"Ian Calderbank" ian_calderbank at dont-spam-me.hotmail.com wrote in
message ...
Dear all,
I'm looking to get the GFCH system upgraded on a large 4/5 bed 1970's
detached house we just moved into last winter. The boiler is an
almost new (recent replacement by previous owner) potterton kingfisher
80BTU so that won't be changing any time soon. A key goal is to have
a substantial volume mains pressure (which is pretty good) hot water
supply for the bathroom (2x) refurbs that are the next job along the
line... existing cylinder is an old (and fairly small) vented
indirect header tank fed which takes forever to reheat, so it goes,
along with changing the pumping layout to something sensible. The
airing cupboard is huge though. I can't diy this as I'm too busy at
work and its too big a job (3 new rads, TRV's all round - 16 rads in
total, new cylinder, new piping runs between boiler in kitchen and
airing cupboard upstairs, changing pumping layout which is also a bit
weird (some dual pump + flow check valve bodge onto gravity system we
think).
the debates that I'm having are mainly around the cylinder selection.
All the local heating engineers (the ones that want to turn up and
quote that is) have a default recommendation of Heatrae Sadia Megaflo.
Whilst I'm sure this is a decent product I want to look at a few
alternatives, including the possiblity of a non-pressurised option
such as a thermal store, avoiding the need for safety relief, outflow
pipes, etc, and to have something that an unqualified person (i.e. me)
can work on in the future. also I have read on various websites
discussing the different system types about requiring building regs
and annual inspections for unvented cylinders, is this true?
I also _might_ look at adding solar hw heating to the system at some
point in the future (no decisions made on that score though), so I'd
like to avoid doing anything that would preclude that option, the HS
site suggests this may not be the easiest thing to do with their
product.
I'm found a bunch of info about various unvented/heatbank/thermal
store products on the web, but as I said the local heating engineers
all want to do megaflo, what I'm really after is any unbiased
experience of the different types to be able to make an informed
decision, so any help is appreciated.
Lastly, I am in Milton Keynes area which is ultra-hard water, so its
been suggested to look at electronic scale inhibitors, any good/bad
stories in this area?
any trade on here who want to contact me directly by email please feel
free to do so.
thanks in advance,
Ian
Go for a heat bank. The local plumbers fit megaflows because they know no
different. A heat bank requires an electrical connection so they shy away.
A Megaflow requires you to service it each year to reinstate the air pocket
(PITA). They require large 1" copper overflows too. If there is a burst the
insurance will not pay up.
Get a heat bank with a solar coil already in the bottom, ready for
connection. Also have the CH fed from the heat bank too. Then solar heated
water will supply the CH as well as DHW.
Most makers will supply a "integrated" (CH & DHW) heat bank.
http://www.heatweb.com
http://www.range-cylinders.co.uk (go thermal storage)
Contact the makers and they will identify a model for you. DPS make heat
banks that don't require an overflow.
If these plumbers say heat banks are no good they are not worth employing as
they don't know their stuff. They are superior to unvented cylinders in most
points, and especially when you are incorporating solar panels.
Scale? Fit a phosphor de-scaler, available from, B&Q and the lies for
around £45-50, on all the water except the kitchen drinking tap and garden
hose. A heat bank can be DIY descaled by removing the plate heat exchanger.
Make sure they incorporate full bore isolation valves either side of the
plate to remove the plate heat exchanger without a drain down and re-fill
which can be expensive as they require about 3 bottles of inhibitor.