My central heating system will not turn off!

[jaba]

It’s an old system but never had an issue before.

If I turn down the hall thermostat it still runs non stop.

Sliding the switches to off on the Honeywell programmer doesn’t make any difference.

Over the last 2 weeks I could hear a squeak from one of the valves when the heating turned off.

When I turn the hot water off I can hear its valve working.
But when I turn off the heating on the programmer no sound from the heating valve! The pump keeps running, the boiler keep running.

Only way to turn off boiler and pump is by turning off power to the control programmer, then everything stops, but I don’t hear any noise from the valve as I normally would when everything stops.

The hot water valve has some resistance when pushed all the way to the left, but the central heating valve has no resistance at all and moves freely all the way to left and right!

The valves are Honeywell V4043H1056 2-Way Zone
Programmer is Honeywell ST699

Is this maybe just the header or motor problem and I can simply just change that?

Or is it the valve has seized and maybe blown the motor/header etc and I need to swap out for a complete valve and header unit?

Not familiar with heating systems but willing to have a bash at it (without a hammer)!
View media item 97448View media item 97447

 

[dilalio]

I think you've diagnosed the fault yourself. You could do some testing with a multimeter - plenty of threads on this forum describing how to do that. Once done you could remove valve and have a look inside while manually manipulating it. Or you could just bite the bullet and replace an old valve with new!

 

[Agile]

Search for the dimple.

On most you can remove the head and will probably find the shaft is tight.

To an extent you can lubricate the shaft with WD40 or similar and lots of turning to help free it up.

This often happens when the CH is not turned on for five minutes every week during the summer as prudent people will do.

Tony

 

[jaba]

 

[jaba]

I think you've diagnosed the fault yourself. You could do some testing with a multimeter - plenty of threads on this forum describing how to do that. Once done you could remove valve and have a look inside while manually manipulating it. Or you could just bite the bullet and replace an old valve with new!

Don't have a working multi-meter at the moment but did take the header unit off and I can turn the valve spindle by hand.
It moves approx between the 1 and just past the 3 o'clock position. It has a small resistance by hand but firmly stops when turned either way. This doesn't seem 70° as I've read this unit should have, but maybe it is.
I think it's just the header but I'll play safe and buy a complete unit just in case.
Thanx for info.

Search for the dimple.

On most you can remove the head and will probably find the shaft is tight.

To an extent you can lubricate the shaft with WD40 or similar and lots of turning to help free it up.

This often happens when the CH is not turned on for five minutes every week during the summer as prudent people will do.

Tony

Thanx for reply.
I use the heating even in summer, not that many days in summer when the bathroom is warn enough to leave it off, so it has constant use even if only for 10 mins!
As I said to OP above, the shaft is moving just fine by hand, have no idea how if this is normal as I would have thought it should be more stiff than it is!!
And it seems a little short on 70° of turn but I could be wrong.
BTW. The shaft was stopped approx. in the 2 o'clock position!
So I assume it's stuck on closed and making a circuit and keeping power constant keeping pump and boiler running constantly etc!

 

[AGAS]

probably its turning enough ( only travels short distance ), just do as agile has suggested with wd40 , to be sure to save future problems change whole valve and head . but head could be just be changed if you want .

 

[D_Hailsham]

The Honeywell valves only turn about 20° between stops, not 70°!

If the spindle can be turned easily by hand, something else is holding the valve open.

A silicon based lubricant is preferable to WD40, which will rot the 'O' rings sealing the shaft.

Have you checked that the return spring is OK?

You can buy replacement ball and 'O' ring kits - part no '272752A/U CARD'

 

[dilalio]

I think it's just the header but I'll play safe and buy a complete unit just in case.
Thanx for info.

I would replace the whole thing and be done with it for what it costs and the upheaval for a DIYer

 

[jaba]

probably its turning enough ( only travels short distance ), just do as agile has suggested with wd40 , to be sure to save future problems change whole valve and head . but head could be just be changed if you want .

I took off the header for the hot water and the valve has the exact same resistance as the heating valve so it's not the valve sticking.
I''ll buy a new unit complete and try replacing just the header and see how that goes.

The Honeywell valves only turn about 20° between stops, not 70°!

If the spindle can be turned easily by hand, something else is holding the valve open.

A silicon based lubricant is preferable to WD40, which will rot the 'O' rings sealing the shaft.

Have you checked that the return spring is OK?

You can buy replacement ball and 'O' ring kits - part no '272752A/U CARD'

Right that makes sense, I read on a site it was 70° so that must have been a typo or maybe I was reading the wrong section.
Yeah the spindles are fine, both turning with small resistance but both feel the same.
Both springs that I can see are connected, looks the same as the good header!
But the lever feels like it's no longer connected, no resistance at all when moved all the way left and right!
I can also see that the brass plate is all the way down and jamming the switch closed! So that's why as soon as I turn on the power it fires up!
To check this I swapped over the headers and was able to turn off the heating valve with the programmer.
So it seems like the motor when last on jammed when heating was last on keeping heating on constant.
Maybe the motor burnt out at that point!

I would replace the whole thing and be done with it for what it costs and the upheaval for a DIYer

Well I'll try the header when I get a complete unit as I can do that myself.
But I'm not sure about removing the valve, worried about creating a waterfall!

Would I need to drain down the system?
It's very old and not a pressurized type boiler so hopefully not. But I'm 100% sure the valve body is ok.
I think the header motor is dead or the bits between the motor and the valve, cog jammed etc.

I've seen a few motors online and most have red wires, not the blue wires mine have.
Are these red wired motors ok to use as long as they state "V4043" ?

It might just be the motor that has failed but if it's mechanical outside of the motor then replacing that on its own won't work, so yeah I'll get the complete unit and hope the header on its own will be job done.

 

[D_Hailsham]

t the lever feels like it's no longer connected, no resistance at all when moved all the way left and right!

If the lever has no resistance then:

1. The valve is stuck in the fully open position, or
2.The lever is not making proper contact with the opening mechanism.

If the valve works OK when you swap the heads, carefully compare both heads to see if you can identify the difference.