Goodman Heat Pump checkup

[appliancethug]

I have two Goodman Heat pumps (upstairs/downstairs).

Model CPLT36-18

Model PHKJ036-1C

They both perform the same way, which IMO is WRONG. When the thermostat starts the heat pump(s), it (they) blows unheated or lukewarm air continuously unless the Auxiliary Heater is switched on by the RITETEMP digital Thermostat. It "seems" (because I can't get a clear answer from RITETEMP) the thermostat enables Auxillary Heat when the room temperature and target temperature is greater than 5 degrees variance. Once the Auxillary Heat is enabled, I get 95 (downstairs) to 126 degree (upstairs) heat.

Ritetemp Model 625 Thermostats links are here:

• Home Depot: http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&catalogId=10053&productId=100625727&N=1663+90401&marketID=401&locStoreNum=8125
• http://www.ritetemp-thermostats.com/6025.html
  

So do I need a service tech to come tell me my thermostats are hooked up wrong or the heaters need some new part? I ask because my electric bill this month was 2.5 times it was the previous month.

[dkpd1581]

You may want to check and see if the heat pump's outdoor unit has an outdoor sensor or thermostat that will lock out the condensing unit below a certain temperature.  This would cause the heat strips to come on a first stage call for heat and give you similar symptoms that you have described.

Your units are only able to provide heat - or "pump" heat from outside - to the inside your house without any electric strip heat assistance (called the balance point) down to the mid to low 30's on average.  This depends on the outside air temperature that they are operating in, the proper refrigerant charge, clean coils inside and out, the state and settings of your defrost control, the proper insulation of line sets and ductwork, and the overall insulation/tightness of your home. 

Heat pumps generally speaking will not provide much over 100-120F air on the best day without electric strip heat back up.  In fact it is not uncommon to have supply air in the low 80's.  Our bodies will interpret 80F air as a draft; however, the 80F is above the ambient temp in the house of say 68-72F and the unit is therefore technically heating the space and doing its job.  That is one of the chief complaints of heat pumps.

That you experience "cold air" and then later the strip heat engages indicates that the mechanical heating is trying to do the job but cannot meet the demand and the electric strips kick in.  Thermostats generally speaking look for a 0.4-0.6F rise in room temperature every 60-90 seconds.  When that heat rise is not met/established after a manufacturer's preset time of say 5 minutes, then the strips engage.  Also, a wide disparity between room temperature and set point temperature (what you want it to be) will engage the strips straight away as well.

It seems your units are attempting to do what they are designed to due based on the "luke warm air" reference you made.  A few things to do are:

1. Change the filter inside

2. Make sure the outdoor coil is clean, if not then clean it

3. Make sure the connecting copper lines (lineset) is adequately insulated from outdoor to indoor unit

4. Make sure you have no leaks in the ductwork (supply and return)

5. Check to see that no thick ice builds up on the outdoor unit and that the unit goes into defrost correctly and actually is able to defrost the coil

6. Change the defrost frequency to a lower number ie: 30 mins vs 60 or 90 mins

7. Make certain that you have proper airflow around the units - no over hanging decks, awnings, trees, shrubs, bushes, nothing stacked on top of the outdoor unit

8. Realize that ambient outdoor temps in the mid 30's and below reduce the units ability to heat the house

9. Insulate the home, window, and doors

10. Measure the supply air and verify that it is at least 10F above the entering air at the indoor unit

11. Have the unit professionally serviced if necessary

What temperature are you trying to keep indoors and what temperature is it outside.  What City and State are you in.  This will help get a better idea of the conditions the unit is in and what you are expecting and help determine if it is the machine or your expectations that are not meeting the desired goals.

 

[appliancethug]

Thanks for your reply. To answer your questions

1. Indoor desired temperature is 72 F; however, the thermostat has a "power saver" mode that freezes us out on a cold day. Today outdoor temp is 50F so heat is nearly un-needed; I cycled the heater today it and it works great: 136 F degrees!

2. Location: Nashville, Tennessee

Heat pumps are called "efficient" but they don't seem so. A good ole fireplace would do the trick, but the Homeowners association doesn't allow wood fire burning in our gas-log fireplaces (Btw, these neighborhoods have natural gas fireplaces but no natural gas service).

My expectation is that the HVAC system should blow hot air in the winter and cold air in the summer. Summertime AC is good. So it seems with our tripled Electric bill, we're doing something wrong.  It's true, those 20-30 F degree days/nights the heat pump doesn't work and requires manual intervention (dial-up the thermostat to force the aux or set jumpers on the thermostat) to get the strips/aux heat to kick in. But it doesn't seem my electricity usage should jump 250%.

[dkpd1581]

The power saver mode may very well be causing you the problems.  When it goes out of "Power Savings," your temperature differential may be just enough to engage the strip heats. Most t-stats will maintain the auxiliary strips until the set point is satisfied instead of turning them off when you are close enough to set point and the stat is registering the degrees rise per minute.

Heat pumps do save you money when you consider the amount of energy invested in running the machine (watts of electricity input converted to BTUs) compared to the BTU output.  That ratio of energy in to energy out in the form of heat is called the COP or coefficient of performance.  So when compared to what you are spending on electricity in versus heat out you can get favorable ratios of in versus out.

General reasoning would suggest a regular fireplace would heat better; however, a real wood burning fireplace with open flue and all is only around 10% efficient.  You loose 90% of your heat right out the flue/chimney.  As the hot gas goes up and exits your house and more air is consumed to support combustion, the house becomes a lower or more negative pressure than outdoors atmospheric pressure.  The cold unconditioned air will find its way in which in turn must be conditioned by warming.  The heat you feel is only radiant.

Although you have no natural gas service, you can get a propane tank set in an inconspicuous spot and convert the natural gas fireplace to a propane fireplace.  Be sure to get a vent free log set that does not require the flue to be open.  That will give you 99% efficiency versus the 10% of regular wood fires and vented gas log systems.

Just for giggles, put both heat pumps into emergency heat (strip heat only) and go outside to your electric meter with nothing else electric running (tv, computer, washer, drier) and clock your meter.  Time the meter for 1 minute and see how many watts you use in that one minute by the system running the strips.  Multiply that by 60 and that how many watts per hour.  Then you can get your bill and multiply the watts for one hour by the rate and get a real eye opening idea of the real costs to run the machine like that.  If you are handy with a meter you can use the Power Law with P=IE and read it directly.  It will work with the strip heats exactly because they are a truly resistive circuit.  It wont work as well when adding the motor's amp draw because it has capacitive and inductive loads (the sum of which is technically referred to as Impedance).  You will get a real close idea of what it really costs and you will be surprised.

Best of luck.