Faulty Zone Valves?

[slavetodiy]

I have a fully-pumped gas CH system with two-port valves serving the hot water and radiators. It is quite elderly yet the original HW valve still works perfectly. The CH valve (controlled by a modern programmer and roomstat) has, in the last four years, been replaced THREE TIMES! Each time, there was a live supply at the junction box terminal block, but no movement in the actuator. Manually opening the actuator switched on the heating ok, but releasing it immediately switched it off again as the actuator sprung closed. Fitting a replacement actuator immediately solved the problem.

Why am I going through so many actuators?

 

[D_Hailsham]

What is the make of the valve?

 

[slavetodiy]

The first two were Horstmann, but the latest one, just replaced, was a Salus (I deliberately picked a different make).

 

[ChrisR]

Can you just change the motor - much cheaper,, and quite easy, usually.
There are a lot of Chinese motors , including the ones in some new heads, which don't seem to last long.

It may be that the shaft in the wet part of your valve is stiffening up. Often you can (get wet and) strip them apart for a re-grease, if you have the patience.

Honeywell heads do seem to be about the longest lasting, though I've always thought they look like a pre-war "friction driven" toy inside!

The quality of most of the bits in plumbing is pretty poor, and the trend is going the wrong way...

 

[Alfredo]

I've always had good service from Drayton diverters and Honeywells (though on 3 ports we got a whole batch of honeywells that wouldn't switch one microswitch due to too much free play in the actuator quadrant. Ideally it needed a circlip to hold it firm, but they aren't going to fit one on my say so are they )

They don't last forever, but less than five years is not good and my current drayton on my own system is ten years old.

Alfredo

 

[iep]

Just replaced a honeywell valve on the HW pipework our system that had last 30 years! The one on the CH is still going strong.

I agree that the internals look like a pre-war toy but I reckon the mixture of plumbing, electrical and clockwork engineering is nice.

The honeywells are good too as you can buy the head and/or motors individually (and change them without removing the actual valve from the system) which makes changing parts very easy if they do fail.

iep

 

[slavetodiy]

I've been able to buy and change the actuator only when using the same make, but the valve body had to be changed as well when changing makes. If this one goes again, I will probably look for a Honeywell.

The valve itself moves freely (and is pretty new).

Thanks to all who replied.