pressure gauge at zero

stevo00

Hi guys,

I have oil central heating in my new house, first night I moved in had the heating on rads were not heating up properly and could hear bubbles in the rads so I bled them pressure dropped so I topped it up to 1 bar everything heated up fine pressure increased to 2 bar when hot . The next morning I checked it and the gauge had dropped to 0.5 bar overnight. I left it as it was, I had to leave town for a few days, I came back after the weekend and checked the gauge in the hot press and it was at 0. I went around to all the rads turned the bleed screw and water came out of them all which I thought was strange, I presumed that if the gauge was at 0bar then system would be really low and would not have water especially upstairs. I turned on the heating and all rads heated up again no cold spots, I checked the gauge after 2 hours and it was just over 1 bar. Does this sound like the pressure gauge is reading incorrectly ? or does it seam like I have a leak somewhere ? checked every fitting I could see in the hotpress and on the rads for leaks . PRV on the boiler seems dry. Any Ideas as I'm pretty confused. The install is less than 6 months old

Steve

spongerobinson

From past experience, it doesn't take much of a leak for pressure to go to 0. We had a couple of leaky towel rail valves, and it was a very slow drip which caused the pressure to drop rapidly. One of them the drips were actually evaporating before they'd even be seen. Could only see them by removing the valve cover while the heating was on.

I'm not a plumber, just a householder like yourself so I don't know the ins and outs of fixing the problem. We had our valves replaced on the radiators in question, which appeared to stop the bulk of the pressure drop, however our pressure still drops slowly over a month or so, so it's possible we still have a small leak somewhere else.

stevo00

Hi thanks for your reply, did your pressure rise up much from 0bar when you had the leak ? I'm going to get in contact with the developer and see if they will send someone to look into hoping that because it's a new house a that there's some sort if a guarantee from the plumber on work. I'm just hoping that the issue isn't under the concrete floor the pipes are all qualpex so they should have no joins under the floor but then again you would never know. I heard that it might be a bad expansion vessel would this cause the pressure to read low when cold ? I can't locate the valve on the vessel because the plumber stuck it in behind the hot water cylinder and access is quite tight

sky6

You should ask the Developer to arrange for a pressure test done on the system. Make sure it's left on pressure for 24 hours. Which will show up any small leaks. I've seen guys do a pressure test for a few minutes and then say the system is sound. Even a small leak will show itself over 24 hours.

stevo00

Thanks I will do that I don't know much about plumbing but is there any other reason the pressure will drop besides a pipe or fitting leak or the pressure release valve acting up. I'm dreading the thought of the floors being ripped up even if I don't have to pay for it

pmce4

hi
the pressure relief valve will only open when the pressure goes high and will not drain the entire system. So unfortunately like myself you most likely have a leak.

pmce4

check all visible piping for leaks and all rads. If you find one above ground you are lucky. Mine is deffo underfloor

stevo00

Thanks
The builder is sending a plumber today so we will see what he finds im hoping it's on the boiler side that is the only place I have not checked for a leak