Reliable 3-Port valve actuator?

[spamlet]

[geoff]

In message , spamlet writes

I've repaired hundreds

It depends on the make actually, believe it or not

for some reason Drayton heads seem particularly prone to microswitch burnouts, irrespexctive of the uswitch make

Sorry, that's bollocks

... Or exactly the same as the ones sold specifically for the task

[spamlet]

Well bollocks or not that is what happened when I took my first one apart. Motor was dead; replaced it and found it was on all the time; then opened up microswitches and found one of them burnt out; replaced switch; motor no longer on all the time. All ok for a year or so till switches burnt out again. From other comments frequent in these columns this is quite 'normal'.

S

[YAPH]

I use the SDMV2304 3-port valve which is a drop-in replacement for normal Honeywell-et-al valves, wiring wise, and are about £50 at B&Q.

There's a website run by someone who's disgruntled with these sorts of valves as he says the electronics fails, due to high voltage spikes on the mains I think, but I've never had it happen to any of the ones I've fitted.

[YAPH]

Ah! is that what it's for?!

I always wondered.

[spamlet]

Well thanks for that John, it certainly looks promising and in some places surprisingly cheap:

I'm a bit confused as, although the various ads say it fits into existing systems with no need to change pipework or controls, I can find no pictures of the actuator on its own - so the implication is, it has it's own dedicated valve. There are other pictures of actuators of the same make but none look like the one pictured on the valve and they have several different numbers of wires. Can anyone clear up this confusion? Do I have to buy the whole thing and then just put the actuator on my old valve, or is this not going to work? This 'buyaparcel' lot looks too good to be true if it's the real momo deal!

Cheers, S

[Phil]

In message , Harry Bloomfield writes

I'm somewhat confused about some of the comments so far. I have a Honeywell 3 Port which I had to replace recently after 10 years of service. It was itself a replacement for one that was 15 years old when it died.

Anyway, the motor head had worn out its gears and research revealed the downside of the system when used in my CH/HW setup. My CH timer is on

24/7 and the control is via a programmable thermostat in the living room. I was shocked to learn that this invariably left the motor sitting in the CH position with the full 240 volts applied to the motor so, I devised a simple fix using a relay which returns the motor to the rest position when the HW and CH thermostats are no longer calling for the boiler.

My main confusion is with the "hunting" or "rocking motion" mentioned and presumably this refers to the centre position i.e. HW and CH on, as I have no such motion on my control head.

The motor moves to the central position, hunts once to find the second microswitch and then sits there with no further movement.

[spamlet]

I'm no expert on the electronics: just the faults. Possibly with your mod the contacts last longer, but when they get burnt the motor can be heard hunting and the pop pop pop each time it hits the contact can be picked up on any radio you have near the device. Mine has just gone again: which will be about three actuators and two sets of replacement contacts now. As yet I haven't decided on what to buy this time. The 'momo' type has been suggested, but no one has enlightened me yet as to whether a momo actuator can be bought separately and directly replace the current spring type.

S