Main System Eco HE boiler pressure too high

Boiler pressure is too high on stand by.. but when the boiler is woring pressure indicator decreases to Green! Do you know why...( Give you a clue.. Pressure goes low when the pump is on)

[@repairs4pcrepairs4pc67]

Correct Dan, according to the manual online from main, it says 0.5 bar. When I removed the expansion vessel in my main combi eco 25, it says 0.8 bar on the label attached to it, which is roughly around 11.60 psi. I had the same issue where upon turning off the boiler, it will reach 4 bar and I had to top up every 2 or 3 days. Took out the expansion vessel, emptied it completely, then recharge using a compressor up to roughly 0.8 bar. Put everything back and boiler works fine now. Thanks Dan for sharing your knowledge.

[@k956upg]

The expansion vessel on most main Eco / elite boilers is low from production.
I have fitted about 150 of them & they usually need to be empty of water then empty the expansion vessel then refil with foot pump to about 1-1.2 bar
It's all u need to do.
The mistake people do is
Lowering the pressure by bleeding a rad will bring it down but when u run it the air particles in the water will expand with heat & up the pressure will go.
Then it will contract to a low pressure when cold.meaning unstable pressure.
The only other thing is if you have lots of radiators you may exceed the expansion vessels capacity.but that's only in very big houses.

[@stitcheruk1150]

One suggestion for the pressure issue is to check the filling loop. If it is still fully connected, as mine was, it may well be that it is still letting a small amount of water in to the system. Excess water escaped through the pressure valve but also leaked through the thermostat valves on the radiators. I just had to slightly back off the filling tap and my pressure was sorted - a fault in the tap on the filling loop.. However, as the high pressure had been happening for some time I also had to replace the expansion vessel which had started to leak - possibly due to continual high pressure.

[@ndukaanalogbei1043]

Is it safe to bath when the boiler bar is at 3.5, would it have any effect on the boiler?

[@Waynetywh4526]

Has this problem always been present on the boiler?

[@bhataamjad4074]

Jeffrey Harvey i agree with you

[@Memories4lifemedia]

its the same with all main eco elite boilers installed hundreds of them

[@sharonfrost4323]

God ours is forever doing this

[@tonywit55]

Connections reversed on pressure guage

[@chalker1100]

Reset "....WHERE