Boiler losing pressure?

Vanilla

Vanilla

Vanilla

Soldato
Joined
18 Oct 2002
Posts
9,515
Heya,

We have a combi boiler that is fairly new (3 years?).

Recently it has started to have an issue with pressure. It goes far too low and can't operate. No how water or heating.

The quick fix is to allow more water into the system...which a friend says means there is a leak somewhere.

Is this typically the case? is there a sure fire way to find out? I can't dig up the floor boards :(
 
What the make of boiler,
Maybe faulty pressure vessel, pressure relief valve sticking & loosing pressure.

If it was my place I probably would do wet pressure test first, & see if the pressure drops when the system is full of water.
 
Last edited:
Nightglow said:
What the make of boiler,
Maybe faulty pressure vessel, pressure relief valve sticking & loosing pressure.

If it was my place I probably would do wet pressure test first, & see if the pressure drops when the system is full of water.
Click to expand...


+1
Both of these were the issues i've experienced in the same situation.

We also had a kinked pipe in the boiler from the previous service. The engineer that came to fix it was not amused, he was actually furious.
 
Vanilla said:
Days.

About 3 days ago I let more water in. Now same thing, low pressure.
Click to expand...

Not a leak in my opinion then.

Look at pressure relief valve, pressure vessel.

Also you have a drain pipe which goes outside, water could be force out of this,causing loss of system pressure, if the pressure valve, etc isn't working correctly.
 
Last edited:
One trick is to pressurise the system, then switch off boiler say for 24 hours.

You then secure a small sandwich / freezer bag over the outside drain pipe & see if it fills with water.

Normally it will not fill with water, & DO NOT switch on boiler with the bag still in place.


Need to get the engineer in to sort the problem.

EDIT: One other thing springs to mind, is a faulty pressure gauge, it's showing empty, when it's actually full, so you charge the system,& the pressure relief valve kicks in, if it's faulty, it may take time to release the pressure.
 
Last edited:
The old Worcester boilers used to have an issue with the auto air vents they would give up the ghost after a while.
 
Nightglow said:
One trick is to pressurise the system, then switch off boiler say for 24 hours.

You then secure a small sandwich / freezer bag over the outside drain pipe & see if it fills with water.

Normally it will not fill with water, & DO NOT switch on boiler with the bag still in place.


Need to get the engineer in to sort the problem.

EDIT: One other thing springs to mind, is a faulty pressure gauge, it's showing empty, when it's actually full, so you charge the system,& the pressure relief valve kicks in, if it's faulty, it may take time to release the pressure.
Click to expand...

No harm running the boiler with a bag over the pressure release run off, it's a fairly standard test for a faulty pressure release valve or expansion vessel just don't leave it there.
 
Nightglow said:
Not a leak in my opinion then.

Look at pressure relief valve, pressure vessel.

Also you have a drain pipe which goes outside, water could be force out of this,causing loss of system pressure, if the pressure valve, etc isn't working correctly.
Click to expand...

Why?

We had a dodgy joint in our pipes, system was very slowly leaking causing loss of pressure over a period of days.
 
~Divine~Wind~ said:
Why?

We had a dodgy joint in our pipes, system was very slowly leaking causing loss of pressure over a period of days.
Click to expand...

I was confused by that too. Sounds exactly like a leak to me.

For a faulty pressure vessel, isn't one likely symptom that the boiler pressure rises when hot and then drops when cool? And that a sudden loss of pressure is caused by the pressure rising too much (when hot) and the pressure release valve emptying water from the system. And this sort of effect would be caused if the pressure vessel had an internal leak and/or needed re-inflated?

I'm certainly no boiler expert, but a leak seems the more likely cause imo.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom