robgraham wrote:
Just go away and try to do it. Then you'll find out.

Hey, come on what sort of posting is that ? we're here to help one
another here and that is just downright destructive.

The thread has analysed the OP's problem and a relatively low cost
solution has been suggested, that I admit I am interested in too, and
then you come along and rubbish without saying what the problem is.
Are you really happy with yourself allowing several of us to go ahead
and invest £100 or so plus time effort only to find there is a
weakness with this set up that you know all about and won't tell us ?

Come on - where's the catch please Mr Capitol?

Rob


dIMM is the problem. Christian has already pointed out that the pump
will cavitate if the input flow is too low. If the pump cavitates, then
the pressures will not equalise correctly(ie fast enough). If you
attempt to feed a bath and a shower from two points of the same cylinder
at the same time ( particularly via a Surrey flange), with a pump
sucking on one of them, the odds are that the pump will not have enough
input flow producing cavitation, a pressure equalising valve cannot cope
with this (you will see that the description says "CAN turn a manual
shower into one which doesn't suffer temperature fluctuations--- not
WILL") . The other problem which you will probably see is that the cold
water intake into the tank will be too fast and the hot water in the
tank will not stratify correctly. The result will be a shower which has
very erratic temperature characteristics, as even with a thermostatic
mixer the required correction is just not fast enough. That's before you
start to look at the size of the feed pipes and the required head/flows.
The Surrey flange will not work correctly if there is not enough input
flow into the tank.

Interesting that Grundfoss show an Essex flange in their drawings,
These give more flexibility in positioning and higher flow rates. dIMM
couldn't possibly accept that Essex was a better proposition!

You can't solve a problem until you define it, this had not been done.

Re -reading the thread, my impression is that the OP may have in all
probability a basic flow problem into/through or out of the hot water
tank. Even nastier, the feed pipes from the hot water tank to the rest
of the house may be furred up (downstairs flow is also poor). Is it a
hard water area? Is there a loft tank feeding the hot water tank? First
steps are to check the pipe sizes, hot water feeder tank size and
position(height primarily) and then to measure the hot and cold flow
rates at the bath/sink taps and the kitchen hot tap. Distance flowed
would also be useful in the case of the hot. Given this information,
there is a chance that the first step required would be to replace some
pipework and/or some valves. Pressure equalisation may well be a good
idea, but do bear in mind that it is not the answer to all problems.
Pressure reduction may be an equally valid approach. Roger's experience
is valid in that often you can get away without Surrey/Essex flanges,
particularly if you are a small household and the shower has a fairly
low flow rate. For very high flow rates multiple flanges can be a good idea.

Using a low pressure booster pump as a panacea will not solve the
problem if it is elsewhere. The pump could in some cases give a head
below about 12' if mounted at bath floor level. Shower pumps normally
give heads of 20--80'.

This thread had lots of advice, some very poor due to inexperience
(dIMM) which probably would not solve the real problem.

That's why the thread was not worth keeping.

Regards
Capitol