"Richard Skeen" wrote in message
...
Mike Holmes wrote:
I am shortly going to convert my conventional open vented DHW cylinder
into a Heat Bank following the design given at
http://wiki.diyfaq.org.uk/index.php?title=DIY_Heat_Bank

I had thought about something similar, but was wondering about the
possibility of eliminating the thermostatic mixing valve.

As far as I can see, the DPS Pandora heatbank has a flow switch to
control the pump and a TMV to regulate the output temporature, whereas
the Gledhill Pulsacoil heatbank doesn't have a TMV. Instead, it has a
temperature sensor on the DHW side and a variable speed pump.

What do people think about using a variable speed pump and temperature
sensor instead of a TMV? Would this approach would also give better
stratification inside the thermal store? How easy is it to find a
variable/multi-speed circulator pump?

Rich.

Best see this thread:
http://tinyurl.com/3bwlpa
Use a mixing valve on the primary water sensing DHW temp on the secondary
water. This will only alllow water into the bottom of the cylinder at the
rate which is required - the minimum rate preserving stratification.
Speader pipes will assist too.