Noise from pump?

[mark482]

I have started getting strange noises from my hot water tank cupboard, which I think are coming from the pump.

The system is a standard "open vented" (correct name?) type - gas boiler in the kitchen, hot water tank upstairs, cold tank and feed/expansion tank in the loft.

Only had the house a couple of weeks, heating seems to be working fine. Everything is on an old mechanical timer. I have turned the central heating "off" by setting a wall-mounted thermostat to zero, doesn't seem to be another control. Hot water is working bar the noise.

What I have done which I think has caused the problem: Removed a radiator for decorating, by closing both valves.

Everything sounds normal then occasionally there is a sudden "whoosh" sound followed by gurgling. Sounds a bit like flushing a toilet. This is pretty loud, enough to wake me up anyway...

I looked in the loft - cold tank has plenty of water, ball cock is a little "lazy" (dribbling) but does shut off. Feed/expansion tank has water, and ball cock seems fine.

Googling my guess is air in the pump? Does this sound likely? It's a Grundfos 15-50. Should I try to vent it? I understand I do this by turning the big screw on the end - do I do this with the system on or off? (sorry if stupid question, complete newbie) Does anyone know whether I turn clockwise/anti-clockwise? (I had a go but it seems very stiff both ways, and is not very accessible...)

 

[ChrisR]

ANticlockwise, just enough for water to come out.

Check for an air vent here:>

Sometimes because of gunge of various sorts old systems take a day or two to settle. Until then you can get noises like gravel going round, which is air bubbles.

 

[mark482]

Thanks for the reply, I'll have a go at the pump once I've got hold of a better screwdriver - can't shift it and don't want to damage the head more...

I'm not sure about a vent on the cylinder.

The part which I think matches your diagram looks like this:

The top end comes off the cylinder, the bottom goes into the mechanical valve. I can't identify the part sticking out, some kind of vent?

Here is a close-up (color is from my LED torch, it's brass colored). There are little holes around the fitting, and there are drops of water there.

Any ideas?

 

[ChrisR]

No that's a pressure relief valve - I think, it's hard to see anything!

Do the pipes whcih go into the side of the cylinder go on up?

 

[mark482]

Not the best pictures I know! The pipes going into the cylinder don't go on up. I've had a look around, plenty of "gate valves" (?) and a pair of "pump valves" (?) around the pump but nothing that looks like it could be used to bleed some air.

BTW I tried to run the heating to see if this would get things moving i.e. I set the thermostat on and opened the radiator valves around the house and was a bit surprised that none of the radiators came on. I still have one upstairs off the wall (both valves closed), so I wouldn't expect anything to work upstairs, but does this suggest that the whole house is on one "loop"?

 

[kevindgas]

yes it is a pressure relief valve on your cylinder, yes the screw on the pump will bleed the pump (do it with it running) are you sure that water is getting to system ? get an old towel, open a radiator bleed valve and see if 1. water squirts out under a small amount of pressure and then 2. check that the header tank in loft has started to fill if it hasn't repeat 1 again and then recheck tank if it still has not started to fill then you will probably have a blocked cold feed

 

[mark482]

I've bled the pump, and thoroughly bled all the radiators again, but with no effect. Definitely doesn't seem to be any vent around the cylinder or in the loft.

Reading some other posts it sounds like the boiler is kettling - it runs quietly for a few minutes, then sounds like a kettle coming to the boil, then a few bangs and "sloosh" sounds, then it shuts off.

Any ideas? The plan is to replace the (ancient Concord WRS) boiler in the near future, so I am safe to just live with it?

 

[Dan Robinson]

It sounds like there is no circulation.

Have you actually checked the pump is spinning?

 

[mark482]

Sorry, I should have mentioned the radiators are all hot again - possibly I was just stupid and had the thermostat the wrong way - presumably this means the pump must be working?

How do I check if it is spinning please?