Why would you want to do this? What is wrong with the factory defrost cycle?

I wasn't expecting this response, especially from a hv tech. Google "heat pump blows cold air". And please don't suggest the back-up strips off set the cold air. The heat pump process of air conditioning the back yard sounds like a big joke, but I fell for it, and I do save on the power bill during spring and fall, here, down south, and now I am expected to accept the process of the defrost cycle, 15000 watts for 10 minuets every 30, 60, or 90 minuets, whether frost is on the coil or not, and the heat from the vent is lowered significantly. Is the heat trace wire possibly worth a test? I will appreciate your educated opinion. Thanks.

Too bad you don't have have HP with EDD....it eliminates/reduces unnecessary defrost cycles that are expensive not to mention the extra wear and tear to outdoor condenser.

IMO

Wilson, I think there are three considerations here for what you are asking. 1) "Will it work?", 2) "Will it save energy?", and most importantly, 3) "Will I damage my heat pump by trying this?" I'm not sure that anyone knows the answer to the first two, but I would be very concerned about the third one. There is a difference between keeping a pipe above freezing with a heat tape and putting a heat tape on the coil of a heat pump.

Just a note, the three settings 30, 60, and 90 minutes refer to compressor run time below a certain temperature, not clock time, so unless it is very cold the compressor would not be running continuously and the interval is longer.

I don't see how you'd get efficient heat transfer to the coils so you'd be substituting resistance heat inside the house for more resistance heat outside the house. You might stand a better chance of defrosting the coils with a large fan-powered heater. If you can do that with a natural gas heater, it might make short-term economic sense. At that point, however, you would probably have greater gain by putting the furnace inside the house.

Tigerdunes: I appreciate your understanding comment, "unnecessary defrost" when there is no frost or ice on the coil. And yes, extra wear and tear every time the heat-pump reverses from heat mode to air conditioning mode in order to defrost. Like shifting your car into reverse at 90 mph. What is EDD?

Tigerdunes: I appreciate your understanding comment, "unnecessary defrost" when there is no frost or ice on the coil. And yes, extra wear and tear every time the heat-pump reverses from heat mode to air conditioning mode in order to defrost. Like shifting your car into reverse at 90 mph. What is EDD?

dovetonsils: "Will it work", eliminate the defrost, cold or cool air no longer being purposely blown into the house during the winter, is 100% of my goal. "Will it save energy" could be a fringe benefit in 2 ways. The defrost cycle uses 10000 to 15000 watts and still lowers the inside temp 2 to 5 degrees.
And would the warm heat wire be similar to a warmer outside ambient temp, therefore heating your home more efficiently? Oh, thanks, I had forgot the 30, 60, 90 minutes was after the permissive outside temp switch closed. To bad the manufacturer used the cheaper temp and time system to control the defrost instead of a humidity or dew-point switch to detect frost.

ionized: Remember the main goal is to keep cold or cool air from being blown into the home during the defrost cycle, even if no energy is saved. But the heat-trace wire only uses 100 or 200 watts until the frost and ice obstruction is removed from the coil.
Oh, by the way, your gas heater inside the home idea, is already being used by many naïve, gullible people to off-set cold air during defrost, it's called auxiliary heat. Oh, let me know how your gas heater and fan in your back yard works out.

hvtech42: And technicians that are advocates for the heat-pump defrost process, WHERE ARE YOU. I will respectfully listen to any reasonable solution, please.

"Oh, by the way, your gas heater inside the home idea, is already being used by many naïve, gullible people to off-set cold air during defrost, it's called auxiliary heat. Oh, let me know how your gas heater and fan in your back yard works out."

You should develop your sense for irony.

I suggest that you go ahead and try your experiment. Catch the system with a frost load or ice it up manually, Turn it off and fire up your wire. Let the coils cool off before you start back up and there will be no danger to your system.

My prediction is that your 200 W will not go very far applied in the way you suggest. You need to have efficient conduction with sufficient power. Look at the mass of the coils are, the transfer rate of heat to the coils, the transfer rate from the coils to the cold air that you will be bucking, and the latent heat needed to melt the ice.

You might be more likely to succeed with an infrared heater.

If you are looking for a home-brew way to hold temperature without dropping the resistance heat penalty, figure out a way to increase the mass of what you are heating. Maybe you can heat water somehow, store it in a tank and then recirculate it in a coil in your AH during defrost instead of hitting the electrical coils.. Here is an idea for you. Use a HPWH to heat the water.

Adding a second compressor to provide the heat is always a possibility. On the other hand, another outdoor coil as the heat source and variable refrigerant flow might be less expensive.

EDD stands for electronic demand defrost. It is a feature that reduces/eliminates unnecessary and expensive defrost calls not to mention wear and tear on the condenser. Only a few brands incorporate this feature in their heat pumps. Trane/AmStd, Rudd,Rheem, York and a few more. Without going into more explanation, I suggest you google the topic. Lots of information available.

TD

This is a little OT, but some other refrigeration applications are using demand rather than timed defrost. I believe that some residentail refrigerators employ it now.

I think it is great for anyone who can think outside of the box as long as they are willing to ask and also listen. If you have the heat tape and ability to set up a test that will not put your system in jeopardy I say go for it. Sometimes the attempts lead to more thinking that lands a viable solution.

Waste heat recovery is another system that runs residential water through a coil surrounding the hvac lines more for pulling heat about to get expelled into the outside air in the summer into the hot water tank and some are supposed to work with heat pumps.

At the time of my system upgrade I could not swing geothermal but have since found a way to get the pipe and access to a trackhoe or trencher to do a loop large enough to support a geothermal system. I considered getting the loop completed and adding a waste heat recovery unit and running the loop through it to see what impact it would have before going geothermal. If it worked it would allow geothermal to be done in stages rather than swallowed in one project. The whole slugging the compressor and causing a complete system failure holds me back. I guess one of the units is designed for a heat pump and works in both modes. Who knows. Keep thinking.