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Roger Mills Roger Mills is offline
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Default Pipe thermostats and pumped HW

In an earlier contribution to this discussion,
Stephen wrote:

Hello,

I was thinking of converting my HW to a pumped system because I'm
fed-up of waiting ages for hot water to come out of the tap!

I understand I need a pump with a bronze impeller: are there any
available for under £100?

AIUI the pump is controlled by a pipe thermostat. I have had a look at
the instructions of the Horstman cylinder thermostat and it says it
can be used as a pipe stat on pipes of 28mm and above. Presumably to
give a sufficient surface area for heat transfer but I was only going
to use 15mm pipe. The Honeywell cylinder thermostat instructions do
not mention anything about use as a pipe thermostat.

Will all 'stats require 28mm pipe or will any work with pipes of
smaller diameters?

Using a short length of 28mm pipe with a 15 to 28 reducing coupling is
one way around it but it seems a waste to have to buy a length of 28mm
pipe just to use a couple of inches of it.

When I get hot water to the taps I wonder whether I might have the
opposite problem of the water being too hot! AIUI the water has to be
60C to kill bacteria so is the only answer to have thermostatic mixers
at each tap to cool the hot water down to say 40C?

Thanks,
Stephen.



Are you sure that the pump is controlled by a stat? Shower pumps serve a
similar purpose, and they are often controlled by a flow switch. As soon as
a tap is opened, there is *some* flow - by gravity - and this is enough to
trigger the flow switch to make the pump cut in.
--
Cheers,
Roger
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