Hi,

I have an old central heating system which needs changes and
improvements and so I would be grateful for some expert advice please.
At present I have a Homeglow fire/back boiler combination system which
feeds an old rectangular indirect tank in the bathroom. There is only
one pump for the three radiators which it also feeds and the hot water
tank appears to heat from conduction only. With the combined header
tank in the bathroom, at two feet above the sink and bath taps, means
that ground floor user's gets priority for hot water.

My ideal is to eventually do away with the fire/back boiler combination
and to put a condensing boiler outside in the lean-to section of the
house. An on-demand system seems ideal but advice, or pointers to
information, on this would be appreciated. I'm not sure of the
benefits between different systems at present to make any kind of
informed judgement.

Right now I have to move the existing tank into the loft so that I can
update the bathroom and so I need to install something which will fit
in with my future plans of moving the heating source to the outside
location.

Ideally I'd like to do something at this point in time which didn't
involve having to have two water tanks in the loft as I've seen
heating cylinders which look to be completely self contained and highly
efficient.

By sighting a new hot water cylinder directly above where the present
one is then I can simply extend the existing piping up into the loft
and through adding pumps and valves I can make things much more
efficient and suitable for the house. Basically I need a two stage plan
that will allow me to expand and improve the existing system but which
will hopefully contribute components to an eventual ideal system.

All comments and advice grateful received and thanks in advance
Kind regards and best wishes
Phillip

In an earlier contribution to this discussion,
phillipthorne wrote:

Hi,

I have an old central heating system which needs changes and
improvements and so I would be grateful for some expert advice please.
At present I have a Homeglow fire/back boiler combination system which
feeds an old rectangular indirect tank in the bathroom. There is only
one pump for the three radiators which it also feeds and the hot water
tank appears to heat from conduction only. With the combined header
tank in the bathroom, at two feet above the sink and bath taps, means
that ground floor user's gets priority for hot water.

My ideal is to eventually do away with the fire/back boiler
combination and to put a condensing boiler outside in the lean-to
section of the house. An on-demand system seems ideal but advice, or
pointers to information, on this would be appreciated. I'm not sure
of the benefits between different systems at present to make any kind
of informed judgement.

Right now I have to move the existing tank into the loft so that I can
update the bathroom and so I need to install something which will fit
in with my future plans of moving the heating source to the outside
location.

Ideally I'd like to do something at this point in time which didn't
involve having to have two water tanks in the loft as I've seen
heating cylinders which look to be completely self contained and
highly efficient.

By sighting a new hot water cylinder directly above where the present
one is then I can simply extend the existing piping up into the loft
and through adding pumps and valves I can make things much more
efficient and suitable for the house. Basically I need a two stage
plan that will allow me to expand and improve the existing system but
which will hopefully contribute components to an eventual ideal
system.

All comments and advice grateful received and thanks in advance
Kind regards and best wishes
Phillip

I'm not quite sure what your ultimate aim is - except for having a new
boiler in a different location. You mention an "on demand" system - which
suggests that you have a combi boiler in mind. If a combi would meet your
requirements, you wouldn't need any stored hot water - so any new tanks in
the attic would be wasted. Combis are ok for small houses with single
bathrooms, where you're more likely to shower than bath, and when you don't
mind the bath taking a long time to fill. But they are only viable if you
have a good mains water supply, capable of delivering at least 20 litres per
minute at the tap nearest to the stopcock. Under all other circumstances,
some means of storing hot water for instant use is higher preferable.

Do you really need to get rid of everything from the bathroom? If you could
accommodate a new, more efficient circular hot tank there, with a header
tank in the attic, you would greatly improve the hot flow in the bathroom.
You really need to pump the HW circuit too, rather than relying on gravity
(convection) to heat it. Do you have a separate small header tank for the
primary circuit? If not, you've probably got a primatic tank where a single
header does both jobs - which isn't particularly desirable and, among other
things, prevents the use of corrosion inhibitor. So you'll need two tanks in
the attic - a big one (50 gallons) as a header tank for the hot water
system, and a small one (5 gallons) as the fill and expansion tank for the
primary circuit. [When you replace the boiler, you'll almost certainly have
a pressurised/unvented primary circuit, and won't need a F&E tank - but your
existing boiler almost certainly wouldn't like that. If your current boiler
*is* ok with an unvented system, you could go to that striaght away and do
away with the need for a F&E tank.]

Before putting *any* water tanks in the attic, make sure that you can
support them adequately - water is heavy stuff! If your ceiling joists are
only designed to support the ceiling, they won't like being asked to support
several hundredweight of water - so you'll need to locate the tanks
somewhere where they're directly supported by a load-bearing wall.

If you have a good cold mains supply, but don't fancy a combi, you might
consider a heat bank. With that, you maintain a tank of hot water at a high
temperature, and use it to heat mains pressure cold water by passing it
through a heat exchanger on the way to the hot taps. You could potentially
put your heat bank in the attic provided it is supported properly. [It's
also possible to have mains pressure hot cylinders - but they need
specialist installation and maintenance, and should probably be avoided.]

These are a few ideas anyway - come back with your own thoughts/reactions.
--
Cheers,
Set Square
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Hi,

Thanks for all your pointers and advice. Lots to think about.

My primary concern at the moment is to free up space in my bathroom
while refurbishing it. The bathroom is tiny and the current tank takes
up 15-20% of the space which could be better used for other things.
That's the reason for looking at a new one going into the loft.

As you say, the present tank has just one combined header tank which is
very limiting especially when it comes to adding anticorrosion
chemicals. I would love to do away with a tank altogether but it
undoubtedly means abandoning the Homeglow BBU and getting a new boiler
which I really don't want to do just yet, not until the summer at
least. This is why I'm trying to find a kind of half way house solution
but it seems that it may not be possible from what you say.

I take your point about supporting structures in the loft and I have
that planned. I haven't heard of the heat bank system which you
mentioned and would be very interested to look at this system but again
I have no idea if it that can be run from my present boiler. I'm not
sure if the Glowworm would work with an un-vented system either and
will need to establish this. I haven't been able to find much in the
way of information in the net about the boiler yet but I'll keep
looking.

Installing whatever system is not a problem as I can do the work but my
technical knowledge is lacking in systems suitability and make-up hence
my appeal for help. I would be more than happy for someone to do a good
design for me and happy to pay as well if that's the sensible route to
go.

Many thanks for your help
Kind regards and best wishes
Phillip

Hi,

I've just been researching the heat bank system and it looks very
interesting. In practice how well does this system work in winter when
the mains feed water is nearly ice cold and you want a reasonable
supply to fill a nice hot bath. Flow rate and feed water temperature
obviously have an impact on the system as does the BTU output of the
boiler no doubt.

Kind regards and best wishes
Phillip

Re converting from backboiler to new system


Hi


I would stay away from an unvented system myself. While currently in
vogue, a header tank in the loft makes for a more reliable and easier
to maintain system.

Backboilers normally must use a gravity circuit, not pumped, so
circulation continues in the event of a power cut.

Moving the hot tank from bathroom to loft means, if you keep the
backboiler, large pipes to maintain gravity circulation.

Combis typically have poor flow rates, taking 15 minutes to get a bath
ready is normal. If you do go combi, there is one trick that can help
with this: transferring the heat from the hot water in the CH system to
the hot water when the hw tap is on. This reduces bath fill times
significantly in winter, when most needed, and will help a little in
summer too, when ambient (CH) temp is well above water supply temp (eg
25C versus 10C). The trick is achieved by passing cold supply to the HW
thru a heat exchanger, the other circuit of which is in the CH.

A drain heat exchanger will also help significantly with shower flow
rate. This uses the warm drain water to heat either the cold supply to
the shower or the cold supply to the HW system. It recovers a lot of
the shower heat, allowing a better shower and reducing energy
consumption. Payback is in the region of 100% pa.


NT

Hi,

The existing tank is a Rolyat Calorifier which has 28mm pipes linking
it to the BBU. It would mean extending these pipes about 6 to 8 feet up
to site a new tank in the loft. I would imagine that the current run
for these pipes is about 10 feet vertically and 16 feet horizontally.
The Homeglow BBU is set on the lowest thermostat setting and has no
problem providing hot water to the tank although the conduction system
is a little slow when waiting for a full tank from cold. It would be
nice to have a pump on the new system if that's possible.

Thanks for all the help
Kind regards and best wishes
Phillip