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Comment by pacbard | Hacker News Reader

The problem with my experience in the Midwest (Michigan in particular) is that their power grid is so bad that I would lose electricity for an average of 1 week each year (the problem is so widespread that Michigan has laws in place to protect utility companies against customer claims for interruptions less than 5 days[^1]).

If you get a nasty February ice storm that cuts a power line, you can be without electric power in 0F weather for up to 5 days. I guess people can install natural gas generators for that occurrence, but that seems to be a little bit counterintuitive (also, would a gas company provide emergency-only service?). I am not sure if heat pumps can work off regular gas powered portable generators that people usually use for emergency power.

[1]: https://www.michigan.gov/-/media/Project/Websites/mpsc/consu...

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> If you get a nasty February ice storm that cuts a power line, you can be without electric power in 0F weather for up to 5 days. I guess people can install natural gas generators for that occurrence

Why would they? They already have one. They don't have to rip it out just because they get a heat pump. Heat pumps don't go where the furnace is.

> I am not sure if heat pumps can work off regular gas powered portable generators that people usually use for emergency power.

Depends on the generator, although some heat pumps run on 120 V. More often they're like central air conditioners, washing machines, and stoves, and run on split-phase 240 [1]. 240 V generators are not as common as 120 V, but they are still very easy to find: https://www.homedepot.com/p/318061554

[1]: your house gets 2 "hot" (one positive voltage, one negative) wires and 1 neutral, with most things connected between neutral and a hot wire, with a ground to check for shorts. High power (anything over 1.4 kW) appliances get a NEMA connector between the two hot wires, and a ground to check for shorts.

> Heat pumps don't go where the furnace is.

They certainly can. Are you thinking heat pumps only come as mini-splits? Drop-in replacement of the furnace is likely the cheaper option when replacing an existing gas furnace over a multi-head system.

Okay? They virtually always are outside, because it's far more difficult to put a unit in a basement. Heat pumps need outside air and a furnace typically has a single 2" PVC pipe to the outside. That's very far from sufficient.

If you have a furnace it's trivial to have it left in place.

I don't think you understand what a heat pump is or how they work. Its an air conditioner that can run in reverse. So in the centralized case like we are discussing, the outside part is the compressor, the inside part does a heat exchange between the refrigerant and the air handling system and then on to the duct work.

Air is not moved from outside to inside via PVC or other method. Refrigerant (freon in older systems, more obscure names now) moves from outside to inside via a small copper pipe.

Air handlers are not heat pumps. An air handler can be put in place of a furnace, but it certainly does not have to. If you have a furnace, it's trivial to have it left in place.

I didn't say air handlers are heat pumps, I said the product of the heat pump are passed off to the air handler. But again you seem confused about basic terminology about the subject you are talking about.

> An air handler can be put in place of a furnace, but it certainly does not have to.

An air handler just moves air around, it doesn't replace a furnace. Its an essential part of a central heating / cooling system regardless of whether its attached to a heat pump, gas furnace or anything else.

I'm not sure why you keep doubling down on speaking authoritatively about something you don't understand. Why don't you read a basic intro and then you'll understand?

> > Heat pumps don't go where the furnace is.

> They certainly can.

I am responding to what you said.

Heat pumps can also replace the AC heat exchanger in a home HVAC setup. It’s what we did. We’ll have gas backup for when winter sucks, but otherwise we’ll use the heat exchanger.

To add to this, there was a major storm last week that knocked out power for significant chunk of the Detroit area for up to three days. That's in August, mostly from wind.

My neighbor was out from Monday until Friday evening. I think it was actually up to _6_ days...

These kinds of storms happen rarely if ever happen in the winter and they typically happen in the spring and summer so I’m not sure how this presents much of an issue for heating. They seem to impact rural areas much worse though.

SE Michigan has outages all year round, it's just an infrastructure problem. Before I moved, I was used to (fortunately short) DTE outages at least once a month, every computer needed a UPS or you would lose work. In Nashville I haven't had an outage without a tornado coming through (knock on wood). I remember being woken up by the UPS beeping at night all the time and I just spent four years with it right next to my bed with no issues (albeit only because I wasn't sleeping during the tornado sirens anyways).

In the northeast all my worst power outages happened during the winter. Usually from ice storms or even just an overabundance of wet snow causing tons of tree limbs to come down at once.

We were talking about Michigan though. Also, power lines can be constructed or maintained in a way that trees and ice aren’t an issue.

They can be, but in large parts of Michigan they haven't been - a quick check says 15% of power lines are buried. So any weather event that risks damage to tree limbs also risks power outages.

Burying power lines is extremely expensive - and the utilities aren't going to eat that cost, it's going to be passed right on to you! Moreover, when there are problems with underground power lines, which ironically tends to also happen in the winter due to the salt used on roadways, it's very time-consuming to resolve issues. The utilities would need 5x the crews they currently have in order to restore power in as timely a manner as they do now.

How do I know this? I work for a major utility serving the midwest. Winters are no joke in these parts. As others have noted, heat pumps are only good down to 20F. If it gets colder than that, which it frequently does, you're going to want a natural gas furnace because electric furnaces are stupid expensive to operate! This coming from a guy who works for the power company!

There's not going to be any phase-out of natural gas for decades - which is the amount of time we need to build all the nuclear generation we need to make power as cheap and abundant as we need. We can't heat our homes and power our cars with wishes and desires - we need a hard-nosed energy policy and plan of execution.

> As others have noted, heat pumps are only good down to 20F. If it gets colder than that,

Others said no such thing. Did you leave out the minus sign?

You're right - they said -20F. I didn't leave out the minus sign, I didn't even see it!, and it's interesting why. Thirty years ago my parents had a house having both a gas furnace and a heat pump that worked in tandem. They had a problem with their furnace that they didn't immediately fix because they were using the heat pump. Then they got the bill. It was nearly 3x more expensive than usual. My dad immediately got the furnace fixed.

What I recall my dad saying is when the furnace guy came out to fix the furnace my dad was talking to the furnace guy about the bill. The furnace guy said heat pumps get very inefficient below 20F. So my dad's system was designed to run the heat pump until the outside temperature got to 20F and then it would switch over to the furnace, if available. If it detected the furnace not coming on then it would continue to run the heat pump. So I've had it in my head ever since that you don't want to run a heat pump below 20F.

Are the new heat pumps different? Is it now -20F instead of 20F before your costs soar?

Yes, apparently there have been huge advances in the efficiency of heat pumps since then. And this is why ground source heat pumps are less of a thing these days: you don't need the help of that underground temperature as much.

This guy gets really excited about heat pumps:

https://www.youtube.com/watch?v=MFEHFsO-XSI

https://www.youtube.com/watch?v=43XKfuptnik

Thanks for the links!

It is still not too smart to run your heat pump below 10F. It will work, but the BTUs it can produce will be limited, right when you need a lot more because it's f*%&in' cold out.

> If you get a nasty February ice storm that cuts a power line, you can be without electric power in 0F weather for up to 5 days

I live in Indiana and we've had power outages like this during both winter and summer. What sucks is that newer (last 25 years) gas furnaces have fancy-dancy blower motors (power vent) and if I lose electricity, I also can't run the furnace because the power vent won't work. My gas water heater was the same way. Last time it failed (they only last 10 years these days), I switched to electric because the power vent on the gas water heater was so noisy you could hear it throughout the entire house.

My house is somewhat livable in the summer heat with a power outage because I have a basement, but in winter, forget it.

Having said that, I'm not so keen on spending $10-15K to convert two gas furnaces to heat pumps.

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