Boiler pressure dropping so it cuts off once a day

15 Feb 2014
Reaction score
United Kingdom
Hi all

Noticed the condenser pipe had come out of the bottom of our boiler a couple of days ago so switched the boiler off for a day and then realised it was an easy fix so pushed the pipe back into place.

When I put the boiler back on again I noticed the pressure was low so opened the valves and that seemed to fix it but the pressure dropped back out quite quickly and the boiler switched itself off.

Did it again the next morning - same thing.

Today I did it again but left the heating on all day and it was on when I got home. Did a few things that used the hot water and it dropped off again.

I've bled the rads pretty recently but have noticed that even after bleeding them they whistle a bit – the whistling stops with an adjustment to the radiator thermostat gauge.

Any idea what it's likely to be?
Sponsored Links
What boiler do you have ?
What does pressure rise to when heating is in use ?
Does the copper pressure relief pipe ( usually external), show any signs of expelling water ?
Thanks for the reply Terry

Ecotec Pro 24
Pressure was at about 1.5 but dropped to maybe 1 with the heating on
No pipes show any signs of expelling water - we only noticed the water leaking from the condenser pipe and since that was pushed back it's been fine
Does water drop continually from the condensate pipe ,when boiler is not in use ,and hasn't been in use for say 1 hour ? If it does ,you probably have a pin hole leak in your heat exchanger.
Sponsored Links
Nope, when we switched the boiler off it stopped dripping - no drips at all after less than an hour
Whistling sounds like it could be the trv. The pressure loss could be a leak either a small one inside (please do not remove the cover to look) the boiler or a radiator leak.
Thanks - so the whistling noise and the pressure loss are unrelated?

Any risk of damaging anything if I keep opening the valves to increase pressure? Will get a professional round after Easter
Update – heating has been on the whole time and the boiler is staying on for at least 24 hours a time now. I'm having to increase pressure if we don't use hot taps for quite a few hours now.

Will obviously a professional round but would that behaviour suggest what might be at fault? Is there any risk of damaging anything if I keep opening the valves to increase pressure?
Had similar problem meself a while back and eventually boiler man realised that pressure relief valve was faulty and replaced it, end of. Mine was about £25 but it didn't take long for my man to fit it so no massive bill.
mine was doing the same - losing pressure over a few weeks , and needing refilling. could not find the problem. we had a kitchen refit and the pipework moved and found an elbow was not soldered very well, not wet, but must have been the issue , once repaired we had no further issues and the pressure remained constant for over 2 years , until i made more changes
But i was losing pressure so when checked each month or less , it was down to between 0 and 0.2 ........ and needed filling back up to about 1.2 when cold
@jammycodger thoroughly check all your radiator valves for signs of a leak... Best tool is a dry finger wiped around the joints (3 on each valve) start at the top joint and proceed down.

You'd be surprised how many I find leaking when I attend and homeowner says none are, so be thorough.

Then check all other pipework you can access, ie not under floors.
Check all ceilings for any signs of damp patches, staining. All water connections under boiler.

Start there... "if" your discharge pipe is definitely not leaking/dripping.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links