Problem with Central heating

[Louise]

We have a problem with our central heating....The upstairs radiators work, and the pipe leading downstairs to the radiators is also hot, but none of the radiators are getting hot. A plumber friend suggested it might be the pump, so we installed a new pump, but no change. So we drained the system completely and refilled it, bled the rads to get any air out from draining, but still no change.

Any ideas what we can do next would be gratefully received please. Also could someone clarify,if when the system is drained completely and the downstairs radiators fill up ok that means there is not a blockage, all the radiators filled up at the same speed, one wasnt slower than any other.

When we bled the radiators after draining the system yesterday, the first radiator bled, drew out clean water, but the others upstairs and down let out dirty water.

Also today we bled the radiators again to see if any air had been missed and they all let out nearly clean water.

We have checked the 3 way valve by taking the motor off and can be operated by hand so is not stuck, and when the motor was replaced it moved positions when either the central heating control,or hot water control for the boiler was switched on.

The boiler seems to be making a lot of noise could there be air in the boiler that is causing our problems, and if so, could someone please tell us how to bleed the boiler to remove any air.

The boiler itself when the central heating is switched on is only on for a minute or so, then switches off. I am assuming this is because the water is not being pumped through to the radiators.

 

[breezer]

our "resident plumbers / heating engineers" will be about shortly, but more info required

Type of system (do you have a "large copper cylinder" or not)

make model of boiler

how old is system.

has anything else changed?

 

[Louise]

Thanks Breezer.

have a combi boiler, an economist, 10 years old, but nothing has changed on it except the new pump we put in yesterday. Just to add to my earlier post, forgot to mention, when we put in new pump and turned off the taps either side of it as you water continued coming out of it, and had to turn water off at the mains, so these taps either side did not stop the water coming out.

We have fitted a new pump successfully before in an old house, so did know what we were doing and taps were turned off as tightly as they could be. So not sure if this is connected, or a completely different problem.

 

[breezer]

as its still early, have you bled the pump? (big scew in the middle, and have you put it on the right way round? arrow on side points in direction of flow)

 

[Louise]

Yep, bled the pump, only got a little water out of it and no air, and yes the arrow is facing down, the way the water flows

 

[Louise]

Our main concern is that, if it is as we think the boiler containing air, or steam pockets because of the noise it makes, can we sort it out ourselves or do we need to get someone in.

 

[breezer]

you will have to wait for our resident heateing engineers / plumbers.

incidentaly, to add something you can click the

button

 

[oilman]

Oops! sorry were late.

You have a contradiction which I need some help on. You say the upstairs radiators work, but the downstairs don't. BUT you say the boiler is only on for a minute or so before it switches off.

The noise in the boiler sounds like there is air in it, are there other bleed points in the system other than the radiators? Is there a bleed point on the boiler?

Can you run the pump without the boiler firing? this may allow you shift the air without the system shutting down.

 

[breezer]

Oops! sorry were late.

for being THAT late you will get no tea

and as my new signature says "Merry Christmas to you All"

 

[Louise]

Thanks for the reply..All I can tell you is what I can suss out...When the central heating is switched on first thing in the morning the boiler runs for a fair amount of time, obviously heating the water that has gone cold over night, then it switches off, as far as we can make out the water then is only getting as far as the 2 upstairs radiators and the pipe down to downstaris radiators, but not reaching to the actual radiators themselves, so this is not using much water out of the boiler, so I am assuming it just comes on for a few seconds to heat up the new water coming in to replace it, so that is not a lot of water.

We know for definite its not the pump..as said before put a new one on yesterday, as this was the most obvious problem of the rads downstairs not getting hot, and the pipes either side of the pump are both boiling hot and can feel a vibration from it.

Sorry, no idea about any more bleed points in the system, I dont really know what i would be looking for to find any.

 

[oilman]

Do the downstairs radiators get hot if you turn off the two working upstairs rads?

 

[Louise]

No they dont. But the pipe leading down from the pump upstairs is still as hot as it usually is.

We took your advice about trying to see if can get pump to work without boiler being on, so turned off boiler,and turned heating on, and one of the radiators downstairs which had not been working before, began to get hot, so we switched the boiler back on and that one rad downstairs has stayed hot all day, but none of the others. This is working with the pump setting on 1. We tried turning the pump up to 2 to see if the other radiators downstairs would get hot, but as soon as pump is turned up the boiler begins making louder noises and the downstairs radiator that was getting hot cools down.

 

[Louise]

So could this be a case of a build up of sludge or something in the boiler, which was shifted slightly earlier when the pump was run with the boiler off, and as soon as the pump was turned up it tried to take too much water out of the boiler and sucked the sludge back into the outlet pipe from the boiler?

 

[oilman]

As youhave these problems, and the boiler is making some noise, sludge is a possibility. It would be worth draining the system and flushing it through to see if you get some sludge out of it.