After replacing pump problems occurred

[voicey]

Hi,

I replaced my criculating pump yesterday as it was making loads of noise. The job went ok, I followed the instructions and bled it before use.

Now there is a gurgling noise in the radiators and boiler. Last night I had to bleed the rad closest to the pump as it was mostly full of air (only the very bottom was warm). This morning I had to bleed 3 of 5 radiators in the flat, they all had loads of air in. The other 2 were fine. There is still the gurgling noise. Can anyone suggest why this is happening? I checked the pump conectors for tightness and leaks and everything was fine. I never had to bleed the rads much before I changed the pump.

On a plus side the new pump isn't noisey!

Pump is grunfos, boiler is potterton nettaheat electronic.

Thanks in advance.

 

[voicey]

After reviewing some other posts on this forum I have just tried to test if the gas bled from the rads is hydrogen. It didn't light when I tried to set fire to it, so it can't be. I deduce that air must be getting into the system somehwere. Any suggestions?

 

[boilerbeasty]

Could still be air in there. Keep bleeding it, and check the water pressure is in there.

 

[voicey]

Thanks for the reply. How do I check the water pressure?

I have just re-tightend the pump fittings. Could the pump have been drawing air into the system?

 

[sterose]

After reviewing some other posts on this forum I have just tried to test if the gas bled from the rads is hydrogen. It didn't light when I tried to set fire to it, so it can't be. I deduce that air must be getting into the system somehwere. Any suggestions?

Haha.

That hydrogen problem is the least of your worries. No-one on this forum knows whether it is hydrogen, because no-one has ever seen the problem before. So it must be very rare. So dont worry.

You have air in the system, because when you do work, air gets in. So you may have to bleed the rads a couple of times.

Is the pump primed. Pumps cant pump air, so you must ensure that there is water in the pump, otherwise it will just spin and wont pump.

 

[voicey]

Thanks Sterose. The pump is pumping the water around, it's just making a gurgling noise as are the rads and boiler. I can only think that the air must be getting in through the pump fittings. Have just re-tightened them.

 

[voicey]

Well, I've been running the CH all afternoon and periodically bleeding the rad closest to the pump. It seems as soon as I bleed the rad it fills up with air in about an hour. I can't think where all the air is coming from. Any ideas?????

 

[breezer]

just a thought.

if each rad can hold say 1 cubic foot of air and you have 5 rads thats 5 cubic feet of air + air in pipes you have to remove thats a lot of air and some may get pushed around and take a while to come out.

 

[COG]

Are you sure its pointing in the correct way, you will find a direction arrow on the body ,have you got it on the corect speed?try turning it down to 2

 

[voicey]

Breezer: I didn't drain the system to fit the pump. There were valves either side of the pump.

COG: Yes I fitted it the correct way. I noted the direction and made sure the new pump was pointed the same way. I have just turned it down to 2 but it seems to make little difference.

I'va had enough and reckon I'll throw in soem fernox super leak sealer. Anyone used this before?

 

[voicey]

PS: Thanks for the replys guys.

 

[breezer]

you don't sem to have mentioned bleeding the pump. have you ? and is the bleed screw tight? (big screw in the middle)

 

[voicey]

I did bleed the pump and made sure the screw was tight. I'm at a loss as to where the air is coming from. I also checked the tightness of the valve fittings above and below the pump.

 

[masona]

This might sound stupid but is the pump valve open ?

What about if you bleed the first radiator then shut down the rad valves and then onto the next one,do the same thing until you get to the last radiator and then open all the others radaitor valves.

 

[karlos]

Assuming you are on an open vented system (CH expansion tank in loft) it is worth checking your open vent/cold feed are round the right way.

Pipework should be configured as below:

Open vent (usually 22mm) - Cold Feed (usually 15mm) - Pump

If these two pipes are the wrong way round the pump will suck air in when it is operating.