Pressure gauge keeps dropping, combi boiler?

CandyButcher

Hello,

I have a very new combi boiler and the pressure gauge keep dropping after I turn valve to refill system. Drops from 1.5 to 0.7 within a week im sure it will keep dropping further if I let it. Now all signs would point to a leak! But Im not seen signs of leak anywhere, which is not to say I dont have one.

Now what is bizarre to me is that 3 different people have told me that when they had a new combi boiler that they experienced the same thing and just had to keep refilling every week or so.

doesn't make sense to me.

Just wondering has anyone reading this ever experienced or know someone that had a similar issues with these where it wasn’t a leak ?

con747

https://www.boards.ie/discussion/2058323813/pressure-gauge-keeps-dropping-combi-boiler

In the same boat, installed about a month ago and lasts about 5-7 days then acts up. So far they have been putting a sealant in the system to see if it stops it. The latest was just earlier today so if it doesn't work it's find a leak time I think.

Edit, Sorry mine is a condensing boiler.

Lenar3556

Undersized or failed expansion vessel(s) would be the first thing to rule out.

Locate the outlet from the 3bar pressure relief valve and put a container under it to see is it allowing water escape as the system heats up.

You could also watch the boiler pressure gauge as it heats up from cold and see how much it rises. 1.5bar cold should be in the region of 2.0bar hot.

standardg60

Yep mine does the same, always slowly returns to 1 when cold. I imagine that's where it's supposed to be and the PRV releases when the pressure is too high when on.

When i had a leak it went to zero so maintaining 1 is fine.

standardg60

https://www.boards.ie/discussion/comment/121402880#Comment_121402880

Mine sits at 1 bar cold and hits 2.5 (red line) when on. Filling to 1.5 bar when cold is going to trigger the release valve when on until cold returns to 1 imo, hence my advice is to leave it alone unless it drops below 1 when cold.

CandyButcher

Apologies I should have mentioned it does go below 1. So far I let it drop to 0.7 then I refilled. But next time im going to see how low it will go.

It did cut out on me a few weeks before I was aware of this, and displayed a message saying “purge” then “fill”. Im guessing it dropped all way down to zero without me being aware.

With that being said 2 individuals still told me they also drops down to zero regularly (and been happening for them over a year) and they just keep refelling no leaks.

Again sounds too bizzare to me that a new modern boiler would require refilling every week or so.

Lenar3556

https://www.boards.ie/discussion/comment/121402964#Comment_121402964

That’s quite a rise. Your expansion vessel may be slightly undersized.

Lenar3556

https://www.boards.ie/discussion/comment/121403100#Comment_121403100

You need to get to the bottom of it.

constant refilling with fresh water will damage the new boiler and encourage corrosion in the radiators/heating system.

standardg60

https://www.boards.ie/discussion/comment/121403525#Comment_121403525

That's possible, I would have added a couple of rads to the system over the years.

I wonder what the OP's pressure rises to when on

CandyButcher

So if my pressure is 0.7 it may rise to 1.3 or so when hot.

It might be worth me mentioning after the boiler was installed, I then had 4 radiators replaced by a different plumber. Would that have anything to do with it ? I checked all the valves and no signs of moisture.

I did here a strange air like sound at one of the thermostats but it stops when I turn it slightly