Heating failing downstairs, now also upstairs

[popjoerg]

Saturday afternoon we noticed that it was getting very cold downstairs while the upstairs seemed OK. The boiler (Glowworm Ultimate) only ran for a minute at a time, then took a break of several minutes, while the pump seemed to be running all the time.

Monday we had an engineer round. He checked the boiler and the pump; they're OK. He said it was probably a build up of sludge in the manifold which stopped the water going to the downstairs radiators. The boiler simply switches off when the circulating water's sufficiently hot.

He recommended a power flush which is booked for Friday, and also said that we could try closing all the upstairs radiators bar one to put some pressure on the ones downstairs.

We've tried this since Monday, but now the heating upstairs is also failing! There's no air in the system when we bleed it, but something strange has happened with the water that comes out: On Monday it looked very dirty, but this evening it's practically clean both upstairs and downstairs.

What's happening?? Will the powerflush help? I'm really nervous now that we'll be left without any heat at all

 

[bookahandyman]

You have to establish whether its block or unbalanced( more heat going to some rads than othes.) Turn your heating on and crank up the stat. turn all rad valves off and then in turn try each radiator one at a time by opening both valves. if that rad heats up turn it off and go to the next etc... if all heat up individually then no blockage. then open the TRV side of each one if you have TRV's otherwise ( note when trying a rad which side heats first.) open the side that heated first(the flow) then open each other side (the return) only a couple of turns or so. then leave heating running for a few minutes as you go round adjust the colder ones by opening the return valve more and warmer ones by turning down valve. it takes some time but you should end up with equally heated rads at the end. if it works cancel your powerflush unless you want it doing.

 

[kevplumb]

just cos the pump motor is running does not mean its shifting water

upstairs will get hot by gravity

you don't tell us what system you have

i would be looking at the pump first

 

[popjoerg]

The downstairs radiators don't get properly hot, even if just one of them it turned on, all other radiators turned off. It's possible to get them no more than lukewarm.

I think the system's pretty standard. GlowWorm Ultmate boiler downstairs, hot water cylinder upstairs, header and cold water tanks in the loft. In the closet next to the hot water cylinder is a pump and a three way diverter valve. Controller unit in the kitchen downstairs.

The diverter valve is a Honeywell which has a lever for turning it to manual. I tried this yesterday to no avail --- even with the valve on manual, the system still behaves in the same way.

 

[popjoerg]

After those posts in November we had the powerflush, but problems remained. One radiator downstairs stayed cold, and when the system was hot, the boiler kept switching on and off in a cycle of about two minutes, as if the circulation in the system wasn't sufficient to dissipate the heat.

Now, two and a half months later, the situation is deteriorating: We seem yet again to be losing heat on the downstairs radiators.

I had another, independent heating engineer looking at it on Friday. According to him, the diverter valve, pump, and boiler are all OK. He couldn't figure out the reason for the poor circulation! I'm getting pretty desperate.

The only thing he did say was that apparently there's a lot of air in the system: You can hear it circulating if you turn the pump up and open the closet with the hot water cylinder and pipes. The strange thing is, none of this air ever makes it to the radiators --- only water comes out whenever we bleed them.

 

[popjoerg]

The plot thickens. I just tried bleeding the pump, and no air *at all* escaped! While the screw was loose, I could still hear what I thought was air passing through the pump every now and again --- but nothing came out! Perhaps the pump is actually broken. Is there any way to check for that?