On Thu, 10 Oct 2019 09:08:04 +0000, Tim+ wrote:
A while back a friend asked me if there was any way he could have a warm
water supply outside for washing his dog.
As there was easy access to hot and cold supplies inside I fitted one of
these.
https://www.bes.co.uk/thermostatic-m...-3-15mm-12162?
Before purchase I checked with the manufacturer that it was suitable for
a mixed mains pressure cold feed and gravity fed HW.
It worked fine for several months but then water stopped coming out of
the tap. Sometimes if you waited the flow would start and it would
produce premixed warm water. Eventually it stopped working altogether.
Thinking that hed just been unlucky my friend opted to buy a new valve
and now a month after fitting the same thing is happening. All rather
annoying.
Before fitting the new valve I blew through the non-return valves and
discovered that they needed a fair bit of pressure to persuade the valve
to €ścrack open€ť the first time, after that they seemed to open
reasonably easily.
It seems likely to me that the HW non-return valve is sticking on its
seat, perhaps because its being exposed to reverse mains pressure cold
water when the outside tap is off.
Now Im sure I could disassemble the things and blow through the valve
again to free it but I would really rather not have to keep doing this.
One thought that occurs to me is that if I could think of a simple way
to produce an upstream €śpressure pulse€ť above the non-return valve I
could pop it off its sticky seat.
Long term answer may be to just go back to external H & C taps but he
does like the pre-mixed warm water.
Any suggestions?
Tim
Fit a shut off valve to the cold feed so that the hot side can start to
flow before the cold pressure is added.
That is, turn the mains pressure cold off, turn the mixer on, then slowly
crack open the cold mains.
Possibly only have the cold mains on when the shower is running, turning
it on after the hot is running then off before turning the mixer off.
This might stop the non-return on the hot side having to open against
mains pressure.
A simple gate valve with a handle should do the trick.
Cheers
Dave R
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