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  1. #1
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    Air Source Heat Pump - Need of Fresh Air or Forced Hot Air is Important?



    We are the manufacturer of Air Source Heat Pump.
    At one of the location, a multistory, vertical building, the client would like to put up heat pump in the boiler room, in the basement, 3 floors from down.
    Being 3 fl0ors down, there is not much fresh air ventilation available. however, being the boiler room, inside temperature is always 40 deg. C plus.
    The air flow required is 16000 CFM at 20 deg. C.
    My planning is to suck the air (whatever is available) from surrounding and the exhaust, cool air to be vented out with the help of duct.
    My queries:
    In air source heat pump, is it free flowing air that matters or forced air with higher temperature matters?
    With these conditions, whether heat pump performance will get affected and how much?
    Your suggestions and guidance is highly appreciable



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    Re: Air Source Heat Pump - Need of Fresh Air or Forced Hot Air is Important?

    You would need to know the total heat generated by the boiler vs the total heat absorbed by the hart pump evaporator I suspect this will cool the room pretty quickly. There is no need for the air to be fresh just at a suitable temperature

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    Re: Air Source Heat Pump - Need of Fresh Air or Forced Hot Air is Important?

    I do not want to sound rude, but bloody hell, you say you are a manufacture of ASHP, you should have some knowledge of an energy mass balance, and how a refrigeration system works, I feel pity for your client!
    Saying that we are here to assist, so a clue, whats your boiler air usage "fresh air", what is the balance of the fresh air load inconjuction with losses from the boiler.

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    Re: Air Source Heat Pump - Need of Fresh Air or Forced Hot Air is Important?

    Whatever your ASHP takes out of the boiler room in airflow must be made up by forced ventilation otherwise your boilers will operate in dangerous conditions.
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    Re: Air Source Heat Pump - Need of Fresh Air or Forced Hot Air is Important?

    Your flow rate will be 27.000 m/h, so 27.000 m/h must enter the boiler room.
    You need at least 4 to 5 m passage through grilles to the outside.
    Are the boilers gas/oil fired with a free-flow chimney or a forced blown chimney? This can become your biggest problem if you create an under-pressure
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

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    Re: Air Source Heat Pump - Need of Fresh Air or Forced Hot Air is Important?

    Dear Peter,
    Thanks for the reply.
    The boilers are Oil Fired with Forced Blown chimney as the flue gases has to be carried up to the top floor of 35 story building. I will talk to the client and will come back with feedback, if any.

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    Re: Air Source Heat Pump - Need of Fresh Air or Forced Hot Air is Important?

    Dear Peter,
    Just an afterthought. The boiler room is appro. 40 ft x 25ft x 20ft. If the ASHP cool air outlet is vented out in the boiler room it self in one corner and ASHP is installed in another, diagonally opposite corner, still it will create a problem for boilers? No doubt, heat load might get reduced and our performance will drop. But, hopefully it won't affect the boilers?

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    Re: Air Source Heat Pump - Need of Fresh Air or Forced Hot Air is Important?

    Dear Peter,
    Thanks for the reply.
    The boilers are Oil Fired with Forced Blown chimney as the flue gases has to be carried up to the top floor of 35 story building. I will talk to the client and will come back with feedback, if any.

    Just an afterthought. The boiler room is appro. 40 ft x 25ft x 20ft. If the ASHP cool air outlet is vented out in the boiler room it self in one corner and ASHP is installed in another, diagonally opposite corner, still it will create a problem for boilers? No doubt, heat load might get reduced and our performance will drop. But, hopefully it won't affect the boilers?

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    Re: Air Source Heat Pump - Need of Fresh Air or Forced Hot Air is Important?

    Thanks Roger

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