?introduced an airlock into my heating system

[Jon Telfer]

Hi, In a fit of winter diligence I bled an upstairs radiator which produced a reasonable hiss. I then found a vertical pipe with a brass ferrule-like end with a small screw end piece in a vertical line from my 3 position valve. I loosened it and it hissed. Ah more air found I thought and let it hiss for a few mins. **this was with the heating on**

No heating this morning + no woofs from the boiler. On googling I suspect the hiss from the brass ferrule thing was air going in rather than out. I'm holding my hands up, in retrospect it doesn't look to have been a bright thing to do.

Current situation with controller asking for heating+hot water:

1) Boiler (Potterton Netaheat Profile 50e) seems dead, on getting home I turned the boiler knob up and it fired for 2-3 mins and then stopped without much fuss i.e. no banging. Presumably it reached some kind of thermal cut-out as it won't do this any more.

2) pump whirrs and is pretty hot to the touch

3) All pipes around are cold - this doesn't change if I change mid pos valve to man.

Any help much appreciated.

Jon

[Christian McArdle]

You need to refill it. Turn it off first! If the pump is running and it is a vented system, or a sealed system at low pressure, then it may well suck air.

Now find out if it is a header tank vented system or a pressurised system with pressure gauge. If the later, connect up the filling hose and turn on the tap until it reaches 1 bar.

Now go around the house bleeding the rads and any other bleed valves. If you have the sealed system, you'll need to occassionally return to the tap to bump the pressure back up. Ensure that you get water expelled at each bleed point (unless it is an automatic bleed valve which turns itself off).

Finally, turn the system back on.

Christian.

[Rupert]

There is a thermal cut out on the boiler which may need resetting.

each radiator of air and allow them to spew water for a while which should pull the airlock out.

[Jon Telfer]

OK thanks, I've got a small header tank in the loft. This is around half full. The upstairs radiator I bled initially gives no air. A nearby one had some air in but I'm now at a intermediate stage where the valve is open but I get neither air nor water through. Thoughts?

Thanks, Jon

[Nigel Molesworth]

Reminds me of my first encounter with bleeding a radiator ...

1970s. Age 16, parents out, heating on, radiator in my bedroom is cold at the top. Dad bled it last year and cured the problem, can't be that hard. I open the vent, hear a quiet hissing noise, noise gets louder as vent is opened. I decide to open it fully.

At this point, the water level reaches the vent and fires the bleed nipple across the room. Scalding, black, smelly water gushes out onto new carpet. I put my thumb over vent, it starts to burn, so I swap thumbs, it starts to burn ...

Over an hour later, my parents finally return and find bleed nipple.

It's amazing that I ever did any DIY again.

[Rupert]

Me too except I was 40 years old :-)

[Jon Telfer]

I think there must be a blockage somewhere. The radiators don't seem to produce any air or water. I drained about half a washing up bowl from the outlet at the bottom of the house and there was no movement from the loft header tank at all. The drained fluid was clear with no real hint of corrosion, but where did it come from if there was no replenishment from the loft?

Thanks,

Jon

[Christian McArdle]

This is one of the advantages of a sealed system. Filling is easier.

To get rid of airlocks, it might be an idea to close off all the valves and back feed the drainage point from the garden hose. That way the water blasts in under pressure. Have someone standing by in the loft to shout when the header tank is about to overflow.

Christian.