2 cold radiators downstairs

[coldasfcuk]

Right we bought a house and everything with the central heating was semi ok. We were decorating and noticed that pretty much every radiator was leaking, so we changed all the valves on all the radiators. While all the rads were off the walls, we thought why not flush them out. When we did big fat lumps of muck came out. Before we touched these, all rads got hot.

Now that may have nothing to do with anything, but thought I would put that anyway.

Now, the heating up stairs is fine, boiling in fact. Heating downstairs is non existant. If we turn off all the rads upstairs, the downstairs ones get hot, but only the tops of them. Now I thought ok, maybe its some of the sludge and other crap that we saw before and that it had got moved round the system downstairs and is blocking the radiators and maybe the pump can't move it back up. However I took both rads downstairs off again today and flushed them again and nothing really came out.

Put them back on the walls and filled everything up (bled everything and removed all air pockets, at least I think) and again the rads upstairs are boiling and the rads downstairs are cold.

The pump, a Grundfos 15/50, appears to be working away quite happily. Its spinning like crazy anyway. Its currently set to 2 however I had it on 3 and it made no difference. So for noise sake as it made no difference either way I put it on 2 again.

Motorised valve appears to be working. This is a Honeywell V4073.

The boiler is a Potterton Flamingo 50, bit old but is doing a great job. Its on its lowest setting and heats the water and upstairs rads in no time at all. It gurgles a little now and then, but overall it is heating things so that appears to be working.

The heating as far as I can tell is a Y plan system although this is a best guess.

Hot water is fine.

Central heating thermostat is downstairs so its surrounded by cold and is making the boiler fire pretty much constantly.

Ideas?

 

[MANDATE]

With the valve you have it is a 'Y' plan. The pump and valve are operating OK. If a radiator gives you a problem of hot at the top, it suggests to me there is water and not air at the top so bleeding is not the answer.
I would also think the restriction is due to sludge along the bottom of the radiator and maybe in the middle vertical tubes. It is reasonable to assume water enters the radiator, goes straight up to the top along and down and out. Even if it can pass along the bottom you could still have the middle tubes blocked.
I was also thinking that with two radiators being affected, could a partial restriction be in the pipe work. This would allow the radiators to fill when you bleed them, but would restrict the flow and maybe give the symptons you've got?.
I think I'd be tempted to remove one of the radiators and fit a hose to one of the valve outlets and then run some water off in a bucket, then repeat on the other side. You may notice a difference in flow if one side is partially blocked.
Can't think of anything else!.

 

[ChrisR]

Bet your pump is blocked with all that sludge. Take the 4 allen screws out and you'll see the impeller which is 2 discs with a 4mm or so gap between. If the gap is full it won't do much pumping. Allen keys again useful - for clearing them out!

It would be worth putting some desludger like Kamco Hyperflush or Fernox HD Restorer in there for a while then flush it before adding inhibitor. You've probably cleared most of the sludge reasonably but there are always Klingons, Jim. Sentinel X400 works if you want to leave it for weeks.

 

[coldasfcuk]

Thanks Mandate, but thats what I did already.

I turned off all the rads up stairs again today and whacked the pump on full and let the rads downstairs do there thing for 3 hours. And they are now getting baking hot, top and bottom. So the flushing I gave them yesterday has worked in terms of rads not getting completly hot. Then turned two rads on upstairs and once again the rads downstairs started getting cold again.

ChrisR, I will try your suggestion about the pump. 1 question though, I don't have an isolater just for the pump. So I would have to turn off all the electicity to the house. Is this necessary? Ie, am I gonna electricute myself if I take it off?

Also if the rads downstairs are getting hot when I turn the rads upstairs off, does that mean there can still be a faulty pump?

1 other question which has been bugging me. The motorised valve has a manual option. What exactly is the manual option?

 

[MANDATE]

The lever on the side of the valve holds the valve in the mid position when on the latch. This is to aid filling the system so one side can't get blocked off. I believe you can use the lever to push the valve the full distance to CH only. This is useful for checking if the motor has driven the valve the full amount and the valve then operates a microswitch, so you can check for voltage on the orange wire when calling for CH only.
If the voltage is not there then either the microswitch is faulty or the motor has not moved the quadrant the full distance.
Regarding the radiators, from what you say it sounds as though the water is taking the easiest path and starving the downstairs rads.I think you'll need to adjust the upstairs lockshield valves by closing them a little.
This will restrict the flow to the upstairs and give more flow to the downstairs.

 

[teddyboy]

Have you had any luck with your radiators yet? Please tell us

Cheers
Teddyboy

 

[coldasfcuk]

YES!

Bit of a delayed reply due to work, but all is good now. A couple of days of just letting the radiators do there thing seems to have worked after the flushing out.

Only thing is there is a little gurgle from the boiler, but I can add some solution to the system which should get any air out of the system. However at the moment I am just happy everything is working

No more freezing while I am downstairs

Thanks guys