Motorised Valve - faulty?

[Marty74]

Apologies for starting another Motorised valve thread!

I've had a good search through so think I know what the problem is but wanted some opinions please.

We moved into our house about a year ago. We had some problems with the general heating but after changing the MV actuator all seemed ok. The MV is a Danfoss 3 port. Obviously the heating's been off until recently. Now to activate the heating we have to manually slide the MV leaver across for the radiators to warm up. As far as I can tell this is because a, the actuator has a problem or b, the valve is a bit seized?
Last night I took the head off the MV and clicked the heating on and off at the room stat, the head seemed to be working fine. The small half moon bit that the head controls moved by hand but seemed a bit tight. I moved it back and forth a few times put the head back on and the rads warmed this morning without me having to manually move the MV lever.

Now what I can't work out is is it because the valve was a bit stiff and I freed it last night or is it because the head motor is a bit knackered and hasn't got the power to move the valve its self, or is it a bit of both!??

How feely should the valve move?

thanks

 

[seco services]

i would say the spindle may of just got stuck where you hadn't used the heating.
maybe the system is full of muck etc and not helping the situation.

 

[Marty74]

I hadn't thought about muck in the system. Hopefully it should all be ok now.

If it happens again do you think it would be a need for changing the whole thing rather than just buying a new head? I was hoping it would be the head at fault as changing that would be no problem, I'm not too keen on draining the system!

Do you think that because the head is moving it is probably ok?

Sorry for all the questions.

 

[seco services]

if it happened again i would check the condition of the water in the system etc maybe give it flush through.
rare for a valve to play up after only a yr

 

[Marty74]

Thanks Seco, fingers crossed.


It was only the bit inside (forgot the name) replaced last year not the whole MV or head on the top.

 

[seco services]

maybe in that case it may be time for a new valve.

 

[MANDATE]

I reckon the spindle being stiffish is what caused your problem.
You did the right thing by taking the head off the spindle, that way you can try spindle which should be quite free and you can try head without the spindle interfering.
The lever is there to latch the valve in mid position when re filling system.
As I understand it, it will only take the valve just past mid position, but it does help when you can use it to overcome the resistance of the spindle.
The geared quadrant has attatched a fairly strong spring so the motor is working against the spring and the spindle.
If you delve deep enough, you will find the valve stays in the last position when system is turned off. That really means CH, cause HW is soon satisfied where CH is almost always on demand.
And that means the motor inside the actuator head is energised all night long and most of the day, 7 days a week. So it's understandable that motors become faulty.
I have a spindle that stiffens up a bit and I treat it to WD 40 every so often. It will turn completely so its helped along with a hand drill and some plastic tube.

 

[Marty74]

Thanks again.

I'll keep my eye on it, see how things go.

If not I'll replace the whole thing after learning how to drain down the system properly!!!



PS. Completely off topic!
How do I tell if I have a sealed or un sealed system?
We have a boiler in the garage, airing cupboard with MV and pump next to it. Can't remember if we have a small tank next to the big tank in the loft though!

 

[MANDATE]

With a sealed system you will have a pressure gauge on the boiler.
Also there would be a filling loop and/or provision for filling loop in order to increase the pressure after filling system or bleeding radiators.
Also you would not have any tanks in loft.
So I'd say you don't have a sealed system.

 

[Marty74]

With a sealed system you will have a pressure gauge on the boiler.
Also there would be a filling loop and/or provision for filling loop in order to increase the pressure after filling system or bleeding radiators.
Also you would not have any tanks in loft.
So I'd say you don't have a sealed system.

Sounds like it, thanks again