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  1. #21
    Senior Member Rank = Sansai Point's Avatar
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    In theory, either of those two boilers could work but I would strongly recommend speaking to the technical team of whichever one you choose and ask them about turndown ratios. Boilers require a certain amount of heating load to operate so if you boiler is 9kW, with a turndown ratio of 5:1, the minimum heat load required for the boiler to fire would be 1.8kW. Your pond heat loss probably won't be that much so the boiler won't fire.

    You need to find out what the turndown ratio is for all of your options.. some ratios could be as high as 10:1, which would require 0.9kW of heat load.

    One way to get around this is to add a radiator into the system and either heat the boiler house, or even a greenhouse, to meet the minimum heat load requirement but really you are just wasting heat just to get an oversized system working, which is neither cost effective or energy efficient.

    Using a heating boiler in the way you want is outside of it's normal use so you should have a long chat with the tech departments of the boiler manufacturers before you commit. It is a very expensive way to heat your pond tbh mate and the low heat loss could cause operational issues with the boiler.

    If it were me, I'd be looking at alternative methods before you get too deep into a central heating boiler system as they are simply not meant to run with a 1kW(ish) load. A 9kW boiler will need a turndown ratio of at least 9:1 and even then it might only operate when external temps are into the minus'. In warmer weather, say 10°C, I doubt the boiler will fire as the heat load won't meet the minimum requirement so your pond temp would fall until the heat load is met.. this could mean your pond temps will be up and down all the time. I know you've already bought the heat exchanger but you should consider your options and potential issues before you shell out another £1500 on a system that might not work. If the heat exchanger could have been run off an existing boiler serving your house it wouldn't be an issue.

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  3. #22
    Senior Member Rank = Sansai Point's Avatar
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    With regards to covers, the 25mm poly sheets give a U value of around 1.57W/m²k, whereas 10mm + 10mm air + 10mm gives 0.973.

    The more air gap you have, the lower the U value.

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  5. #23
    Member Rank = Nisai Smiffy's Avatar
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    Quote Originally Posted by Point View Post
    In theory, either of those two boilers could work but I would strongly recommend speaking to the technical team of whichever one you choose and ask them about turndown ratios. Boilers require a certain amount of heating load to operate so if you boiler is 9kW, with a turndown ratio of 5:1, the minimum heat load required for the boiler to fire would be 1.8kW. Your pond heat loss probably won't be that much so the boiler won't fire.

    You need to find out what the turndown ratio is for all of your options.. some ratios could be as high as 10:1, which would require 0.9kW of heat load.

    One way to get around this is to add a radiator into the system and either heat the boiler house, or even a greenhouse, to meet the minimum heat load requirement but really you are just wasting heat just to get an oversized system working, which is neither cost effective or energy efficient.

    Using a heating boiler in the way you want is outside of it's normal use so you should have a long chat with the tech departments of the boiler manufacturers before you commit. It is a very expensive way to heat your pond tbh mate and the low heat loss could cause operational issues with the boiler.

    If it were me, I'd be looking at alternative methods before you get too deep into a central heating boiler system as they are simply not meant to run with a 1kW(ish) load. A 9kW boiler will need a turndown ratio of at least 9:1 and even then it might only operate when external temps are into the minus'. In warmer weather, say 10°C, I doubt the boiler will fire as the heat load won't meet the minimum requirement so your pond temp would fall until the heat load is met.. this could mean your pond temps will be up and down all the time. I know you've already bought the heat exchanger but you should consider your options and potential issues before you shell out another £1500 on a system that might not work. If the heat exchanger could have been run off an existing boiler serving your house it wouldn't be an issue.
    So the smallest boiler available will still be only operating at around 10% in order to prevent big temperature swings? If this can work then it sounds very economical to run?

    What are the other realistic options and are they cost effective long term? I thought that the main reason everyone uses gas is because it is more cost effective than leccy? So now that we have an approx. number of around 1kW of heat output even the smallest ASHP in this ThermoTec range would be ample?
    https://www.cotswoldkoi.co.uk/produc...EaApNfEALw_wcB

    This is rated for above ground pools of typically 183m up to a max of 253m and is highly efficient. I appreciate that this is nonsense without the thermal loss ratings but is all there is to go by and my pond is half in the ground so this gives even more margin.
    This unit works from a standard 13A plug with a maximum draw of 6.4A at full tilt but hopefully it would be running at a fraction of that most of the time.

    Is this the way to go? It's more expensive than a boiler at £1,550 but I could fit it myself which would probably save me around £500-£700 - total guess but that's the ballpark I'd expect so the end price would be very similar.
    My plumbing/returns aren't ideally laid out for an ASHP but I'm sure I could re-hack it to make it work with only short pipe runs external to the filter house.

    I'm warming up to the idea of an ASHP (no pun intended )
    Cheers

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  7. #24
    Member Rank = Nisai Smiffy's Avatar
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    Quote Originally Posted by Point View Post
    With regards to covers, the 25mm poly sheets give a U value of around 1.57W/m²k, whereas 10mm + 10mm air + 10mm gives 0.973.

    The more air gap you have, the lower the U value.
    Hi Point, thanks for the stats - I guess I need to work out the efficiency rating of all the extra time and hassle of creating double glazed panels. If I can find some aluminium extrusion with the correct triple channel type profile it wouldn't be too difficult I guess.

  8. #25
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    Quote Originally Posted by Smiffy View Post
    So the smallest boiler available will still be only operating at around 10% in order to prevent big temperature swings? If this can work then it sounds very economical to run?

    What are the other realistic options and are they cost effective long term? I thought that the main reason everyone uses gas is because it is more cost effective than leccy? So now that we have an approx. number of around 1kW of heat output even the smallest ASHP in this ThermoTec range would be ample?
    https://www.cotswoldkoi.co.uk/produc...EaApNfEALw_wcB

    This is rated for above ground pools of typically 183m up to a max of 253m and is highly efficient. I appreciate that this is nonsense without the thermal loss ratings but is all there is to go by and my pond is half in the ground so this gives even more margin.
    This unit works from a standard 13A plug with a maximum draw of 6.4A at full tilt but hopefully it would be running at a fraction of that most of the time.

    Is this the way to go? It's more expensive than a boiler at £1,550 but I could fit it myself which would probably save me around £500-£700 - total guess but that's the ballpark I'd expect so the end price would be very similar.
    My plumbing/returns aren't ideally laid out for an ASHP but I'm sure I could re-hack it to make it work with only short pipe runs external to the filter house.

    I'm warming up to the idea of an ASHP (no pun intended )
    Cheers
    It might sound that running a boiler at 10% load would be efficient but it's not really, and that's not really the problem.

    Lets say, for arguments sake, that your pond heat loss is 1.5kW when the external ambient temp is -5°C (typical design temp in UK). If a 9kW boiler had a turndown ratio of 6:1 the boiler would fire as it meets minimum heat load. If the external ambient temperature is say 8°C, then your pond heat loss could be, say, 500W. When the pond thermostat called for heat the boiler would fire then very quickly shut off. This on/off short cycling would continue and that isn't good for the boiler and will reduce its lifespan. When cycling the burner also goes through a purge cycle.. think of it like starting your car... it uses more fuel to start it than to run it so if you are constantly stopping and starting, the fuel use will increase. That's where efficiency is lost.

    The more I think about this, the only option I can think of would be to install a thermal store/buffer in the system. The boiler would then heat the water in the store and when heating is called for the water in the vessel would be circulated to your heat exchanger. When the heat within the buffer vessel is used up, the boiler would then re-heat the buffer water volume. This would at least reduce cycling but you are probably adding several more £100 into the cost. Not all plumbers have the knowledge how to set this up correctly either so you may end up paying premium rate for installation.

    As to your options, yes, an ASHP would work well, and running costs can be reduced by using pv panels to help offset electricity costs. Another possible option would be to use an electric boiler.. the smallest of these is circa 4kW I believe but not sure if you can find a system boiler at that size. If not, you would need a heat only boiler, then you have to also buy and install a pump, expansion vessel and control valve.

    Perhaps another option would be to use an electric heater, either plugged directly into the power socket or connected to pv panels but again, cost wise, the pv would be what you would pay for the ASHP.. but at least you could use the spare elec during the summer months.

    I'm afraid there isn't really an easy and cheap solution.. you either use a plug-in elec heater and have quite high running costs, or install expensive equipment and reduce running costs.

  9. #26
    Senior Member Rank = Supreme Champion davethefish1's Avatar
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    i think this may be going a bit deep into design specs, i've seen plenty of koi ponds running on dedicated boilers.
    the fact that the boiler may not fire for that long until satisfied, isn't an issue really.
    the boilers pump over run will allow the boiler to dissapate the latent boiler heat through the heat exchanger, and that isn't going to lift 2500 gallons by more than a fraction of a degree...
    the digital controller would also have a hysteris programmed in, to stop the boiler cutting in and firing too often.
    but having a radiator in the filter house would help with condensation issues in winter, and if you wanted a sink too you could make it a combi and have hot water

    ASHP are great but even the guys that run them will tell you they don't work as efficently as gas in sub zero temperatures,
    but they benefit massively in temperate weather with very high COP rates.
    as for sizing ASHP you need to go over what is specced for gallonage,
    as when it isn't working hard to meet the temperature the inverter will modulate and moderate the fan speed and noise levels. so for 2-3000 gallons i'd go for a 12kw model.

    BUT if you have neighbours houses near your pond ASHP's are quiet, but not silent, especially at night...
    so a consideration is how you intend to heat your pond, winter only, all year round, or spring to autumn?

    boiler @15.53


    boiler @ 6.10

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  11. #27
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    Thanks Dave. I'm glad someone with knowledge of heating a pond with a dedicated boiler has chipped in. I've been trying to consolidate domestic/commercial boiler use with pond heating so my thoughts have been purely from a design perspective.

    As is usual with consulting design engineers.. I've probably overthought it

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  13. #28
    Senior Member Rank = Supreme Champion davethefish1's Avatar
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    Quote Originally Posted by Point View Post
    Thanks Dave. I'm glad someone with knowledge of heating a pond with a dedicated boiler has chipped in. I've been trying to consolidate domestic/commercial boiler use with pond heating so my thoughts have been purely from a design perspective.

    As is usual with consulting design engineers.. I've probably overthought it
    maybe a little, but it's better to be thourough then make an expensive mistake

    the only thing i haven't noticed on either of those installations is a method for reducing the speed that the boiler can increase the temperature by.
    other than to reduce the boilers operating stat. with either a low loss header, or a bypass.
    the boiler has the capacity to lift the temperature very quickly even if just be a degree or so. which fish don't like.
    that is something i would want more control over, rather than relying on the boiler stat.

    the second issue is failsafe,
    it doesn't happen often but the stat sensor failing, or accidentally getting removed from sensing water temperature could lead to the boiler running non stop and killing the fish.
    especially with a boiler that has a tenfold capacity to heat.
    i have always used two stats in all my fish keeping, one to operate, and another as a failsafe a few degrees higher than the operating stat.
    and in 30 odd years of keeping various fish i've only ever had it happen once, but it saved a tank full of corals and fish....

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  15. #29
    Member Rank = Nisai Smiffy's Avatar
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    Quote Originally Posted by Point View Post
    It might sound that running a boiler at 10% load would be efficient but it's not really, and that's not really the problem.

    Lets say, for arguments sake, that your pond heat loss is 1.5kW when the external ambient temp is -5°C (typical design temp in UK). If a 9kW boiler had a turndown ratio of 6:1 the boiler would fire as it meets minimum heat load. If the external ambient temperature is say 8°C, then your pond heat loss could be, say, 500W. When the pond thermostat called for heat the boiler would fire then very quickly shut off. This on/off short cycling would continue and that isn't good for the boiler and will reduce its lifespan. When cycling the burner also goes through a purge cycle.. think of it like starting your car... it uses more fuel to start it than to run it so if you are constantly stopping and starting, the fuel use will increase. That's where efficiency is lost.

    The more I think about this, the only option I can think of would be to install a thermal store/buffer in the system. The boiler would then heat the water in the store and when heating is called for the water in the vessel would be circulated to your heat exchanger. When the heat within the buffer vessel is used up, the boiler would then re-heat the buffer water volume. This would at least reduce cycling but you are probably adding several more £100 into the cost. Not all plumbers have the knowledge how to set this up correctly either so you may end up paying premium rate for installation.

    As to your options, yes, an ASHP would work well, and running costs can be reduced by using pv panels to help offset electricity costs. Another possible option would be to use an electric boiler.. the smallest of these is circa 4kW I believe but not sure if you can find a system boiler at that size. If not, you would need a heat only boiler, then you have to also buy and install a pump, expansion vessel and control valve.

    Perhaps another option would be to use an electric heater, either plugged directly into the power socket or connected to pv panels but again, cost wise, the pv would be what you would pay for the ASHP.. but at least you could use the spare elec during the summer months.

    I'm afraid there isn't really an easy and cheap solution.. you either use a plug-in elec heater and have quite high running costs, or install expensive equipment and reduce running costs.
    So what do you see as being the final installed cost of a gas set-up bearing in mind that it also needs to be connected to the meter box/gas supply?

    Can't deny that my heads spinning a bit with the gas side of things. Maybe I should have gone down the ASHP route at the start. My research pointed me in the direction of gas and the two videos that DTF just posted I have seen before and were major influencers in my decision as the set-ups looked amazing and the guys that put them together sound highly knowledgable. i see there is some kind of expansion vessel or header tank on the first video which I think is Franks own set-up. A radiator might also be a good shout if condensation is likely to be an issue when it's proper cold. Electric just seams a lot less complicated at this point!

    If I use PV panels would I also need batteries to store the energy and then run the ASHP via an inverter?

  16. #30
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    Boilers just don't have that level of control, in terms of rate of rise. If the boiler primary flow temperature was dropped it would probably slow down the temperature rise somewhat. The heat exchanger would need to be oversized to do this but in Smiffy's case, he has a 29kW unit which is plenty big enough. Dropping the temperature would also enable the boiler to run in condensing mode and increase efficiency. Most people think that their house boiler is efficient because it's a condensing boiler, not knowing that it won't start condensing until the return water temp falls below 54°C, and even at that temp it is only circa 80% efficient.

    That's a very good point about the failsafe. I suppose that could apply to all parts of a koi system as well.. although perhaps not as lethal, as quickly, pumps, filters etc could also cause problems in the event of a failure. It's a tricky one.. I suppose people have to weigh up the risk/outcome of a failure against the cost and space required for backups.

  17. #31
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    Quote Originally Posted by davethefish1 View Post
    i think this may be going a bit deep into design specs, i've seen plenty of koi ponds running on dedicated boilers.
    the fact that the boiler may not fire for that long until satisfied, isn't an issue really.
    the boilers pump over run will allow the boiler to dissapate the latent boiler heat through the heat exchanger, and that isn't going to lift 2500 gallons by more than a fraction of a degree...
    the digital controller would also have a hysteris programmed in, to stop the boiler cutting in and firing too often.
    but having a radiator in the filter house would help with condensation issues in winter, and if you wanted a sink too you could make it a combi and have hot water

    ASHP are great but even the guys that run them will tell you they don't work as efficently as gas in sub zero temperatures,
    but they benefit massively in temperate weather with very high COP rates.
    as for sizing ASHP you need to go over what is specced for gallonage,
    as when it isn't working hard to meet the temperature the inverter will modulate and moderate the fan speed and noise levels. so for 2-3000 gallons i'd go for a 12kw model.

    BUT if you have neighbours houses near your pond ASHP's are quiet, but not silent, especially at night...
    so a consideration is how you intend to heat your pond, winter only, all year round, or spring to autumn?

    boiler @15.53


    boiler @ 6.10
    Thanks for the input Dave. I have seen both of those videos and as I said to Point were major influencers in my thought process. Even James the Koi Whisper has intimated that he is getting a boiler fitted and has run the gas pipe similar to me. Our pond builds have run pretty much in parallel but I got the builders in I have however fitted out the filter house so am happy to get my hands dirty within my comfort zone. Not that I ever did solvent weld pressure pipe plumbing before!

    I really didn't expect the gas to be so complicated and it sounds like the total install cost could be expensive with all the special bits n bobs. The radiator does sound like a good plan to reduce condensation but I could easily install a greenhouse type of electric tube heater.

    We usually only get a week or two of proper cold weather (I live down South) and when we do my neighbours windows will be firmly shut so I can't see noise being a major factor with an ASHP so I guess it comes down to cost and simplicity, assuming both options are equally effective in heating the pond in the correct manor. With COP rates of 13 and effective covers over the pond maybe I've over complicated things myself by even considering gas and the potential dangers associated with it? I assume it will also need a service every year at £100 a pop?

    I do not intend to run at 20+ degs through the winter, more like 15 which I think is the lowest setting on the ASHP's that I looked at yesterday so no heating required spring to autumn.

    What the hell do I do

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  19. #32
    Senior Member Rank = Supreme Champion davethefish1's Avatar
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    Quote Originally Posted by Smiffy View Post
    Thanks for the input Dave. I have seen both of those videos and as I said to Point were major influencers in my thought process. Even James the Koi Whisper has intimated that he is getting a boiler fitted and has run the gas pipe similar to me. Our pond builds have run pretty much in parallel but I got the builders in I have however fitted out the filter house so am happy to get my hands dirty within my comfort zone. Not that I ever did solvent weld pressure pipe plumbing before!

    I really didn't expect the gas to be so complicated and it sounds like the total install cost could be expensive with all the special bits n bobs. The radiator does sound like a good plan to reduce condensation but I could easily install a greenhouse type of electric tube heater.

    We usually only get a week or two of proper cold weather (I live down South) and when we do my neighbours windows will be firmly shut so I can't see noise being a major factor with an ASHP so I guess it comes down to cost and simplicity, assuming both options are equally effective in heating the pond in the correct manor. With COP rates of 13 and effective covers over the pond maybe I've over complicated things myself by even considering gas and the potential dangers associated with it? I assume it will also need a service every year at £100 a pop?

    I do not intend to run at 20+ degs through the winter, more like 15 which I think is the lowest setting on the ASHP's that I looked at yesterday so no heating required spring to autumn.

    What the hell do I do
    there are pros and cons to both...

    imo ASHP are simpler and more cost effective to install and run long term, if noise is not an issue.
    but if you could tap it into your existing home heating, it would also be very cheap to install and run, and utterly silent.

    you pays your money and you takes your choice....

  20. #33
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    Quote Originally Posted by Smiffy View Post
    So what do you see as being the final installed cost of a gas set-up bearing in mind that it also needs to be connected to the meter box/gas supply?

    Can't deny that my heads spinning a bit with the gas side of things. Maybe I should have gone down the ASHP route at the start. My research pointed me in the direction of gas and the two videos that DTF just posted I have seen before and were major influencers in my decision as the set-ups looked amazing and the guys that put them together sound highly knowledgable. i see there is some kind of expansion vessel or header tank on the first video which I think is Franks own set-up. A radiator might also be a good shout if condensation is likely to be an issue when it's proper cold. Electric just seams a lot less complicated at this point!

    If I use PV panels would I also need batteries to store the energy and then run the ASHP via an inverter?
    Hi Smiffy, as above, I may have been overthinking things a bit. As you say, the two systems in the videos appear to be working fine. I apologise if I've muddled your head a bit. The radiator I suggested has the benefit of heating your filter house but the main reason I suggested it is to use it as a heat load that the boiler could use to ensure the minimum heat requirement is met. Yes, the vessel you see is an expansion vessel.. you'll also see a pump. That is a heat only boiler. A system boiler has the vessel and pump already within the boiler casing.

    Just throwing budget figures at it:
    Boiler - £1000
    Pipework to ht exchanger & rad - £100
    Insulation - £100
    Gas Safe engineer - £300
    Radiator, TRV, lockshield valve - £100
    Installation - £300
    Then you've got to add your ht exchanger and thermostat cost. Installation cost might be able to reduce if your installer is a gas safe engineer. You could save some money by installing the system yourself.. it's not too difficult. Just be sure to use a certified Gas Safe engineer for everything gas related.

    I'm no expert on electrics or pv but you could use panels to provide power to the ashp during the day, then use grid electricity overnight, or you could use battery storage and run the ashp off those all the time.

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    Quote Originally Posted by davethefish1 View Post
    but if you could tap it into your existing home heating, it would also be very cheap to install and run, and utterly silent.
    That would be the ideal solution.. not sure if I should offer the option of changing the pipework throughout the house to free up one of the zone circuits though.. Smiffy's head might explode lol

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    Extreme Koi Member Rank = Adult Champion NickK-UK's Avatar
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    I have a sun catching garage roof that I will add some water solar panels on - sort of my nod to heating but keeping with the zero running costs. I would probably run a 2nd hand solar electric panel to run the small pump. A brass coil in the return down pipe would then act as a heat exchanger. That way it runs in sun and with a thermocouple it can switch off during the winter. Keeps with the eco-friendliness but means the 13000l isn't purely dependent on the sun hitting the surface of the water.
    I think with all the eco changes in gov policy I think more people will go for that in the longer term, possibly fitting the panels on the tops of their pagodas
    14000l, my mutts: Chargoi (2010), Doitsu (2022), Tancho (2022), Kujaku (2022), Hi Utusri (2022)

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    Quote Originally Posted by Point View Post
    That would be the ideal solution.. not sure if I should offer the option of changing the pipework throughout the house to free up one of the zone circuits though.. Smiffy's head might explode lol
    Pop - too late

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    Quote Originally Posted by Point View Post
    Hi Smiffy, as above, I may have been overthinking things a bit. As you say, the two systems in the videos appear to be working fine. I apologise if I've muddled your head a bit. The radiator I suggested has the benefit of heating your filter house but the main reason I suggested it is to use it as a heat load that the boiler could use to ensure the minimum heat requirement is met. Yes, the vessel you see is an expansion vessel.. you'll also see a pump. That is a heat only boiler. A system boiler has the vessel and pump already within the boiler casing.

    Just throwing budget figures at it:
    Boiler - £1000
    Pipework to ht exchanger & rad - £100
    Insulation - £100
    Gas Safe engineer - £300
    Radiator, TRV, lockshield valve - £100
    Installation - £300
    Then you've got to add your ht exchanger and thermostat cost. Installation cost might be able to reduce if your installer is a gas safe engineer. You could save some money by installing the system yourself.. it's not too difficult. Just be sure to use a certified Gas Safe engineer for everything gas related.

    I'm no expert on electrics or pv but you could use panels to provide power to the ashp during the day, then use grid electricity overnight, or you could use battery storage and run the ashp off those all the time.

    Cheers for the budget figures Point and I get that the main reason for the rad is to create a reasonable load for the boiler in order to smooth out the thermal swings. Would the rad and the H.E. be connected in series so as to operate together?

    I must admit I thought the install would be dearer so thats good. Totting it all up it comes in at around £2,400 with the thermostat and H.E. (already paid for and fitted). I'm sure I can get at least half the H.E. cost back on eBay or see if Darren will do me a deal to part X against an ASHP.

    A 12kW ASHP would cost £1,825 (£2,245 for the wifi controllable version) plus I would need to rip out some 2" pipework and re-do so that's probably £100 materials and my brother has a core drill set that I can borrow. No doubt there will be some optional extras that I'll need to buy as we are talking Koi. This I can certainly install myself. I would be inclined to see what the costs are over the first winter and then decide on whether PV panels are a viable option.

    I assume the ASHP is zero maintenance? More than likely less than a gas boiler service.

    I probably would not be inclined to do the boiler plumbing as my time is fairly limited and the learning curve a bit too steep just now - I should be working right now !

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    No problem mate. I've assumed, as the boiler would be in the filter house, that the pipework runs would be very short so a plumber should be able to mount a boiler and run a few metres of pipe in half a day or so. It may cost you a bit more for installation but not much.

    I'd run the pipework to the hx but have a branch before it to the radiator, controlled just by a trv. The hx would be controlled via the stat and the rad via the trv.. they both operate when they need to, either singularly or together.

    You are correct, the maintenance on an ASHP is minimal and doesn't need a yearly service. If you go down that route, fit a filter on the pipework before it returns to the ASHP.

  30. #39
    Member Rank = Nisai Smiffy's Avatar
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    The pipework would only be around 2.5m from the boiler to the HX so not too bad I guess. So the HX and rad are actually in parallel.

    All input greatly appreciated. I will chat it over with my gas fitter chap and if he is comfortable with everything I'll get a quote and see how it looks. At least now I can talk with a level of basic knowledge thanks to yourself, Dave and Simon as opposed to zero knowledge a few days back.

    Reading your final comment, I should put a filter on the cold feed side to the ASHP. The feed is actually puled through my drum so would that not do the job sufficiently?

  31. #40
    Senior Member Rank = Sansai Point's Avatar
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    It's neither series or parallel really. Here is a basic sketch of the arrangement..

    POND HTG.pdf

    With regards to the ASHP, if it were me I'd be using a pump and heat exchanger. All plant is sensitive to debris in the system, and running pond water through a heat pump will very likely reduce it's working life. They may be suitable for swimming pools, with very little debris in them, but using them directly plumbed into ponds like that is a bit of a stretch imho. The cost of them would make me want to protect it as much as possible.

    I'd be dong it like this..

    ASHP.pdf


    ps. ignore the attachment sketch.. can't delete it for some reason
    Attached Files Attached Files
    Last edited by Point; 28-09-2021 at 05:00 PM.

 

 
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