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Post by Jeff on Mar 10, 2013 4:55:34 GMT -5
Mike,
After reading your excelent repair knowledge base can I just confirm that I have understood your article on the "pressure" issue that I am now experiencing. I find now that my 14 year old Powermax requires me to constantly top up the pressure via the filling loop on a weekly basis. In the last week though I have now noticed that the pressure when running creaps up to the 3 bar mark, where I immediatly turn the boiler off. Is this all down to a faulty diaphram in the expansion tank? I have noticed that water is dripping out of the expansion tank on occasion. At what pressure should the diaphram be inflated to and is this a job that can be carried out easily by myself?
Thank you
Jeff
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Post by Mike the Boilerman on Mar 10, 2013 13:43:36 GMT -5
Jeff,
This problem is caused by the pressure vessel losing it's gas charge. The pressure vessel should be pressurised to to 1.0 bar (15psi) using a car or bike tyre pump. Occasionally the diaphragm inside the expansion vessel fails, indicated by water instead of air behind the schrader valve. If you have this then the expansion vessel needs to be replaced.
If the pressure in yours is zero (using a car tyre pressure gauge to measure), then it is probably also FULL of water which will need to be expelled when you pump it up to restore the pressure. Release this water by opening a drain cock on the heating system to allow the water to escape as you re-pressurise the expansion vessel.
When the vessel is holding a pressure of 1.0 bar and no more water is escaping from the drain cock, you are done. Close the drain cock and pressurise the water system with the filling loop. The pressure will no longer rise to 3 bar when the boiler is running.
You may find the pressure relief valve still dribbles water - they do this sometimes once opened. Try turning the red release knob on it a few revolutions, this may re-seat it properly. If this makes no difference it will need replacing.
Hope that helps,
Mike
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Post by Aza on May 30, 2013 5:21:19 GMT -5
Mike,
please advise where the pressure valve could be bought for Powermax 155x.
Many thanks,
Aza
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Post by Mike the Boilerman on May 31, 2013 10:47:42 GMT -5
Aza,
Any good boiler spares merchant!
E.g. Sparesbase, Parts Center, etc. Or try on line. Hundreds of boiler spares sellers on line.
Mike
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Post by Dont Panic on Oct 17, 2016 23:56:04 GMT -5
Mike, I have a similar issue with the pressure being lost over a period of weeks. As it appeared the vessel had failed I replaced it, but the situation remains. It is a tenanted property so getting feedback from the disinterested tenant is poor. I am starting to suspect the 15mm pipe connecting the expansion vessel to the Central Heating is blocked at the horizontal section as it enters the CH system. I've had this on a number of HE's, but I am surprised that the 15mm would block on sealed system. Have you come across this in the past. If so have you relocated the expansion vessel or was the swept bend easy to clear. My preferred choice would be to replace the bend and affected pipe with 10mm flexible. I would value your reply
Dean
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