Pressure relief..

20 Nov 2009
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United Kingdom
I have a closed CH system, with an expansion tank.
Boiler is a Suprima 60, expansion tank is a red bulbous thing with a pressure relief valve on top that has a gauge that red lines at 3.0bar.

Earlier today I noticed pressure was shown as .60 on a luke warm system that was just starting up. I topped it up to 1.0bar and left it. Now its hot the pressure has risen to 3.0bar, so its venting water via the overflow.
From memory it used to go to about 2 bar when hot.

Any idea what's wrong please....thanks
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check what the pressure is on the ex vessel by the Schrader valve.

sounds like it low on pressure.
Thanks, will check it tomorrow...
Did I read somewhere it should be 10 psi without any water pressure?
Is this ok:

I used a hand pump on the schrader valve and pressurisd the system to about 1 bar, I then used the overpressure release vale by the pressure gauge on the expanion vessel to release all pressure to zero. This caused the pressure on the schrader valve to also zero.

I repeated this about 4 times until the overpressure release valve stopped emitting water (I assumed that I have negated the water pressure). I then pumped the schrader valve to 1 bar.

I have set the water pressure to just below 1 bar.

I have now restarted the system that is heating up nicely and I've noticed that the expansion bottle pressure gauge is not rising quickly like it used to.
Its now hot and the expansion pressure gauge has only moved a small amount from just below 1 bar to just above 1 bar.

Please tell me is this ok....
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At the moment its not leaking. It did tend to take a while to shut off when I was mis-using it. I could hear water leaking through but its now sealed so I'll leave it alone.

The CH is getting to full temp, the pressure valve reading is rising only slightly and there's no leak from the overflow so fingers crossed...


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