Boiler losing water pressure

ian-d

I have a Potterton Powermax HE (150ltr) boiler (approx. 5 years old) which appears to be losing water pressure quite quickly.

I was originally told that topping up the water pressure via the value is quite normal once or twice a year, but I noticed yesterday that the boiler was on lock-out and after topping up to 1.5, it is back down to 0.9 today.

Would this suggest a leak? Anything easy I can test prior to having to get someone in?

macman

Is it leaking via the PRV? Have a look outside.

ian-d

Nope, seems fine. Next door seem to have always had a drip of water coming out of theirs but ours has never done the same.

macman

Then it must be leaking elsewhere on the CH circuit unfortunately.

gas4you

More than likely the expansion vessel is flat or knackered. This is extremely common on these. I look after loads of these and all have had to have the expansion vessel replaced after about 4-5 years.

Yorkie1

gas4you wrote: »

More than likely the expansion vessel is flat or knackered. This is extremely common on these. I look after loads of these and all have had to have the expansion vessel replaced after about 4-5 years.

Would you say Baxi105e boilers have similar issues with the expansion vessel, gas4you?

ian-d

Oddly the pressure is now showing 1.4/1.5 without a top up, rising to 2.0 when running/warming the house, so weird how it was 0.9 this morning then back up again! Is topping up quite normal at least a couple of times a year?

Just in case, where is the expansion vessel located?

gas4you

Op. yes topping up 2 or 3 times a year is quite normal. The expansion vessel is inside the top right of the boiler. The grey metal vessel. Easy access and you don't have to disturb any seals or gas parts to get to it.

Yorkie1. Yes it could also be a fault with the 105e EV, but not to such a common extent. It is a different EV on the 105e and not prone to faulting so often.

bengasman

ian-d wrote: »

Would this suggest a leak? Anything easy I can test prior to having to get someone in?

It doesn't suggest a leak, it proves it.
Look for water where it shouldn't be.

ian-d

Just a follow up to this, the water pressure hasn't reduced much since topping it up, so possibly needs doing every 2-3 months. However, I've noticed that when the boiler isn't in use, it is set to about 1.5, yet when the boiler is running, it reaches 2.5. Is it normal for the pressure to increase?

SYNERGY

ian-d wrote: »

Just a follow up to this, the water pressure hasn't reduced much since topping it up, so possibly needs doing every 2-3 months. However, I've noticed that when the boiler isn't in use, it is set to about 1.5, yet when the boiler is running, it reaches 2.5. Is it normal for the pressure to increase?

Yes the pressure increase is normal and due to the expansion of the water in the CH circuit when heated.

The extra volume of water is taken up by the expansion vessel

As a matter of interest, if you set the boiler pressure when the system was slightly warm (whole house at 15deg ) to say 1bar, the CH wasn't used for the next day, the temperature in the house dropped to say 5deg then you would see the pressure drop to below 1bar due to the colder water taking up a lower volume in the system.

Just wondering if you have set the pressure slightly too high at 1.5bar ?

Most systems are 1bar when cold.

You say that when hot it is 2.5bar, this is not a problem in itself but at 2.5 bar it is approaching the lift off pressure of the pressure release valve at 3bar.