Replacing 3 port valve head

[KX36]

Hi all,

I have a 20 year old gravity fed system in a house I moved into last year and the other day my honeywell V4073A 3 port valve got stuck with its lever all the way to the left and no central heating. I moved it all the way to the right "manual open" without latching it and after the house warmed up it was able to move its lever left again towards the middle. I checked all the wiring is correct and by fiddling with the cylinder thermostat and poking the microswitches in the valve actuator head I can get it to move by itself in both directions although it seems to struggle moving to the right. Yesterday the house wouldn't get as hot as the room thermostat was telling it to and now I've latched it to the manual open and the house is warmer.

I'm looking at replacing the actuator head. It says on it to replace with Honeywell 4000-3916-002 but that doesn't seem to be widely available. I have found 2 online shops selling the -002 model but I don't know if that's old stock or whether it's been superseded by 4000-3916-003 or what.

Should I get the £30 compatible replacement on ebay (?Banico branded) that claims to be 40003916003 compatible or get the genuine Honeywell part. BHL.co.uk sells the genuine -002 for £57 and -003 for £65.

Cheers,
Matthew

 

[JohnD]

Honeywell are fine quality.

There are some cheaper brands about, in both senses of the word.

You can often get a complete valve including head for about the same price as a new head. 20 years is typical life so your rubber ball in the valve may be worn out as well.

 

[jackthom]

It would be a good idea to power off the system and remove the actuator. Then power up and see how it moves when it doesn't have to drive the valve internals.

The valve spindle may be sticky so try turning it with a small pair of pliers. It's only meant to rotate around 20 degrees so don't try to force it any further than that.

 

[KX36]

Thanks guys, both good points.

I might power it off, take off the head and try turning the valve manually. and If I do replace it get a whole valve from BHL for £77. As you say it's only £12 more for the whole valve.

I didn't want to have to drain the system to change the valve which is why I was hoping to change just the head. I suppose I could take the head off the new valve and change that and wait until I have a go at putting TRVs on 5 radiators in the spring/summer to change the valve body as I'll drain it to do that. If the new head struggles to turn the old valve I could swap it back and leave it on manual until I have the chance to change both.

 

[JohnD]

As you have an old system, if you think you will need to drain it, get a litre of Sentinel X400 chemical cleaner. You can circulate it round the system, running it as normal, for up to 4 weeks, and it will loosen sludge and sediment so that it washes away during the drain. This is likely to improve the performance and reliability of your system. It is not acidic or aggressive, it is a mild cleaner. You will want a litre of corrosion inhibitor such as X100 for final fill after you have done all your repairs.

The chemical clean gives you very little extra work or cost if you are already planning to drain. I expect you have a small feed and expansion tank in the loft, bale it out and sponge it clean with bleach to remove all mud, fungus and drowned wildlife before you start work.

(A valve in good condition, you can turn the spindle with your fingers, no need for pliers)

 

[cowley]

Some of the old Honeywell valve heads you can't remove without draining down make sure yours has a dimple on the head cover if not you will have to drain to remove it.
Regards MIck.