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  1. #21
    Quote Originally Posted by Tom Koi View Post
    Hasn't the ashp got a heating element in it for winter time, bit pointless having one otherwise, as winter time is when its must needed
    No - there is no heating element inside water heat exchanger - so when switching it off for winter you need to drain it. There can be heating cable added to the drain hose discharging condensed water on those ASHP capable runnning OK in sub zero temperatures.

    In fact ASHP performs best above 5 dC - some expensive types - for example Mitsubishi Zubadan deliver 100% of their rated output down to m8nus 25dC - but COP is only 2 at best.

    Sent from my SM-G955F using Tapatalk
    You get what you pay for - or better - what you make yourself.

  2. #22
    Senior Member Rank = Nanasai Tom Koi's Avatar
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    Quote Originally Posted by milaz View Post
    No - there is no heating element inside water heat exchanger - so when switching it off for winter you need to drain it. There can be heating cable added to the drain hose discharging condensed water on those ASHP capable runnning OK in sub zero temperatures.

    In fact ASHP performs best above 5 dC - some expensive types - for example Mitsubishi Zubadan deliver 100% of their rated output down to m8nus 25dC - but COP is only 2 at best.

    Sent from my SM-G955F using Tapatalk
    How can they make the claim that some work at -15 degrees then, defeats the purpose of having them if they're no use in winter. If i want to keep my temps above 10 degrees over winter I need another heating source

  3. #23
    Better ones = more expensive ones do work indeed down to minus 15 or even down to minus 25 degrees of Celsius - just the fine print - and laws of physics - define, that lower the outside air temperature = lower the efficiency of heat extraction from it. More precisely greater the difference between outside air and desired pond temperature, harder ASHP needs to work. So better ASHP do work at sub zero temperatures, but with substantially lower COP than those advertised at ideal conditions.

    Bottom line - even with COP down to 2 it still means such ASHP still uses 50% less electricity than in line electric heater. With COP down close to 1 such ASHP uses almost the same electricity as in line heater - so - given complexity and cost of ASHP, it looses sense to keep using it in such case with COP close to 1.

    Best reference can be found in performance curve of any specific ASHP - defined by manufacturer - how much heat and how efficiently it can extract from air at given operating conditions.
    You get what you pay for - or better - what you make yourself.

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  5. #24
    Senior Member Rank = Nanasai Tom Koi's Avatar
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    Quote Originally Posted by milaz View Post
    Better ones = more expensive ones do work indeed down to minus 15 or even down to minus 25 degrees of Celsius - just the fine print - and laws of physics - define, that lower the outside air temperature = lower the efficiency of heat extraction from it. More precisely greater the difference between outside air and desired pond temperature, harder ASHP needs to work. So better ASHP do work at sub zero temperatures, but with substantially lower COP than those advertised at ideal conditions.

    Bottom line - even with COP down to 2 it still means such ASHP still uses 50% less electricity than in line electric heater. With COP down close to 1 such ASHP uses almost the same electricity as in line heater - so - given complexity and cost of ASHP, it looses sense to keep using it in such case with COP close to 1.

    Best reference can be found in performance curve of any specific ASHP - defined by manufacturer - how much heat and how efficiently it can extract from air at given operating conditions.
    Are Thermal inverters better do you know ?

    Thanks

  6. #25
    ASHP with inventor is better and more expensive too - as it is able to adjust RPM of its compressor unit based on required output in case if 100% power output is not needed - so rather than frequent on off switching it runs at lower output smoothly and saves energy too.

    Do not know the specific ASHP type you mentioned.....
    You get what you pay for - or better - what you make yourself.

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  8. #26
    Senior Member Rank = Nanasai Tom Koi's Avatar
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    Quote Originally Posted by milaz View Post
    ASHP with inventor is better and more expensive too - as it is able to adjust RPM of its compressor unit based on required output in case if 100% power output is not needed - so rather than frequent on off switching it runs at lower output smoothly and saves energy too.

    Do not know the specific ASHP type you mentioned.....
    https://www.heatpumps4pools.com/pool...ps-9kw-to-24kw

    Im gonna use a Duratec 10kw plus heat pump, bought it 2nd hand

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  10. #27
    Moderator Rank = Supreme Champion Feline's Avatar
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    I have a Duratech Dura 10 plus on my pond.
    it works perfectly at low temperatures- has a a built in defrost cycle that it runs intermittently. There is an extra item you can buy for it to keep the drip day defrosted- available from heatpumos4pools. This is simply wired in to the inside of the control panel and the heated wire aluminium taped to the drip tray at the bottom inside the heat pump. Its a really easy DIY installation (I did mine myself).

    It is also dead easy to rig a Duratech (or any heat pump) up to an external thermostat- lots of people do this just because the hysteresis is a bit wide on them using the built in stat (1C). That said, I have been using the built in stat on mine for 3 years with no problems at all, my fish are not bothered by minor temps fluctuations. They would get many magnitudes more change every night if the pond was unheated. The key in the winter is to cover and insulate your pond, giving your heat pump less work to do.

    People moan about the COP rating not being so good at low temps, and yes this is true. But you would certainly not get a better COP from an inline electric heater!

    Not everybody wants to invest in a new boiler for their house with extra zone valve and dig up their patio to connect to the central heating to use a heat exchanger. If I were you I would just fit the heat pump and see how you get on with it over winter. Having a backup heater just in case if emergency or really extreme weather is a good plan (although I have not bothered coz mine works fine down to at least -8C, temps have not been lower than that ti test it where I live as yet).

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  12. #28
    Moderator Rank = Supreme Champion Feline's Avatar
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    One further point (and then I will shut up ):

    Dont rig up the thermostat so the heat pump loses all power when the shat shuts off- that will prevent the heat pump being able to defrost itself or save itself from freezing if the pumps stopped.

    Instead use the correct terminals inside to connect up your own stat- its just a case of getting the wiring diagram from the manufacturer to do this. Manky Sanke can probably help with that if you tell him the make and model also.

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  14. #29
    Moderator Rank = Supreme Champion Feline's Avatar
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    Heat pump working fine during the 'beast from the east' weather last year

    IMG_4750 by Lara Day, on Flickr

    They look a bit scary inside but it's fine so long as you know which terminals you are looking for:
    IMG_3683 by Lara Day, on Flickr

    Drip tray heater taped down to the floor inside by moi
    IMG_3685 by Lara Day, on Flickr

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  16. #30
    There you are, the wiring diagram showing how to connect an external stat to a Duratech heat pump:

    On the main circuit board there is a link (marked
    EXT in the diagram below) that can be replaced by external control equipment. You can connect your external stat in this place.

    You can also connect additional equipment, such as a timer, in series with this link and it is the correct place to control the heat pump by external equipment. The electronics only require a low current contact rather than the high current contact you would need if you attempt to control the power supply to the heat pump or to the compressor itself. There is also some electronics behind this link that protects the compressor against rapid cycling or any other circumstance that may damage it.

    Just two steps:


    1. Take the live and neutral supply for the stat from the mains input connector block. (You should include a small fuse holder with a 3 amp or 3.15 amp fuse for safety).
    2. Connect the stat contact in place of the link marked EXT.


    BTW this link can control the pump from any other device you might think of such as a timer - just make sure that you use a volt free contact for all external devices and connect them all in series.



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  18. #31
    Senior Member Rank = Rokusai Handy Kenny's Avatar
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    Quote Originally Posted by Feline View Post
    I have a Duratech Dura 10 plus on my pond.
    it works perfectly at low temperatures- has a a built in defrost cycle that it runs intermittently. There is an extra item you can buy for it to keep the drip day defrosted- available from heatpumos4pools. This is simply wired in to the inside of the control panel and the heated wire aluminium taped to the drip tray at the bottom inside the heat pump. Its a really easy DIY installation (I did mine myself).

    It is also dead easy to rig a Duratech (or any heat pump) up to an external thermostat- lots of people do this just because the hysteresis is a bit wide on them using the built in stat (1C). That said, I have been using the built in stat on mine for 3 years with no problems at all, my fish are not bothered by minor temps fluctuations. They would get many magnitudes more change every night if the pond was unheated. The key in the winter is to cover and insulate your pond, giving your heat pump less work to do.

    People moan about the COP rating not being so good at low temps, and yes this is true. But you would certainly not get a better COP from an inline electric heater!

    Not everybody wants to invest in a new boiler for their house with extra zone valve and dig up their patio to connect to the central heating to use a heat exchanger. If I were you I would just fit the heat pump and see how you get on with it over winter. Having a backup heater just in case if emergency or really extreme weather is a good plan (although I have not bothered coz mine works fine down to at least -8C, temps have not been lower than that ti test it where I live as yet).
    Running your pond heating from the house heating system may also require a more powerful heating water pump, a thermostat to control the pond zone valve and wiring from the thermostat to the the zone control valve. Just in case anyone thought about doing that.

    I actually ran a 4 inch pipe from the house to my "Wizard of Oz" pond contol centre in my greenhouse. This carries heating pipes, control wiring, armoured mains cables i.e. everything needed to make the pond work. It's all in the planning.

    I did actually look into an ASHP but our temperatures here regularly hit -20 on a winters night and a few years ago we had days when it didn't get over -10, so thought heating from the house was a safer bet.

    Kenny

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