Anyone got a link or any info for those heat exchangers comprising a
bundle of microbore that fit into an immersion heater boss on a standard
vented DHW cylinder, to give mains pressure DHW for a shower?
I think that may be an old Yorkshire fittings pdf file. I'm fairly
sure that neither the Micraversion or the Sidewinder are still made;
this would be because they were crap.
The Micraversion was intended to heat the HWS cylinder up, not provide
mains pressure hot water. The surface area would be inadequate, as
would the temperature differential for that application. You'd need a
plate heat exchanger, heated by the boiler primary water, with a pump
to shove the boiler water through the primary side of the PHX. You
could use a tube-in-shell heat exchanger similar to the Micraversion,
but I suspect it would work out at 20 feet long to achieve the heat
transfer surface area.
The old Range Powermax combi boilers (not the current Potterton HE
ones) generated mains pressure hot water like this. If you're thinking
of building something from parts, you could look at the Installation &
Maintenance manual to see how they'd done it.
search draws a blank for both. That pdf on the latenightengineer
site must be 5 years old, at least; probably 10.
You'd find their surface areas to be very small in comparison with
that of a modern British Standard DHWS cylinder. They were used in the
days when 'short-coil' cylinders were the standard replacement
supplied to clueless householders.
What about the 'sidewinder'? Was that another manufacturer's version of
the same think (i.e. indirect heating element)?
I'm sure I've seen a more recent beast along similar lines but definitely
intended as a thermal-store-type adaptation for providing mains pressure
DHW for showers from a standard gravity cylinder.
However I just had a go at a DIY lashup with 10m of 10mm pipe in a tub of
water at 60C and although it gives a decent heat transfer when the HW in
the tub is agitated a bit it quickly drops off when the water is standing
I was interested to see what the commercial version looked like to get an
idea how much copper I should be using.
It must be possible to get adequate transfer from a suitably-sized and
laid-out exchanger in a cylinder since thermal stores such as boilermates
use this principle, but my crazy-idea-but-it-might-just-work experiment