I have an outside tap, currently fed from the mains.
I have a combi-boiler.
I want to be able to switch between hot and cold water to the outside tap.
I don't want to actually mix the hot and cold - I just want to electrically
switch between the two supplies to the tap.
I think that is the way I am going to go. Thanks to you and all others with
their comments and suggestions.
I have looked at motorised valves - and it would seem that there is a danger of
them "wearing" out. I think I would like to try a simple solenoid type valve
- which is only activated when needed. So - normally closed - apply the power
and the solenoid opens. I am guessing that these are different from
"motorised" valves which appear to have limited life and a finer adjustment
(not just on or off) : or is it just a different name for the same thing?
Any further suggestions/comments on solenoid valves would be appreciated.
(PS I am not actually going to DIY it - I am looking for ideas/components which
I can discuss with a professional when I am ready to go)
Again: thanks to all for comments - appreciated.
A motorised valve only takes current while it operates - moves from open
to closed or the reverse.
A true solenoid valve would need power all the time it was in one state,
or some form of latch mechanism to hold it after it's moved.
Think central locking in a car. At one time this did use solenoids. But
these days invariably motors.
Motors are also more efficient than solenoids.
*I started out with nothing... and I still have most of it.
Dave Plowman email@example.com London SW
Not generally true for the sort used in heating systems. They have a
spring return and close as soon as power is removed. To keep them open,
the motor needs to be continuously powered - and simply stalls.
Since the OP wants to feed an outside tap, that will presumably only use
water for short periods, so requiring continuous power during 'on'
periods shouldn't be a problem.
CH-type motorised valves are not designed for mains pressure, whereas
the solenoid valves used on washing machine inlets *are*. A couple of
these from a scrap hot & cold fill washing machine would probably do the
job as long as you can find a way of connecting them. The ones I've seen
have a 3/4" male BSP thread on the inlet side - which is easy to connect
to - but the outlet side feeds into a chamber, so it would be necessary
to make a housing of some sort with a pipe connector on *its* outlet in
order to use the valves in an in-line situation.
It's also not true, in the common case of spring-return motorised valves.
I agree, having checked, that CH valves are no good as one quotes a max
differential pressure of 0.7bar
Lists quite a few and one is fine up to 9.8bar.
The other question is: does the OP care if the valve is approved for
Possible the cheapest source of electrically controlled valves
would be from a scrap washing machine.
You should probably also make sure you fit non-return valves to
prevent any chance of back-flow.
Chris J Dixon Nottingham UK
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