Advice on pond heating

[PAUL U]

Hi all,
Built my 11500 gal pond this year and is currently covered, would like to heat next year and thought i would keep an eye out for a second hand oil boiler (no gas where we are ) an ideas on what size boiler and heat exchanger would do the job?

Regards Paul

[vippymini]

have you ever considered bottled lpg gas. i think one if not more of our members heat this way??

[B.Scott]

For a 1500 gallon pond I think you need to be thinking about 70,000 BTU

[kayoss]

Hi Scott

I read 1500 gallons at first, then noticed it was 11,500 gallons - lots of money to heat that one!

Cheers

[dannyboy]

Hi, do some reserach on heat pumps .

As you have no gas supply, might be the way to go

They say for every £1 spent you get £5 of heat

[Davej]

Hi Paul

Heating 11500 gallons is not going to be cheap.

What are you looking for, something that will take the swings out and maintain temps at 10+ or something that will give you 15+.

Sure that AndyB will pop in and give you the benefit of his expert knowledge.

Sorry Heatpumps are a non starter... Airsource Heat pumps performance at UK winter air temps is negative.

Regards

Dave

[dazzafjr1300]

would a sollar pannel that you see on house roof if you could get a cheep second hand one and use your main pond pump so using no extra heating so you have one outlay and no gas boilers to fit i know it will be at its best in day light but as you say you have a cover the heat lose wont be to bad at night i might be barking up the wrong tree its that i am looking at ways to do same but want it for free so have many silly ideas floating around in my head
my other idea was to use copper pipe as i was was going to use 90 deree bends so pipe was going up and down 20 mm apart so would make a large surface area and then fit a under floor heating pad around it as copper will grab the heat very fast and the out side was just going to be plaster board all this would need to be under cover but i asked a plumder and he says it will be very hot on the outlet so would need to sort out entre to pond tis will use electic so is on hold till last resort i am also wondering if the copper pipe is ok ?we drink from it and i hear it might have an effect on blanket weed

[PAUL U]

Hi Dave,
Mainly looking to keep temp swings to a minimum and would be nice to keep above 10 but realise with this volume of water might be difficult, fitted cover and temp seems to be holding at 10 at the moment.


Regards Paul.

[Dave Collins]

Sorry Heatpumps are a non starter... Airsource Heat pumps performance at UK winter air temps is negative.

Regards

Dave

Hi Dave

Where did you get this advice on heat pumps from? They're better than you think

rgds

Dave C

[netsukekoi]

Agree with DaveC - Heat pumps are getting better and cheaper and depending where you are, ground source may be an option.

On Dazzajfr's points - solar panels will only help on sunny days and then, with winter sun, not much - and they will not help smooth out temperature fluctuations - in fact, more like the reverse. Copper pipe on an underfloor heating pad sounds odd - you don't want copper anywhere near the fish - their tolerance is much lower than ours and if you are going to use an electric heating pad you might as well just go straight to an electric pond heater - more efficient and thus cheaper, though for 11,500 gallons incredibly expensive at 7p Kwh of whatever todays price is.

Martin

[Dave Collins]

I currently heat the house with an Air/Air heat pump and it's saving me £800 a year. I have plans to heat my 41 tonnes pond with one but am still saving as they're about £2700's and the wife's watching......

Dave C

[Davej]

Hi Dave

I spent a lot of time researching the options prior to a big capital investment in a gas line, boiler etc,

I got the info from the heat pump manufactures, I probably have the efficiency tables somewhere. I found that when asked the manufacturers were reluctant to provide details of performance at temps of less than 6 degrees. At around 8 degrees air temp the cost of running the pump was equal to the gain, performance dropped off steeply at lower temps than this.

If you have efficiency tables from a manufacturer that shows a positive benefit at low air temps then please share them. Which air /air pump are you looking at for your pond?

What make of pump do you run for your house system? Is this the only heating you run, 365 days a year?

Must say that heating air is one thing, a large volume of water an entirely different matter.

Martin - Agree ground source is an option is you have the land and 15 to 20K spare to invest!

Regards

Dave

[Dave Collins]

Hi Dave
If you have efficiency tables from a manufacturer that shows a positive benefit at low air temps then please share them. Which air /air pump are you looking at for your pond?
What make of pump do you run for your house system? Is this the only heating you run, 365 days a year?
Must say that heating air is one thing, a large volume of water an entirely different matter.

Hi Davej
As I said, I currently heat my house with a heat pump. It is a Fujitsu Air/Air system (this means heat source/type of heat used). Other sorts include water/air, geo/water, water/water etc. The most efficient are water or geothermic as the heat source is a constant temperature. Unfortunately this is also the most expensive type to install. The system I use works to -10°C and still gives a positive coefficient. At 0°C it gives me 2.96kw of heat for 1kw of electric. It is a 12kw unit and heats the house all winter and cools me down in summer.

Anyway back to koi. My plan is to install something like the Climexel swimming pool heat pump. Note:- all manufacturers quote heating pumps at ambient temperatures. In the case of houses it’s at +7°C, for swimming pool pumps it’s +15°C.
Most swimming pool heat pumps are unsuitable but the Climexel 7KW is a purpose built Air/Water heat pump that could be used for Koi ponds. The essential good points of this pump are:-
It works down to -15°C
You can control the temperature done to +10°C, to give your large Koi a proper winter
The heat exchanger is made from titanium, safe for Koi & chemicals.
Obviously because it is an Air/Water system the coefficient will drop as the heat source (air) drops in temperature. As you can see from the Climexel technical specification, at +15°C we have a COP of 4.1 with an output of 7kw.Even at 0°C the unit gives a COP (Coefficient of Performance) of 2.54. This means that the unit will consume 1.71kw but gives 4.34kw of heat. At -8°C the COP is 2.17 giving 3.71kw of heat.

Before you say that this is not much at low temperatures (it’s already more than an electric heater) look at your local average temp.. It is higher than you think. The average temperature for all of the uk the last two winters are as follows:-

Nov 2006 7.3°C Dec 2006 5.5°C Jan 2007 6.0°C Feb 2007 5.2°C
Nov 2007 6.9°C Dec 2007 4.4°C Jan 2008 5.3°C Feb 2008 4.9°C

As you can see from page 4 of
http://www.procopiuk.co.uk/downloads/Climex ... ctions.pdf" onclick="window.open(this.href);return false;
at +6°C the machine will give you 5.38kw of heat.

Hope I've not rambled on too long

Dave C

[netsukekoi]

If I read it right - it says that at an ambient temp of 15 degrees and a water temp of 28 degrees, you get the stated 4.1x co-efficient and that drops toabout half that if the air temp drops to (our winter average of) 6 degrees. But assuming you are only trying to hold the temperature at, say, 16 degrees, then I imagine the co-efficient is going to be near 4.1x as the difference between input and output is less than the 13 degrees it is designed for.....

So pretty good for an air-2-water box. What do they cost?

Martin

[Davej]

Hi Dave

They appear to be impressive performance figures. Things have certainly moved on rapidly, I spoke to Elecro before investing in the gas line and Boiler and they were not confident that a Heat Pump would deliver at low temps yet they now advertise an Aquatic Heat Pump. Cool price though!!

My issue would be the off line time due to frosting when air temps are low and humidity is high and the effect this would have on “claimed” COP figures..

Looking at running cost; differential between gas and electricity prices suggest you need a COP of greater than 2.5 to make running costs cheaper, but where Gas isn’t available then it could be an option; provided there is long term reliability and spare parts are reasonably priced!! even with simple electric pond heaters the spare parts cost an arm and a leg!! Need to work out the figures based on say a 5 year lifespan.

Working on 120 days a year with a Unit rate of 12p per KW and a 6kw heater on 12 hours a day, over 5 years a Heat pump working at COP of 3 would save a total of £3,400.

Working on 120 days running solely on Economy 7 at say 6p per Kw over 5 years the heat pump would save a total of just over £1,000.

Martin - [url]http://www.aqua-mania.eu/heating/aquatic-he ... d_271.html[/url]

Regards

Dave