirt out of the system. This not only cleared the problem but for about two weeks the pressure gauge sat happily on the same bar, before slowly over about a week starting to lose pressure increasingly quickly until I was back to topping up the old boiler at least once a day. One engineer said it must have been coincidence, but I don't really buy that. I am sure that that process did something to stop the problem for a bit.
A similar thing happened after the new install. I thought everything was great for the first week. The second week was still okish but I started to see a slight drop in pressure, now after 3-4 weeks I am back to topping up regularly, though it is still a bit better than the old boiler.
The other thing I notice is that when I turn on the kitchen tap which is right by the boiler I can often see the pressure drop quite noticeably - about 1/4 bar. When I turn the tap of the pressure does go back up a bit but usually not to where it was. The tap does have a bit of a drip. I understand that taps shouldn't effect the pressure but that is what I see pretty much every time I run the tap.
Obviously I will go back to my installers and maybe to Worcester, but both have had a look at it in the past, so I thought I would though it open to the web to see if anyone had any advice.
All suggestions would be gratefully received.
Thank you,
James
Pressure drop when you turn on the cold tap?Could be caused by an air lock on the HW slide
 

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