Change Out/Repair of 3-Way Diverter Valve

[Jackvois]

Hi

The three way diverter valve on my Y type system appears to have stopped working.

The symptoms are:
When the system is turned on at the time switch the CH and HW both work i.e get hot. However when the thermostat is turned down the CH (rads) remain hot. The thermostat has been replaced so that's not the issue.

Running some tests yesterday:
1, Turning on the CH and HW then turning off the CH with the thermostat - The actuator didn't move the valve.
2, Turning off power to the whole system - The Valve didn't return to the Port B rest position.
3, Whatever combination of Power on/off, Time Switch on/off, Thermostat on/off etc etc the valve doesn't move at all.

So I thought I'd get a plumber to replace the valve and/or actuator but after looking at it there are isolation valves around each of the branches so I may be able to do it myself without draining the system.

My question is therefore: Can each of the branches be isolated and the valve replaced without draining the complete system? What would be the effects of the air getting into the system when the isolation valves were reopened? Could it be bled out of the system through the rads?

Attached are pictures of the pipework and valve for reference. The actuator has no pip on the top of the shroud therefore replacing just the actuator would be difficult I think? Do they do a conversion kit?

Thanks

[GALLERY=media, 38931][/GALLERY]
[img] [GALLERY=media, 38932][/GALLERY]

 

[D_Hailsham]

Turning off power to the whole system - The Valve didn't return to the Port B rest position.

If you turned the power off at the supply and didn't just set the programmer to CH and HW OFF, it means your valve is sticking.

Turn off the power, then check the lever in the end slot. If it moves easily, the valve is definitely sticking. But if you feel some resistance moving from AUTO to MAN and the lever returns to the Auto end with a whirring sound when released, the valve is not sticking; you have an electrical fault.

There is a conversion kit, but you will still have to drain down to install it. It's the Plate & ball assembly kit, Part No 40003918-007

Your valve is at least 24 years old, so it might be better to replace it!

As you have valves on each branch, you should have no problem changing the valve, but the valves may not shut completely. The one above the Grundfos pump looks as if it may be stuck, so I wouldn't try closing it - the pump will act as a valve. Don't touch the valve which is in the branch between pump and motorized valve; it's a bypass which will have been set when the system was installed.

You only need to drain down below the level of the valve. Lock the valve in the MAN position when you refill.

 

[Jackvois]

Hi

Thanks for the reply.

Well it appears that the valve is sticking, there's definitely no resistance when the lever is moved.

Do you know of any way to free off a sticking valve with an actuator head on like this?
I've seen other posts that state after removal of the actuator on later models the valve shaft can be manually turned and this can potentially free off the valve. Obviously this model cannot have the head removed without draining the system, however is there a way to turn the shaft?

Thanks again

 

[D_Hailsham]

Obviously this model cannot have the head removed without draining the system, however is there a way to turn the shaft?

You can't remove the complete actuator, but you can remove the cover. This will expose the innards, including the shaft and motor. If you remove the motor (two screws), the shaft will be exposed and you can then turn the shaft with a pair of pliers. A light application of a silicon lubricant may free the shaft.