Air locked boiler water pump

amandstu

I have an Interpart boiler pump next to the outside boiler that seems to have got air in it . Can any explain to me how I get the air out if it is in?

I have bled the cylinder in the upstairs hot press but tat has not helped.

Will it eventually come back or might I actually be damaging the pump by leaving it on?

There are no radiators being fed by the boiler so it seems simple but I can't see where to air bleed this pump.

John.G

If the boiler is fed from a small tank in your attic ensure this is full of water, if a pressurised system with expansion tank ensure pressure 1 to 1.5 bar.
Is the pump running?, there should be a vent screw right in the middle of the pump.
If a oil boiler there will/should be a PRV (safety valve) mounted on the top of the boiler or very close to it, turn the (normally red) plastic knob on its top very slowly anti clockwise, you will feel a bit of resistance as its opening, this should vent air as well.

amandstu

John.G wrote: »

If the boiler is fed from a small tank in your attic ensure this is full of water, if a pressurised system with expansion tank ensure pressure 1 to 1.5 bar.
Is the pump running?, there should be a vent screw right in the middle of the pump.
If a oil boiler there will/should be a PRV (safety valve) mounted on the top of the boiler or very close to it, turn the (normally red) plastic knob on its top very slowly anti clockwise, you will feel a bit of resistance as its opening, this should vent air as well.

The tank in the "attic" is full(actually I have just topped it up with extra water for a little extra head or pressure -to no avail)

Yes , i have been looking for that vent screw in the middle of the pump (having trouble uploading a photo as it is too large and I am unsure how to edit it) but cannot see it at all.

And the safety valve on top of the Firebird Super-q 90/120 Boiler is also nowhere to be seen .

On my old boiler I did that procedure all the tiime but this boiler I can't see it anywhere.

I am not damaging the pump by leaving it running in the hope it will free itself in a day or two ,am I?

John.G

I presume there isn't an isol valve shut or a blockage between the header tank and the cold feed to the system?.
Try slackening the outlet from the pump at the compression fitting where its connected to the 3/4 or 1 ins pipework and pull it back a bit to try and release any air and/or the compression fitting where it leaves the boiler.
I can't see the airlock clearing after a day or two and its not doing the pump any favours by running it continuously.

amandstu

I have been told that the pump bleeds itself .

But I have noticed a screw just above the pump ,about 3 inches along the piping (just before the main piping)

I turned that anti clockwise a quarter turn (which is the most it seems to want to go)

I noticed a "whoosh" and things seem better now. (A very small amount of air came out and also a small bit of water)

Have had to go out now so I have the boiler turned it off but expect normal service to be resumed when I return and start it again


Not sure whether that screw is meant to be turned clockwise or anti clockwise under normal running conditions -clockwise or "in" I suppose.

John.G

Maybe its the pump discharge isolating valve??.

amandstu

John.G wrote: »

Maybe its the pump discharge isolating valve??.

I think so (looks very similar.)

Anyway the water is back.

Is it really important to reset that nut to the vertical or just leave well alone now?

John.G

That should always be vertical, its a ball valve which is fully shut in the horizontal, there is another one on the pump inlet, I wonder did someone throttle in the discharge one because of water venting into the header tank, is this a newly installed pump?.

amandstu

John.G wrote: »

That should always be vertical, its a ball valve which is fully shut in the horizontal, there is another one on the pump inlet, I wonder did someone throttle in the discharge one because of water venting into the header tank, is this a newly installed pump?.

No,not recent (about 2 years).

My theory is that it may have been set only approximately vertical at the outset or that I may have touched it sometime for whatever forgotten reason and so it was only half closed.

Then ,yesterday I was working on the downstairs radiators ( they use a separate pump attached to the same boiler) and emptied out the expansion tank on the roof because I was bleeding one of the radiators "full throttle"

This ,I am wondering may have brought down a piece of algae growing in the expansion tank (it should be covered from the sunlight but is not)

The pipe from the expansion tank feeds in about 6 or 8 inches below the pump so I am not sure whether any such debris would be sucked up into the works.

Anyway when I touched that isolation valve it reacted very quickly and the water has been hot ever since.

It sounded as if it could have been a blockage and not just air in the system.

jimf

you may have solved the problem yourself

just be careful with those pump valves as they leak/drip if you even look at them

John.G

It might be no harm to look into the header tank when either system and both are in use and ensure that there is no water coming from the vent or any movement in the tank as any air entering the system will lead to sludge formation and corrosion problems.