Central Heating/ radiator question

[emmi]

Hi I don't know if anyone could help me as I know very little about cental heating. My radiators downstairs were cold whilst upstairs were hot. I googled this to find most answers were coming up with faulty pump. I have discovered my pump in loft and turned it onto setting no 3, whilst doing this I have discovered a silver box with a lever, I have pulled the lever to manual and hey presto my radiators are hot. What does this mean and what is the silver box ? Really appreciate help on this,
Cheers

 

[Space cat]

That siver box is almost certainly a three port valve. It normal operation it rests in the hot water only position. That is to say that the hot water from the boiler goes only to the heating coil in your hot water cylinder. (It's possible that some would leak past the valve, just enough to warm up the upstairs radiators.)

When your programmer and room thermostat call for heat, a motor inside that box drives the valve to its mid position. This allows boiler water to go to the radiators as well as the hot tank. The lever is there for filling/bleeding the system and for test purposes. When you pushed it to Manual, you did what the motor should have done so now you have hot radiators.

The question is, why didn't the motor do its job. There are many possible answers: faulty programmer, faulty room thermostat, faulty motor, broken wire --- To get to the bottom of it you'll need some knowledge of electric circuits and a meter - or some help.

Incidentally, you should have posted this in the Plumbing and Central Heating forum. The mods might move it for you.

 

[emmi]

Does that mean I can rule out the pump being faulty if all my rads are hot I do have a crack in the thermostat so maybe it's faulty, but I don't understand how the rads upstairs were hot when downstairs cold if thermostat broken Strange, going to quick pop out for thermostat to try that 1st I guess. Cheers and really appreciate yr help
ps i'm new to this posting thing so not sure where I posted this if not in plumbing HA HA

 

[45yearsagasman]

Chances are from the described symptoms, is that the synchron motor has failed(most common fault) and that the rads upstairs were heating due to the valve passing. In that case a new valve is required. Test it, don't chuck parts at it.

 

[WedgeAntillesRed2]

You can rule out the pump. If all your rads get hot with lever on manual circulation isn't the problem. The synchron motor inside the actuator (silver box) for some reason isnt opening the valve up fully. I would be inclined to change the whole valve.
It wouldnt be a difficult job for a competent diy'er. If its in the roof, you wouldnt have to drain much system water.
Cheapest place for a 22mm mid-position valve is Toolstation. About 40 quid i think

 

[Space cat]

If its in the roof, you wouldnt have to drain much system water.

If the motor unit can be removed from the valve - which is not uncommon - you won't have to drain any water at all. Also, 45yearsagasman is correct. Test first. If there's no power reaching the motor it won't move.

 

[WedgeAntillesRed2]

Either way the 3 way valve was passing limited flow. Its a new valve for sure for sure

 

[emmi]

This site is fab, thank you so much guys. I will see if can get tested tom and if can seperate motor from valve saving time and probably a flooded house LOL. I'll keep you posted how get on

 

[emmi]

Either way the 3 way valve was passing limited flow. Its a new valve for sure for sure

Thank you I checked out site and not too bad price Do you think bad or good idea to purchase off ebay for even less?

 

[WedgeAntillesRed2]

Definitely Maybe, your protected by pay-pal, if the sellers got no strikes go for it. Not checked on e-bay, there must be an Oasis of them i guess!