Capitol wrote:
OK, I've escaped from picking plums, so back to plumbing!

I'd rather be picking plums than installing radiators, or dicking
around getting soaked trying to measure flow rates from body jets!

The 22l/m
flow rate corresponds to about a 3-5ft head on 22mm pipe.
this tells us
the problem is on the inlet side of the pump, as the flow rate with 3bar
head would be up to 400l/m!!! It is a 22mm inlet size pump isn't it?

400l/m wow that is a lot. Yes it is a 22m inlet size pump.

A
15mm inlet can't cope. It seems as though you are looking for a flow
rate of around 30l/m, which with your head would require at least 28mm
piping into the hot water tank from the loft tank and separately fed
28mm piping from the loft tank into the cold side of the pump. The
problem is probably coming from the hot feed out of the tank being in
22mm with a few bends in the way. A 90 bend corresponds to about 2ft of
piping if in copper and about 5-8 ft if compression.

I am using 22mm push fit and there is a 90 degree elbow and then it
goes into the pump, likewise for the cold. Maybe I could shorten the
pipe run and make it fall more than it currently does, I was wondering
about the fall its more like a 90 degree angle than a curve

What I would
suggest is that you double up on the Essex flange by adding a Surrey
flange and connecting the two together with 22mm, opening up to 28mm
where they combine keep the bends to a minimum, use street elbows if
possible and feed to the pump in 28mm as far as possible.

Why would I not use 2 essex flanges, what is the difference? So I would
just use a 22mm to 28mm T?

Are you suggesting I pipe the cold feed in 28mm too? and if not why
not, not sure I understand why it would just be the hot feed causing
the problem?

This on paper
and with a bit of guesswork will give you about 40-50l/m into the pump
which hopefully will be sufficient. I would add however, that if you are
using water at this rate, the chance of a hot shower lasting more than
5-10 minutes is pretty unlikely, also the loft tank will empty, as the
inlet valve almost certainly can't deliver more than 10l/m.

The cold tank is a seperate one for the shower. I am a little worried
about the hot water supply as SWMBO takes forever in the shower or used
to

Maybe I should try shortening the hot water feed to the pump first and
then go the other route? how does that sound??

Thanks very much for your reply, I was kind of giving up hope........

Cheers

Richard




Hope this helps

Regards
Capitol