Boiler drops pressure quickly

d0nkeyk0ng

New WB combi boiler fitted a couple of months ago. Over the past few weeks, it loses pressure intermittently. I checked on Saturday lunchtime and it was fine at 1.2 bar. Checked Monday evening and it was now 0.2 bad. I have to top it up every infrequently (less than once a week, more than fortnightly). 

Waiting for plumber to turn up but thought I’d pick others’ brains for ideas on why it’s happens quickly but infrequently. 

Bendy_House

All sorts of possibilities, from leaks (internal or external to the boiler), to a letting-off discharge pipe.
The latter is easy to check - ID the 15mm copper discharge pipe on the outside wall - it'll either be pointing down at the ground, or bent back towards the wall. Place a pot under it, and protect it from rain. If anything ends up in there, you have a 'pressure' issue, usually easy for them to sort.
If NO water in there, then it's usually a 'leak'... Check all visible pipes and rads.
Let us know what they find, please.

another_casualty

Hope you don't mind me chipping in here , but I too have a WB and currently have similar issues ..
My WB is 2 years old this month .  In the winter of the first year , there began to be random banging noises . @powerful_Rogue had same issue . 

When the first service from WB engineer happened last year I forgot to mention it as I thought that the banging was coming from elsewhere .
The engineer replaced right hand hinge ( I think ) .

Back to the pressure issue ; I noticed that the pressure was very low indeed in December last year . Since then I adjust the pressure every couple of weeks . Tbh, it seems like I should have been checking the pressure more often than I had been . 

Then again , it seems these things always happen in the cold winter months .

10 days ago, my hand ' locked' and the pressure went over 2 . 7 days later it is 1.5  . 

This tells me there is an issue similar to OP

I have my annual service next month , and will mention to WB engineer.

It has got me thinking though, whether the quality of WB boilers are not as good as some people swear by . 

Thankfully I have a guarantee for a few more years . I will always use a WB Engineer for service as although it costs more , at least it's continuity and they can't blame other engineers etc ..
 

macman

Assuming this is a combi, then it can only be one of 3 things: a leak on the CH circuit, a faulty EV, or a faulty PRV. The latter two are easily checked, and it'll be obvious if there is a discharge from the PRV.
All except the former will be covered under the warranty, so get WB in to sort it out.

Bendy_House

Have you checked the obvious, A-C - the discharge pipe?

(If you accidentally put the pressure up over 2bar, that should be fine as long as it wasn't anywhere close to 3. If it happens again, simply release some pressure using a rad bleed screw. You ideally want it at 1 to 1.2bar, that sort of figure; it just doesn't have to be higher than that, and the lower it is, the less stress all round!)

another_casualty

Bendy_House said:

Have you checked the obvious, A-C - the discharge pipe?

(If you accidentally put the pressure up over 2bar, that should be fine as long as it wasn't anywhere close to 3. If it happens again, simply release some pressure using a rad bleed screw. You ideally want it at 1 to 1.2bar, that sort of figure; it just doesn't have to be higher than that, and the lower it is, the less stress all round!)

Thanks @Bendy_House
As the boiler is in the small bedroom 😾🙀, I didn't check the discharge pipe etc
With the boiler being in that room I tend to leave well alone and adjust pressure as and when . ( The joy of converted flats 😾) .

I will update here if it's a good idea. 

One general question now springs to mind ; how often should one check the boiler pressure?
It may sound a dumb question ...😼

Bendy_House

I suspect a large number of folk never do, at least not until the boiler stops working.

Really, sealed systems shouldn't lose any water, so a good system should 'never' require a top up. That's probably unrealistic, but I literally cannot recall when I last did mine - it was almost certainly only because I replaced a part, and that was two+ years ago.

Most things I've read seem to imply that a wee top-up every 6 months or so is 'acceptable', ie normal/not a cause for worry.

A near-complete drop in pressure should ring alarm bells, tho'.