[TRNSYS-users] Set air flow rate of an air-air heat pump for residential both heating and cooling system

[thornton at tess-inc.com]

On 2022-05-12 08:46, Jacopo Valente via TRNSYS-users wrote:

> I have to set the air flow rate of the heat pump. The pump works all
> year in both heating and cooling modes. I calculate the flow rate from
> the maximum hourly load that I have in my load profile, but having two
> different max values for heating and cooling i have two different air
> flow rate. So I would like to set the air flow rate to change when the
> system switches from heating to cooling.

Most residential heat pumps that I have seen don't modulate the air flow 
depending on whether the unit is in heating or cooling mode.  The heat 
pump is sized to meet the larger of the heating or cooling loads, and 
then runs at the set fan speed; turning on and off by the signal for the 
thermostat.  And that's exactly how Type 954 operates.  The fan is fully 
on in heating or cooling mode, and then either fully on or fully off if 
there is not call for heating or cooling (depending on the fan control 
signal).

If you truly want to have two different air flows (one for heating and 
one for cooling), then you'll need to use two instances of Type 954 and 
turn one on in heating mode and one on in cooling mode.

Jeff

-- 
Jeff W. Thornton
President
Thermal Energy System Specialists LLC
3 N. Pinckney Street, Suite 202
Madison WI 53703 USA
(608) 274-2577
www.tess-inc.com