On Wed, 22 Sep 2004 22:41:23 +0100, Pete C wrote:

On Wed, 22 Sep 2004 18:38:52 +0100, "IMM" wrote:

"Pete C" wrote in message

Sorry, by preheat I don't mean heating DHW before it reaches the heat
exchanger, just keeping the DHW hot in the pipes to save water and
have a quicker response when the hot tap/shower is turned on.

When the pump kicks in, heat is taken from the heat bank to the plate very
quickly giving an excellent response.

True, but if the tap is some way away from the exchanger you'll still
need to run a couple of litres of water before hot flows.

Would the DHW have it's own pump or share it with the CH?

I was suggesting using a non DHW circuit alongside the DHW pipe and
separate pump connected to the heatbank to keep the DHW hot. Though as
a pump is used on the secondary side there might be a way of getting
it to do this too.

Read my post on this thread on this point using a pipe stat and secondary
bronze pump.

How much is a bronze pump, I'd expect they are pricy. Pumps with a
plastic impellor in an iron body are cheaper though might seize up if
used for water with no inhibitor in.


The DHW is oxygenated mains pressure water.[1] It will rust all the
iron/steel fittings it runs through. Bronze pumps are around £150.





[1] It is usual to reduce the pressure to around 2.5-3 bar from the mains.
1) Becasue the is a good enough pressure to provided a very good flow
through typically sized pipe work.
2) You can split the pressure reduced cold water into cold and hot feeds
which can greatly improve the usability of the manual mixers.
3) It is not too high to create a lot of wear and strain in average taps.
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html