RADIATORS ALWAYS HOT?

[BigRon]

I have a problem with my central heating.
When the heating comes on everything is fine until the thermostat clicks to turn the motorized valve.

The problem is the valve dosen't move and the radiators stay hot.
There is a lever at the side of the valve, the slightest touch on this starts the valve and the heating goes off.
This is the fouth valve that BG have fitted in about two years.

The Gas man says its sludge makinig the valve stick?
Yet the water in the system is almost crystal clear, it just has a slight amber tint to it.
If the motor is removed from the valve it works every time the thermostat is turned.

Its as though the motor just isn't strong enough to turn the valve, but the slightest touch on the side makes it work no problem.


I think its a faulty switch/valve but is it possible to get four faulty units?

Hope someone can help

Ron

 

[ollski]

No you wont get four faulty heads. Sludge or scale will prevent the valve from making a good seal and prevent it reching the contacts. I would guess that your BG man has suggested a powerflush, it would solve the problem although you can just ignore it and BG will continue putting on new valves ad infinitum.
I have drained systems and got clean water then cut through an upstairs rad pipe to find it 50% filled with magnetite!

 

[BigRon]

Thanks for that, I understand what your saying, its just that the system was flushed a couple of years ago. Then the water was black and I flushed it out about three times( cost me a fortune in flushing chemicals) until the water was clean..

An inhibitor was put in and the water has been clean ever since.
The water sample drained from the kitchen radiator is really clear. I just can't see it blocking anything and I can't see me getting four faulty valves either.

Iv'e got a water sample from my brothers radiator:: He's is black yet he's central heating works fine.

I'm stuck and not keen on paying for a power flush.

Ron

 

[ChrisR]

Has the whole valve been changed or just the heads? What make is the valve? Sometimes the Honeywell ones need the head fixing screws loosened half a turn so they don'r stick. Have known them work for years like that after sticking.

 

[BigRon]

Hi! Yes they replace the full thing.

I don't know the make. all I know is its blue.

It always comes on. but only seems to stick when it should turn off.


Thanks

Ron

 

[ChrisR]

Forgotten which make is blue but whichever, look for the head-fixing mechanism - can be a clip or springs or screws. Try wiggling the head - having loosened if necessary, when the thing is stuck. If it lets the valve spring-return, leaving it loose would be worth a try. Cos I can't think what else I'd do!.

What flushing chemicals did you use? Wondering if residues of that could be attacking the valve. There was a period when Honeywell rubber balls were attacked by Fernox inhibitor! If I'd had 3 valves all the same make stick, I'd call the mfr.

 

[BigRon]

HI , I can't see a make, it just says BVMVSP on the motor bit. its blue plastic and it just pushes on the the valve with a clip.
It also has some sort of toggle switch underneath at the bottom.

I doubt its contamination because they don't work from new.
For the last couple of years iv'e operated in manually.

Now Iv'e decided to get it fixed.
The systems on a contract with BG and they do keep changing the valves but it really needs to be fixed.


Also another question!
Can you use Normal ethylene glycol antifreeze in central heating systems?

Ron

 

[ChrisR]

Obvious question - does the head bit move properly when it's off the body? Once the valve bit is off you should be able to dismamtle it to see if the problem's in there - one more (free) bg replacement perhaps.

Anti-freeze - dunno - different materials in there. I usually use frost stats!

 

[BigRon]

Yes the motor moves fine when you turn the thermostat switch on and off.

When its removed from the valve.

It just dosen't seem strong enough to turn the the valve.
Yet the valve dosen't seem that stiff. I can easily turn it with my fingers and it feels smooth.

How powerful are these motors that drives the valve.


Ron

 

[ChrisR]

Not very, but the gearing makes the torque quite high at the output shaft. You shouldn't be able to prevent it turning VERY easily with a couple of fingers when it operates. (ie with screwdriver or similae poked in the ole)

 

[BigRon]

The man from BG came again today.

He still thought it was sludge, untill I explained that the valve stays in the mid position. ( he thought the motor was winding back but sludge was not letting the valve seat properly.


Now its seems I have a 5 wire motor fitted to a 3 wire system..
And he now thinks this is the problem.

He has ordered a 3 wire motor and will fit it next week.

Any thoughts anybody.


Ron

 

[BigRon]

Well folks, the man from BG came today and fitted a new 3 wire valve in place of the 5 wire.

And its working perfectly.

BG replaced the valve two years ago and it as never been right, they kept saying that it was sludge (despite the water being crystal clear)

Anyhow it turns out they fitted the wrong valve two years ago.
HA!HA!

Glad I didn't go for the power flush at about £500.

Thanks for all your input


Ron

 

[boxster]

yea some people are to quick to shove a power flush, the load of good that it anyway,

pleased its working...

 

[oilman]

Also another question!

Can you use Normal ethylene glycol antifreeze in central heating systems?

Not recommended. Ethylene glycol is very toxic, propylene glycol is not. It's not just a price issue.