Yes. I do know there are umpteen thousand hits on the web!

How many kW would be needed to space heat 200m2 of single storey offices
meeting current building regs. but only 4 to 5m wide (lots of outside
wall and roof)?

How much useful heat could I extract from pumped groundwater within the
current *no licence* abstraction limit of 20m3/day?

regards
--
Tim Lamb

On Jul 15, 12:49*pm, Tim Lamb wrote:
Yes. I do know there are umpteen thousand hits on the web!

How many kW would be needed to space heat 200m2 of single storey offices
meeting current building regs. but only 4 to 5m wide (lots of outside
wall and roof)?

How much useful heat could I extract from pumped groundwater within the
current *no licence* abstraction limit of 20m3/day?

regards


R measures insulation, U measures conductance
U value is thermal conductance in W/m^2k
(watts, metres square, kelvin)

R value = 1/ U value


Normally with GSH one doesn't abstract any water, one just takes the
heat from the water.


NT

"NT" wrote in message
...

Normally with GSH one doesn't abstract any water, one just takes the
heat from the water.

But sadly, the environment agency consider it 'abstraction' even if you put
it back again. So is you put more than 20m3 a day of say river water
through your heat pump then you would need an abstraction licence.
Regards
Bruce

On Jul 15, 1:56*pm, "BruceB" wrote:
"NT" wrote in message
....

Normally with GSH one doesn't abstract any water, one just takes the
heat from the water.

But sadly, the environment agency consider it 'abstraction' even if you put
it back again. *So is you put more than 20m3 a day of say river water
through your heat pump then you would need an abstraction licence.
Regards
Bruce

I thought with a GSH pump you don't even move the water - the heat
pump pipes are a sealed system pumping coolant round the pipes. The
coolant is warmed up as it passes through the pipes which are immersed
in the groundwater, and that heat is then extracted in the building.
That can't possibly count as abstraction of water. I may be wrong
about the mechanism though.

A

wrote in message
...
On Jul 15, 1:56 pm, "BruceB" wrote:
"NT" wrote in message
...

Normally with GSH one doesn't abstract any water, one just takes the
heat from the water.

But sadly, the environment agency consider it 'abstraction' even if you
put
it back again. So is you put more than 20m3 a day of say river water
through your heat pump then you would need an abstraction licence.
Regards
Bruce

I thought with a GSH pump you don't even move the water - the heat
pump pipes are a sealed system pumping coolant round the pipes. The
coolant is warmed up as it passes through the pipes which are immersed
in the groundwater, and that heat is then extracted in the building.
That can't possibly count as abstraction of water. I may be wrong
about the mechanism though.
***********

You are right, but the term GSHP is often used loosely. Taking water from a
river I would normally call a water source heat pump. More accurately
perhaps, we are talking about the difference between an open circuit and
closed circuit collector.

I was really making the point that even if you put water back it is still
abstraction.

Regards
Bruce

"BruceB" wrote in message
.. .

"NT" wrote in message
...

Normally with GSH one doesn't abstract any water, one just takes the
heat from the water.

But sadly, the environment agency consider it 'abstraction' even if you
put it back again. So is you put more than 20m3 a day of say river water
through your heat pump then you would need an abstraction licence.
Regards
Bruce

He said that 20m3 a days needs no licence.

wrote in message
...
On Jul 15, 1:56 pm, "BruceB" wrote:
"NT" wrote in message
...

Normally with GSH one doesn't abstract any water, one just takes the
heat from the water.

But sadly, the environment agency consider it 'abstraction' even if you
put
it back again. So is you put more than 20m3 a day of say river water
through your heat pump then you would need an abstraction licence.
Regards
Bruce

I thought with a GSH pump you don't even move the water - the heat
pump pipes are a sealed system pumping coolant round the pipes. The
coolant is warmed up as it passes through the pipes which are immersed
in the groundwater, and that heat is then extracted in the building.
That can't possibly count as abstraction of water. I may be wrong
about the mechanism though.


If the water does not leave the ground - pumped into a below ground chamber
and out again, then I would assume he can pump as much as he wants.

"BruceB" wrote in message
.. .

wrote in message
...
On Jul 15, 1:56 pm, "BruceB" wrote:
"NT" wrote in message
...

Normally with GSH one doesn't abstract any water, one just takes the
heat from the water.

But sadly, the environment agency consider it 'abstraction' even if you
put
it back again. So is you put more than 20m3 a day of say river water
through your heat pump then you would need an abstraction licence.
Regards
Bruce

I thought with a GSH pump you don't even move the water - the heat
pump pipes are a sealed system pumping coolant round the pipes. The
coolant is warmed up as it passes through the pipes which are immersed
in the groundwater, and that heat is then extracted in the building.
That can't possibly count as abstraction of water. I may be wrong
about the mechanism though.
***********

You are right, but the term GSHP is often used loosely. Taking water from
a river I would normally call a water source heat pump. More accurately
perhaps, we are talking about the difference between an open circuit and
closed circuit collector.

I was really making the point that even if you put water back it is still
abstraction.

The most efficient are water sourced heat pumps. Pumping ground water
through a heat exchanger and back to ground can do the same thing.
Extracting heat from a running stream is by far the best. Water contains 4
time more heat per volume than earth.

You can have a plastic pipe run under the earth circled as in Heat Pump
slinkies. But to improve matters run this pipe through a collection of
large water cylinders or plastic barrels above ground. Extract heat via the
heap pump at the hottest part of this system the storage cylinders . A
normal water pump would pump heat from the ground via the slinkies 24/7 and
dumps it into the cylinders, then the heat pump extracts the heat when
needed from the cylinders. The heat from the surrounding air, heating the
water in the barrels has some gain too. The mass of water in the
cylinder/barrels hold 4 times more heat than earth, so acts as a
concentrator upping the heat efficiency.

This is a slinky for a ground sourced heat pump, made from a concrete block.
http://www.ebuild.co.uk/forums/messa...tml?1208929618

On Jul 15, 1:56*pm, "BruceB" wrote:
"NT" wrote in message
....

Normally with GSH one doesn't abstract any water, one just takes the
heat from the water.

But sadly, the environment agency consider it 'abstraction' even if you put
it back again. *So is you put more than 20m3 a day of say river water
through your heat pump then you would need an abstraction licence.
Regards
Bruce

It can be done that way, or the well water can simply be left where it
is and heat harvested from it by conduction/convection


NT

On Jul 15, 4:51*pm, "Doctor Drivel" wrote:

This is a slinky for a ground sourced heat pump, made from a concrete block.http://www.ebuild.co.uk/forums/messa...tml?1208929618

Interesting idea. But I think the assumption that the same amount of
heat will get extracted when all the pipes are bunched up close is
rather unrealistic. On the plus side the concrete used could contain a
high percentage of hardcore if the top of the cage is left open.


If the water does not leave the ground - pumped into a below ground chamber
and out again, then I would assume he can pump as much as he wants.

so much for assumption


NT

In message
, NT
writes
On Jul 15, 4:51*pm, "Doctor Drivel" wrote:

This is a slinky for a ground sourced heat pump, made from a concrete
block.http://www.ebuild.co.uk/forums/messa...tml?1208929618

Interesting idea. But I think the assumption that the same amount of
heat will get extracted when all the pipes are bunched up close is
rather unrealistic. On the plus side the concrete used could contain a
high percentage of hardcore if the top of the cage is left open.


If the water does not leave the ground - pumped into a below ground chamber
and out again, then I would assume he can pump as much as he wants.

so much for assumption

I have posted an enquiry to the EA on the basis that they would be
informed by the planners if I specified using part of their flood plain
to extract heat. Secrecy is not the way forward!

The slinky system can extract about 1kW per 10m of trench but my
uncalculated guess is that a huge system would be needed to supply the
heating energy for 200m2 of buildings.

ISTM that pumping *river* water from the gravel beds in the land next to
the bank should give a clean supply not full of fish or blanket weed.
Extracting the useful heat using DD's heat exchanger and then returning
the chilled water some distance from the source should give better
results than the usual pipe in a well. The slinky pipe has to be filled
with anti-freeze leading to ground water contamination risks although I
understand this can be brine.

20m3/day or 833kg of water per hour. Extract 5deg. C is how much energy?

As this project is right on target with current govt. thinking, a
licence might be forthcoming anyway:-)

The waste can feed an ornamental fountain.

regards


NT

--
Tim Lamb

"NT" wrote in message
...
On Jul 15, 4:51 pm, "Doctor Drivel" wrote:

This is a slinky for a ground sourced heat pump, made from a concrete
block.http://www.ebuild.co.uk/forums/messa...tml?1208929618

Interesting idea. But I think the assumption that the same amount of
heat will get extracted when all the pipes are bunched up close is
rather unrealistic. On the plus side the concrete used could contain a
high percentage of hardcore if the top of the cage is left open.


The concrete is poured onto the bedrock. Soil can be an insulator. The
bedrock is not. There will be a constant movement of heat from the bedrock
to the concrete block. Concrete is a fair thermal conductor, at least
compared to dry soil. The same with the bedrock that the concrete is
bonding to. So, the area that you scavenge heat from is greater than if you
were running through soil. He's not scavenging from the soil above the
concrete "block". If you were doing this in soil, you'd need a much much
larger contact area.

In some buildings, concrete piles supporting buildings have plastic pipes
run in them for heat pumps to extract heat.

I would have the blue plastic the pipe in a figure of 8, so it crosses right
through the concrete block. As it is, it is wound around the outside of the
concrete block.

If the water does not leave the ground - pumped
into a below ground chamber and out again, then
I would assume he can pump as much as he wants.

so much for assumption


He has not extracted from the ground any water. It all stayed under the
ground.

In an earlier contribution to this discussion,
Tim Lamb wrote:


20m3/day or 833kg of water per hour. Extract 5deg. C is how much
energy?
If I can correctly remember my schoolboy physics from 50 years ago, it goes
like this:

833,000 gm x 5 degC = 4,165,000 calories per hour

[Divide by 3,600] = 1156.9 calories per second

[4.1868 Joules/calorie] = 4844 Joules/second = 4844 Watts ~ 4.8kW

[I'm sure somebody will correct me if this is wrong!]

I don't know how much heat is needed to heat your 200 M^2 offices - but it's
almost certainly more than 4.8kW. [The heat calculations for my *house* come
out at over 10kW in the dead of winter]

You need to do a heatloss calculation for the offices - taking account of
all the areas, U-values, air exchanges etc. - just as if you were designing
a central heating system (which you *are* really). If you can get hold of a
copy of the Barlo or Myson heatloss programs, they will help - otherwise
just do it in a spreadsheet.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

On Wed, 15 Jul 2009 18:56:49 +0100, Tim Lamb wrote:

20m3/day or 833kg of water per hour. Extract 5deg. C is how much energy?

Specific heat capacity water 4.187 kJ/kgK

20000 * 5 * 4.187 = 418.7MJ

--
Cheers
Dave.

On Jul 15, 7:33*pm, "Doctor Drivel" wrote:
"NT" wrote in message
...
On Jul 15, 4:51 pm, "Doctor Drivel" wrote:

This is a slinky for a ground sourced heat pump, made from a concrete
block.http://www.ebuild.co.uk/forums/messa...tml?1208929618

Interesting idea. But I think the assumption that the same amount of
heat will get extracted when all the pipes are bunched up close is
rather unrealistic. On the plus side the concrete used could contain a
high percentage of hardcore if the top of the cage is left open.


The concrete is poured onto the bedrock. Soil can be an insulator. *The
bedrock is not. There will be a constant movement of heat from the bedrock
to the concrete block. Concrete is a fair thermal conductor, at least
compared to dry soil. The *same with the bedrock that the concrete is
bonding to. So, the area that you scavenge heat from is greater than if you
were running through soil. *He's not scavenging from the soil above the
concrete "block". * If you were doing this in soil, you'd need a much much
larger contact area.

Interesting - but how many of us have bedrock 2m down?


In some buildings, concrete piles supporting buildings have plastic pipes
run in them for heat pumps to extract heat.

For the cost of some hardcore one can make a shallow underfloor void
to suck coolth from too. Only requires a fan and heat exchanger.


I would have the blue plastic the pipe in a figure of 8, so it crosses right
through the concrete block. *As it is, it is wound around the outside of the
concrete block.

that would cause it to freeze where it crosses, putting the system out
of action


If the water does not leave the ground - pumped
into a below ground chamber and out again, then
I would assume he can pump as much as he wants.

so much for assumption


He has not extracted from the ground any water. It all stayed under the
ground.

so much for assumption


NT

On Wed, 15 Jul 2009 19:53:56 +0100, Roger Mills wrote:

I don't know how much heat is needed to heat your 200 M^2 offices - but
it's almost certainly more than 4.8kW. [The heat calculations for my
*house* come out at over 10kW in the dead of winter]

Our offices (400m^2) take *no* heating, even in winter - with one or two
PCs per person, there's plenty of heat to go round.

On the other hand, a decent GSHP can cool on the cheap as well...


Also, my (average sized?) 3-bed semi has two floors of about 10mx9m each
- so his offices aren't that much bigger than my 180m^2.

"NT" wrote in message
...
On Jul 15, 7:33 pm, "Doctor Drivel" wrote:
"NT" wrote in message
...
On Jul 15, 4:51 pm, "Doctor Drivel" wrote:

This is a slinky for a ground sourced heat pump, made from a concrete
block.http://www.ebuild.co.uk/forums/messa...tml?1208929618

Interesting idea. But I think the assumption that the same amount of
heat will get extracted when all the pipes are bunched up close is
rather unrealistic. On the plus side the concrete used could contain a
high percentage of hardcore if the top of the cage is left open.


The concrete is poured onto the bedrock. Soil can be an insulator. The
bedrock is not. There will be a constant movement of heat from the bedrock
to the concrete block. Concrete is a fair thermal conductor, at least
compared to dry soil. The same with the bedrock that the concrete is
bonding to. So, the area that you scavenge heat from is greater than if
you
were running through soil. He's not scavenging from the soil above the
concrete "block". If you were doing this in soil, you'd need a much much
larger contact area.

Interesting - but how many of us have bedrock 2m down?


I don't know, but you were implying the setup woud not work.

In some buildings, concrete piles supporting buildings have plastic pipes
run in them for heat pumps to extract heat.

For the cost of some hardcore one can make a shallow underfloor void
to suck coolth from too. Only requires a fan and heat exchanger.


I would have the blue plastic the pipe in a figure of 8, so it crosses
right
through the concrete block. As it is, it is wound around the outside of
the
concrete block.

that would cause it to freeze where it crosses, putting the system out
of action


Could do.


He has not extracted from the ground any water. It all stayed under the
ground.

so much for assumption


No assumption. water has not left the ground above ground level.

NT

NT wrote:
On Jul 15, 1:56 pm, "BruceB" wrote:
"NT" wrote in message
...
Normally with GSH one doesn't abstract any water, one just takes the
heat from the water.
But sadly, the environment agency consider it 'abstraction' even if you put
it back again. So is you put more than 20m3 a day of say river water
through your heat pump then you would need an abstraction licence.
Regards
Bruce

It can be done that way, or the well water can simply be left where it
is and heat harvested from it by conduction/convection



I think you have a basic misconception.

Ground source heat pumps that use water as a heatt reservoir take the
heat, not the water. The primary curcuit is antifreeze loaded water in a
closed loop.

That loop is generally buried in the ground, but it can be laid at the
bottom of a pond.


NT

NT wrote:
On Jul 15, 7:33 pm, "Doctor Drivel" wrote:
"NT" wrote in message
...
On Jul 15, 4:51 pm, "Doctor Drivel" wrote:

This is a slinky for a ground sourced heat pump, made from a concrete
block.http://www.ebuild.co.uk/forums/messa...tml?1208929618

Interesting idea. But I think the assumption that the same amount of
heat will get extracted when all the pipes are bunched up close is
rather unrealistic. On the plus side the concrete used could contain a
high percentage of hardcore if the top of the cage is left open.


The concrete is poured onto the bedrock. Soil can be an insulator. The
bedrock is not. There will be a constant movement of heat from the bedrock
to the concrete block. Concrete is a fair thermal conductor, at least
compared to dry soil. The same with the bedrock that the concrete is
bonding to. So, the area that you scavenge heat from is greater than if you
were running through soil. He's not scavenging from the soil above the
concrete "block". If you were doing this in soil, you'd need a much much
larger contact area.

Interesting - but how many of us have bedrock 2m down?


In some buildings, concrete piles supporting buildings have plastic pipes
run in them for heat pumps to extract heat.

For the cost of some hardcore one can make a shallow underfloor void
to suck coolth from too. Only requires a fan and heat exchanger.


I would have the blue plastic the pipe in a figure of 8, so it crosses right
through the concrete block. As it is, it is wound around the outside of the
concrete block.

that would cause it to freeze where it crosses, putting the system out
of action


If the water does not leave the ground - pumped
into a below ground chamber and out again, then
I would assume he can pump as much as he wants.
so much for assumption


He has not extracted from the ground any water. It all stayed under the
ground.

so much for assumption


Drivel is completely wide of any mark here.

Ignore him.



NT

In message , Roger Mills
writes
In an earlier contribution to this discussion,
Tim Lamb wrote:


20m3/day or 833kg of water per hour. Extract 5deg. C is how much
energy?
If I can correctly remember my schoolboy physics from 50 years ago, it goes
like this:

833,000 gm x 5 degC = 4,165,000 calories per hour

[Divide by 3,600] = 1156.9 calories per second

[4.1868 Joules/calorie] = 4844 Joules/second = 4844 Watts ~ 4.8kW

[I'm sure somebody will correct me if this is wrong!]

Your memory over a similar time scale is much better than mine:-)

Looks like a licence will be necessary. Oh well...

I don't know how much heat is needed to heat your 200 M^2 offices - but it's
almost certainly more than 4.8kW. [The heat calculations for my *house* come
out at over 10kW in the dead of winter]

Yes. I also have rather a lot of outside wall to consider.

You need to do a heatloss calculation for the offices - taking account of
all the areas, U-values, air exchanges etc. - just as if you were designing
a central heating system (which you *are* really). If you can get hold of a
copy of the Barlo or Myson heatloss programs, they will help - otherwise
just do it in a spreadsheet.

Hmm.... I'm OK with a big sheet of paper!

regards

--
Tim Lamb

In an earlier contribution to this discussion,
Dave Liquorice wrote:

On Wed, 15 Jul 2009 18:56:49 +0100, Tim Lamb wrote:

20m3/day or 833kg of water per hour. Extract 5deg. C is how much
energy?

Specific heat capacity water 4.187 kJ/kgK

20000 * 5 * 4.187 = 418.7MJ

Yes, that answers the question asked - "how much energy per day?"

However, a more useful calculation would be the *rate* of extracting energy
(i.e. power) in kW. Have you worked that out?

[I'd be interested to know whether your calculation arrived at the same
result as mine].
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Roger Mills wrote:
In an earlier contribution to this discussion,
Dave Liquorice wrote:

On Wed, 15 Jul 2009 18:56:49 +0100, Tim Lamb wrote:

20m3/day or 833kg of water per hour. Extract 5deg. C is how much
energy?
Specific heat capacity water 4.187 kJ/kgK

20000 * 5 * 4.187 = 418.7MJ

Yes, that answers the question asked - "how much energy per day?"

However, a more useful calculation would be the *rate* of extracting energy
(i.e. power) in kW. Have you worked that out?

[I'd be interested to know whether your calculation arrived at the same
result as mine].
Yes it does work out the same

418.7MJ divided by number of seconds in a day (3600 x24) gives 4.84kW

Bob

On Wed, 15 Jul 2009 22:48:59 +0100, Tim Lamb wrote:

[4.1868 Joules/calorie] = 4844 Joules/second = 4844 Watts ~
4.8kW

Looks like a licence will be necessary. Oh well...

But only if you do extract the water cool it and put it back surely?

Can't you have a closed loop system, like that of a ground source
heat pump, dangling in the river with the water naturally flowing
past it? I guess you'd need some form of grid/channel to keep it
clear of weed/branches etc which the EA might then consider
"abstraction"... B-(

--
Cheers
Dave.

In message , Bob Minchin
writes
Roger Mills wrote:
In an earlier contribution to this discussion,
Dave Liquorice wrote:

On Wed, 15 Jul 2009 18:56:49 +0100, Tim Lamb wrote:

20m3/day or 833kg of water per hour. Extract 5deg. C is how much
energy?
Specific heat capacity water 4.187 kJ/kgK

20000 * 5 * 4.187 = 418.7MJ
Yes, that answers the question asked - "how much energy per day?"
However, a more useful calculation would be the *rate* of extracting
energy (i.e. power) in kW. Have you worked that out?
[I'd be interested to know whether your calculation arrived at the
same result as mine].
Yes it does work out the same

418.7MJ divided by number of seconds in a day (3600 x24) gives 4.84kW

Unfortunately the pumped concept falls at several hurdles.

More than 4.84kW is needed. Although river Lea water is *warm* (largely
sourced from effluent treatment plants upstream) 5deg.C seems a
realistic figure considering prolonged adverse winter weather.

The EA website gives abstraction charges of 15 to 28ukp per 1000m3 and
trade effluent discharges are charged on anything exceeding 10m3 per day
so it looks as if the project is doomed!

However, by cleaning out an existing drain paralleling the river bank, I
can probably create a flow which would improve the performance of the
slinky version. I am beginning to think that gas is best!

regards

--
Tim Lamb

"The Natural Philosopher" wrote in message
...
NT wrote:
On Jul 15, 7:33 pm, "Doctor Drivel" wrote:
"NT" wrote in message
...
On Jul 15, 4:51 pm, "Doctor Drivel" wrote:

This is a slinky for a ground sourced heat pump, made from a concrete
block.http://www.ebuild.co.uk/forums/messa...tml?1208929618

Interesting idea. But I think the assumption that the same amount of
heat will get extracted when all the pipes are bunched up close is
rather unrealistic. On the plus side the concrete used could contain a
high percentage of hardcore if the top of the cage is left open.


The concrete is poured onto the bedrock. Soil can be an insulator. The
bedrock is not. There will be a constant movement of heat from the
bedrock
to the concrete block. Concrete is a fair thermal conductor, at least
compared to dry soil. The same with the bedrock that the concrete is
bonding to. So, the area that you scavenge heat from is greater than if
you
were running through soil. He's not scavenging from the soil above the
concrete "block". If you were doing this in soil, you'd need a much
much
larger contact area.

Interesting - but how many of us have bedrock 2m down?


In some buildings, concrete piles supporting buildings have plastic
pipes
run in them for heat pumps to extract heat.

For the cost of some hardcore one can make a shallow underfloor void
to suck coolth from too. Only requires a fan and heat exchanger.


I would have the blue plastic the pipe in a figure of 8, so it crosses
right
through the concrete block. As it is, it is wound around the outside of
the
concrete block.

that would cause it to freeze where it crosses, putting the system out
of action


If the water does not leave the ground - pumped
into a below ground chamber and out again, then
I would assume he can pump as much as he wants.
so much for assumption


He has not extracted from the ground any water. It all stayed under the
ground.

so much for assumption


Drivel is completely wide of any mark here.

Ignore him.

This idiot built his own house and put single glazing in. He hasn't a clue.
Sad but true.

Dave Liquorice wrote:
On Wed, 15 Jul 2009 22:48:59 +0100, Tim Lamb wrote:

[4.1868 Joules/calorie] = 4844 Joules/second = 4844 Watts ~
4.8kW
Looks like a licence will be necessary. Oh well...

But only if you do extract the water cool it and put it back surely?

Exactly.


Can't you have a closed loop system, like that of a ground source
heat pump, dangling in the river with the water naturally flowing
past it?

Yup.

You never use actual water from a river in a heatpump..its merely a heat
exchanger.


I guess you'd need some form of grid/channel to keep it
clear of weed/branches etc which the EA might then consider
"abstraction"... B-(


Not even that. You simply throw some coils 9figurateviely speaking) in
te river bottom. and let them silt up and over.

Grund or water source heatpumps extract so little over such a large area
that perfect conductivity is not an issue.

The working fluid in the primary will exit the heatpump at probably -5C
or so. Its merely necessary to get it more or less up to +5C. Then the
pump will boost the secondary temperatures to about +30 - +40C and chill
the primary.

On Jul 16, 9:57*am, Tim Lamb wrote:
In message , Bob Minchin
writes
Roger Mills wrote:
In an earlier contribution to this discussion,
Dave Liquorice *wrote:
On Wed, 15 Jul 2009 18:56:49 +0100, Tim Lamb wrote:

20m3/day or 833kg of water per hour. Extract 5deg. C is how much
energy?
Specific heat capacity water 4.187 kJ/kgK

20000 * 5 * 4.187 = 418.7MJ
*Yes, that answers the question asked - "how much energy per day?"
*However, a more useful calculation would be the *rate* of extracting
energy *(i.e. power) in kW. Have you worked that out?
*[I'd be interested to know whether your calculation arrived at the
same *result as mine].
Yes it does work out the same

418.7MJ divided by number of seconds in a day (3600 x24) gives 4.84kW

Unfortunately the pumped concept falls at several hurdles.

More than 4.84kW is needed.

Have you calculated exactly what you need to maintain 19C on a cold
winter day? As well as heat from the river you can also collect a bit
more from the pipe run from house to river, plus additional insulation
may sometimes be an option, plus other heat sources.


Although river Lea water is *warm* (largely
sourced from effluent treatment plants upstream) 5deg.C seems a
realistic figure considering prolonged adverse winter weather.

Do you actually know the winter river temp? It might be better.


The EA website gives abstraction charges of 15 to 28ukp per 1000m3 and
trade effluent discharges are charged on anything exceeding 10m3 per day
so it looks as if the project is doomed!

However, by cleaning out an existing drain paralleling the river bank, I
can probably create a flow which would improve the performance of the
slinky version. I am beginning to think that gas is best!

regards


NT

On Jul 15, 12:49*pm, Tim Lamb wrote:
Yes. I do know there are umpteen thousand hits on the web!

How many kW would be needed to space heat 200m2 of single storey offices

Which 200m2 are you heating, at the floor or at the ceiling or
somewhere in between?

MBQ

On Thu, 16 Jul 2009 02:36:41 -0700 (PDT), NT wrote:

Unfortunately the pumped concept falls at several hurdles.

More than 4.84kW is needed.

Don't forget that your calculated total heat requirement doesn't have
to all come from one source. Yer average a working PC/monitor chucks
out 100W or so, humans another couple of hundred watts each just sat
still...

Although river Lea water is *warm* (largely sourced from effluent
treatment plants upstream) 5deg.C seems a realistic figure
considering
prolonged adverse winter weather.

Do you actually know the winter river temp? It might be better.

I suspect it probably is the north sea surface temperature in mid
winter doesn't get down to 5C, 8C is sort of average. It's about 15C
ATM... With the river being fed "warm" effluent as well...

And is the absolute temperature all that important? We are dealing
with a heat pump. It'll move the heat provided there is a positive
delta T between the incoming circulated loop and the water. Obviously
efficiency drops off at small delta Ts and if you freeze the water
around the slinky. That's where the design is critical have a big
enough area over which to extract the heat such that it doesn't
freeze or the delta T get too small.

--
Cheers
Dave.

If this is from a river, how fast does it flow, is there a fall across the
land?

It might be better to put a turbine in, generate electricity and use that.

"Dave Liquorice" wrote in message
ll.co.uk...
On Wed, 15 Jul 2009 22:48:59 +0100, Tim Lamb wrote:

[4.1868 Joules/calorie] = 4844 Joules/second = 4844 Watts ~
4.8kW

Looks like a licence will be necessary. Oh well...

But only if you do extract the water cool it and put it back surely?

Can't you have a closed loop system, like that of a ground source
heat pump, dangling in the river with the water naturally flowing
past it? I guess you'd need some form of grid/channel to keep it
clear of weed/branches etc which the EA might then consider
"abstraction"... B-(

He needs a heat exchanger. Pump water from river into heat exchanger. Pump
water from heat pump into other side of heat exchanger. Sorted.

"The Natural Philosopher" wrote in message
...

Not even that. You simply throw some coils figurateviely speaking) in te
river bottom. and let them silt up and over.

If they allow you too, which I doubt they will.

Man at B&Q wrote:
On Jul 15, 12:49 pm, Tim Lamb wrote:
Yes. I do know there are umpteen thousand hits on the web!

How many kW would be needed to space heat 200m2 of single storey offices

Which 200m2 are you heating, at the floor or at the ceiling or
somewhere in between?


If the building is square, its about 14 meters square.

If its say 3 metres high, the total area external to the world is
200 sq meters of roof and 4x16x3 meters of wall

say 400 square meters in all.

I've ignored the floor here. If you feel its important add another 200
and make it to 600 sq meters worst case. That will just about cover the
'long thin' building. Presumably UFH is in the frame with a heat pump,
so teh floor will be well insulated..

No with a U value of about 1 for reasonable insulation, that's about
600W per degree centigrade differential, and with say 25 degrees
absolute worst case in winter, that's a total of 15KW.

However by my reckoning the average person in an office is around 200W
of human heat, PCs etc and lighting and about 20 people minimum will be
in that office, so its likely to only need around 9KW. Worst case. With
about 3:1 upscale on the heat pump, about 3Kw electricity with a good
ground source pump.




MBQ

On Thu, 16 Jul 2009 13:11:42 +0100, dennis@home wrote:

If this is from a river, how fast does it flow, is there a fall across
the land?

It might be better to put a turbine in, generate electricity and use
that.

An idea, but to get a few 10's of kW of electricity you need a good
head and a hefty flow. IIRC 3kW of lecky needs a 20m head and 20l/sec
flow, if that is available it could drive the heatpump of course...

--
Cheers
Dave.

Dave Liquorice wrote:
On Thu, 16 Jul 2009 13:11:42 +0100, dennis@home wrote:

If this is from a river, how fast does it flow, is there a fall across
the land?

It might be better to put a turbine in, generate electricity and use
that.

An idea, but to get a few 10's of kW of electricity you need a good
head and a hefty flow. IIRC 3kW of lecky needs a 20m head and 20l/sec
flow, if that is available it could drive the heatpump of course...

There is absolutely no doubt that in terms of energy input versus useful
house heating out, a heatpump is the no. 1 technology.

The only problems are cost of installation and the heat exchanger.

And of course where the energy comes from, BUT with a heat pump in a
typical situation providing about 3:1 uplift in terms of heat output to
electrical input, it means that even a 30% efficient power station
matches a 90% efficient boiler.

If the electricity is at least partially carbon free (nuclear) then its
also a huge carbon reducer.

Likewise, with UFH in winter, you can use off peak electricity when the
outside temps are coldest, to get the house up to temperature - a
temperature it may well keep (if well insulated and reasonably massive)
for the whole day.

I would 100% use it in a new build, if adequate land area or pond volume
is available, but its a bitch to retrofit. Air source might work in a
small flat installation in urban environments where temperatures are
constantly high because of heat leakage from buildings, but its crap in
rural locations.

In message o.uk, Dave
Liquorice writes
On Thu, 16 Jul 2009 02:36:41 -0700 (PDT), NT wrote:

Unfortunately the pumped concept falls at several hurdles.

More than 4.84kW is needed.

Don't forget that your calculated total heat requirement doesn't have
to all come from one source. Yer average a working PC/monitor chucks
out 100W or so, humans another couple of hundred watts each just sat
still...
60W ISTR:-)

Although river Lea water is *warm* (largely sourced from effluent
treatment plants upstream) 5deg.C seems a realistic figure
considering
prolonged adverse winter weather.

Do you actually know the winter river temp? It might be better.

No. Ask me next January. I was using 5deg.C as a starting point to
enable ball park figure calculations. 4.8kW is way too low. The hope was
to use a *green* heat source as a planning lure. The project requires a
change of use consent for agricultural buildings in the green belt.

I suspect it probably is the north sea surface temperature in mid
winter doesn't get down to 5C, 8C is sort of average. It's about 15C
ATM... With the river being fed "warm" effluent as well...

Maybe.

And is the absolute temperature all that important? We are dealing
with a heat pump. It'll move the heat provided there is a positive
delta T between the incoming circulated loop and the water. Obviously
efficiency drops off at small delta Ts and if you freeze the water
around the slinky. That's where the design is critical have a big
enough area over which to extract the heat such that it doesn't
freeze or the delta T get too small.

Quite. I expect the EA will come up with some unaffordable
abstract/discharge fees and the project reverts to the multiple slinky
model.

regards


--
Tim Lamb

In message , "dennis@home"
writes

If this is from a river, how fast does it flow, is there a fall across
the land?

It might be better to put a turbine in, generate electricity and use
that.

No. uk.business.agriculture kindly did some sums and came up with about
3kW for the achievable fall and estimated flow.

If you use a leat, you fall into the abstraction/discharge pit.

regards


--
Tim Lamb

In message , The Natural Philosopher
writes
Dave Liquorice wrote:
On Thu, 16 Jul 2009 13:11:42 +0100, dennis@home wrote:

If this is from a river, how fast does it flow, is there a fall
across the land?

It might be better to put a turbine in, generate electricity and use
that.
An idea, but to get a few 10's of kW of electricity you need a good
head and a hefty flow. IIRC 3kW of lecky needs a 20m head and 20l/sec
flow, if that is available it could drive the heatpump of course...

There is absolutely no doubt that in terms of energy input versus
useful house heating out, a heatpump is the no. 1 technology.

The only problems are cost of installation and the heat exchanger.

Payback and CO2 reduction isn't huge if it is only displacing natural
gas.

And of course where the energy comes from, BUT with a heat pump in a
typical situation providing about 3:1 uplift in terms of heat output to
electrical input, it means that even a 30% efficient power station
matches a 90% efficient boiler.

If the electricity is at least partially carbon free (nuclear) then its
also a huge carbon reducer.

Likewise, with UFH in winter, you can use off peak electricity when the
outside temps are coldest, to get the house up to temperature - a
temperature it may well keep (if well insulated and reasonably massive)
for the whole day.

I would 100% use it in a new build, if adequate land area or pond
volume is available, but its a bitch to retrofit. Air source might work
in a small flat installation in urban environments where temperatures
are constantly high because of heat leakage from buildings, but its
crap in rural locations.

All the conversion work here is planned for under floor heating.

regards


--
Tim Lamb

In message
, Man
at B&Q writes
On Jul 15, 12:49*pm, Tim Lamb wrote:
Yes. I do know there are umpteen thousand hits on the web!

How many kW would be needed to space heat 200m2 of single storey offices

Which 200m2 are you heating, at the floor or at the ceiling or
somewhere in between?

Floor. Unfortunately the existing layout leads to rather a lot of
external wall:-)

regards

--
Tim Lamb

In message , The Natural Philosopher
writes
Man at B&Q wrote:
On Jul 15, 12:49 pm, Tim Lamb wrote:
Yes. I do know there are umpteen thousand hits on the web!

How many kW would be needed to space heat 200m2 of single storey offices
Which 200m2 are you heating, at the floor or at the ceiling or
somewhere in between?


If the building is square, its about 14 meters square.

If its say 3 metres high, the total area external to the world is
200 sq meters of roof and 4x16x3 meters of wall

say 400 square meters in all.

I've ignored the floor here. If you feel its important add another 200
and make it to 600 sq meters worst case. That will just about cover the
'long thin' building. Presumably UFH is in the frame with a heat pump,
so teh floor will be well insulated..

No with a U value of about 1 for reasonable insulation, that's about
600W per degree centigrade differential, and with say 25 degrees
absolute worst case in winter, that's a total of 15KW.

Target U value figures are 0.35 for walls, 0.25 for floor, 0.2 for roof
and 2.2 for windows.

However by my reckoning the average person in an office is around 200W
of human heat, PCs etc and lighting and about 20 people minimum will be
in that office, so its likely to only need around 9KW. Worst case. With
about 3:1 upscale on the heat pump, about 3Kw electricity with a good
ground source pump.

I thought the allowance is 60W per person? I would expect occupancy to
be less than 10. Toilets, stairwell, kitchenette, reception etc.

regards




MBQ

--
Tim Lamb