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

--
ian_calderbank at dont-spam-me.hotmail.com

Ian Calderbank wrote:

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 have a FlowMax thermal store, which I installed after having one at
our last house. I'm very happy with its performance, and intend to carry
on using thermal stores for a long time to come.



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?

By all means look at them, but don't actually buy one. Looking at them
is just as effective at inhibiting scale formation as fitting one, but a
lot cheaper.


--
Grunff

"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.

"Grunff" wrote in message
...
Ian Calderbank wrote:

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 have a FlowMax thermal store, which I installed after having one at
our last house. I'm very happy with its performance, and intend to carry
on using thermal stores for a long time to come.

Flowmax is made by range cylinders. They will fit solar coils if requested
too.

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?

By all means look at them, but don't actually buy one. Looking at them
is just as effective at inhibiting scale formation as fitting one, but a
lot cheaper.

I'm surprised they never insulted you by saying MK is a **** hole. As that
is what most of them have been saying on this ng.

BTW, use a "directly" heated heat bank, not heated via an intermediate coil.

IMM wrote:

Flowmax is made by range cylinders. They will fit solar coils if requested
too.

They're very helpful people IME.

If adding a solar component later, it's probably a lot easier to so it
with an external heat exchanger rather than a coil.



BTW, use a "directly" heated heat bank, not heated via an intermediate coil.

Hey, right again! That's twice in the same post. Drugs started working?


--
Grunff

"Grunff" wrote in message
...
IMM wrote:

Flowmax is made by range cylinders. They will fit solar coils if
requested
too.

They're very helpful people IME.

If adding a solar component later, it's probably a lot easier to so it
with an external heat exchanger rather than a coil.

Having the solar coil at the botom of the cylinder reat to be connected is
the best way. It doesn't take up much space either.

BTW, use a "directly" heated heat bank, not heated via an intermediate
coil.

Hey, right again! That's twice in the same post. Drugs started working?

They must be. Keep taking them. Well not quite, you screwed on the solar
addition part. Can you take a stronger dose?

On Thu, 12 Aug 2004 12:56:18 +0100, "IMM" wrote:



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.



well, I've spoken to Range and DPS, interestingly I got opposing
stories....

range talked about both but preferred to recommend unvented cylinder
(tribune) as this can come with dual coils as standard, saying service
requirement was simply a matter of a pressure check with a car-tyre
pressure gauge, and a test of the relief valve you can do yourself,
vs flowmax with a 2nd coil would be a special build and in their
opinion not as well suited to providing the volumes needed for a large
house, more designed for new-build smaller homes, and also not so good
for hard water area.....

DPS on the other hand straightaway suggested their heatbank, and it
certainly seems to eliminate a lot of the pressure/temperature relief
requirements of the unvented.

With the heatbank, the option for heating the store itself is direct
onto the CH circuit or indirect via coil, the difference being whether
the CH system is sealed(=indirect) or unsealed (=direct), at the
moment its unsealed (good old feed-expansion tank in the loft which I
want rid of but there is room for one in the airing cupboard along
with a big cylinder), boiler capable of running either way, I have no
strong preference, any pros/cons in each direction?

one interesting point between the two is the temp requirement for the
stored water. 60 degrees in unvented, 75 degrees in the heatbank. So I
would guess that as a possible solar input also has to heat-exchange
into the tank, the lower temp would be easier to make use of that
energy? But I do like the sound of not having all that pressure stuff
to worry about....

neither had any suggestions about who to use for system design/install
other than IOP listed (which I am trying to stick with anyway). So I
guess I will just have to wave the names under peoples noses and see
what reaction I get....

ta,
Ian

"Ian Calderbank" ian_calderbank at dont-spam-me.hotmail.com wrote in
message ...
On Thu, 12 Aug 2004 12:56:18 +0100, "IMM" wrote:

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.

well, I've spoken to Range and DPS,
interestingly I got opposing stories....

range talked about both but preferred to
recommend unvented cylinder
(tribune) as this can come with dual coils
as standard, saying service
requirement was simply a matter of a
pressure check with a car-tyre
pressure gauge, and a test of the relief
valve you can do yourself,

Still a service. If you did it yourself and there was a burst, would the
insurance company pay up? I doubt it,as they will find any excuse not to
pay.

vs flowmax with a 2nd coil would be
a special build and in their
opinion not as well suited to providing
the volumes needed for a large
house, more designed for new-build
smaller homes, and also not so good
for hard water area.....

Range are big and want to sell off the shelf stock. Their FloMax is geared
towards smaller homes.

An unvented cylinder will not use solar heated water for CH, it is only used
for DHW. Scale? "Always" fit a phosphor scale reducer in any hard water
area on any system.

DPS on the other hand straightaway
suggested their heatbank, and it
certainly seems to eliminate a lot
of the pressure/temperature relief
requirements of the unvented.

It eliminates all of it as it is at low pressure

With the heatbank, the option for
heating the store itself is direct
onto the CH circuit or indirect via
coil, the difference being whether
the CH system is sealed(=indirect)
or unsealed (=direct), at the
moment its unsealed (good old feed-expansion
tank in the loft which I want rid of but there
is room for one in the airing cupboard along
with a big cylinder),

Heat banks come mainly wit the F&E tank integrated with the cylinder.

boiler capable of running either
way, I have no strong preference,
any pros/cons in each direction?

With a direct heat bank keep it the open vented. the heat bank provides the
CH F&E tank.

one interesting point between
the two is the temp requirement for the
stored water. 60 degrees in unvented,
75 degrees in the heatbank.

The heat bank uses the hot water to instantly heat the incoming cold mains
water. the unvented cylinder is the water you use at the taps. the water in
a heat bank is primary water.

So I would guess that as a possible solar
input also has to heat-exchange
into the tank, the lower temp would
be easier to make use of that
energy?

Having a solar coil at the bottom of a heat bank will heat the water in the
cylinder. Fully in summer, not so much in winter. In winter it may only be
tow temp, but it is being used to preheat the cylinder, it all counts and it
is used for CH and DHW.

But I do like the sound of not having
all that pressure stuff to worry about....

If you have ever seen they aftermath of an exploded unvented cylinder you
would shy away. Total devastation.

neither had any suggestions about who
to use for system design/install
other than IOP listed (which I am
trying to stick with anyway). So I
guess I will just have to wave the names
under peoples noses and see
what reaction I get....

A heat bank can have all the controls, pumps etc all on the cyinder, DPS
would do this for you. All yu do is connect up the relevant wires and pipes.
The flow and return of the CH circuit is connected up to the CH tappings.
The DHW is a matter of cold in hot out pipes, and the boiler is a matter of
connecting up the boiler flow and return to the heat bank. Simple stuff, no
real design work for an dumb installer to do, and the experts who design the
heat bank do virtually all of it for you.

A heat bank eliminates inefficient boiler cycling, which an unvented
cylinder will not. Eventually I would replace that cast iron boiler.
Modern "heating" condensing boilers are far more efficient.

If you want to replace it now then consider a Powermax or Gledhill
Gulfstream 2000, which incorporate incondesning boilers. An all in one
solution. The 2000 is available from Travis Perkins plumbing dept.

http://www.powermax.co.uk
http://www.gledhill.net

On Fri, 13 Aug 2004 13:05:40 +0100, Ian Calderbank wrote:

On Thu, 12 Aug 2004 12:56:18 +0100, "IMM" wrote:



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.



well, I've spoken to Range and DPS, interestingly I got opposing
stories....

range talked about both but preferred to recommend unvented cylinder
(tribune) as this can come with dual coils as standard, saying service
requirement was simply a matter of a pressure check with a car-tyre
pressure gauge, and a test of the relief valve you can do yourself,
vs flowmax with a 2nd coil would be a special build and in their
opinion not as well suited to providing the volumes needed for a large
house, more designed for new-build smaller homes, and also not so good
for hard water area.....

DPS on the other hand straightaway suggested their heatbank, and it
certainly seems to eliminate a lot of the pressure/temperature relief
requirements of the unvented.

With the heatbank, the option for heating the store itself is direct
onto the CH circuit or indirect via coil, the difference being whether
the CH system is sealed(=indirect) or unsealed (=direct), at the
moment its unsealed (good old feed-expansion tank in the loft which I
want rid of but there is room for one in the airing cupboard along
with a big cylinder), boiler capable of running either way, I have no
strong preference, any pros/cons in each direction?

one interesting point between the two is the temp requirement for the
stored water. 60 degrees in unvented, 75 degrees in the heatbank. So I
would guess that as a possible solar input also has to heat-exchange
into the tank, the lower temp would be easier to make use of that
energy? But I do like the sound of not having all that pressure stuff
to worry about....

neither had any suggestions about who to use for system design/install
other than IOP listed (which I am trying to stick with anyway). So I
guess I will just have to wave the names under peoples noses and see
what reaction I get....


Take a look at the sealed CH system FAQ. It may well be better to heat the
heat bank indirectly from a sealed system. The heat bank water itself
beeing a simple F+E header tank.



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html

"Ed Sirett" wrote in message
news
On Fri, 13 Aug 2004 13:05:40 +0100, Ian Calderbank wrote:

On Thu, 12 Aug 2004 12:56:18 +0100, "IMM" wrote:

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.



well, I've spoken to Range and DPS, interestingly I got opposing
stories....

range talked about both but preferred to recommend unvented cylinder
(tribune) as this can come with dual coils as standard, saying service
requirement was simply a matter of a pressure check with a car-tyre
pressure gauge, and a test of the relief valve you can do yourself,
vs flowmax with a 2nd coil would be a special build and in their
opinion not as well suited to providing the volumes needed for a large
house, more designed for new-build smaller homes, and also not so good
for hard water area.....

DPS on the other hand straightaway suggested their heatbank, and it
certainly seems to eliminate a lot of the pressure/temperature relief
requirements of the unvented.

With the heatbank, the option for heating the store itself is direct
onto the CH circuit or indirect via coil, the difference being whether
the CH system is sealed(=indirect) or unsealed (=direct), at the
moment its unsealed (good old feed-expansion tank in the loft which I
want rid of but there is room for one in the airing cupboard along
with a big cylinder), boiler capable of running either way, I have no
strong preference, any pros/cons in each direction?

one interesting point between the two is the temp requirement for the
stored water. 60 degrees in unvented, 75 degrees in the heatbank. So I
would guess that as a possible solar input also has to heat-exchange
into the tank, the lower temp would be easier to make use of that
energy? But I do like the sound of not having all that pressure stuff
to worry about....

neither had any suggestions about who to use for system design/install
other than IOP listed (which I am trying to stick with anyway). So I
guess I will just have to wave the names under peoples noses and see
what reaction I get....

Take a look at the sealed CH system FAQ. It may well be better to heat the
heat bank indirectly from a sealed system. The heat bank water itself
beeing a simple F+E header tank.

It may be, but in this case I can't see that it is beneficial. The boiler is
cast iron and open vented. I see no reason why just the boiler and the flow
and returns to the heat bank would need to be pressurised. If installing a
high efficiency boiler that can only be pressurised then I could see why.

On Fri, 13 Aug 2004 15:42:55 +0100, "Ed Sirett"
wrote:

Take a look at the sealed CH system FAQ. It may well be better to heat the
heat bank indirectly from a sealed system. The heat bank water itself
beeing a simple F+E header tank.

yes, I'd read all the faq's many times.
I just had another chap round, he made what seemed like a good
negative point against sealed versus unsealed

- heating installation is 30 yrs old, mid 70's house, system
definately never been u/g'ed and there are several rads with cold
lower sections downstairs so I'm sure its got sludge in, and all the
heating pipework downstairs is buried in screed floors
- if there is any leakage, sealing/pressurising the CH circuit will
only make it more so, and as most of its buried, it'll be a complete
**** to find...

and he was at least aware of the existence of thermal store/heat
banks, but he said he had to go away and do some reading up before
recommending options..

Ian

"Ian Calderbank" ian_calderbank at dont-spam-me.hotmail.com wrote in
message ...
On Fri, 13 Aug 2004 15:42:55 +0100, "Ed Sirett"
wrote:

Take a look at the sealed CH system FAQ. It may well be better to heat
the
heat bank indirectly from a sealed system. The heat bank water itself
beeing a simple F+E header tank.

yes, I'd read all the faq's many times.
I just had another chap round, he made what seemed like a good
negative point against sealed versus unsealed

- heating installation is 30 yrs old, mid 70's house, system
definately never been u/g'ed and there are several rads with cold
lower sections downstairs so I'm sure its got sludge in, and all the
heating pipework downstairs is buried in screed floors
- if there is any leakage, sealing/pressurising the CH circuit will
only make it more so, and as most of its buried, it'll be a complete
**** to find...

and he was at least aware of the existence of thermal store/heat
banks, but he said he had to go away and do some reading up before
recommending options..

If he has to read up on it I would take his recommendations with a pinch of
salt. Tell us what he recommends.

"IMM" wrote in message
...

snip

If he has to read up on it I would take his recommendations with a pinch
of
salt.


So you were born with all your knowledge then - some how that figures !...

"Ed Sirett" wrote in message
news
On Fri, 13 Aug 2004 13:05:40 +0100, Ian Calderbank wrote:

On Thu, 12 Aug 2004 12:56:18 +0100, "IMM" wrote:



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.



well, I've spoken to Range and DPS, interestingly I got opposing
stories....

range talked about both but preferred to recommend unvented cylinder
(tribune) as this can come with dual coils as standard, saying service
requirement was simply a matter of a pressure check with a car-tyre
pressure gauge, and a test of the relief valve you can do yourself,
vs flowmax with a 2nd coil would be a special build and in their
opinion not as well suited to providing the volumes needed for a large
house, more designed for new-build smaller homes, and also not so good
for hard water area.....

DPS on the other hand straightaway suggested their heatbank, and it
certainly seems to eliminate a lot of the pressure/temperature relief
requirements of the unvented.

With the heatbank, the option for heating the store itself is direct
onto the CH circuit or indirect via coil, the difference being whether
the CH system is sealed(=indirect) or unsealed (=direct), at the
moment its unsealed (good old feed-expansion tank in the loft which I
want rid of but there is room for one in the airing cupboard along
with a big cylinder), boiler capable of running either way, I have no
strong preference, any pros/cons in each direction?

one interesting point between the two is the temp requirement for the
stored water. 60 degrees in unvented, 75 degrees in the heatbank. So I
would guess that as a possible solar input also has to heat-exchange
into the tank, the lower temp would be easier to make use of that
energy? But I do like the sound of not having all that pressure stuff
to worry about....

neither had any suggestions about who to use for system design/install
other than IOP listed (which I am trying to stick with anyway). So I
guess I will just have to wave the names under peoples noses and see
what reaction I get....

Take a look at the sealed CH system FAQ. It may well be better to heat the
heat bank indirectly from a sealed system. The heat bank water itself
beeing a simple F+E header tank.

Pressurised thermal store/heat banks are available. These have the sealed
primary flow and return from the boiler directly connected to the cylinder.
They are basically grade 1 cylinders which are rated at 2.5 bar working
pressure and a test pressure 1 bar above that. When used as a thermal
store/heat bank connected to the boiler they operate at approx 1.5 bar
working pressure and a blow valve of 3 bar, so well within range. The makers
tend to stipulate that the thermal store/heat bank has its own blow off
valve as well as the boiler.

I would rather go with one of these than a thermal store/heat bank using a
an intermediate primary heating coil.

"IMM" wrote in message ...
Pressurised thermal store/heat banks are available. These have the sealed
primary flow and return from the boiler directly connected to the cylinder.
They are basically grade 1 cylinders which are rated at 2.5 bar working
pressure and a test pressure 1 bar above that. When used as a thermal
store/heat bank connected to the boiler they operate at approx 1.5 bar
working pressure and a blow valve of 3 bar, so well within range. The makers
tend to stipulate that the thermal store/heat bank has its own blow off
valve as well as the boiler.

I would rather go with one of these than a thermal store/heat bank using a
an intermediate primary heating coil.

At the risk of being associated with 'dumb plumbers' I'll give my
reasons for recommending an unvented cylinder rather than a thermal
store. I've got nothing against the technology of a thermal store but
personally feel its had its day now that condensing boilers will soon
be mandatory to the mass market.

I agree that an unvented cylinder must be installed by a trained
person. IMM says that UV cyls can explode and while true it is rare
due to the safety features that are mandatory. UK regulations are lot
stricter than many countries were UV cyls have been the norm for many
years.

To the points in question;

1. Reinstating the air bubble in a megaflow is not a difficult task.

2. 1" copper overflows are not required unless the route to discharge
is extraordinarly long. The tundish has a 22mm output and this is
sufficient for most installations. However, the discharge pipework
must not be plastic.

3. KISS. Which is easier to understand; the UV cyl or a heatbank?

4. Solar. As far as I know OSO and Viessmann are the only UV cyls to
have dual coil models. Yes, the solar won't heat your radiators, but
since solar systems are designed to work at their peak in summer,
surely this a moot point?

5. condensing boilers. I commented this elsewhere in the NG. UV cyls
are a better option with a condensing boiler. With inefficient boilers
there is no such choice between an uv cyl and heatbank.

6. DIY. Yes I'll agree that a heatbank can be DIY-ed. This suggests
the owner has some interest in the heatbank technology, which is fair
enough. Future owners may not be so inclined. Still, future employment
for 'plumbers' when the next owners rip it out to put a megaflow in?

7. The marque. A 'Megaflow' has become something of a must-have.
Probably due to marketing and keeping up with the Jones. Still, the
educated customer wins out. It may be a plus-point on a future house
sale.

8. Boiler cycling. Any system is susceptable to this if badly
installed. I've not seen a modern UV cylinder which causes the boiler
to cycle before it reaches the desired temperature. I only install the
keston celsius 25, which has some features to avoid cycling.

9. All in one packages. Not something I go for myself but just a
personal choice. There are equally valid pros/cons for this type of
unit.

Martyn