Carrier 5 Ton Heat Pump - not enough heat, 2nd stage may not be wired in
History: Home was built in 2004, Central Ohio. Ended up becoming a bank owned property that needed some work that we bought in 2009. Move into it in June 2009 and discovered are inspector sucked and the A/C didn't work. All electric house (no gas of any kind). Home is about 3300 sq/ft + 1800 sq/ft of basement w/ 8.5' ceilings and another 600 of crawl space. 19' ceiling through 1/2 of the 1st floor (1st floor is about 2400 sq/ft), remainder is 9' ceilings excluding the office which has a vaulted ceiling. The about 900 sq/ft upstairs is around an 8' ceiling if memory serves. Basement has 4 air vents, all of which I leave closed as we aren't down there much.
Had a HVAC place come out, who finds some history on the previous unit. They say the heat pump wasn't original and this one also was dead, due to contamination in the line. He believes there was contamination in it from the original unit and when that died the 2nd unit was replaced, they didn't replace the lines.
Installer installs a new base for the unit to sit on (better than what was there for sure), all new lines, new wiring from the heat pump to the air handler. For everything I observed they did a professional job, charging $$$$ out the door. Unit was a new 5 ton Carrier 25HNA6 unit.
They did no wiring at the thermostat. The thermostat was a cheap builder grade slider unit (but designed for a heat pump) - it ended up dying early that winter as it would randomly read the house as being cold, put the heat pump in emergency mode, and cook the house while we were out.
Replaced it with a Hunter touchscreen thermostat. Set it to heat pump and default settings. I was very careful to mark all wires and match the description between the old unit and the new unit. Here is the wire description for the heat pump wiring of the Hunter unit:
Rc/R - 24VAC Power Supply
C - 24VAC Common
Y1 - Compressor Stage 1
Y2 - Compressor Stage 2
W2 - Auxiliary Heat
E - Emergency Heat
O - Cool Mode Powered Reverse Valve
B - Heat Mode Powered Reverse Valve
G - Fan
L - System Monitor
How I have it wired:
Y1 = yellow wire. This is wire nutted at the air handler side to the yellow wire going to the heat pump
W2/E = bridge together at the unit, ran to the white wire
G = green wire
RH/RCR = bridged together, red wire, to the terminal in the air handler the red wire to the heat pump also shares
C = blue wire. This went to the common terminal, I think the white wire off the heat pump wire goes to that.
O = orange wire. This is wire nutted at the air handler side to the orange wire going to the heat pump
What I find curious is the 2nd stage of the compressor isn't wired in. Only 4 wires total wired into the heat pump unit.
- Heat out of the registers is never that warm. Air handler (set to auto) runs almost constantly when it is below freezing outside. But it would maintain heat in the house, but god forbid you need to raise the temp. We burn wood in the fireplace a lot or run a good sized portable electric heater, which helps a lot as the layout of the house allows the heat to spread nicely. My electric bill is insane no matter what I do.
- Few days ago it was 30 degrees out, thermostat was set to 68 yet it was only 64 in the house. I put it on emergency heat and the house quickly heated back up. Furnace doesn't run a whole lot when set to emergency heat.
- Ordered an Infrared temp gun and tried it out tonight. Pulled the air filter (which I changed while doing so - dirty but could have been worse); was 67 degrees on the inlet, which was the temp of the house at the time. I opened a basement register; one directly off the air handler maybe a 7' run total - 72 degrees. Outside temp was 39 at the time. Of note, I also cleaned the heat pump this fall, ensuring all the vents were nice and clean.
As for the A/C side, this home has zero shade all day and we get some hot days, so it really gets cooked. The A/C struggles to keep up when it is over 90 degrees and full sun outside, otherwise it is fine.
Summary: I think my 2nd stage isn't wired into my thermostat and I don't get good heat out of my vents!
Last edited by jpsmith1cm; 11-29-2012 at 07:07 AM.