Radiators - help

[Plump Bob]

Help!

Having removed and replaced a couple of radiators, my central heading now doesn't work. Last night the pump (I think) was making all sorts of funny clicking noises and this morning, despite there being hot water, the radiators didn't heat up at all.

Any one able to advise?

Thanks

 

[kevplumb]

did you bleed the pump
is it running
what system ?

 

[Plump Bob]

I didn't bleed the pump - I don't know how!

I think the pump is running, I can hear it buzzing, but no hot water is getting round the system.

Not really sure what kind of system it is. It's not modern, but it's not super old either.

 

[kevplumb]

unscrew the big screw in the middle of the pump should get a dribble of water then use a small screwdriver inserted in the space and see if the shaft is turning
there is a slot in the top of the shaft to free it if it sticks
if the pump has a black nut in the middle just undo it and pull back (it wont fall out)
and turn the nut
does the same thing

 

[Plump Bob]

It's a Grundfoss pump, not sure of the model. It's got a big silver screw in the middle. So, with the heating switched on, should I unscrew this and see if the shaft is turning and if it's not, get it going with a smaller screwdriver?

Will this get the water flowing round the system again? Is this the idea?

 

[kevplumb]

yes try first with the power off if the shaft turns then put the power on and feel gently with the driver you will know if the shaft is turning

 

[Plump Bob]

I'm at work at the moment so this is all theoretical but, if I manage to get the pump going again how much should I re-tighten the big screw?

Also, last night I tried to bleed the radiators I'd just re-fitted, but air just went in them instead of coming out. So, I'm concerned that the system is full of air! Do I need to top it up again or anything?

Thanks for the advice btw

 

[kevplumb]

check the feed tank in the loft aint empty
dont overtighten the screw its got an o ring seal so dosent need to be that tight

 

[Plump Bob]

There ain't no loft! How do I identify the feed tank? Should I worry particularly about the possibility of the system being full of air?

 

[kevplumb]

feed tank is (usually ) the smaller of the two
is there a valve in the airing cupboard near the cylinder
lump of brass with either a silver metal /plastic head on ?

 

[Plump Bob]

As far as I can tell there's only one tank - unless it's split into two. There are a number of valves, some with round red metal handles and one with a T-style handle, more like a tap...

What about the air in the system?

 

[kevplumb]

where the rads upstairs sucking air in ?
bear with me this is getting confusing

is your hot water tank square with a smaller tank at the side ?
or round with a smaller bit on the top ?
or neither of the above ?

 

[Plump Bob]

Confusing...tell me about it!

Last night when I tried to bleed the rads, they did start to suck air in, yes.

Tank is square, but I can't see a second one.

 

[kevplumb]

is there a makers name on it

elson springs to mind

 

[Plump Bob]

I'm pretty sure there's no name on it. What about the sucking in of air? That's got me worried...