Boiler pressure problems - pressure high after heating

sadako · Sep 30, 2021

I have a Worcester Greenstar 30i boiler which is about 5 years old and fully serviced. As the days have become colder I decided to put the heating on and noticed that the pressure gauge was sitting at 2 bars cold. I bled a radiator and brought in down to just below 1.5 bars and put the heating on for an hour. Heating worked fine and radiators worked. Once the heating went off, I noticed a few hours later that the pressure gauge had reduced in pressure, but not back to 1.5 bars (sitting half way between 1.5 and 2). I bled a different radiator in the morning and this time reduced pressure to just above 1 bar. I put the heating on and it hit 2 bars while operating. Once it went off and cooled down, again, it hasn't gone back down to 1 bar but is sitting at just below 2.

In summary, I am having to bleed the radiator every time the heating has been on.

Can anyone explain what the issue might be?

Additional info:
A new bathroom was fitted in summer including a towel warmer in place of old radiator.
I have noticed that the keyless filling link doesn't work when pulled - could this contribute to pressure in some way if faulty?

Many thanks

John.g · Sep 30, 2021

Have you disconnected the filling loop.

sadako · Sep 30, 2021

I haven't disconnected anything but can't be sure if the plumber who fixed new radiator has. Taken some photos of what I can see which probably isn't that helpful. I have been told by somebody else that I needed to bleed ALL radiators, but I thought 1 would suffice if it reduced pressure.

John.g · Sep 30, 2021

You should get rid of the air in all rads, you might have to top up the system then as water will replace the released air.

SJB060685 · Sep 30, 2021

All rads need to be bled. Any idea what your static cold main pressure is? I'm thinking the HW plate heat exchanger has split.

sadako · Sep 30, 2021

John.g said:
You should get rid of the air in all rads, you might have to top up the system then as water will replace the released air.

Thank you. I can't top up the system as the refill isn't working

Out of curiosity, what difference does draining all of the radiators make rather than just one? If one is enough to reduce pressure, why would bleeding them all stop the issue?

SJB060685 · Sep 30, 2021

Bleeding the system is done to remove trapped air. Air caught in the system can cause air locks which will prevent circulation of water and rads to heat up. Air will also cause corrosion. ALL air must be removed.

As I said above I suspect the PHX

sadako · Sep 30, 2021

SJB060685 said:
All rads need to be bled. Any idea what your static cold main pressure is? I'm thinking the HW plate heat exchanger has split.

No idea on the main pressure. Got a feeling this is a problem I can't fix myself as I am totally out of my depth.

I can bleed all the radiators, but can't refill boiler if the refill isn't working.

Thanks

SJB060685 · Sep 30, 2021

You are not allowed to touch your boiler and I commend you for acknowledging that and that you're out of your depth. If the filling valve isn't working then no you can't top the pressure up.
If you were to drain all of the water out of the system you would then see if the plate had failed as the system would start filling again and stabilising at whatever the cold mains static pressure is, or the discharge valve setting, whichever is lower. However if it wasn't the plate then you can't refil the system and would have no heating or hot water.
I suggest getting a gas engineer out ASAP.

sadako · Sep 30, 2021

sadako said:
No idea on the main pressure. Got a feeling this is a problem I can't fix myself as I am totally out of my depth.

I can bleed all the radiators, but can't refill boiler if the refill isn't working.

Thanks

When I am bleeding all, am I just doing it until the air is out or completely draining system to stop the issue. All radiators are hot, top to bottom before I do it.

sadako · Sep 30, 2021

SJB060685 said:
You are not allowed to touch your boiler and I commend you for acknowledging that and that you're out of your depth. If the filling valve isn't working then no you can't top the pressure up.
If you were to drain all of the water out of the system you would then see if the plate had failed as the system would start filling again and stabilising at whatever the cold mains static pressure is, or the discharge valve setting, whichever is lower. However if it wasn't the plate then you can't refil the system and would have no heating or hot water.
I suggest getting a gas engineer out ASAP.

Thank you for trying to help anyway! I have booked one. Coming tomorrow.

SJB060685 · Sep 30, 2021

sadako said:
When I am bleeding all, am I just doing it until the air is out or completely draining system to stop the issue. All radiators are hot, top to bottom before I do it.

When bleeding do one radiator at a time. Vent it until all air has been removed and water begins to show.

sadako · Sep 30, 2021

SJB060685 said:
When bleeding do one radiator at a time. Vent it until all air has been removed and water begins to show.

Was fairly easy. No air in any and water straight away. Guess I have a bigger problem on my hands. 😔😔

SJB060685 · Sep 30, 2021

sadako said:
Was fairly easy. No air in any and water straight away. Guess I have a bigger problem on my hands. 😔😔

Just explain to your engineer the problem and he/she should get you sorted.

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Boiler pressure problems - pressure high after heating

sadako

John.g

sadako

John.g

SJB060685

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sadako

SJB060685

Plumbers Arms member

sadako

SJB060685

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sadako

sadako

SJB060685

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sadako

SJB060685

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