Switchmaster VA1 CH Valve

[Mark Carver]

I think I've got a Switchmaster VA1 Central Heating valve ?

See:-

at 90 degs :-) )

It seems to be almost dead. Gets stuck as it rotates clockwise at the 5 o'Clock and 2 o'Clock positions (as viewed without rotating photo)

The only useful info I can dig out from the Internet, is from 2002 in this group:-

Or

colour codes quoted by Kevin Gibbs in Post 6 certainly correspond.

I've pulled the device off of its plate. The valve itself is fine, nice and loose. The device itself rotates round when decoupled from the valve plate, but gets stuck when attached back on the plate. I can force it along with a coin.

What are my options, back in 2002 they seemed rather bleak. I assume I need to completely replace the device. I've got zero plumbing skills, which is a shame. I was hoping it would be a simple electrical DIY job, but it seems not ?....

Any advice greatfully received.

[John Stumbles]

??

You might get it to limp along by applying wd40 to the shaft of the mechanical valve and working it back and forth by hand before refitting the head. Failing that it is a plumbing job. If you're lucky a replacement Honewyell or Sunvic will have the same plumbing connections and you'll have enough movement in the horizontal pipes to spring them apart to get the old valve out & the new one in. You'll also have to wire in the new valve using appropriate transposition of colours, which you can work out from the diagram linked to in the article on the wiki page.

[John Stumbles]

Oops, my bad: looking more closely at the article you referred to I see the switchmaster wiring would NOT be the same as a spring return so it's not just a matter of transposing colours: you'd have to change the wiring somewhat. Alternatively you might get away with replacing it with a MO-MO Sunvic.

[geoff]

In message , Mark Carver writes

Sorry, but replacement is your only realistic option unless someone has one on ebay or suchlike

If it's sticking, then it's broken teeth on a cog in the gearbox or (if it's not always at the angles you mention) the synchron motor(s)

The gearbox is riveted to the motor - which is two motors piggybacked, not a standard one.

I repaired one for my parents a few years ago, but then I had the parts available to do so as I have repaired plenty in the past

One problem is that it has a non-standard "wet" configuration, you will have to drain down and re-route the pipework for a standard valve configuration

The other is that it is also unique electrically, you will have to do a certain amount of re-wiring

[geoff]

no, no, no, no, no

[Mark Carver]

Thanks John, and Geoff for your contributions, and yes John, please feel free to use my photo.

With the aid of a multimeter, I've written out a Truth Table for each of the states of CH/HW/Boiler-Pump working and switching.

I'm not certain what's going on with the water tank thermostat, and the connections HW on /HW off. I assume it's effectively a changeover switch ?

[Heliotrope Smith]

I think your best option here is to replace the whole valve and actuator as is looks like the actuator is knackered.

The Honeywell 3 port valve will go directly onto the pipework as is without modification, however, in your photo you will note that the actuator is on the front of the valve but the Honeywell actuator sits on top of the valve.

If there is insufficient clearance between the pipes and the wall (and other fittings/pipes) and there is not enough flexibility in the pipes to fit the Honeywell then you would need to extend the pipework to accommodate the new valve.

Wiring is fairly straightforward with one modification at the wiring centre.

[Mark Carver]

Thanks, it looks that way :-(

A tame plumber, who's done excellent and reasonably priced work for us before is coming tomorrow. He'll do the plumbing, and I'm doing the wiring.

Yes, I've finally got my head around it now. Some useful diagrams on the Interweb, as well as John and Geoff's info.

[John Stumbles]

Yup, with the wrinkle that the HW off has got to be live whenever HW is not demanded i.e. HW_on = programmer_on AND cylstat_on HW_off = programmer_off OR cylstat_off which is acheived by connecting the programmer's HW off terminal in parallel with the 'stat's:

on (DEMAND) o----------> HW_ON HW on / o--------------o to motorised LIVE o o off valve \ | (SAT) o----------------+----------> HW_OFF HW off

PROGRAMMER CYLSTAT

[geoff]

In message , Heliotrope Smith writes

no it won't

no it isn't

if you don't have a clue, better keep quiet, eh ?

[John Stumbles]

Is it? Pretty sure the ones I've seen are standard

CH ---T--- HW | ^ flow

though now you raise the subject I couldn't swear to it and I can't readily get at one to see.

How unique? :-)

Is it compatible with the sunvic motor-on/motor-off ones (which I also know nothing about :-))

[geoff]

difficult to find the right words to explain, but looking from the top, the VA1 operates orthogonally, i.e. as would the hands of a clock, the mid position is at 3 o'clock. On e.g. a standard Honeywell valve, the mid position would be going into the wall

No, there are three wires which drive the motor to three positions (white, yellow and orange IIRC) and one to drive the relay coil which selects which motor to energise

I do have a diagram somewhere - did I not post it to the FAQs (ten) years ago ?

[Heliotrope Smith]

I change Switchmaster valves for Honeywell fairly regularly and I know what I am talking about.

The ports are the same configuration and the same dimensions and fit directly on without modification. (different threads so need to chop off olives and use new nuts and olives).

However as I said I my previous post the the actuators are on a different plane and sometimes it is necessary to alter the pipework to fit into the space available. I Have a (knackered) Switchmaster valve still on my van and am willing, at my expense to post it to you for examination/comparison against a Honeywell.

The Switchmaster is six wire against Honeywell five wire and is very simple to wire up. I will post details of wiring up tomorrow (Monday).

Best keep off the sauce before you jump in with both feet eh!

[geoff]

In message , Heliotrope Smith writes

Which is what I said - the wet side needs modification to the pipework

I've repaired dozens, lots of dozens, in fact TYVM,

I know the VA1 much better than you do

but not the same, eh?

a degree of rewiring is necessary

I don't see where you were right and I was wrong ...

[Heliotrope Smith]

I do not even try to repair the actuators on the Switchmaster, much easier to replace the lot, (no comebacks).

The wet side does NOT require alteration in the majority of cases.

The pipe configuration is EXACTLY the same.

Sometimes the pipework has to be extended because the valve will not fit into the space available.

Yes. A degree of wiring modification is required, but takes no more time than wiring like for like.

[geoff]

In message , Heliotrope Smith writes

Of course you don't

you don't have the means or ability

So explain to me how a valve which is (as you have also posted) in a different plane needs no modification

above ...

a detailed explanation would be priceless here ...

VA1 to Honeywell 4043 spring return for example

[Heliotrope Smith]

If you go to the OP jpg you will see the switchmaster valve as a T with HW to the left and CH to the right. Flow from the boiler/pump enters at the bottom of the T. The spindle to the rotary shoe comes from the front of the T and the actuator fits over it and that is why you cannot actually see the whole valve.

The Honeywell ports are EXACTLY the same configuration as the Switchmaster, but the spindle comes out of the top of the valve and therefore the actuator sits on the top of the valve. So, you have a T with HW to left or right and CH to right or left (as required by spinning round) and boiler flow entering at the bottom.

The Honeywell will fit directly onto the pipework setup for the switchmaster WITHOUT alteration. Only (rarely) if there is obstructions in the way of the actuator would it be necessary to reposition the valve but not alter the configuration of the ports.

Hope this is clearer.

[Mark Carver]

Latest news, plumber came this morning, and fitted a Honeywell. As you can see from my originally posted photo, the pipework had to be rearranged. The wiring was as per my own deductions last night, though I needn't have bothered, he's done dozens of these swap outs on our estate this last couple of years, and had a record of the wiring mods in his note book.

Later I'll post a photo of the new device, and the wiring changes for posterity, and so John can update his Wiki page if he wishes.

Thanks all.

[Mark Carver]

As promised:

Switchmaster VA1 Honeywell V4073A Connection

Red Orange Live to Boiler & Pump Orange Orange(Link to above)Tank Stat HW on White Grey Tank Stat HW off Yellow White CH on (from room stat) Blue Blue Neutral G/Y G/Y Earth

Picture of new fitting:-

[Roger Mills]

Excellent! You didn't actually say whether it *works*?