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Thread: ASHP question

  1. #1

    ASHP question

    About 18 months ago I bought an 8.5kw ASHP second hand

    I’m looking to install it within next week or so and I’ve just read the manual and it says that it has to be sited a minimum of 3.5mtrs from pond AND it has to have a bypass system to adjust the flow through the system to get it to operate and it’s proper pressure
    I thought it was more simple than this lol

    My question is, can I ditch the bypass system and get a separate pump to run it which is variable or is it better to incorporate it into main filtration
    Cheers



  2. #2
    To get the correct flow, you can either install it with a bypass which will be the least expensive or, if that's too complicated, you can run it from a separate variable pump. Either method will produce the same result.

  3. #3
    Thankyou mate

    much appreciated, more expensive yes but it’s going to be way easier

    Thr manual states 2 different minimum flow rates. 3.5 meters cubed an hour and also 4 meters cubed an hour. If I’ve worked this out correctly that equates to 770/880 gph

    Does this sound correct ?

  4. #4
    Yep those are correct if you want to convert 3,500 to 4,000 litres per hour into gallons per hour and then convert back to litres per hour to find a suitable pump ratings but it would much simpler to say that you would need a pump with a flow of between 3,500 and 4,000 litres per hour and buy, for example, a Whizzy Pump model 4,000 which is 4,000 litres per hour

  5. #5
    Cheers
    I was looking at the ea 10000 variable. They go down to zero practically so I thought they’d be easier to control ?

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  7. #6
    Quote Originally Posted by Carlejo View Post
    Cheers
    I was looking at the ea 10000 variable. They go down to zero practically so I thought they’d be easier to control ?
    So the EA 10,000 will pump a maximum of (10,000 ÷ 4.55) = 2,197.8 gallons per hour which conveniently works out to 10,000 litres per hour

    But seriously, yep that will be fine.

  8. #7
    Senior Member Rank = Gosai Jampot's Avatar
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    Distance from the 'pool' is usually to do with the safety of human swimmers rather than fish I think!

    A by-pass won't cost any more than a pump and has no running costs.......

    Jim
    I don't keep fish, I keep water. I don't keep fish, I keep water. I don't keep fish I kee........

  9. #8
    Quote Originally Posted by Jampot View Post
    Distance from the 'pool' is usually to do with the safety of human swimmers rather than fish I think!

    A by-pass won't cost any more than a pump and has no running costs.......

    Jim

    Yep, the minimum distance is derived from the regulations to prevent people in swimming pools being able to touch electrical equipment while touching the water in the pool. The link below is to the explanatory diagram from the 17th Edition Wiring Regulations. (I retired early after that so that's the latest edition I have).

    The distances may look extreme in the diagram but the way I made sense of it was to consider a tall person standing on the deck or any raised surface and reaching up. Or the very extreme circumstance of someone of laying on the deck with their toes just in the pool and reaching out as far as they could.

    You can be officious and apply swimming pool regulations to ponds literally in which case no electrical equipment should be anywhere near ponds unless it's separated in a plant room or by some other valid means to prevent it being touched while you're touching the water or you can install electrical equipment sensibly and, obviously, protected by an RCD.

    http://www.premiersolutions.co.uk/im...ion%20Regs.pdf

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  11. #9
    Senior Member Rank = Jussai Spongebob's Avatar
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    Personally I’d fit a bypass, it’s simple and cheap, my interpretation of the bypass is that you can increase flow rates as required by diverting some of the flow to the pond and decrease the amount through the heater. Having spoken to the manufacturer of my heat pump they don’t seem to have a clue on the correct flow rates. Not sure why you’d want to run on a separate system and add another pump into the equation unless you need another line anyway?
    Fibreglassed/5000 gals/4.5 m Tunnel/Spindrifter/Twin drums/Bio chambers/Beads/Showers/Remora ASHP

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  13. #10
    Thankyou guys

    One last question, would it be ok to take supply from last vortex chamber, then pump to ASHP and return to same vortex. It’s going to be the easiest way for me to do it tbh
    thanks

  14. #11
    Senior Member Rank = Adult Champion Gazkoi's Avatar
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    Hi Carlejo,

    I use these pumps and have some in stock too if you were looking to source one.

    Cheers

    Gaz

    Quote Originally Posted by Carlejo View Post
    Cheers
    I was looking at the ea 10000 variable. They go down to zero practically so I thought they’d be easier to control ?
    Hobby and business gone but when you’re hooked you’re hooked.

    Always happy to help!!

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  16. #12
    Moderator Rank = Supreme Champion Feline's Avatar
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    If you did decide to use a variable pump instead of a bypass to regulate flow to your heat pump, just be careful because some variable pump have a minimum speed of 30% of max. Now in reality, that will not actually be 30% of the advertised flow, because pipe and bend resistance always decreases it. But if you buy too big a pump you could find you had no adjustment possibility down at the lower end.

    Pumping to and from a chamber is not a good idea at all.
    This is because you will have some of the same water going through the heat pump repeatedly and it will reduce the efficiency of it to heat the whole pond volume- plus make it difficult to adjust.

    Let me explain- most heat pumps are meant to be set so that the difference in temperature between water going in and water going out is 1-2C. You basically adjust the flow until the difference falls in this range.

    Can I ask where the water currently goes after the vortex?

    If there is a pump already after your vortex then it really couldn’t be much simpler to do the bypass system. Don’t be put off by its name- all a bypass consists of is a couple of valves and two T connectors in a bit of pipe- takes seconds to assemble!

    Adding an extra pump will just increase your electricity bill for no gain at all. I wouldn’t do it that way personally.

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  18. #13
    Moderator Rank = Supreme Champion Feline's Avatar
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    This link has some good pictures explaining it in bottom half of the page https://www.heatpumps4pools.com/pool...allation-tips/

  19. #14
    Quote Originally Posted by Feline View Post
    If you did decide to use a variable pump instead of a bypass to regulate flow to your heat pump, just be careful because some variable pump have a minimum speed of 30% of max. Now in reality, that will not actually be 30% of the advertised flow, because pipe and bend resistance always decreases it. But if you buy too big a pump you could find you had no adjustment possibility down at the lower end.

    Pumping to and from a chamber is not a good idea at all.
    This is because you will have some of the same water going through the heat pump repeatedly and it will reduce the efficiency of it to heat the whole pond volume- plus make it difficult to adjust.

    Let me explain- most heat pumps are meant to be set so that the difference in temperature between water going in and water going out is 1-2C. You basically adjust the flow until the difference falls in this range.

    Can I ask where the water currently goes after the vortex?

    If there is a pump already after your vortex then it really couldn’t be much simpler to do the bypass system. Don’t be put off by its name- all a bypass consists of is a couple of valves and two T connectors in a bit of pipe- takes seconds to assemble!

    Adding an extra pump will just increase your electricity bill for no gain at all. I wouldn’t do it that way personally.
    Pond is 4300g
    4” BD supplies an OASE drum filter (installed several weeks ago). Superfish 20,000 pumps directly after drum to bakki shower. I converted skimmer to 4” pipe and that goes to other inlet on drum
    Other outlet from drum then goes to 2 vortices of aerated K1, superfish 8000 then pumps to uv, and then to midwater returns

    So with this info, do you think I’d be better off making a bypass directly after last vortex ?
    Last edited by Carlejo; 19-10-2020 at 09:45 PM.

  20. #15
    Quote Originally Posted by Carlejo View Post
    Thankyou guys

    One last question, would it be ok to take supply from last vortex chamber, then pump to ASHP and return to same vortex. It’s going to be the easiest way for me to do it tbh
    thanks
    Ideally run the pond water through the ASHP and send it straight back to the pond passing using the shortest route to get maximum heat back to the pond.

  21. #16
    Quote Originally Posted by Doitsusanke View Post
    Ideally run the pond water through the ASHP and send it straight back to the pond passing using the shortest route to get maximum heat back to the pond.
    Thankyou

    My only concern is that the superfish 8000 would be pumping at about 5000/6000 lph as it would be throttled back a bit prior to the ASHP. After the ASHP it would then be pumped through my UV and then back to pond via midwater returns at an even more reduced rate

  22. #17
    Moderator Rank = Supreme Champion Feline's Avatar
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    Quote Originally Posted by Carlejo View Post
    Thankyou

    My only concern is that the superfish 8000 would be pumping at about 5000/6000 lph as it would be throttled back a bit prior to the ASHP. After the ASHP it would then be pumped through my UV and then back to pond via midwater returns at an even more reduced rate
    By installing a bypass you don’t throttle the pump or reduce the flow- it’s just that some of it goes through the heat pump and some of it goes through the bypass valve instead, then they join and go back to the pond exactly as before.

    I would put in in that line after your pump and UV before the midwater returns myself.

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  24. #18
    Thanks Feline, I think you’ve convinced me lol

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  26. #19
    Right

    Its plumbed/wired in but not working. I haven’t built a bypass because I though the flow would have been enough anyway. My superfish 8000 is sited just after my last vortex. It then pumps 2/3 meters into shed where my UV is and it has to pump through there (with a few 90 bends as that’s all I could do years ago when I installed it) and then back out of shed into the ASHP and back into shed then to midwater returns.

    The manual says that it requires a pressure of between 21 to 35 kg/cm2

    When the unit is off it’s at 11.5 and when I switch it on it only gets to just under 17

    Im not being thick but am I correct in saying I need more flow through it to get pressure up ?
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  27. #20
    Moderator Rank = Supreme Champion Feline's Avatar
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    It could be that your super fish by the time all the resistance losses are taken into account just doesn’t have the flow rate to reach the minimum, yes.
    If that’s the case you might be best off replacing that pump with a variable one anyway as you must be getting a pretty low flow through your UV also.

 

 
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