More on 3port valve actuators... 'seered'

http://www.seered.co.uk/sunvic.htm
Finally got suitably bent and welded rad for bay window, and plumber is making a start on replacing our leaky old ones at last. This prompted me to revisit the 3 port valve actuator situation again, which, when we last discussed what was best, it was suggested that 'momo' type valves might be more reliable because they were either on or off and not bouncing against a spring.
Earlier in the year I failed to find whether momo valve actuators would fit on the valve bodies of other types, and could not find anyone selling them separately anyway, so the replacement was put on hold. Now I have found the Sunvic site itself and seen that they do sell actuators separately, though at getting on 80, this is not necessarily such a good deal...
Anyhow, once I had the part number, I googled and... ho hum, there is a whole website devoted to how awful - if not downright dangerous - some of the momo actuators have proven to be. Some v scary looking pics on the handy seered site, and some useful hints and tips for d-i-y ers interested in CH valves. Seems that the momo design has just moved the failure proneness from microswitch to capacitor (and they actually have 3 microswitches in instead of the spring type actuator's 2). Just can't win it seems.
I'll see if I can email the site writer to ask if he thinks *any* 3 port valve actuators can be relied on.
S
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On 01/09/2010 16:19, Spamlet wrote:

Why not cut your losses - like I did - and replace the 3-port valve with 2 x 2-port valves[1] - and convert to a much more reliable S-Plan system?[2]
[1] You may also need an automatic by-pass valve.
[2] The motors are still continuously powered (and stalled) in the valve open position - but, unlike 3-port valves, the micro-switches play no part in motor control - and you don't need all the other unreliable gubbins associated with finding and holding the mid position.
--
Cheers,
Roger
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I'd like to Roger, but what with recent new ensuite shower room, an already painfully tight cupboard has become pretty well impossible to move in, and I'm a bit stuck with the pipework we've got for now. And it does all work well enough, except for these stupid actuators. It was handy today though, with a new rad put in coming on hot even with CH 'off'. But surely, someone must make an actuator that can be trusted: they are certainly expensive enough after all!
Anyhow, your suggestion does seem to be the favourite with a number of writers, so should I feel up to a serious bit of d-i-y one of these days I may give it a go.
Cheers,
(Incidentally, as I know readers all like to hear the latest on wasps too: we'd been waiting for some time to have a rad angled to fit in a downstairs bay window wall, and the great day of fitting came at last. There is some 18" of space under the floor joists so feeding plastic pipe through wasn't too difficult. The interesting part was that two 'air vent' bricks outside, had been pretty well covered by the joist support around the bay inside: except they had been tunnelled out by wasps and the nest on each side was about a yard across! Not a single wasp though. They do seem to have gone into quite a decline in our house in recent years.)
S
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On Wed, 01 Sep 2010 16:19:02 +0100, Spamlet wrote:

I've seen the site you mention.
I've fitted maybe a dozen or so of the Sunvic MOMO drop-in-replacement valves and not had the problems they suggest. (No doubt I will, having said that though :-()
At B&Q they're about £50. Used to be about £40 IIRC but seem to have gone up a bit over the last year or so.
--
John Stumbles -- http://yaph.co.uk

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Oddly, though Screwfix does not even give Sunvic a mention, B&Q *only* seems to list Sunvic, and, currently at the knock down price of 29 ! However, a first inspection does not bode well for actually finding a local store that has any in stock...
Stephen Wozniac, who wrote the pages on the Sunvic faults, has, surprisingly, still come back to me saying that he still thinks they would be his choice over the spring variety.
What he also mentions (which I did not know) is that the momo only rotate one way, so the valve they sit on presumably needs to rotate fully, and my previous 'V'block, and 'ball and stick' valves would therefore not work with a momo actuator. Unless anyone here knows more...
S
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I think his preference is for a valve that uses no power when it's not doing anything.
The MoMo valve internals are 'rotary shoe' types; the alternative, in commercial HVAC, is a 'plug & seat' type valve. Google for those terms for shed loads of information. Both are usually used for modulating control applications, rather than simple on/off.
The domestic ball/flap type zone valve or 3-port valve is virtually unknown in commercial applications, I can't recall having seen one used anywhere other than in a house.
There are commercial spring return actuators available, but this would be selected as an optional extra if there was a requirement for a valve to move to on or off in the event of a power failure, e.g., to prevent a hot water cylinder over-heating in the event of a power failure. I have always thought that having a motor powered and stalled against a return spring was something that was best avoided, if possible.
I would prefer to use Sunvic MoMo valves if the entire package was reliable ( I have several in my shed) , but their dodgy actuators have scared off most domestic plumbers. As noted on Seered, Sunvic used to make a Minival, a valve with an average lifespan of several decades. I think value engineering and short-sighted cost shaving has tarnished a formerly outstanding reputation.
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PS S-Plan with Honeywell actuators is the way that I would go.
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Thanks for the extra info Onetap.
As I've noted before, there is little room to move to make major alterations, but, when our next two rads are replaced, I will take it up with the plumber (can't lift things myself at the moment.)
Cheers,
S
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More interesting valve facts from Sunvic correspondence: Reads from the bottom (Still not entirely sure that I understand all this without having specimens to play with though!)
Sunvic latest reply:
I sent the PDF of the spring return valve as the internals are the same as for the MoMo. I dont have a PDF for the MoMo valve. The only difference is, in the MoMo valve there is only one shoe, where there are two in the spring return valve.
The MoMo actuator always moves in the one direction in increments of 90 turns. The spring return moves in one direction in increments of 45 turns, but always comes back the way it went.
The MoMo actuator will fit and operate on a spring return valve, but a spring return actuator, although it will fit a MoMo valve, will not operate because there is only one shoe in the valve.
--------------------------------------------------------------------------------
Sent: 03 September 2010 18:25 To: Sunvic HelpDesk Subject: Re: SDMV2304 3 port momo valve actuator.
Thanks for the additional info.
But you have provided a pdf for a spring return valve, which creates more confusion.
I had assumed that you said the momo actuator would not suit a ball type valve because the momo spindle needed a complete rotation. Separately, I have been told that the momo actuator only rotates in one direction, which would appear to back up what I had assumed: that the momo must rotate a third of a turn in the same direction with each activation. Thus I would need to buy the complete valve and actuator.
Now you have sent me your picture of the valve, which looks like it would revolve completely, but indicated that it works with a spring return, so may not rotate completely after all!?
Still has me scratching my head: but your valves do indeed look cleverer inside than the other makes I have seen so far, so I'll probably be buying a complete unit anyway, but I'd be interested in clearing up these points before I do.
Cheers,
rom: Sunvic HelpDesk
Sent: Friday, September 03, 2010 9:22 AM Subject: RE: SDMV2304 3 port momo valve actuator.
Our valves have either one shoe or two shoes (depending on the type of valve) which rotates to cover the port which is not calling for heat at that time. Please refer to the bottom page of the attached file which shows a sectioned view of one of our valves.
The cam that drives our valve spindles round, is located dead centre of the mounting plate. I believe on a Honeywell actuator, its offset.
Sent: 02 September 2010 16:36 To: Sunvic HelpDesk Subject: Re: SDMV2304 3 port momo valve actuator.
Thanks for the reply.
You have me puzzled though. The current actuator is a Honeywell, but I don't think the valve was the same make. It does have a ball at the water diverting end though - which is what I thought most of these valves had. I was thinking any differences might be in the mounting plate screw holes and/or spindle pattern, and had not thought the internals of the valve would make a difference.
Can you explain what exactly would be the problem with trying to fit to a ball type valve please?
Thank you,
From: Sunvic HelpDesk
Sent: Thursday, September 02, 2010 7:58 AM Subject: RE: SDMV2304 3 port momo valve actuator.
Thank you for your enquiry regarding the MoMo actuator. When looking for the actuator without the valve, you need to quote the number SDM 1901. We deal with companies such as Plumb center, C.E.F. Stearn electrical, Edmundsons etc.
The actuator will fit your existing valve (as long as its not a Honeywell type with a ball) and has the same wire colours, less an Earth wire, as our actuator is double insulated.
No new programmer required.
Subject: SDMV2304 3 port momo valve actuator.
Dear Sunvic,
I have, over the last few years, had to replace the actuator on our 3 port valve three times, due to the failure of the microswitches in conventional designs.
I only recently heard of your 'momo' type valves, and it seems that these might be what I have been looking for, and the SDMV2304, would appear to be equivalent to what we have.
However, I have not come across a site that sells the momo actuator alone, so I am wondering if you can tell me if the actuators are available separately and if they fit the conventional valve plate and spindle of existing valves? Obviously I would prefer not to have to interfere unnecessarily with the pipework - especially as this one is in a very tight cupboard space.
Also, would the momo type actuator be wired in in the same way as the conventional actuator, or are there more control wires, and hence a need for a new CH/HW controller as well?
Much appreciate your guidance on this as I am fed up with changing conventional actuators every year or two.
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