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

On 01/09/2010 16:19, Spamlet wrote:
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



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
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

"Roger Mills" wrote in message
...
On 01/09/2010 16:19, Spamlet wrote:
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



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
____________

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

On Wed, 01 Sep 2010 16:19:02 +0100, Spamlet wrote:

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.

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

If a tree falls in a forest, can one hand hear it clap?

On 2 Sep, 23:29, "Spamlet" wrote:

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.

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.

PS S-Plan with Honeywell actuators is the way that I would go.

"Onetap" wrote in message
...
PS S-Plan with Honeywell actuators is the way that I would go.

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