No heat in CH rads

Hi, following on from a previous post, my gas boiler (potterton netaheat

10-16) provides hot water but it doesn't seem to heat the radiators. There was a new towel rail installed recently which introduced some air into the system, after a week or 2 the rads stopped heating up.

As suggested I bled the radiators and a lot of air came out of some of them however upon turning on the boiler still no heat in the rads. The pump hums quietly so i assume its running and it gets quite hot to the touch, but would this need to be bled too?

Any help on what is at fault here is much appreciated!

Reply to
jh
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Have a look how the heating pipes go to the rads, if they come down from the loft you may find there is air at the top of the pipes. If this is the case have a look for air pips in the loft.

Andy

Reply to
Andy

Is the HW heating fully pumped or gravity? If the HW is gravity then the pump only comes on for CH, it might be full of air and so ineffecitve, try bleeding it via the plug at the back of the motor.

Otherwise you have some other reason why the radiators are not coming on. Pumps can also (partially) fail on the water side.

Reply to
Ed Sirett

The pump only comes on when the CH is turned on, so I guess thats it. I will try to bleed it, presume it should be off while I do it ?

The CH system needs its annual service/inspection anyway so I will probably get someone in to take a look at it soonish. Any recommendations for someone in the east london area?

Reply to
jh

On further inspection, nothing seems to come on when I turn *only* the CH on (i.e. no boiler or pump). When I turn on the HW the boiler kicks in as well as the pump. Maybe there is something wrong with the controller switch?

I will bleed the rads tomorrow again one by one from the downstairs working my way upwards, but somehow i dont think this will have any affect if the CH does not come on when i switch it on.

Reply to
jh

If you have a wall thermostat is it turned up far enough?

Reply to
Ed Sirett

jh wrote in news: snipped-for-privacy@news.zen.co.uk:

Ed beat me to it on the thermostat - it's turned warm, whack it well up for maintenance.

My place is full of airlocks, and I turn off radiators and branches (at the radaitor valve) after refilling, leaving only one open.

A branch is where there's more than one rad in series on one branch off of the main circuit; then shutting one of the rads will do for both, though the air may end up at the top of each, so they'll bothe need checking/bleeding. But usually it all ends in the first one on the branch.

Then I turn up the pump to full speed, and it blasts the air through, and itno the rad, which I bleed, and turn off.

I repeat this procedure until all the branches are clear.

(My hovel is "top down", with concrete floors, all the pipework in the loft, and dropping down to the rads - I get *plenty* of airlocks.) :-)

When I've sorted all the rads I return the system to normal and wind down the pump.

It doesn't take long when you've got the idea - I start on the assuption I'll need to go through the drill and get right on with it.

HTH

mike

Reply to
mike

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