Heat Pump - Time between defrostings

11 years ago

About 5 years ago I had a Goodman heat pump installed. The installer initially set it to defrost every 30 minutes. After about 3 years I figured out I could change it to only defrost every 60 minutes. About February of this year I noticed that even at 60 minutes it never frosted at all, so I changed it to 90 minutes between defrosts and still never had a problem with frost. Could I damage my heat pump if it gets iced up and tries to run? I live in the Seattle area.

I know - I should have gotten a heat pump with demand defrost, but I did not know about that feature when I bought it.

Sort by:Oldest

Comments (8)

tigerdunes
11 years ago
Yes, you could possible damage your heat pump but considering your location and relatively mild winter climates, the chance is small.

Your bigger issue might be losing efficiency and costing you more to operate. If you get a rare, hard snow or ice storm, then the timed defrost method most likely would be completely overwhelmed and unable to defrost completely. Here the best solution is to go to emergency heat until weather moderated.

I hate timed defrost and encourage homeowners depending on location to purchase new HP systems with electronic demand defrost. It eliminates nuisance, unnecessary, and expensive defrost calls.

IMO
borisswort
Original Author
11 years ago
My heat pump changes over to my gas furnace whenever the outside temperature is under 35 degrees, so is there a way to just eliminate the defrosting? Or, should I still just keep it defrosting every 90 minutes?
Related Discussions
Fol-up on 'Heat pump blows cold air on defrost'
Q
Comments (5)
tigerdunes: The installer is also the Amana service person. We have a 10 yr parts and labor contract w/Amana. I could call Amana and see if they will send over another company at no charge to us, but we thought if it was an install problem, then Amana wouldn't cover the service. So... 1) Is there any way we can tell if there is an 8kw heat strip installed? And, if it is, is there anyway for us to tell whether it is hooked up properly AND working properly? 2) Again, the installer/service person "tells" us it is working (i.e., he put the compressor into defrost, came inside and looked at something and said "yup, the heat strip is working") He has even called a couple other HVAC people to ask them questions while he was here. He feels since we are getting 36,000 BTU's of cool and only 30,000 BTU's of heat (with the 8kw strip) that it will always be colder. But what I've read on other posts is that the heat strip has a 30/70 and I wondered if perhaps in defrost mode that it is only operating at 30% capacity??? (Like I really know what I'm talking about, so forgive me if I'm WAY off base). We did have him adjust the CFM down to 1100. It was running at I think 1400 and the noise through the duct/vent was too much (the vents were cleared out, though). Also, in the summer, it would only run for about 4 minutes, not enough time to help w/the humidity in the house. When the temps are above 40, the "heat" runs for 9-15 minutes normally. If you or anyone else has any further info for me, let me know. Otherwise, I will try to get someone else to look at it. I'll let you know.
...See More
Heat Pump problem after defrost cycle
Q
Comments (1)
The tech can manually initiate a defrost cycle. I would try a different company if you haven't already.
...See More
new 'fossil fuel kit' installed heat pump often defrosting
Q
Comments (4)
Thank you all for your replies. I did download the installation manual, and after mapping out all the wiring, I found out why the pump was always defrosting and corrected it, along with some other wiring mistakes, and I replaced his wires twisted around the relay terminals with proper spade connectors. I also found a dip switch on the thermostat that was causing the 2 minute delay. However, I couldn't find an exterior thermostat as ziggyhere mentioned, but the heat pump's wiring diagram shows a temperature sensor; could the old system have used that as the outdoor thermostat? If not, my parents are on a dual rate from their power company: they get a discounted rate as long as the outside temp stays above -12 degrees Celsius or around 10 degrees Fahrenheit. The power company installs a temp sensor in a housing that mounts between the meter pan and the meter itself, with 24 VAC present at the furnace when the temperature is above the setpoint of 10 degrees. Could the old system have been using the signal from the POCO sensor to shut off the heat pump and switch to oil? Also, when the temperature outside was around 16 degrees Fahrenheit, sometimes the oil burner would come on for a couple minutes (and the heat pump would shut off), and it doesn't do that anymore; could that be a feature of the old system, or could it be a feature of the heat pump itself? Also, with the old system if we raised the thermostat's setpoint even by a few degrees, the oil burner would kick in until the desired temperature is reached, but the new system doesn't do that; is it typical of dual heat systems, or was it just a feature of the old system and I shouldn't worry too much about it? Finally, I have heard and read several times that below a certain temperature, heat pumps lose their efficiency and there was indeed a chart in the heat pump cover, but after 21 years out there, it isn't legible anymore. It's an ICP 2-ton unit, if that matters. Because the system would often rely on the oil burner past the 16 degree mark, I assume that is where that particular heat pump starts losing its efficiency. Is it putting more strain on the compressor to let it run below that threshold? Thanks again for taking time to help me, and have a nice day!
...See More
Heat pump defrost-cycles but doesn't actually defrost
Q
Comments (10)
Thanks, everyone. Pro was here today and he wants to replace the outdoor coil temperature sensor. He thinks it is cutting off the cycle too soon. He also wanted to replace the board but I said no to that -- it seems to me that the board is working the way it is supposed to. While he was there I asked him to check the pressures just to humor me. He did and said, "Oh, it's low". He didn't have the sensor in stock, so he's coming back tomorrow to replace that and top up the system.
...See More
tigerdunes
11 years ago
With DF being the case, I would just deactivate the defrost function. I assume you are only the seeing the defrost function under 40 degrees. Correct?
borisswort
Original Author
11 years ago
I think it defrosts every 90 minutes of running time no matter the outside temperature.

How do I disable the defrost function? I figured out how to change it from 30 to 60 to 90 minutes, but there are no other jumpers to switch it to. Do I just disconnect the jumper?
SaltiDawg
11 years ago
borisswort,

I do not believe my Carrier defrosts if either the backup or emergency heat is activated... and of course it does not defrost in cooling mode. :-)

I would think the designers would cause this to be the norm.

Are you sure your unit defrosts when in backup heat or emergency heat mode?
borisswort
Original Author
11 years ago
No, my heat pump never defrosts when it is below 35 degrees out because my gas furnace is working then. There has been times when my heat pump gets a few inches of snow on it because it does not run for a few days because of the outside temperature. I have missed seeing what happens when the outside temperature goes above 35 degrees and there is still a pile of snow on the heat pump.
brickeyee
11 years ago
"defrosts if either the backup or emergency heat is activated... "

Since the heat pump is no longer operating to pull the outside unit (now an evaporator) below the frost point, why would it?
SaltiDawg
11 years ago
brickeye,

Re-read my post... I never suggested it would "defrost if either the backup or emergency heat is activated..."

I was in a non-confrontational manner indicating, " I do not believe my Carrier defrosts if either the backup or emergency heat is activated..." and going on to ask if the OP was sure it did defrost in those modes... as he had previously stated.

Heat Pump - Time between defrostings

Comments (8)

tigerdunes

borisswort
Original Author

Related Discussions

tigerdunes

borisswort
Original Author

SaltiDawg

borisswort
Original Author

brickeyee

SaltiDawg

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

Heat Pump - Time between defrostings

Comments (8)

tigerdunes

borisswortOriginal Author

Related Discussions

tigerdunes

borisswortOriginal Author

SaltiDawg

borisswortOriginal Author

brickeyee

SaltiDawg

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

borisswort
Original Author

borisswort
Original Author

borisswort
Original Author