In message , andrew
writes
Tim Lamb wrote:

Ah! I had not considered you as a Hetas adviser.

I'm not, the commercial stuff I did didn't need part J. Unfortunately the
firm I was doing that for went bust when the Austrian boiler manufactures
decided to market to GB directly, order book suddenly vanished. The staff
and directors seem all to have been paid off, it was only creditors that
were caught, that included my last months bill ;-(.

Let us hope their pension investments are in something Icelandic.

Angela is badgering me
to install a wood burner to back up the central heating. I have got as
far as discovering that anything over 4.9kW requires an air supply and
that you can mix gravity water with pumped CH water with a neutraliser
but my cheque book hasn't twitched yet:-)

It's only a 6" air brick! Actually 5kW is fine for a back up.

Yes. Actually there is a suspended floor so I am considering installing
a duct terminating next to the hearth. Logistically, any log burner will
only operate while there is somebody to light and feed so early morning
heat will always be gas.

Lining the existing chimney looks straight forward as does adapting the
register plate. Where I am struggling is whether to go for room heat
only , graft a 2-3kW gravity back boiler into the existing gas system or
go for something with a wrap around boiler producing 10kW or so but,
presumably, needing much more complication by way of controls.

In fact for
mild days you'll have noticed that a cheap reversible air conditioner is
cheaper than gas or oil because the delta T it pumps through is low and the
COP is high.

I have ground/water source heat pump in mind for a different project.
Air-con is something I have never considered for a domestic use.

The neutraliser is just a ridiculously small, expensive thermal store, I'll
bet you can do it cheaper with a hot water cyclinder and some zone valves.

2-300ukp from Dunsley. I assume there is a limit to how much heat you
can transfer using gravity and a fixed bore/head system. I must ask
them. They don't seem to answer e-mail:-(

cross posted to uk.d-i-y

regards



--
Tim Lamb

On Thu, 9 Oct 2008 08:56:13 +0100, Tim Lamb wrote:

The neutraliser is just a ridiculously small, expensive thermal store,
I'll bet you can do it cheaper with a hot water cyclinder and some zone
valves.

2-300ukp from Dunsley.

Not cheap, the trick that the neutraliser performs is to have all the
inlets/outlets at the same static pressure. Not sure if all inlet and all
outlets have to be the same pressure or if just all the members of a set
have to be the same with the other set at a different pressure,

This could be tricky to arrange on a cylinder, adding extra primary
connections isn't that easy on a cylinder as access inside is a tad
restricted. Getting something fabricated might be an option.

I assume there is a limit to how much heat you can transfer using
gravity and a fixed bore/head system.

There probably is but I'd be using 28mm tube for the gravity loop and that
is well capable of shifting a few kW from a wood burner.

--
Cheers
Dave.

On Oct 9, 12:02*pm, "Dave Liquorice"
wrote:
On Thu, 9 Oct 2008 08:56:13 +0100, Tim Lamb wrote:
The neutraliser is just a ridiculously small, expensive thermal store,
I'll bet you can do it cheaper with a hot water cyclinder and some zone
valves.

2-300ukp from Dunsley.

Not cheap, the trick that the neutraliser performs is to have all the
inlets/outlets at the same static pressure. Not sure if all inlet and all
outlets have to be the same pressure or if just all the members of a set
have to be the same with the other set at a different pressure,

This could be tricky to arrange on a cylinder, adding extra primary
connections isn't that easy on a cylinder as access inside is a tad
restricted. Getting something fabricated might be an option.

I assume there is a limit to how much heat you can transfer using
gravity and a fixed bore/head system.

There probably is but I'd be using 28mm tube for the gravity loop and that
is well capable of shifting a few kW from a wood burner.

If its just for use if the main system fails, an electric immersion
element is an easy low cost option. 3kW is adequate for a hw cylinder.


NT

Tim Lamb wrote:

Yes. Actually there is a suspended floor so I am considering installing
a duct terminating next to the hearth. Logistically, any log burner will
only operate while there is somebody to light and feed so early morning
heat will always be gas.

In which case the dhw cylinder will probably be hot before the woodstove is
lit.

Lining the existing chimney looks straight forward as does adapting the
register plate. Where I am struggling is whether to go for room heat
only , graft a 2-3kW gravity back boiler into the existing gas system or
go for something with a wrap around boiler producing 10kW or so but,
presumably, needing much more complication by way of controls.

Its all to do with capital expense, I serviced a log gasifier which heats a
large house, the owner was a timber framing contractor and his wife stoked
the device, it was filled each afternoon and then set itself going at 6:00
the next day, it could be reloaded during the cycle and I think it was
25kW(t), now that's about 7kg of dry wood an hour at 70% efficiency, double
for fresh oak. I wouldn't want to traipse through the house with that much.
It cost GBP20k installed with a heatstore. I doubt I often put more than
4kg/day through my little Jotul (30 years old but relined with bits cut
from broken manhole covers). I haven't plumbed in either of my wood
burners.


I have ground/water source heat pump in mind for a different project.
Air-con is something I have never considered for a domestic use.

An air conditioner is a heat pump when run in reverse, its just air sourced.
Actually they run the same way, just swap the hot end for the cold end of
the circulating fluid I think.

AJH

In message
,
writes
On Oct 9, 12:02*pm, "Dave Liquorice"
wrote:
On Thu, 9 Oct 2008 08:56:13 +0100, Tim Lamb wrote:
The neutraliser is just a ridiculously small, expensive thermal store,
I'll bet you can do it cheaper with a hot water cyclinder and some zone
valves.

2-300ukp from Dunsley.

Not cheap, the trick that the neutraliser performs is to have all the
inlets/outlets at the same static pressure. Not sure if all inlet and all
outlets have to be the same pressure or if just all the members of a set
have to be the same with the other set at a different pressure,

This could be tricky to arrange on a cylinder, adding extra primary
connections isn't that easy on a cylinder as access inside is a tad
restricted. Getting something fabricated might be an option.

I assume there is a limit to how much heat you can transfer using
gravity and a fixed bore/head system.

There probably is but I'd be using 28mm tube for the gravity loop and that
is well capable of shifting a few kW from a wood burner.

If its just for use if the main system fails, an electric immersion
element is an easy low cost option. 3kW is adequate for a hw cylinder.

Yes. Long reach installed.

We already have an open log burning fire in the lounge but from a house
heating POV, with open plan rooms, this is probably neutral: radiant
heat to one room but lots of gas heated air sucked up the chimney.

Retirement/more time in the house plus labour cost only fuel leads to an
ambition to offset at least some of the central heating cost.

We started a related thread some time back with some interesting input
from TNP etc. The Demon news feed has been sickly so I am only just
following up. I have been collecting glossy brochures meanwhile:-)

There appear to be three options (4 if you count the do nothing one)....

1) Install a simple room heater. The available fire opening is in the
middle room of three. Using the on line heating requirement calculator
and allowing a bit for open stairwell, around 10kW is needed. I guess
this would make the middle room uninhabitable!

2) Install a 6kW heater with a modest back boiler giving 3kW to the room
and 3 to offset the gas. Costly to install without saving much gas.

3) Install a heater with a wrap around boiler giving 3kW to the room and
7 to offset the gas. Provided the neutraliser can handle this amount of
gravity heat the only extra is more logs.

regards


NT

--
Tim Lamb