News report - Heat pumps struggling in record cold here in the Valley (Phoenix: renting, house)

[Pink Jazz]

According to this news report:
Four days of freezing takes a toll on Valley heaters

In the record cold we have been having here in the Valley lately, people are widely reporting problems with their heat pumps. Normally, heat pumps are ideal when it isn't too cold due to their high efficiency, however, when it gets as cold as it has been lately, that is when they begin to struggle.

In some areas, heat pumps often include an auxiliary heat source, which can either be electric heating strips in the air handler (basically an creating an electric forced air furnace), or it can be a gas furnace. Because it is rare for it to get this cold in this climate, many heat pump installations here in the Valley have no auxiliary heat source at all. Because of this, many heat pump installations here in the Valley are cycling between heating and defrosting, thus cycling between blowing warm and cold air. On systems equipped with auxiliary heat, the auxiliary heat would kick in to offset the cold air produced by the defrosting cycle.

We have a house in Tolleson with a heat pump that we are renting out, and luckily there have been no reported issues from the renters. Our house in Gilbert (the one we actually live in) has natural gas heat, so no issues for us.

I wonder, how are everyone's heat pumps working here?

[DetroitN8V]

I stayed warm and toasty here! I think we have heat pumps at least. One unit that does AC and heat and looks like a big AC unit? (forgive the AZ newbie!)

[Pink Jazz]

Originally Posted by DetroitN8V

I stayed warm and toasty here! I think we have heat pumps at least. One unit that does AC and heat and looks like a big AC unit? (forgive the AZ newbie!)

Yep, that's a heat pump all right. Basically, when heating, a heat pump is basically an air conditioner working in reverse, drawing heat into the house. When cooling, it is no different from a standard air conditioner, drawing heat out of the house. Since the air outside that the heat pump draws heat from is already cold, they are ideally suited when the outside air isn't too cold, which is why they are very common here in the Valley due to it rarely getting too cold. If it gets too cold, the coils can freeze, thus forcing the heat pump into a defrost mode, which unfortunately requires the heat pump to switch into cooling mode to defrost the coils. That is one of the reasons why heat pump systems in some areas have an auxiliary heating source to compensate for the heat pump blowing cold air into the house.

[Desertspiritsteve]

I noticed that the air temp from the registers was cooler for several nights. The heat pump ran more, too. Last night the register temp was warmer. There was more heat for the unit to gather outdoors than the previous nights. My inside temp was a consistent 74 degrees. People get into trouble with the heat pump when they play with the thermostat..like turning it down at night and up in the morning. You need to just set it so you're comfortable and leave it alone. The efficiency is much better with the heat pump moving heat into or out of the house than a gas furnace burning fossil fuels. The 140 degree air temp of a furnace drives me up a wall. You'll never get carbon monoxide poisoning from a heat pump.

[TiredOfyycCold]

Thanks for the post Pink Jazz - I had no idea how the heat pump worked. My inlaws are using our house right now, hope they aren't freezing!

[Cleveland_Collector]

Originally Posted by Desertspiritsteve

The efficiency is much better with the heat pump moving heat into or out of the house than a gas furnace burning fossil fuels.

A heat pump's efficiency isn't even close to that of a gas furnace. Also, most electricity is generated by burning fossil fuels which, in turn, runs a turbine. Electricity is, at best, 40% efficient when considering generation and delivery losses by the time it gets to your home. Most gas furnaces run better than 90% efficient these days. Boiler systems can be close to 95% efficient. The reason heat pumps are used in warmer climates is because they're cheaper to install than 2 independent units. In colder climates, heat pumps have a hard time keeping up and, due to the fact that they require more operational energy to pull heat energy on colder days, they can be very expensive to run. If you want heat, your best and most efficient bet is to be as close to the heat source as possible (i.e., burning natural gas).

[fennec2009]

Mine has been working fine. I set it and forget it, not turning it up and down like desertispiritsteve stated. It's at 68 degrees, kind of cold but manageable with blankets

[Desertspiritsteve]

Ooops! This subject has always been of interest to me. Many years ago I heard that heat pumps are so efficient because they move heat from one place to another. According to this Heat Pump Systems | Department of Energy heat pumps create four times the heat for the energy consume. (Whatever that means) My preference would be with nuclear generated electricity. You can go one better in cooler climates than Phoenix by putting in a geothermal heat pump that deposits and extracts heat into the earth around your home or business or whatever. I guess you would have to replace a compressor now and then. Do I understand correctly that a heat pump could be 400% efficient as compared to a gas furnace being 90% ? I can tell you that when I switched from a gas furnace to a heat pump nearly 30 years ago, my bills have been much lower and I have been more comfortable. That's with yesterday's gas rates and today's electric rates. There is no fall start-up stink with a heat pump and there are no black streaks on my ceilings from the air registers. Help me here.

[observer53]

Mine is working fine, but I don't vary the temp very much, (only between 66 and 70) which keeps it from struggling when it gets colder and spending a lot of time in that "defrost mode".

[Ponderosa]

Mine is working fine as well. I get the icy blast though. Like Observer said, you get much less of that if you have a constant temp than letting it fall off at night and then warm up again in the morning like I do.