Carrier identification

[Giles]

I recently moved into a 20 year old home. I have a Carrier High Effeciency heat pump model number 38YXA060320.
The previous owners cannot be contacted and I have no paperwork.
I have done a search but cannot find any information about this unit, such as age and if it is a single or dual stage unit.
I don't think I have a problem but the compressor starts to run and runs without the outside fan for about a minute and then the inside fan turns on and gradually speeds up. When the unit shuts down the inside fan starts slowing down untill it stops.
I have never had a unit that operated like this but it seems to be heating alright.
Any information would be appreciated.

[jadnashua]

When in cooling mode, the compressor runs, and it is removing heat from the house... the fan outside needs to run to move the heat transferred from the house via the refrigerant to outside. Now, switched to heating mode, it absorbs what heat it can from outside and moves it into the house, giving up that heat in the coil in the house and moved around by the fan in the house for heat. there's no reason to turn the fan on outside since you don't need to cool it off (that heat's transferred inside instead, but the compressor needs to run to move it).

It's nice feature to have the variable speed fan as it helps keep the system more comfortable. My father has a heat pump, and without going inside the air handler, there's no way to slow the fan down, and it always feels cold since the fan runs at a fairly high speed optimized for cooling rather than heating. A heat pump doesn't make the air as hot as a furnace, and moving air can make you feel cold, so moving it slower than in the summer allows it to get hotter, and not generate the breeze that makes you feel cold. Eventually, as the outside temps drop, it will turn on resistance heat since it won't be able to absorb enough heat to keep the house warm.

Sounds like it's working okay to me.

[Runs with bison]

Try this. Look at page 13. Model # indicates this is an SEER 13, 5 ton unit.

http://www.docs.hvacpartners.com/idc...it/38-11sm.pdf

Below that it shows how to decode the serial number to determine when it was manufactured.

[Giles]

THANKS-- for the clear explanation and the informative link.

[hj]

I assume when you say the compressor starts up, that you mean its blower also turns on. The reason your inside fan does not start immediately is so the unit has a chance to warm up, rather than circulate cool air. A gas furnace does the same thing. The burner turns on and once the unit is hot the fan begins to circulate the air. When the thermostat is satisfied, the outside unit turns off, but there is still warm/hot air inside the unit so your inside fan keeps running to harvest that energy, then it turns off. In cooling mode the inside fan can start immediately because there is no need for the time lag, but it will probably still harvest the remaining cold air when the thermostat turns the compressor off.

[Giles]

I assume when you say the compressor starts up, that you mean its blower also turns on. The reason your inside fan does not start immediately is so the unit has a chance to warm up, rather than circulate cool air. A gas furnace does the same thing. The burner turns on and once the unit is hot the fan begins to circulate the air. When the thermostat is satisfied, the outside unit turns off, but there is still warm/hot air inside the unit so your inside fan keeps running to harvest that energy, then it turns off. In cooling mode the inside fan can start immediately because there is no need for the time lag, but it will probably still harvest the remaining cold air when the thermostat turns the compressor off.

No the compressor runs alone. While in my basement, I can hear the outside compressor start to run without the large fan on the unit running. In approximately one minute the large fan starts and the inside blower starts to blow warm air.
I understand about the inside blower delay.