Hello,

I am trying to decide whether I should heat a swimming pool using a
heat pump, or using LPG. I've already ruled out oil (no room for the
tank) and direct electric (too damn expensive!).

The heat pump is the Calorex 820 (or maybe the model up -- the 1220).
These burn about 2.5kW of electric, but pump about 12kW of heat into
the water. (They extract "free heat" from the air - see
http://www.calorex.com/downloads/uk/...English%20.pdf. I
know these do work - my parents have one)

When the pool is cold, I estimate this will be burning for 8 hours.
When the pool is up to temperature (at say 78F), it won't be burning at
all. So I've assumed an average of 4 hours burning, for 150 days (May
to Septemper) at 6p per kWhour. I make this =A390 onto the electricity
bill. Not bad.

On the other hand I have no idea how to estimate the costs for LPG. We
already have a 2000 litre tank, and we pay about 24p per litre of LPG.
The central heating burns it quite fast, but domestic hot water hardly
uses any.

The pool holds about 15,000 gallons of water. Pool dimensions are 10m
x 5m (16' x 32'). Depth is from 1m to 2.1m (3'6" to 6'6"). We would
probably keep the temperature at about 78 degrees F (25 degrees C).

How can I estimate the costs of heating with LPG?

Simon.

On 5 Sep 2005 06:38:11 -0700, wrote:

Hello,

I am trying to decide whether I should heat a swimming pool using a
heat pump, or using LPG. I've already ruled out oil (no room for the
tank) and direct electric (too damn expensive!).

The heat pump is the Calorex 820 (or maybe the model up -- the 1220).
These burn about 2.5kW of electric, but pump about 12kW of heat into
the water. (They extract "free heat" from the air - see
http://www.calorex.com/downloads/uk/...English%20.pdf. I
know these do work - my parents have one)

When the pool is cold, I estimate this will be burning for 8 hours.
When the pool is up to temperature (at say 78F), it won't be burning at
all. So I've assumed an average of 4 hours burning, for 150 days (May
to Septemper) at 6p per kWhour. I make this £90 onto the electricity
bill. Not bad.

On the other hand I have no idea how to estimate the costs for LPG. We
already have a 2000 litre tank, and we pay about 24p per litre of LPG.
The central heating burns it quite fast, but domestic hot water hardly
uses any.

The pool holds about 15,000 gallons of water. Pool dimensions are 10m
x 5m (16' x 32'). Depth is from 1m to 2.1m (3'6" to 6'6"). We would
probably keep the temperature at about 78 degrees F (25 degrees C).

How can I estimate the costs of heating with LPG?

Hi,

Is the pool in the sun? If so I'd try a solar pool blanket first.

Also have a cool shower before getting in to get acclimatised.

cheers,
Pete.

wrote in message
oups.com...
Hello,

I am trying to decide whether I should heat a swimming pool using a
heat pump, or using LPG. I've already ruled out oil (no room for the
tank) and direct electric (too damn expensive!).

snip
Simon.

More than happy to be corrected but here goes:-
The pool dimensions etc are not relevant you just need the comparative costs
of useable energy
Density of LPG around .55 Kg/l
Calorific value around 46000 KJ/Kg
(I believe LPG is a blend and therefore no specific value - unless there is
a BS spec.)

So 1 litre LPG = .55 Kg LPG
Burn .55 Kg and you get .55 x 46000 = 25300 KJ of energy
If the "burn" took 1 hour ( 3600 seconds) that would be the equivalent of
25300/36000 = 7 KWh and with 80% efficiency boiler 5.6 KWh of usable heat
for LPG cost of 24p = 4.2p per unit
Your "electric" costs show 12.4 KWh being released for 2.5 KWh at 6p per
unit ie 1.2 p per unit

Pete K

Excellent. Heat pump it is then!

I hadn't thought of making the direct comparison in that way, but I see
that http://www.lpga.co.uk/TypicalPropofCommercialLPG.htm has some
figures which are similar to yours.

Thanks for the logic!

Simon.

In article , wrote:
The figure of merit used here seems too high, more typically 3:1
so nearer 2p per unit.

That was my initial reaction but an American government site on pool
heat pumps suggests 5:1 as an average coefficient of performance

http://www.eere.energy.gov/consumeri...heatpumps.html

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm
[Latest version QSEDBUK 1.10 released 4 April 2005]

In article , wrote:
Am I too cynical to believe figures from US govt. sources?

They actually suggest a range of 3-7. The original post made me
suspicious as I am used to the SAP Rating heat pump efficiencies of
300% or so, but on reflection I suspect that you do get a higher figure
when heating a pool as you are using the heat pump to produce loads of
lukewarm water as compared with a UK domestic heating installation
where you'd be looking for 50C or more.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm
[Latest version QSEDBUK 1.10 released 4 April 2005]

I am trying to decide whether I should heat a swimming pool using a
heat pump, or using LPG. I've already ruled out oil (no room for the
tank) and direct electric (too damn expensive!).

Do you have space for solar panels? I presume not, although they can often
be placed above the roofing on buildings or sheds. This has the additional
advantage of cooling the underlying building in summer. Panels for solar
heating swimming pools run more effectively than those for domestic hot
water. This is because the circulating water runs at lower temperatures (25C
instead of 60C), making the heat transfer much more efficient.

In any case, ensure you use a solar blanket as well. It will massively
reduce the extra push required by less environmentally friendly sources.
Saving both your cash, and unnecessary damage to the planet.

Christian.

On 5 Sep 2005 13:39:39 -0700, wrote:

Excellent. Heat pump it is then!

Err, just one thing you might like to bear in mind. A heat pump will almost
certainly have a fan to ensure an adequate flow of air across the heat
exchangers. The fan will probably make quite a lot of noise. If you can
site the thing reasonably out of the way then that won't be too much of a
problem, unless it's near a neighbour's house!

I had a heat exchanger on the pool at my last house, which I used for an
occasional day-time boost towards the end of season. Noise from the fan was
something of a problem. Main heating there, and for my present pool is an
E7 flowboiler (Thermalec).

I keep the pool, 10,000 gallons, at about 30°C and a five month season
costs me in the region of £350. A solar blanket is essential.

The heat pump? It cost me a bottle of Scotch, and it's now sitting in my
garage, one of these days I suppose I'll get round to plumbing it in....


--
the dot wanderer at tesco dot net

wrote in message
ups.com...
Excellent. Heat pump it is then!

I hadn't thought of making the direct comparison in that way, but I see
that http://www.lpga.co.uk/TypicalPropofCommercialLPG.htm has some
figures which are similar to yours.

Thanks for the logic!

Simon.

I guess this heat pump will throw out cold air - this could be directed into
the house (Depending where it is!) and used as air-con too!

Sparks...