heat pump vent temperature - http://www.hvacmechanic.com/ Forums

Original message

mort

67.86.103.150

"heat pump vent temperature" , posted Mon 26 Dec 15:56

What air temperature should heat pumps produce at their vents over the outside temperature rnge of 20-50 degrees? We have 8 year old Payne that seems to never get warmer than 72 degrees F.

Replies:

Superdave

65.30.106.237

"Re(1):heat pump vent temperature" , posted Thu 29 Dec 15:05

Carrier Corp makes Payne Equipment and they have a Spec Sheet that will list the heating capacity at different outdoor temperatures, the supply air temperature will be governed by the following conditions;

Outdoor temperature, rated capacity at that temperature, refrigerant charge, general equipment condition, duct sizing and auxilairy heat mode on/off.

Let's say you have a 3 ton (36,000 btu/h nominal)heat pump.The outdoor temperature is 37f, your unit is clean and charged correctly and your duct system is sized and installed correctly, aux heat off.

Conditions of 37f outdoor, 70f return air temperature,

Total capacity at listed conditions; 24,300 btu/H. To find what the supply air temperature should be, take 24,300 / 1200(CFM nominal)/ 1.08 = 18.75 . With a 70f return air temperature your supply air (at the vents) should be around 88.75f +/- 2f.

Clear as mud?

Remember the indoor CFM remains the same, so as the outdoor temperature changes, your supply air temperature changes, either warmer or colder...

Hope this helps..

Change your filter..

SuperDave