Pressure drop in boiler?

regedit

We live in a 4 year old house. Downstairs underfloor heating, upstairs rads. Hot water cylinder upstairs and gas boiler downstairs. Solar panels too. Last year, we noticed that there was dripping from the pipe connecting the boiler with outside.

Checked what could be wrong and the plumber changed expansion valve cylinder. There's substantially less dripping now but we are noticing a frequent drop in pressure in the boiler resulting in us having to frequently open the valve and 'pressurise' the system/recently even more frequently. I guess there must be a leak somewhere. This was the case in the past too so not sure this is linked with the expansion valve.
Also, we are noticing an intermittent lawnmower-like sound for a few seconds from the unit in the hot press where the hot water cylinder is. This happens when the shower comes on and goes away within seconds. There's 2 valves/gauges there so that a noise coming from there. I asked the plumber what it could be and he asked me to record the sound and send it on to him.
Any thoughts. We live in Kildare

John.G

What pressure is the boiler showing on the front, it should be ~ 1 to 1.5 bar when cold and 2 to a max of 2.5 bar when hot. If this pressure is approaching 3 bar then it will lift the PRV (pressure relief valve) and this may be the dripping your are seeing on the outside.

regedit

John.G wrote: »

What pressure is the boiler showing on the front, it should be ~ 1 to 1.5 bar when cold and 2 to a max of 2.5 bar when hot. If this pressure is approaching 3 bar then it will lift the PRV (pressure relief valve) and this may be the dripping your are seeing on the outside.

Hi John.G: It was zero this morning so I opened the valve and it's 2.5 at present. It may stay like this for a few days or even weeks but then, within a day, it may drop to zero

John.G

It shouldn't go higher than this with a hot system/boiler so keep a eye on it, also no dripping from the PRV which will over a period of time deplete the water reserve of 1 to 1.5 litres pretty rapidly. There should be NO drips whatsoever from that PRV, if so then it will have to renewed by a RGI. who should also check the E.vessel initial (pre) pressure and filling pressure, if externally fitted your plumber can check this which I presume was done when installing the new E.Vessel.

regedit

John.G wrote: »

It shouldn't go higher than this with a hot system/boiler so keep a eye on it, also no dripping from the PRV which will over a period of time deplete the water reserve of 1 to 1.5 litres pretty rapidly. There should be NO drips whatsoever from that PRV, if so then it will have to renewed by a RGI. who should also check the E.vessel initial (pre) pressure and filling pressure, if externally fitted your plumber can check this which I presume was done when installing the new E.Vessel.

Thanks a lot. I guess I'll have to get someone to have a look at it.
Any idea what that rattling sound from the hot press. There are two gauges there and I guess some sort of moving part /valves making the noise...

John.G

No, no idea as to what that might be.

Wearb

regedit wrote: »

Thanks a lot. I guess I'll have to get someone to have a look at it.
Any idea what that rattling sound from the hot press. There are two gauges there and I guess some sort of moving part /valves making the noise...

"A" rated circulating pumps can make a similar sound when set to auto on some heating systems.

regedit

Wearb wrote: »

"A" rated circulating pumps can make a similar sound when set to auto on some heating systems.

TBH, I have no idea where the noise is coming but it's similar to one of a petrol lawnmower makes when started (less power obviously) and it goes away in 2-4 seconds. Nothing was intentionally changed by ourselves so not sure if it's wear and tear or something minor.
The noise is coming from the unit in the pic so not sure if by looking at it, anything is causing a concern.
Finally, if anyone can recommend a good heating expert in Kildare, please PM me.

John.G

That's the pump station for your solar system and may be the pump stopping/starting although these are normally virtually silent, you should be able to switch off the solar controller where ever that is located.

regedit

John.G wrote: »

That's the pump station for your solar system and may be the pump stopping/starting although these are normally virtually silent, you should be able to switch off the solar controller where ever that is located.

Thanks John.G: best to call a heating guy I think

regedit

I managed to identify where the noise is coming. It's from the expansion valve in the hot press. See image exp valve. I thought that valve didnt have ay mechanical parts. the flexible hose seems to vibrate for a few seconds.
I managed to record a short clip of the noise so the experts here will probably be able to advise better what the cause is. I could not attach an mp4 file so I zipped it beforehand. So please open the zip and you'll be able to hear the noise. Could there be air in the system causing this noise?
Spoke to a plumber yesterday so he's going to come over when he gets time but thought I'd check here too

John.G

exp valve.jpeg is opening showing something about covid 19??.

regedit

John.G wrote: »

exp valve.jpeg is opening showing something about covid 19??.

Just tried it on my mac and when I click it asks me to save the file on my laptop and then opens fine but please try this link from Google Drive here

John.G

noise.mp4 opens Ok its the exp valve.jpeg that't my problem.

regedit

John.G wrote: »

noise.mp4 opens Ok its the exp valve.jpeg that't my problem.

Ah, my fault. Thanks @John.G loaded the correct one now. Sorry. Nothing massive. It just shows the expansion valve and I circled the area I thought teh noise came from. That expansion valve was changed a few months ago. Not sure if the noise is coincidental or not

John.G

Ok. thanks, can you take a close up photo of the label on that expansion vessel and confirm that the pressure shown on it is, 7 bar ??, Also the highlighted bit, is this just a pipe attached to the vessel end?

regedit

John.G wrote: »

Ok. thanks, can you take a close up photo of the label on that expansion vessel and confirm that the pressure shown on it is, 7 bar ??, Also the highlighted bit, is this just a pipe attached to the vessel end?

Hi John.G
Please see attached. It seems to indicate 10 bar
Regarding the highlighted bit, there's a flexible pipe that enters the vessel and that one seems to vibrate or create the noise or both...

John.G

This E.vessel may be attached to your solar system, if so, then the noise might coincide with the solar circ pump stopping/starting OR it may be attached to your domestic water system, if pumped. If your system is pumped then you will have two of these E.vessels, one might be smaller (solar) than the other so try and establish if you have this pumped system and if so try and establish which system the "noisy" E.vessel is attached to.

regedit

John.G wrote: »

This E.vessel may be attached to your solar system, if so, then the noise might coincide with the solar circ pump stopping/starting OR it may be attached to your domestic water system, if pumped. If your system is pumped then you will have two of these E.vessels, one might be smaller (solar) than the other so try and establish if you have this pumped system and if so try and establish which system the "noisy" E.vessel is attached to.

Thanks John G.
We do indeed have another vessel for the solar panels (see attached photo) but that one isn't the culprit for the noise. And, yes, the system is pumped I guess as there's pumps in teh utility room etc.

John.G

That so is the E.vessel for the unvented HW cylinder, the expanded water, on heating will enter this vessel via that flexible pipe, this is a gradual process so even if this pipe is restricted then it shouldn't cause noisy operation, however that E.vessel will act as a mini accumulator as well and depending on the pump cutin/cutout pump pressure will pass water in and out through that flexible pipe which may cause that noise. The pump cutin/cutout pressure and the E.vessel prepressure should be checked and also the flexible pipe removed and inspected and probably renewed.
You should be able to determine if that noise coincides with either any hot water draw off or/and pump cut in.

However, if this flexible pipe is blocked then the PRV (just below the Joule sign on the HW cylinder) will lift and expel water.

regedit

John.G wrote: »

That so is the E.vessel for the unvented HW cylinder, the expanded water, on heating will enter this vessel via that flexible pipe, this is a gradual process so even if this pipe is restricted then it shouldn't cause noisy operation, however that E.vessel will act as a mini accumulator as well and depending on the pump cutin/cutout pump pressure will pass water in and out through that flexible pipe which may cause that noise. The pump cutin/cutout pressure and the E.vessel prepressure should be checked and also the flexible pipe removed and inspected and probably renewed.
You should be able to determine if that noise coincides with either any hot water draw off or/and pump cut in.

However, if this flexible pipe is blocked then the PRV (just below the Joule sign on the HW cylinder) will lift and expel water.

It definitely coincides with hot water only (nothing to do with solar panels as it happened winter months when there was no solar collection). The plumber who replaced the EV last year had a look today and unfortunately, he could not replicate the rattling. The EV was light so no water collection there. Switching on the hot water didn't cause the issue. He'll come over again and see if the issue can be replicated and then will start looking at issues one-by-one with the hope he'll find out what is wrong

John.G

Did he check the pressure at the air end? to check it properly he would need to drain down the EV (or at least depressurise the HW cylinder) and then put a pressure gauge on the air end, the pressure may be too high, if you have a tyre pressure gauge you might take the pressure while opening/closing the hot water outlet, some water has to enter the EV, if not the pre pressure is too high and can lead, IMO, to rattling/water hammer. If no pressure gauge can you just press the valve stem on the air end and ensure, at least, that you have air pressure.