OldScrawn wrote:
I'm after a 22 mm motorised "changeover" valve (i.e. it would be SPDT if it
were electrics). As far as I know, central heating "3 port" valves give you
"one or both" rather than "one or the other". I could just use a Tee and two
"zone valves" with a relay to do the changeover, but can anyone suggest a
supplier for what I actually need? It's a very light industrial use (less than
once per day) so I was looking for central heating rather than serious
industrial type prices. Brass will be fine. Any advice on relative merits of
Danfoss / Honeywell?

My 3 port valve, which AFAIK is pretty standard, is SPDT.
There's a rubber flap, which either sits one way, the other way,
or in the middle (both ports open).

--
Grunff

On 06 Jul 2003 19:31:29 GMT, (OldScrawn) wrote:

I'm after a 22 mm motorised "changeover" valve (i.e. it would be SPDT if it
were electrics). As far as I know, central heating "3 port" valves give you
"one or both" rather than "one or the other". I could just use a Tee and two
"zone valves" with a relay to do the changeover, but can anyone suggest a
supplier for what I actually need? It's a very light industrial use (less than
once per day) so I was looking for central heating rather than serious
industrial type prices. Brass will be fine. Any advice on relative merits of
Danfoss / Honeywell?

Steve

You can get 3 port valves which will open to one port or the other
only; or that will do one or the other or both.

In either case, there will be a flow to both branches as the valve
moves.

Zone valves with a relay would also work and you could organise things
such that the water went to only one branch at a time (if that
matters).

www.discountedheating.co.uk have a good online selection; otherwise
any heating merchant.

Honeywell and Danfoss are both good products.

I wouldn't expect to get perfect seals out of this type of valve and
the pressure of operation is quite limited. If the pressure is a bit
higher, then washing machine solenoid valves are very cheap and do
completely shut off.



..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On 06 Jul 2003 19:31:29 GMT, (OldScrawn) wrote:

I'm after a 22 mm motorised "changeover" valve (i.e. it would be SPDT if
it
were electrics). As far as I know, central heating "3 port" valves give
you
"one or both" rather than "one or the other". I could just use a Tee and
two
"zone valves" with a relay to do the changeover, but can anyone suggest a
supplier for what I actually need? It's a very light industrial use (less
than
once per day) so I was looking for central heating rather than serious
industrial type prices. Brass will be fine. Any advice on relative merits
of
Danfoss / Honeywell?

Steve

You can get 3 port valves which will open to one port or the other
only; or that will do one or the other or both.

A valve that will only open to either one port or the other is known as a
"diverter" valve. Those that can divert and allow flow to both ports are
called mid-position. Diverter valves are simpler and the best choice if
only diversion is required.


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"IMM" wrote in message
...

"Andy Hall" wrote in message
...
On 06 Jul 2003 19:31:29 GMT, (OldScrawn) wrote:

I'm after a 22 mm motorised "changeover" valve (i.e. it would be SPDT
if
it
were electrics). As far as I know, central heating "3 port" valves give
you
"one or both" rather than "one or the other". I could just use a Tee
and
two
"zone valves" with a relay to do the changeover, but can anyone suggest
a
supplier for what I actually need? It's a very light industrial use
(less
than
once per day) so I was looking for central heating rather than serious
industrial type prices. Brass will be fine. Any advice on relative
merits
of
Danfoss / Honeywell?

Steve

You can get 3 port valves which will open to one port or the other
only; or that will do one or the other or both.

A valve that will only open to either one port or the other is known as a
"diverter" valve. Those that can divert and allow flow to both ports are
called mid-position. Diverter valves are simpler and the best choice if
only diversion is required.

See for a Myson diverter valve.
http://tinyurl.com/g5xz


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"Toby" wrote in message
...
A valve that will only open to either one port or the other is known
as
a
"diverter" valve. Those that can divert and allow flow to both ports
are
called mid-position. Diverter valves are simpler and the best choice
if
only diversion is required.

See for a Myson diverter valve.
http://tinyurl.com/g5xz

Or the Drayton ZA5, includes a limit switch. At rest Common to port A,
energised Common to port B.

The limit switch is very handy, as many diverters do not have them.

The mid postion seems to be given precedence to the diverter in the
merchants, my local CIty Plumbing only do the diverters 'to order'.

Unfortunately that is the case. It is best to use a diverter and a quick
recovery cylinder that takes all of the boilers heat, rather than a
mid-position valve. The cylinder will re-heat in quick time and make no
effect on the house heating for the short time it is re-heating the
cylinder. Quick recovery cylinders use less gas overall, and can be
downsized as they re-heat so fast.


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In article ,
IMM wrote:
Unfortunately that is the case. It is best to use a diverter and a quick
recovery cylinder that takes all of the boilers heat, rather than a
mid-position valve. The cylinder will re-heat in quick time and make no
effect on the house heating for the short time it is re-heating the
cylinder. Quick recovery cylinders use less gas overall, and can be
downsized as they re-heat so fast.

If you want to wire any system for hot water priority it shouldn't be a
problem. After all, the ability should exist for hot water only in the
summer.

--
*The more people I meet, the more I like my dog.

Dave Plowman London SW 12
RIP Acorn

"Toby" wrote in message
...

SNIP


The mid postion seems to be given precedence to the diverter in the
merchants, my local CIty Plumbing only do the diverters 'to order'.


It is a simple matter to configure the wiring of a mid position valve to
give either/or but not both ports
Reference to the data sheet will clarify the connections

Brilliant, thanks all. I thought there should be such an animal, and I hadn't
come across discountedheating

S

"John" wrote in message
...

"Toby" wrote in message
...

SNIP


The mid postion seems to be given precedence to the diverter in the
merchants, my local CIty Plumbing only do the diverters 'to order'.


It is a simple matter to configure the wiring of a mid position valve to
give either/or but not both ports
Reference to the data sheet will clarify the connections

If buying a new valve it is better to buy a diverter as they are simpler and
more reliable than mid-position valves. If converting a system to a
priority system with a quick recovery cylinder a mid-position can be
converted to a diverter, saving the cost of new valve.


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"Toby" wrote in message
...
See for a Myson diverter valve.
http://tinyurl.com/g5xz

Or the Drayton ZA5, includes a limit switch. At rest Common to port A,
energised Common to port B.

Is the Drayton available in dealers or on the web?

Not sure about web, get nearly all my plumbing over the counter.
An email/call to discountedheating would get you one if you wish.
I believe the part number would be 679H314-30L0 for the 3-wire, not sure
on
the 5-wire.

The valve is just their 2 port zone head bolted to a three port body.
ZA5 head Zone Actuator 5 wire SPST
679-3 Three port body

I guess the only advantage over wiring a standard mid-position valve is
the
independant switch contact if for some reason you didn't want '240v on the
orange wire'

Mid position valves are less reliable than a standard valve top and end
switch.


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