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  1. #1
    Moderator Rank = Grand Champion Feline's Avatar
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    How has your ASHP coped in the cold weather?

    Just thought I would ask how those of you with an ASHP have found it over the past few days.

    The company that sold me by Duratech Dura 10+ warned me that backup heat could be needed in really cold conditions, so I was a little worried it would get frozen solid in all the ice and snow over the past 3-4 days.
    However it's been working well. The drip tray heater I got as an add-on and installed myself has worked well and kept the tray free of ice.

    IMG_4750 by Lara Day, on Flickr

    3 nights ago one of my pond covers blew off in the gales (landed in next doors garden LOL). The temperature was set to 12.5C where it had been sitting fine until that happened. Without one of the covers the temperature dropped to 11.5C. Even once the cover was back on with more bricks on it, pond temps hovered around the 11.2-11.5C range. Only today now things are warming up a bit has it come back up to temp.

    This trace is from the last 36 hours:
    Screen Shot 2018-03-03 at 3.44.34 pm by Lara Day, on Flickr

    Overall I'm really pleased the heat pump coped. Not sure what would have happened if the pond had been at 20C though!



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  3. #2
    Coped ok with a Dura +7, had mine down at 9 degrees since Christmas, put it back ten days ago, was sitting at 11 till the cold spell came but was holding 10 but up to 11 today. 4000 gallons covered in Polycarbonate.

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  5. #3
    Extreme Koi Member Rank = Hassai koinewbie's Avatar
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    Hi I have a 10kW Hydro Pro been fine & kept my 4000gal at 15c easy enough. Not noticed anything excessive With the defrosting but obviously found it much harder during the last few days.

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  7. #4
    Duratech 7+ was at 16C (pond average 15C) and on from 8am until pm each day. Over the last few days the digital ASHP temp reading has dropped to 13C and pond to 12C so has struggled to hold 15C in pond when on 10hours a day in the below zero conditions but not a surprise. Now the air temp is +1C, the reading on the ASHP right now is already 14C so heading back in right direction.

    Ian.

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  9. #5
    my pond water temp dropped about 2 degrees over the past 3 or 4 days, with the heat pump on constantly, water temp is now 16c and it seems to be holding there now, because it was at 16c last night, air temp got just above freezing today and the forecast is much milder, so hopefully over the worst. It seems to be able to hold 17.5 -18c no problem, unless air temps go sub zero, but its running a lot to do that.
    I didn't want the water temp to drop below 14c, so if the cold spell kept going i would have added more heat at that point, to hopefully keep it at or above 14c.
    The slightly cooler water has done nothing to curb their appetites

    5500 gallons with a dura plus 7, everything insulated.

    David

    edit, Feline have your modified your heat pump thermostat so its more accurate, i always felt the standard settings allow too much temperature swing.
    So as you know, if you set it at say 18c, it will heat the water to 19c and then switch off until the water has dropped to 17c.
    Id like to change that so its much more accurate constantly, but i don't know how, does anyone else?

  10. #6
    Moderator Rank = Grand Champion Feline's Avatar
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    Quote Originally Posted by familyman View Post
    my pond water temp dropped about 2 degrees over the past 3 or 4 days, with the heat pump on constantly, water temp is now 16c and it seems to be holding there now, because it was at 16c last night, air temp got just above freezing today and the forecast is much milder, so hopefully over the worst. It seems to be able to hold 17.5 -18c no problem, unless air temps go sub zero, but its running a lot to do that.
    I didn't want the water temp to drop below 14c, so if the cold spell kept going i would have added more heat at that point, to hopefully keep it at or above 14c.
    The slightly cooler water has done nothing to curb their appetites

    5500 gallons with a dura plus 7, everything insulated.

    David

    edit, Feline have your modified your heat pump thermostat so its more accurate, i always felt the standard settings allow too much temperature swing.
    So as you know, if you set it at say 18c, it will heat the water to 19c and then switch off until the water has dropped to 17c.
    Id like to change that so its much more accurate constantly, but i don't know how, does anyone else?
    I havent modified mine, and yes it does have a bit of a swing with the hysteresis.
    Its a pretty trivial matter to wire in an STC-1000 or similar to replace the built in thermostat, I think my heat pump had the instructions for which terminals to wire to if you wanted to do that. Just need a waterproof enclosure for the stat to sit in, unless you buy the proline one thats outdoor rated but more spendy..

  11. #7
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    I’ve got a 10kw invertor on my 4K gallons. Been running Constant over these last 4 days but held the pond at 15 degs while air temps at -5 etc running at 750watt, which is less than half full power. Pond covered wth polycarb and filters insulated. Today reached pond cut off temp and switched off...as the air temp hit 3 degs today, the cop ramps up quickly. I fitted drip tray heater, and worked great..under ashp sheet of frozen water, but pump stayed clear. Well happy with the investment, previous was 6kw elecro still in line as back up.

  12. #8
    Extreme Koi Member Rank = Yonsai sff's Avatar
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    yes david quite easy to do wiring different stat on dura heat pump like you say massive swings on temp if running standard, glad i put on another stat

  13. #9
    Just out of interest, whilst my dura 7+ does as described re the thermostat swings, my pond temp is always constant. So if ASHP set at 16c, swings aside, pond holds at constant 15C, which makes me think the influx of water from the ASHP at 17C or 15C when mixed into 5000 gallons probably makes little difference.

    just a thought and could be wrong.
    ian

  14. #10
    Extreme Koi Member Rank = Mature Champion AdamKoi78's Avatar
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    Maybe I'm reading people's posts incorrectly but my duratech plus 14 only goes through a 1 c swing from turning off and on.

    For instance if the ASHP is set to 15c the temperature will need to drop to 14.5c before it begins heating. When the thermostat reaches 15.5c the ASHP turns off till the temperature falls again to 14.5c. So only going through a 1c swing my 7000+ gallons pond.

    I have tested the thermostat for accuracy with two others one digital and one glass and the duratech is as close as dammit it.

    Edit: under normal operation
    Last edited by AdamKoi78; 04-03-2018 at 08:22 PM.

  15. #11
    Normally the built in thermostat should have in its menu choice of hysteresis - typical min. is 1 dC but manufacturers setting out of the box is often 2 dC - more economical from operating costs perspective - so check out your owners manual on how to change it - 1 dC hysteresis should be fine - no large temperature swings....and no need to change the built in thermostat - unless you want to wire it to your filter house.
    You get what you pay for - or better - what you make yourself.

  16. #12
    Moderator Rank = Grand Champion Feline's Avatar
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    Quote Originally Posted by AdamKoi78 View Post
    Maybe I'm reading people's posts incorrectly but my duratech plus 14 only goes through a 1 c swing from turning off and on.

    For instance if the ASHP is set to 15c the temperature will need to drop to 14.5c before it begins heating. When the thermostat reaches 15.5c the ASHP turns off till the temperature falls again to 14.5c. So only going through a 1c swing my 7000+ gallons pond.

    I have tested the thermostat for accuracy with two others one digital and one glass and the duratech is as close as dammit it.

    Edit: under normal operation
    Yeah it's only a 1C swing which is tiny compared to what some unheated ponds go through. That's why I've been happy to go with the built in stat even though I have a stat with a 0.5C hysteresis I could have wired in if I'd wanted to.
    My Seneye graph does normally follow a bit of a curve up and down, but in the cold weather it was actually a bit flatter since the heat pump was clearly on most of the time so was no downwards swings.

  17. #13
    As for my pond heating setup I have rather pond tempering version - dedicated 6kW ASHP used only from Spring to Fall - last year from March till November - to keep stable 21 dC (JUN - SEP) and 15 dC (MAR - MAY + OCT - NOV) - it has quite low performance at sub zero temperatures - and such operation would sbstantially shorten it's service life - so our main house ASHP - 14.5kW Zubadan takes over - in DEC - FEB heats whole house and via heat exchanger also tempers the pond - DEC - 12dC and JAN - FEB 8dC. With last 10 days night temps bellow -15dC and day temps -8 - 12 dC it worked very well and kept tempeeratures both in the house as well as in the pond as set.

    Only small gitch - one tiny pipe broke in the main house ASHP built in heat exchanger - coolant leaked out, as coolant transports inside also lubricant for the srcoll compressor, this one was not sufficiently lubricated and weared out excessivelly dropping max. pressure by 50% - luckily Mitsubishi supported our installer by free of charge replacement unit - for this out of warranty repair - done in five days - meanwhile the built in 6kW electric heater (inside the main house ASHP system) was helping to keep house and pond at set teempeeratres.

    Good experience - glad we have in our house heating system back up 6kW electric heater - for similar case - lesson learned - keep redundancy in your systems - Murphy's laws DO work - if something can go wrong it will - and in the worse possible moment - not during hot summer when main house ASHP works reversed and cools the house down - but it has choosen to fail in the deepest freeze of several winters
    You get what you pay for - or better - what you make yourself.

  18. #14
    Hi

    I’m just looking over posts regarding heat pumps, I’m looking to purchase a hydro pro 10 k for my 5 gallon pond

    are you happy with yours they are slightly cheaper than dura tech so just want to be sure they are similar standard

    thanks

    your pond looks great

  19. #15
    Quote Originally Posted by Feline View Post
    Just thought I would ask how those of you with an ASHP have found it over the past few days.

    The company that sold me by Duratech Dura 10+ warned me that backup heat could be needed in really cold conditions, so I was a little worried it would get frozen solid in all the ice and snow over the past 3-4 days.
    However it's been working well. The drip tray heater I got as an add-on and installed myself has worked well and kept the tray free of ice.

    IMG_4750 by Lara Day, on Flickr

    3 nights ago one of my pond covers blew off in the gales (landed in next doors garden LOL). The temperature was set to 12.5C where it had been sitting fine until that happened. Without one of the covers the temperature dropped to 11.5C. Even once the cover was back on with more bricks on it, pond temps hovered around the 11.2-11.5C range. Only today now things are warming up a bit has it come back up to temp.

    This trace is from the last 36 hours:
    Screen Shot 2018-03-03 at 3.44.34 pm by Lara Day, on Flickr

    Overall I'm really pleased the heat pump coped. Not sure what would have happened if the pond had been at 20C though!
    them pipes need insulating

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  21. #16
    Extreme Koi Member Rank = Hassai koinewbie's Avatar
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    Quote Originally Posted by Middleton79 View Post
    Hi

    I’m just looking over posts regarding heat pumps, I’m looking to purchase a hydro pro 10 k for my 5 gallon pond

    are you happy with yours they are slightly cheaper than dura tech so just want to be sure they are similar standard

    thanks

    your pond looks great
    Hi I have the Hydro Pro 10 & im really impressed with it. This is my third winter with it & it's kept our pond at 16c throughout winter with outside temps at their lowest of -6c. It did have to work & defrost too but wasn't running an excessive amount of time. I fitted a shower last year & im running the pond at 14c this year as the shower does cool the water a bit but the ponds well covered & pipes insulated.
    Gaz

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  23. #17
    Extreme Koi Member Rank = Adult Champion pip895's Avatar
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    The hydro pro comes in two varieties inverter and non inverter. The inverter version are closer to the duratech. I was also a bit concerned that they only reported working down to -5deg rather than -15 like the duratech.
    Last edited by pip895; 12-01-2019 at 03:28 PM.
    6000g unheated in ground koi pond
    +3000g lily/Anoxic pond attached
    28 koi (40 to 65cm)
    Bottom drain & Skimmer to Drum
    JBR boichamber->Blue eco 500 pump ->below surface return.
    Blue Eco 240 -> Large MB -> Waterfall -> Planted Anoxic pond (25 baskets)

  24. #18
    Extreme Koi Member Rank = Hassai koinewbie's Avatar
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    Quote Originally Posted by pip895 View Post
    The hydro pro comes in two varieties inverter and non inverter. The inverter version are closer to the duratech. I was also a bit concerned that they only reported working down to -5deg rather than -15 like the duratech.
    My Hydro Pro works down to -15c but it's the plus version don't know if that's any different?. The only difference I could find between mine & the dura was the Hydro has a bigger heat exchanger which allows around 30% more flow through it. Also it's black so doesn't stand out so much in the garden.

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  26. #19
    Extreme Koi Member Rank = Adult Champion pip895's Avatar
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    Quote Originally Posted by koinewbie View Post
    My Hydro Pro works down to -15c but it's the plus version don't know if that's any different?. The only difference I could find between mine & the dura was the Hydro has a bigger heat exchanger which allows around 30% more flow through it. Also it's black so doesn't stand out so much in the garden.
    I was just looking at the ones on ebay and obviously there not the + variety. There are a lot of versions about so you need to be carful and pick the right one. Does it come with a drip tray heater? I wonder if that could be the difference?

    This is the one I was looking at :https://www.ebay.co.uk/itm/SWIMMING-...GXP:rk:11:pf:0
    Last edited by pip895; 12-01-2019 at 03:46 PM.
    6000g unheated in ground koi pond
    +3000g lily/Anoxic pond attached
    28 koi (40 to 65cm)
    Bottom drain & Skimmer to Drum
    JBR boichamber->Blue eco 500 pump ->below surface return.
    Blue Eco 240 -> Large MB -> Waterfall -> Planted Anoxic pond (25 baskets)

  27. #20
    Extreme Koi Member Rank = Hassai koinewbie's Avatar
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    No mine doesn't have a drip tray heater fitted. If temps get below -10c (how often does that happen?.) then I would run my inline heater that's a backup. All I know is my fish have thrived since being heated. There's no CHEAP way to heat a koi pond but you need insulation where it can be fitted to save on cost. I was unheated for 2yrs but covered & the fish were active down to 5c but didn't look as happy as they do now as im texting this.

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