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Comment by fuoqi | Hacker News Reader

The biggest issue with mass-scale installation of heat pumps is non-linear load on grid in cold weather. Failing efficiency and ultimately automatic switch to resistive heating causes electricity consumption spike, together with other accidents caused by the weather (be it reduced generation or grid damage) it can cause brownouts or full-blown blackouts. In other words, people can lose heating when they need it most.

Any programs which promote heat pump installations above a certain scale must either include huge investments into grid robustness or mandate that all heat pump installation must include fuel-based backup heating sufficient for a week or two.

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> Any programs which promote heat pump installations above a certain scale must either include huge investments into grid robustness or mandate that all heat pump installation must include fuel-based backup heating sufficient for a week or two.

That's a little extreme. You also need to consider your failure modes. I live in texas where a bunch of people died due to an extreme freeze and a very poorly regulated grid. When that happened, it wasn't just electric that was lost, but a big problem was natural gas wells and pipes freezing up too.

The cost to install and maintain both systems would be an automatic deal breaker for many people. I don't think you need total redundancy, but having some is good. For example, I went and bought a "buddy heater" after that freeze. It runs off of a 5lbs canister of propane and has an automatic Carbon Monoxide cutoff. It gets toasty. It won't last forever, but it's a good emergency backup.

One thing I think everyone needs: An emergency radio with crank power. When the grid goes down, so does internet and cell towers. The only way we got news was via radio.

This is why the technology is best combined with geothermal concepts. You only have to go a few feet deep to get warmth and that solves basically every problem a heat pump has.

Only a few feet deep? Maybe in select areas, but you generally have to go a lot deeper than that. It's been my understanding that the steep cost of geothermal involves the drilling. As much as $80K just to install a decent system, from what I've heard.

Some geothermal systems use deep wells, others use coils of pipe buried a few feet down, below the frost line. If you're lucky enough to have a deep pond or lake nearby, you can put the coils of pipe in that.

In my understanding, it takes more to maintain such setups. Talking to the HVAC guys that do this for a living rather than just the scientists reveal more about the practical realities of these systems.

if you have land a horizontal trench at 7 ft will work just fine. I was going to do this on a new build but building code basically required a heat pump to start with. I was going to put in a cheap furnace for the first year or two and install a ground source heat pump myself, but with the cost of my regular heat pump it will never make sense to change over.

A lot of it depends on how you design the system.

Using the ground as a heat source requires a relatively large installation as you need to make it big enough to draw heat from a large area, even as you use it year after year.

However, you can also use the ground as heat storage, and pump back heat during the summer. This greatly reduces the size, as you are not at risk of "exhausting" it.

Geothermal is just too expensive. Just have a propane or diesel heater around for (hopefully rare) emergencies.

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