We'd like to remind Forumites to please avoid political debate on the Forum... Read More »
📨 Have you signed up to the Forum's new Email Digest yet? Get a selection of trending threads sent straight to your inbox daily, weekly or monthly!
Boiler losing pressure, need help finding the cause (leak?)
Options
Comments
-
Seems like you're doing all the right things.
Here's an idea, based on the problem showing itself only when the system is up and running hot
How's about turning off each radiator, one at a time and seeing how that goes for about three days? I'm thinking that this will not only make each rad stay cold but also should make the joints at each rads entry/exit point run very much cooler. (We have some rads turned off permanently and the joints and feed pipes stay almost cold).
If turning off a particular rad stops the problem, that might just mean something. e.g. a TRV valve with a tiny leak internally, when hot, which evaporates as it occurs.
Just a thought.0 -
It may be a leak inside the actual boiler. I had one in mine where it was leaking from the o-ring seal joint to the heat exchanger, but was then running down inside the bottom of the boiler onto a hot pipe, so was evaporating inside the boiler. As the leak was only drips, then it didnt show any signs on the outside of the boiler or pipework0
-
I would get a gas engineer and your latest information should help them narrow down the issue. Diagnosing issues at a distance isnt reliable.0
-
locky123 said:I would get a gas engineer and your latest information should help them narrow down the issue. Diagnosing issues at a distance isnt reliable.0
-
ThisIsWeird said:That's disappointing, B2600.
You are 100% certain that's the safety discharge pipe? Could we see it without the bag over it, please?
Good info - thanks. One extra useful bit of info would be how the pressure changed as the system heated up. Did it always go to around 2bar? Any higher than this?
Ok. The decisive way to tell whether the loss is from without or 'out of the boiler is to isolate it from the radiator circuit. So that means no CH for the test. You should be ok running the DHW side.
If no pressure loss after, say, a day, then observe the gauge as you reopen an isolating valve - any drop suggests a loss in the rad circuit.
Almost certainly it cannot be a leak from a rad valve, as we must be talking around a cupful each time - that would make quite a mess.
Other source from within the boiler is a cracked main exchanger, and this would drain out via the plastic condensate pipe. You could always place a container under this, but bear in mind it'll produce normal slugs when in use. So you'd be looking at liquid there when the boiler is cold and hasn't been on.
And one more possibility is that an EV is leaking air into the water side. The air could be pumped around until it's expelled by the auto air vent inside the boiler (must surely have one). The system water is then filling up the failed EV, causing the pressure loss - there is no actual 'leak'. In this case, it'll stop happening once the EV is empty of air, and the pressure increases will likely be greater. A generally unlikely cause, tho'.
Pic of what I think is the discharge pipe :-)
Pressure never went above 2. It always seems to go about double what it is when idle. So when pressure is sitting at 1 it goes to 2 once the heating has been on for 1 hour or more. When it was 0.4 it went to 0.8.
The boiler is due a service and I was thinking of getting Ideal to do it this time rather than the normal plumber and let them know what is happening so they can do a proper check.
Regarding CH and DHW, we have a dial with pics on with the following options
(1) BOILER OFF
(2) TAP
(3) TAP & RADIATOR
It is currently set to (3).
I can set it just to TAP (which I guess is DHW?). When we do not use the heating between roughly April and November we do not have the same issue of topping the pressure up so even with 4 of us having multiple showers and using taps etc every day it seems to last 6 months but with the CH (3) on cant last a week1 -
Bullit_2600 said:
Pic of what I think is the discharge pipe :-)
Pressure never went above 2. It always seems to go about double what it is when idle. So when pressure is sitting at 1 it goes to 2 once the heating has been on for 1 hour or more. When it was 0.4 it went to 0.8.
The boiler is due a service and I was thinking of getting Ideal to do it this time rather than the normal plumber and let them know what is happening so they can do a proper check.
Regarding CH and DHW, we have a dial with pics on with the following options
(1) BOILER OFF
(2) TAP
(3) TAP & RADIATOR
It is currently set to (3).
I can set it just to TAP (which I guess is DHW?). When we do not use the heating between roughly April and November we do not have the same issue of topping the pressure up so even with 4 of us having multiple showers and using taps etc every day it seems to last 6 months but with the CH (3) on cant last a weekWell, that does look like a type of safety discharge pipe end, tho' I've never seen one like it! It appears to have a sealed end, and will 'fire' backwards against the wall, which is exactly what you'd want and expect.This is a real mystery. IF the loss was due to the rising pressure hitting around 3 bar, then the water should be ejected out that pipe. But (a) the pressure only reaches 2 bar - which is acceptable - and (b) there is no water coming out that pipe. Sooo, unlikely to be a leaking safety discharge valve/faulty EV scenario.It is possible for certain types of leaking joint to be worse when the system is hot, for the simple reason that the expansion opens up the 'hole' a bit more. This is often the case with cracked main exchangers, for example; they can sit quite happily holding in the pressure, until the boiler is used at full temp. The crack then opens a tad, and the water escapes, and ends out the condensate pipe. But that should really happen with both CH and DHW as both have the MainX running 'hot'.Really, the next obvious test would be to isolate the boiler, but you'd have to be happy doing this. You also wouldn't be able to run the CH during this, and since most of the loss occurs with CH, then the test might be moot anyways.Yup - I guess time to pass it on to a different GasSafe, ideally Ideal.I'm not questioning the original fellow's competence, but I think he should have confirmed whether water was being ejected out the safety discharge pipe before fitting the additional EV. Tho' if the pressure was rising too high with just the boiler's internal EV, then it may have been required in any case.0 -
Last night we were out. The pressure gauge was at 0.4 bar and we left the home about 1pm.
Around 6.30 pm I got an alert on my phone (I have the ideal Logic app) with a 'Low Water Pressure' warning.
This was with nobody home, no heating on and hot water running for at least 6 hours.
Weather is warming up so after today (have in-laws round so need to keep them warm lol) will try it next week without CH (is that what you mean by selecting just the (2) TAP mode?
Thanks for all the advice and help.0 -
0.4 is already sooo borderline low, that it's no surprise it sent you an alert. Most boilers won't operate as low as that.
Unless this boiler is quite different to others it doesn't really matter if the CH is turned off at the boiler with that switch, or just not 'used' - ie the room stat doesn't call for heat.
It's a mystery to me why the pressure drops during CH and not DHW. Both require the boiler to run, the DHW even more full-on. But, only the CH will expand the whole system volume to the point the EV is required to accommodate the additional volume, so whether that's the trigger, I don't know. There are reasons to say 'no', such as now't being ejected out the safety pipe.
Stumped, I'm afraid.
0 -
It had dropped from 0.4 to 0.0 whilst we were out with no heating on. I have been trying to leave it this week without CH on but my wife keeps putting it on lol so still waiting on that test.1
-
Hello @Bullit_2600,
Thank you for sharing your experience and thanks everyone for the support.
I'm currently experiencing a very similar issue with my Ideal boiler, did you manage to solve the issue?
0
Confirm your email address to Create Threads and Reply

Categories
- All Categories
- 351.1K Banking & Borrowing
- 253.1K Reduce Debt & Boost Income
- 453.6K Spending & Discounts
- 244.1K Work, Benefits & Business
- 599K Mortgages, Homes & Bills
- 177K Life & Family
- 257.4K Travel & Transport
- 1.5M Hobbies & Leisure
- 16.1K Discuss & Feedback
- 37.6K Read-Only Boards