Changing zone valve

[craig51]

Ok, I need to change a HW zone valve as part of a s plan system.

Heres a pic of it, its the one on top, and as per my luck, its NOT the type which the head can just come off and be replaced!!!!

The system has an expansion vessel and hot water cylinder as per this picture.

Im my mind, i have two options.

Commando it, whip the old valve off and replace the new one, while trying to minimise the water loss and protecting the zone valve below. Doesnt really appeal to me this option.

Open the drain tap outside in the garden, and I guess the bleed point at the top of the cylinder and change it that way. I am wary of doing it ths way as knowing my luck, I will get an air lock somewhere horrible, like the HW coil or god knows where else.

If there is any easier way, let me know.

 

[picasso]

I am pretty sure I can a dimple on the top zone valve, are you sure it cant be removed?

 

[Mr Smyth]

Not sure about your reason for changing the valve but they are modern Honeywell valves. This means you can replace either the whole head, the sychron motor or the ball and plate.

Depends upon the fault you are experiencing.

Hope this helps

 

[craig51]

can soeone explain how these heads come off.

On the ones i have experienced there wasa we plastic clip which just relased it.

How do these ones come off????

 

[Mr Smyth]

Remove the cover and you will find there are 2 screws diagonally opposite each other.

What is the fault??

 

[craig51]

my bad,

you are correct, there are screws to remove.

Fault is no hot water, only when there is heating is there hot water.

Syncron motor is showing 2.5k ohms, so thats ok, so its probally just the mircoswitch maybe or something else. I think overall it would just be easier/quicker for me to replace the whole head.

Can anyone recommend a replacement for me?

 

[Mr Smyth]

If you have a look at the end of the valve head it will give a number starting with V.

Honeywell 40003916-001 Powerhead for V4043.............. I think

Need to make sure you replace it with a Honeywell 2 port head.

 

[penfold46]

Can you not test and if neccesary replace the Synchron Motor?

 

[mysteryman]

They can just jam.

The removable head ones have two screws diagonally opposite each other with two location pins at the other two corners; the non-removable ones have four screws. You would need to drain the system to change heads on the older type. The newer ones came in in the mid-80s as far as I remember. There is an id involving dimples, which I can't remember about, but others will.

I would swap the complete head rather than fiddle with microswitches, although you can change the Synchron motor fairly easily.

I once changed one which lasted for just ten days. Make sure you get the correct head.

 

[Rob]

Might wanna check the spindle on the valve is nice and free. Usually when the symptoms are what you describe its due to the hydraulic side seizing up. It only needs to move ever so slightly of its seating for it to allow the HW to heat up.

With the cover off you should be able to see it motor open and whether it is hitting microswitches or not. You should be able to turn the valve spindle with fingers.