Investigating Ideal Combi Logic+ C24 losing pressure

macci85

Hello guys!

I had an Ideal Combi Logic+ C24 fitted in August 2021 in my 2 storey house in a bedroom upstairs.
As I started using it for central heating in November 2021 I noticed that the pressure was going down from 1bar to 0 in 1 or 2 days.

I called Ideal and they sent an engineer to check but he said that the boiler was OK and that I had a leak somewhere in the property. He suggested to wait 6 months and the leak would have showed up. Interestingly during his tests the heating was on and we could actually see the gauge going down.

Spring arrived and we stopped using the CH. Pressure started to last about 2 weeks.

Autumn 2022 arrived with no sign of leak anywhere in the property. I checked all radiators, added some paper to see if the leak was there but then drying out, but nothing.

As we started to use the heating same issue again, some times it took a day to go from 1bar to 0bar, sometimes less, sometimes a few hours, sometimes 30 minutes.
I had to bleed radiators quite often, a the towel rail that is pretty high in the upstairs bathroom was often cold at the top.

I checked the TRV and nothing was leaking from there. I was ready to get a leak detection company to come in March 2023 but then the pressure started lasting more, about 2 weeks again.

Autumn 2023 and the same issue is back. I had the boiler serviced in November and the engineer set the pressure to 1.5 bar and asked me to monitor it and then call Ideal again.

It lasted 8 days, then 2 days, then sometimes less than a day. I called Ideal again another engineer came to check.
He checked the expansion vessel and he said it was at 0.7bar and it was OK.
He visually inspected the heat exchange and he said it was fine.
He replaced the TRV just in case that was the issue, but he was 100% sure the boiler was fine.

After his visit the pressure has been lasting way less, just a couple of hours to go from 1bar to 0.
Now in the morning, when I open the filing loop, it takes a bit for the gauge to even move up from 0.

I also tried to look at the condensation pipe when the boiler was cold, but found just a few drops there in a couple of hours while the pressure went from 1bar to 0.

I tried closing the flow and return valves to isolate the boiler and the pressure went to zero over night.

Interestingly this year I only bled the radiators once and even the towel rail is always hot at the top.

There should be a lot of water coming out from the leak and I'm very puzzled on how that can still not show any signs in the property. Unless it air loss causing it? No idea


Any advice? Anything else I could do?

Thanks!

grumbler

Do you monitor the pressure relief valve/pipe?

ThisIsWeird

macci85 said:

Hello guys!

I had an Ideal Combi Logic+ C24 fitted in August 2021 in my 2 storey house in a bedroom upstairs.
As I started using it for central heating in November 2021 I noticed that the pressure was going down from 1bar to 0 in 1 or 2 days.

I called Ideal and they sent an engineer to check but he said that the boiler was OK and that I had a leak somewhere in the property. He suggested to wait 6 months and the leak would have showed up. Interestingly during his tests the heating was on and we could actually see the gauge going down.

Spring arrived and we stopped using the CH. Pressure started to last about 2 weeks.

Autumn 2022 arrived with no sign of leak anywhere in the property. I checked all radiators, added some paper to see if the leak was there but then drying out, but nothing.

As we started to use the heating same issue again, some times it took a day to go from 1bar to 0bar, sometimes less, sometimes a few hours, sometimes 30 minutes.
I had to bleed radiators quite often, a the towel rail that is pretty high in the upstairs bathroom was often cold at the top.

I checked the TRV and nothing was leaking from there. I was ready to get a leak detection company to come in March 2023 but then the pressure started lasting more, about 2 weeks again.

Autumn 2023 and the same issue is back. I had the boiler serviced in November and the engineer set the pressure to 1.5 bar and asked me to monitor it and then call Ideal again.

It lasted 8 days, then 2 days, then sometimes less than a day. I called Ideal again another engineer came to check.
He checked the expansion vessel and he said it was at 0.7bar and it was OK.
He visually inspected the heat exchange and he said it was fine.
He replaced the TRV just in case that was the issue, but he was 100% sure the boiler was fine.

After his visit the pressure has been lasting way less, just a couple of hours to go from 1bar to 0.
Now in the morning, when I open the filing loop, it takes a bit for the gauge to even move up from 0.

I also tried to look at the condensation pipe when the boiler was cold, but found just a few drops there in a couple of hours while the pressure went from 1bar to 0.

I tried closing the flow and return valves to isolate the boiler and the pressure went to zero over night.

Interestingly this year I only bled the radiators once and even the towel rail is always hot at the top.

There should be a lot of water coming out from the leak and I'm very puzzled on how that can still not show any signs in the property. Unless it air loss causing it? No idea


Any advice? Anything else I could do?

Thanks!

Wow, comprehensive!
Q, what kind of pressure gauge do you have, analogue or digital, and - more importantly - what does the pressure 'do' in normal use? Does it go up at any point, like when the CH is turned on?

Ok, a repeat of the test you've already done, but with a wee tweak.
Cut off power to boiler, say last thing before bed, to make sure it cannot be fired up. Repressurise to 1.5, take note of exact pressure. If your gauge is digital (I think you have both? In which case cut the power and just use the analogue), then power will need to remain on, but turn CH and DHW outputs to zero. You know where the isolating valves for the flow and return are, as you've used them before, but make 100% sure you have ID'd them correctly - 22mm copper pipes, often at opposite ends of the boiler. Make sure you turn them a full 90o. Might as well also shut off the mains flow to the boiler - they all have nice big black levers on them?! 
In the morn, check pressure again. 
If it has dropped, repressure to 1.5 again, and then open an isolator valve. Keep an eye on the gauge as you do.
Report back. 
If you can, also rubber-band wee plastic bags over the safety discharge pipe, and the condensate one. Cover most bases in one test!

ThisIsWeird

Q - when the plumber checked the EV pressure, did he first depressurised the CH side? Ie, the rads.

grumbler

ThisIsWeird said:

Q - when the plumber checked the EV pressure, did he first depressurised the CH side? Ie, the rads.

If he didn't the pressure would be 1.5, not 0.7.

ThisIsWeird

If an isolated boiler loses pressure, it can only be via either the discharge pipe, or the condensate one. Or leaking out the bottom of the actual boiler.
It's 'possible' for loss to occur via a perforated P2P exchanger, too, but this would tend to have the opposite effect, as the mains pressure forces its way into the system, to raise the pressure.

(I found this out after I tried cleaning a P2P using brick acid...)

ThisIsWeird

grumbler said:

ThisIsWeird said:

Q - when the plumber checked the EV pressure, did he first depressurised the CH side? Ie, the rads.

If he didn't the pressure would be 1.5, not 0.7.

Yes, if the boiler was at 1.5 at the time. But not if he tried it following the loss. We don't know the system pressure at the time of this check.
Unless the system side is depressurised, you won't know the air charge pressure with any accuracy.

macci85

Thanks for the replies!

@grumbler I monitored it last year for a few days and there was no water coming out, while the pressure was going down. I'm not currently checking, should I?

@ThisIsWeird It is an analogue gauge. The pressure goes up while in use, then back. I could monitor it and give you the readings if it can help?
Do you mean to depressurise it while having the valves closed? They seemed to close to 90 degrees, I'll double check.

turn CH and DHW outputs to zero

Are those the controls on the boiler where I select the water temperature?

He said he emptied the boiler, not sure what it meant but there was water coming out of PRV/condensation pipe (not sure which one as the setup is as they both go to the same pipe, to check them I had to cut the white pipes in the picture). He did not touch the radiators.

macci85

Forgot to mention, now after increasing the pressure when the boiler starts it makes strange noises, like it struggles to start.

I also got a message saying "High flow return diff" when turning the DHW on, it then worked fine.

ThisIsWeird

macci85 said:

@ThisIsWeird It is an analogue gauge. The pressure goes up while in use, then back. I could monitor it and give you the readings if it can help? YES PLEASE.
Do you mean to depressurise it while having the valves closed? They seemed to close to 90 degrees, I'll double check. No, REpressurise it to a good noted figure - say 1.5 - and then shut off the F&R valves, and the boiler mains incoming - the three blue levers shown in your pic. Turn the boiler off - just switch it all off at the mains isolator switch.  

"turn CH and DHW outputs to zero"
Are those the controls on the boiler where I select the water temperature? Yes, but since you have an analogue gauge, the boiler doesn't need to be powered, so leave these controls, and just turn off the mains power supply.

He said he emptied the boiler, not sure what it meant but there was water coming out of PRV/condensation pipe (not sure which one as the setup is as they both go to the same pipe, to check them I had to cut the white pipes in the picture). He did not touch the radiators. Ok, that does sound as tho' he did depressurise the system first, so good. Not sure using the PRV was the best way, as they do tend to not reseal properly after being opened, but hey.

Ok, not sure that setup is conforming either! Boileing water, ejected under 3+ bar pressure, firing into a plastic pipe? Hmm. Anyhoo, let's not worry too much... You can see where that white pipe is outside? Stick a bag over that.

Answers in bold.

macci85

I've kept track of the pressures this morning with times and F/R temperatures:

 06:40   1.5bar   18 -> Turned heating on
 07:10   2.0bar   60 -> Turned heating off
 07:15   1.6bar   50 -> Shower used
 08:22   1.2bar   50
 08:52   1.1bar   44
 09.02   1.0bar   42
 09:32   0.7bar   38
 09:38   0.6bar   35
 10:02   0.4bar   35
 10.32   0.2bar   32

  I turned the boiler off and closed the F/R valves yesterday night with a starting pressure of 1.2bar and this morning it was at 0bar. Not sure they are at full 90deg, this is the max I can turn them: 

Both discharge pipe go to the same pipe outside into the soil. I cut them last year and there was no water from the PRV for a few days. Some drops from the condensation pipe with boiler off and cold. For both experiments the pressure was still going down.
I could try to check that again if helpful.