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I dumped the single stage HP with oil backup and went with a 2 stage HP all electric and have not looked back. I have no lockout and the system will start kicking on banks of 5kW electric backup around 19 degrees. I think the only time it ever kicked on all three banks was when it was sub zero and my house is not all that well insulated (circa 1989 construction).

The only time I force emergency heat is during freezing rain or heavy snow.

Originally Posted by Kroaler

Going to be hard to see an ROI on the extra cost of the furnace if they havent used it in 2 years.

The lesson is that modern heat pumps need minimal backup heat so consider going all electric. But I don’t recommend it with a single stage heat pump.

Originally Posted by kdean1

Inverter heat pumps retain high efficiency and high output to very low temperatures.
Though the government is not my favorite source of information, here's an article about "cold climate heat pumps."
https://www.energy.gov/eere/building...ay-warm-winter

I have my dual fuel system (or "duel" fuel if you're an internet speller) set to lock out the furnace above 15°F. House temperature maintains 72°F. I have read of some with dual fuel who haven't used the furnace in two years.

Going to be hard to see an ROI on the extra cost of the furnace if they havent used it in 2 years.

Originally Posted by kdean1

Inverter heat pumps retain high efficiency and high output to very low temperatures.
Though the government is not my favorite source of information, here's an article about "cold climate heat pumps."
https://www.energy.gov/eere/building...ay-warm-winter

I have my dual fuel system (or "duel" fuel if you're an internet speller) set to lock out the furnace above 15°F. House temperature maintains 72°F. I have read of some with dual fuel who haven't used the furnace in two years.

Ya I think dual is two and duel is a sword fight. Then there's duet and dude & duck which is either a bird or what you better do in a duel.
I've got too much time on my hands.

Inverter heat pumps retain high efficiency and high output to very low temperatures.
Though the government is not my favorite source of information, here's an article about "cold climate heat pumps."
https://www.energy.gov/eere/building...ay-warm-winter

I have my dual fuel system (or "duel" fuel if you're an internet speller) set to lock out the furnace above 15°F. House temperature maintains 72°F. I have read of some with dual fuel who haven't used the furnace in two years.

Originally Posted by Kroaler

This doesn't match what I see in the real world. Real world I see gas furnace and AC combo outlasting heat pumps.

I haven't come across any data that shows the compressor in a heat pump models is built for 2x runtime vs ac only application compressors.

I would welcome to be proven wrong though for my own knowledge and better understanding.

I believe you might have misunderstood. By caparison a gas furnace & AC would outlast a HP that was built 30 years ago. That was what the engineer I mentioned was referring to. 1980's.
I have no data on how that compares today. Today could be different but modern furnaces are more likely to fail more often but for a different reason, the added technology meaning more parts.
HP's have an expected working life and HP's work longer and harder so I have no disagreement with what you wrote. What the engineer said back then I believe is still valid in keeping a HP compressor running might be a better survivor.
When I had a HP I couldn't get comfortable seeing it covered in snow and running all night long. Seemed like a self destruct event.
That a HP can be more efficient than straight strip is true to a point. And a HP's output falls fast so what is looked at isn't the BTU output as
compared to strip heat, it's BTU's out compared to input. The strip is going to put out more heat at 100% efficiency. The HP will put out less but at a slightly higher efficiency. Nothing like what a HP can put out at 50 degF.

Originally Posted by VTP99

No mention of a crankcase heater [emoji848]

Also I typed the number wrong above its AE17-1243

No mention of a crankcase heater 🤔

Originally Posted by Kroaler

So I quoted the wrong post. But that was an interesting read.

My stance is that heat pumps should* be designed for 2x runtime vs ac only units, but I haven't seen anything that supports this is being done?

I have not seen anything in the field to make me think that a heat pump properly installed and maintained lasts any differently than an ac. If a unit cycles a lot it will die early but if it runs long cycles and gets at least some maintenance they last much longer.

So I quoted the wrong post. But that was an interesting read.

My stance is that heat pumps should* be designed for 2x runtime vs ac only units, but I haven't seen anything that supports this is being done?

Originally Posted by hvacker

I once talked to an engineer about this question. His belief was a HP compressor was likely to last
longer if kept running because the compressor oil would be in circulation and not as likely to migrate.

Here is some ammo to help make your point. AE17-1743

They definitely won't "always be more efficient " there is a balance point.
Also they operate year around vs seasonally.

Originally Posted by hvacker

I once talked to an engineer about this question. His belief was a HP compressor was likely to last
longer if kept running because the compressor oil would be in circulation and not as likely to migrate.
They will always be more efficient than strip heat even when they can't satisfy the load.
I had a HP in N Ill. I kept it running but often worried I was wearing it out. Most of the analysis of HP's don't
consider mechanical costs and how many techs fall short on proficiency when understanding them.

The HP I had was in a house I built and got a special deal on electric rates. At the time the electric co, was pushing all
electric houses. A few years later a consumer group sued and I lost my rates.

This doesn't match what I see in the real world. Real world I see gas furnace and AC combo outlasting heat pumps.

I haven't come across any data that shows the compressor in a heat pump models is built for 2x runtime vs ac only application compressors.

I would welcome to be proven wrong though for my own knowledge and better understanding.

Don’t use emergency heat mode unless your heat pump stops heating your home.
Switching your thermostat to emergency means: just using your backup heat (if I am correct). The heat pump works as an electric heater, or it is using the backup heat.
The backup works more efficiently, but less efficient than the heat pump pulling in heat.
Emergency cases used for normal operation are strongly not recommended for any systems. Heating ones, which are most reactive, is the best case where not to use an emergency for normal operation. Soon you might need a repair team to go and check your system, I believe.
Use emergency heat only if your heat pump isn’t heating your home at all.

Edited: if you already invested in the backup, it should switch on without your action, I guess, and keep the system going. With no need for emergency.

I once talked to an engineer about this question. His belief was a HP compressor was likely to last
longer if kept running because the compressor oil would be in circulation and not as likely to migrate.
They will always be more efficient than strip heat even when they can't satisfy the load.
I had a HP in N Ill. I kept it running but often worried I was wearing it out. Most of the analysis of HP's don't
consider mechanical costs and how many techs fall short on proficiency when understanding them.

The HP I had was in a house I built and got a special deal on electric rates. At the time the electric co, was pushing all
electric houses. A few years later a consumer group sued and I lost my rates.

Originally Posted by MADHVACTECH

You need to look at the C.O.P data in the install manual and that will give you actual performance numbers.

Might also take into consideration equipment runtimes with relation to equipment service life.

I'm in manitoba just north of you.
The heat pump will be more efficient at 10 degrees than strip heat. Probably cop of around 1.5 depending on make_model.
So keep running it

The scenario isn't a constant.

Why go COP? If you know the runtimes, compare the AMPS being used. Then you can convert to wattage and cost for each scenario.

You need to look at the C.O.P data in the install manual and that will give you actual performance numbers.