Recurring air locks...

[ricardo117]

Hi there - in desperate need of some help on this one!

I have a fairly conventional hot water / heating setup in my flat in a block. I'm on the top (3rd) floor and I've got header tanks (which feed all the flats) which gives me pressure for the hot water cylinder, which is heated by the boiler underneath it. The hot water pressure has always been fairly poor, so I installed a pump to increase the pressure to the shower / bath taps.

This seems to work OK, but it seems that the system now develops air locks very regularly, which stop the hot water flow. I can manage to get the water flowing by backfilling the pipes from the mixer tap in the kitchen, but this is obviously not ideal!

So my question is: Could the pump (which is quite powerful) be drawing air in to the system to cause this (down the vent pipe from the boiler?) or is it likely to be something else? If it is the pump, would

If it's not the pump, has anyone got any ideas about what might be causing it? I'm guessing a blockage in the pipe from the header tank to the cylinder could cause this as well, but it happens so regularly that I'm sure it can't be constantly blocking - or am I wrong?

I've had a plumber who came round - he got the water flowing, declared it fixed and left...

Thanks! Rich

 

[swidders]

Is it just the hot water that airlocks?

How is the pump connected to the cylinder - if it's just a tee off the pipe therein lies your problem since should be connected to the tank with a surrey flange. Does sound as if air is being sucked down through the vent pipe as you suggest.

 

[ricardo117]

Thanks - yes, just the hot water, the cold (also coming from the tanks) is fine.

The pump isn't connected directly to the cylinder, it's on the hot water feed to the bath, so yes I guess it's just a tee off.