Central Heating Pressure Dropping

John.G

tony glenn wrote: »

Today's update.... dropping 0.3 bar cold in one hour. Still no sign of any leak or damp patch, and the puzzle remains i.e. it was almost ok for two days after the cylinder was changed.
I did put up one shelf in the utility room during the Summer, (timber frame house, plasterboard internal walls) The screws were to the left of the rad below, is it possible that the plastic pipe runs at 45° behind the wall, (in which case I could have holed the pipe) or is it always vertical or horizontal?
PS No markings of any sort on the EV cylinder btw.

I thought the EV capacity might be in the label (below) but if one assumes a 12 litre EV then if pre pressurised to 1 bar & filling pressure of 2 bar will result in a loss of 3 to 4 litres each time the pressure falls to zero so its certainly possible that you have a holed pipe somewhere but it would be very informative if you could beg or borrow a pressure gauge to monitor the EV air end pressure to completely rule it (the EV) out before tearing down any partitions etc. when carrying out the suggested further tests.

The first test I would suggest is to shut down the boiler + programmer, then shut the cylinder coil balancing valve, increase the fill pressure to 2 bar and see if the pressure holds. When satisfied one way or the other, open all zone valves by means of their manual levers, re open the red balancing valve fully, ensure pressure is again at 2 bar and observe it again. (with system still shut down)

tony glenn

John.G wrote: »

I thought the EV capacity might be in the label (below) but if one assumes a 12 litre EV then if pre pressurised to 1 bar & filling pressure of 2 bar will result in a loss of 3 to 4 litres each time the pressure falls to zero so its certainly possible that you have a holed pipe somewhere but it would be very informative if you could beg or borrow a pressure gauge to monitor the EV air end pressure to completely rule it (the EV) out before tearing down any partitions etc. when carrying out the suggested further tests.

The first test I would suggest is to shut down the boiler + programmer, then shut the cylinder coil balancing valve, increase the fill pressure to 2 bar and see if the pressure holds. When satisfied one way or the other, open all zone valves by means of their manual levers, re open the red balancing valve fully, ensure pressure is again at 2 bar and observe it again. (with system still shut down)

Apologies, I couldn't see that label since the new cylinder was fitted with associated new shelving etc.
I'll discuss those suggestions with the plumber next week, I've every confidence in him btw as he's fully qualified/registered/experienced etc, and he's as frustrated as I am over this. Having said that, I certainly could have done without the expense of a new cylinder plus fitting.... only to find the problem returning.
I'm considering trying a leak sealant next, if that doesn't work it's a smaller outlay wasted. After that, maybe a call to a leak detector outfit?

tony glenn

tony glenn wrote: »

Apologies, I couldn't see that label since the new cylinder was fitted with associated new shelving etc.
I'll discuss those suggestions with the plumber next week, I've every confidence in him btw as he's fully qualified/registered/experienced etc, and he's as frustrated as I am over this. Having said that, I certainly could have done without the expense of a new cylinder plus fitting.... only to find the problem returning.
I'm considering trying a leak sealant next, if that doesn't work it's a smaller outlay wasted. After that, maybe a call to a leak detector outfit?

Whatever it is, it got worse today, it's now losing about one bar in about half an hour, and now the upstairs zone has shut down altogether. And still no sign of any leakage...

John.G

Lets just look again at the facts as we know them.

1 Up to now, a few seconds of re pressurising was bringing the pressure back up.
2.Its also established that if the hot water zone valve isn't open that there is no where for the heating expansion to go as it is apparently prevented at one end by the closed hot water zone valve and at the other end by the NR valve.
I would politely ask your plumber why it is configured in this manner, IF indeed it is.

Personally I would insist on your plumber monitoring the E.vessel air end pressure as you just don't know what it was/is, its unlikely but the pre charge pressure may have been set to 2 bar for all you know.

Just for now can you switch off the system and manually open (and latch open) all three zone valves including the hot water zone valve, then re pressurise to 2 bar, this should take at least a minute or two, if it re pressurises again in a matter of seconds then obviously there is a big problem somewhere, if it does take a minute or so monitor the pressure for a 1/2 hour or so and please post back.

Edit:
Can you confirm that the top up valves are to the left of the (top of) braided hose, also, can you see where the red handled lever valve (to the left of the pressure gauge) is teed in, is it teed in to the filling line as well?.

Apoligies, I have looked back through your pics and I can see that the filling valve is actually the red lever valve and the pressure gauge is just measuring the pressure at the coil return.

tony glenn

John.G wrote: »

Lets just look again at the facts as we know them.

1 Up to now, a few seconds of re pressurising was bringing the pressure back up.
2.Its also established that if the hot water zone valve isn't open that there is no where for the heating expansion to go as it is apparently prevented at one end by the closed hot water zone valve and at the other end by the NR valve.
I would politely ask your plumber why it is configured in this manner, IF indeed it is.

Personally I would insist on your plumber monitoring the E.vessel air end pressure as you just don't know what it was/is, its unlikely but the pre charge pressure may have been set to 2 bar for all you know.

Just for now can you switch off the system and manually open (and latch open) all three zone valves including the hot water zone valve, then re pressurise to 2 bar, this should take at least a minute or two, if it re pressurises again in a matter of seconds then obviously there is a big problem somewhere, if it does take a minute or so monitor the pressure for a 1/2 hour or so and please post back.

Edit:
Can you confirm that the top up valves are to the left of the (top of) braided hose, also, can you see where the red handled lever valve (to the left of the pressure gauge) is teed in, is it teed in to the filling line as well?.

Apoligies, I have looked back through your pics and I can see that the filling valve is actually the red lever valve and the pressure gauge is just measuring the pressure at the coil return.

Apologies John, I've only just seen your reply. It's all water under the bridge now (excuse the pun) as this morning I did the usual routine, opened the fill lever to quickly bring up the pressure....but this time it took a good 20 seconds or more to even start the needle moving. I raised it to one bar and switched on the heating, only to watch it cut out after ten minutes as the pressure dropped back to zero. It's now taking at least 30 seconds to bring the pressure up, I can hear the bathroom rad gurgling as it refills each time. And still no sign of any visible leaks. I managed to get one bar this evening, and ran the heating for 20 minutes by keeping the pressure up twice, but surely this must be a worsening leak? Time for the leak detector guys I think...is there any way that in a sealed system, this much rapid pressure drop could be anything other than a serious leak?

John.G

I keep emphazing that if we are interpreting the photos correctly then the HOT WATER zone valve MUST be opened to allow the volume of water in the heating (rads) circuit to expand into the EV via the hot water zone valve otherwise it has to go out through the PRV on top of the boiler. Can you just put the heating and the hot water circuits on together, re pressurise and see if the pressure still falls at the same rate.
If so, I would then only grudgingly say that a leak is a probability.

tony glenn

John.G wrote: »

I keep emphazing that if we are interpreting the photos correctly then the HOT WATER zone valve MUST be opened to allow the volume of water in the heating (rads) circuit to expand into the EV via the hot water zone valve otherwise it has to go out through the PRV on top of the boiler. Can you just put the heating and the hot water circuits on together, re pressurise and see if the pressure still falls at the same rate.
If so, I would then only grudgingly say that a leak is a probability.

When the new cylinder was fitted last week, the plumber added on/off levers both sides so we could isolate the coil if we ever had to. The hot water circuit has been open since then, and yes the pressure now drops at the same rate as with the coil closed off.

John.G

OK but just to be absolutely clear on this, does the HW coil have a zone valve plus cylinder stat and you are saying that this is energised "permanently" while the heating system is on?.

Can't "contribute" much more I think except to say that (if) you are happy with the above, ie, HW zone valve opened either via timer/thermostat or manually at all times then before calling in the storm troopers you might have a look at the boiler condensate drain off with the boiler off, in case that the heat exchanger has failed, this drains into a gully normally but you may be able to check it somewhere, also get plumber to check E.vessel and when finally sorted out ensure that the E.vessel is connected properly into the system.

tony glenn

John.G wrote: »

OK but just to be absolutely clear on this, does the HW coil have a zone valve plus cylinder stat and you are saying that this is energised "permanently" while the heating system is on?.

Can't "contribute" much more I think except to say that (if) you are happy with the above, ie, HW zone valve opened either via timer/thermostat or manually at all times then before calling in the storm troopers you might have a look at the boiler condensate drain off with the boiler off, in case that the heat exchanger has failed, this drains into a gully normally but you may be able to check it somewhere, also get plumber to check E.vessel and when finally sorted out ensure that the E.vessel is connected properly into the system.

Thanks John, for all your assistance to date. You must be almost as worn as we are by now.
Yes, the hot water coil is permanently 'on'.... there's a stat on the side of the (brand-new) cylinder, and when the heating is on, the hot taps run hot water. I've examined the (6-month old) boiler unit on several occasions, hot and cold, opening it's housing outside. There's absolutely no sign of any moisture or leakage there, the entire inside is lined with foil and any water would be easily seen (I think!)
My only concern is that the 'storm troopers' (lol) might discover a fault in the set-up that wouldn't be covered by the house insurance. We're already hundreds out of pocket for a new cylinder that wasn't the solution, so any further expense will be a worry.

John.G

The stat on the cylinder side will open/close the motorized HW zone valve depending on its setpoint, normally 60C, but that means that the HW zone valve may be shut for very long periods which prevents the (central heating) HW from expanding into the EV, hence my worry, if you have the time/inclination just do the following once and I will die happy, turn the cylinder stat to its lowest setting after first noting its present setting, then if you look at the HW zone valve which will be closed, you will see a little lever on the side or the end of the actuator, pull this slowly against the spring pressure and when it has reached its end travel just push it up to "latch" it open, the zone valve will then stay open under ALL circumstances, then carry out your tests again, when completed, unlatch the lever and return the cylinder stat to its original setting.
Re (hopefully unlikely) boiler leak, its possible for the heat exchanger to be leaking without any obvious signs of external leakage, if you look at the very bottom of the boiler you should see a plastic 22mm? pipe running off to drain somewhere, see (with boiler off) can you uncouple/remove this anywhere on its run to drain to see if any water runs out or keeps running out.

tony glenn

John.G wrote: »

The stat on the cylinder side will open/close the motorized HW zone valve depending on its setpoint, normally 60C, but that means that the HW zone valve may be shut for very long periods which prevents the (central heating) HW from expanding into the EV, hence my worry, if you have the time/inclination just do the following once and I will die happy, turn the cylinder stat to its lowest setting after first noting its present setting, then if you look at the HW zone valve which will be closed, you will see a little lever on the side or the end of the actuator, pull this slowly against the spring pressure and when it has reached its end travel just push it up to "latch" it open, the zone valve will then stay open under ALL circumstances, then carry out your tests again, when completed, unlatch the lever and return the cylinder stat to its original setting.
Re (hopefully unlikely) boiler leak, its possible for the heat exchanger to be leaking without any obvious signs of external leakage, if you look at the very bottom of the boiler you should see a plastic 22mm? pipe running off to drain somewhere, see (with boiler off) can you uncouple/remove this anywhere on its run to drain to see if any water runs out or keeps running out.

Checked boiler again, no sign of water exiting from drain pipe. It took 45 seconds to reach 2 bar this morning, and was back to zero an hour later. In case it's relevant, I then isolated the coil and it went from 2 to zero in half an hour. Apart from the big red levers, the only other mechanics I can see are the zone control valves, one downstairs and two in the hot press, all set to auto. Not sure which does what upstairs.
This reply wouldn't send with pics attached, I'll try again with just pics.

tony glenn

tony glenn wrote: »

Checked boiler again, no sign of water exiting from drain pipe. It took 45 seconds to reach 2 bar this morning, and was back to zero an hour later. In case it's relevant, I then isolated the coil and it went from 2 to zero in half an hour. Apart from the big red levers, the only other mechanics I can see are the zone control valves, one downstairs and two in the hot press, all set to auto. Not sure which does what upstairs.
This reply wouldn't send with pics attached, I'll try again with just pics.

Pics.

tony glenn

Pics

tony glenn

tony glenn wrote: »

Pics

Pics

tony glenn

tony glenn wrote: »

Pics

Pics

John.G

The lever should be close to where Auto is, there may be purge/vent or open written at the other end.
OK no pics as yet but you can open the HW zone v/v by another method.
Assuming you have a programmer with HW on it then put that that HW zone to boost or constant on for 1 hour or so and then turn the cylinder stat to MAX and carry out test, if it hasn't any HW on the programmer just turn the cylinder stat to MAX.

Glad to hear that boiler is OK anyway.

tony glenn

John.G wrote: »

The lever should be close to where Auto is, there may be purge/vent or open written at the other end.
OK no pics as yet but you can open the HW zone v/v by another method.
Assuming you have a programmer with HW on it then put that that HW zone to boost or constant on for 1 hour or so and then turn the cylinder stat to MAX and carry out test, if it hasn't any HW on the programmer just turn the cylinder stat to MAX.

Glad to hear that boiler is OK anyway.

Can't send pics for some reason.... keeps saying file too large, even with one pic.
I'll try your suggestions tomorrow if I can find time...now the Fridge Freezer compressor has packed up! If this is Karma, I must have done something really bad .....

tony glenn

tony glenn wrote: »

Can't send pics for some reason.... keeps saying file too large, even with one pic.
I'll try your suggestions tomorrow if I can find time...now the Fridge Freezer compressor has packed up! If this is Karma, I must have done something really bad .....

Time to say goodbye John! It's a leak alright.
The detector guys arrived this morning, after four hours they finally traced it to one side of an under-breakfast-counter rad in the kitchen. They let me kneel down and listen to the testing gas hissing out, lucky me!
The really good news is that the downstairs manifold is in the hall press adjacent to the kitchen wall, (all timber frame, easy to drill)
The kitchen units run from that wall all the way around to the leaking rad. So the plan is to take a new pipe from the manifold through the wall around to the rad behind and under all the kitchen units. Minimum cutting by the rad to connect. I know it can be done as I fitted the kitchen btw.
We'd never have found that leak without the detectors, so fair play to them, and of course to you for all your help during our mini-crisis.
Enjoy Valentine's Day, and thanks once again.

Wearb

tony glenn wrote: »

Time to say goodbye John! It's a leak alright.
The detector guys arrived this morning, after four hours they finally traced it to one side of an under-breakfast-counter rad in the kitchen. They let me kneel down and listen to the testing gas hissing out, lucky me!
The really good news is that the downstairs manifold is in the hall press adjacent to the kitchen wall, (all timber frame, easy to drill)
The kitchen units run from that wall all the way around to the leaking rad. So the plan is to take a new pipe from the manifold through the wall around to the rad behind and under all the kitchen units. Minimum cutting by the rad to connect. I know it can be done as I fitted the kitchen btw.
We'd never have found that leak without the detectors, so fair play to them, and of course to you for all your help during our mini-crisis.
Enjoy Valentine's Day, and thanks once again.

Best Valentine's news I've heard all day. I'm worn out with this thread LOL.

tony glenn

Wearb wrote: »

Best Valentine's news I've heard all day. I'm worn out with this thread LOL.

Tears of laughter here at that reply!
How about we have an annual thread reunion, maybe all meet up to talk about my leak?

John.G

Amen to that, and glad you are sorted out finally.