Testing Honeywell v4073a1039

[RBZ5416]

So the CH picks one of the hottest days of the year to malfunction.

Came in this evening while the HW cycle was running & noticed that the rads were hot. The system is fitted with a Honeywell V4073A1039 three-way valve. If I understand correctly, the valve must be somehow stuck in it's middle position if both HW & CH are being supplied?

I'd appreciate some help on diagnosing this correctly please.

Edit
The manual lever was completely free so I've removed the head. It eventually twanged back to the home position but moving it back, it's clicky & notchy (technical terms there!). So I guess the gearing is shot & the head needs replacement?

Next question, Google suggests that the valve should be turnable by hand over a travel of approx 1/4 turn. I can only turn mine with pliers & only over approx 1/8 turn. Does that suggest that the valve is also shot?

 

[hertsboilers]

finger turnable about 1/8, definitely not 1/4.

Apply WD40 to free the shaft.

Replace head or just the motor.

 

[RBZ5416]

The plot thickens.

I ordered a complete valve from Ebay but with my luck the bloody thing's gone AWOL in the post. While I try to source a replacement I had a couple of ideas, both of which have only served to confuse me further. So I really need some help here guys.

Firstly I thought I'd simply remove the head from the valve & position the vlave manually to just provide hot water - no go. Whether I set the valve fully clockwise or counter-clockwise, hot water it still being fed through both outlets. So I guess this means the valve itself is shot?

Next thought was to shut down all the thermostatic valves on the rads. Also no go as when the HW cycle kicks in the rads are still getting red hot. I don't understand how this is possible with the valves shut down?

HELP!

 

[AGAS]

HELP!!!!! need to shout bit louder , just crack on and change the valve

 

[RBZ5416]

Ah, the old "I haven't got anything useful to post but I'm going to post anyway".

 

[AGAS]

what are you worried about you know the valve is fooked so change it , is that useful enough and the plot is thickening

 

[RBZ5416]

If I had a replacement valve I'd change it, but as you know, the replacement has been lost in the post. So telling me to change it really isn't useful at all.

So while I'm waiting for another valve to arrive it would be quite useful to know how to stop the rads getting hot.

 

[45yearsagasman]

Maybe your valves are passing, so try turning off all the lockshield valves as well. Have fun rebalancing the system afterwards.

 

[AGAS]

SCREWFIX is still open if you hurry about half hour left i think