Two port valve actuator replacement

[F]

The two port valve actuator on our DHW is sticking open (explains why we've got skin-removing hot water out of the taps!) and so I need to source a replacement.

The actuator on the central heating stuck some years ago and the original Boss Therm BZV22 actuator was replaced by a 'Siemens Landis & Staefa Replacement Motor Housing RMH' but I'm having trouble sourcing a similar replacement that has the quick release plastic clips on each side.

Can anyone recommend a suitable replacement actuator and a source? I really don't want to have to drain the system down to replace the whole valve assembly.

[The Natural Philosopher]

I've done both.

In fact it was worse and better taking the whole valve out

I had a idsolation ball valve pissing water all over the adjacent MV and had replaced the head once already, then it popped the RCD and I realised that the gate valve needed to go and snce I had originsally bought a whole new MV and just used the head, I thought to replace the body as well this time.

Turned out that replacing the ball valve needed pipe cutting and a new bit of pipe inserted due to incompatible threads on te new ball valve vis a vis the old. A LOT esasier to do everyhung on the bench with a vice.

But the actual process was pretty easy. I de pressurised the system using the valve in the boiler and then simply unscrewed the joints with a bucket unbderneath. I got about a buckets worth of water out and the rest stayed in - made bleeding much easier.

But using the valve I wanted to replace as the drain point I only drained what I needed to drain.

If the MV has been sticking you PROBABLY really want to replace the valve BODY.

And get a valve that you can get spares for more easily. I got a honywell (allegedly) single port valve for half the price plumbing world sells one, off amazon.

Oddly enough I managed to dry out and clean the head and ended up not using the second replacment valve I bought, However I did have to take a soldering iron to the dreadful crimped connections to the motor BOTH of which failed in disassembly - (one had been buzzing before as well)

So IF te valve is in a place weher water can be mopped up and wont cause damage and you can get a bowl or bucket under the valve, just de pressurise and let the system drain at the valve. It's no big deal.

[F]

Thanks.

It's an open vent system so simpler than yours to deal with.

It's the actuator that's the problem: I've taken it off and the spring-loaded valve mechanism closes freely after I open it by hand. With the actuator in place, and the valve not closed when it should be, a firm tap on the actuator body persuades it to close.

I'm keen to get an actuator replacement for the Boss Therm BZV22/Siemens Landis & Staefa Replacement Motor Housing RMH as it's a really easy clip in, clip out fitting on the valve.