Hacker News Reader

Comment by rgmerk | Hacker News Reader

Indeed, though in colder climates you do have the problem that peak electricity demand is precisely when you get minimum solar production.

But in sunnier, warmer parts of the world (which notably includes India, Pakistan, Bangladesh, Indonesia, Nigeria, Egypt, Ethiopia, Iran, Mexico, and Brazil, amongst others), over the next few decades it's hard to see anything much competing against solar and batteries for the bulk of energy usage.

View on HN

That isn’t true yet, because most cold places don’t use electricity for heating; in Boston for example the norm is oil or gas furnaces. Europe typically uses gas for heating, as we all learned during the Ukraine war’s beginning. When I lived in the Boston area, our electricity use, peaked in the summer during air-conditioning season. That is, until we got a heat pump, then our electricity spiked like crazy in the winter. but we are long way from having the majority of homeowners using heat pumps for their primary heat source. (Also heat pumps are kinda awful compared to furnaces in my experience so we might never get there).

>heat pumps are kinda awful

Heat pumps work great under the right circumstances. In cold climates like Boston and north of it, ideally you want ground source, which means digging deep (or wide) holes to flow water through instead of just pulling heat from outside air. Alternatively, (or additionally, ideally) they're best used in homes with very tight air envelopes, good insulation, and heat/energy recovery ventilation (HRV/ERV) systems. Installed in radiant heating systems in well-built houses, heat pumps are fantastic and you'll be comfortable all year for pennies on the dollar.

The reality is that most (US) construction, especially older, is just terrible in terms of air seal and insulation. Couple that with a potentially undersized air-source heat pump, which gets inefficient as the outside temp gets near the low end of its operating range, and you will not have a great time. But even then they are a good way to supplement gas heating, so you can limit furnace use to the coldest weeks of the year and do the environment a favor, as well as cool in the summer.

The issue with supplementing with gas is that you still need a gas furnace. And if you have a gas furnace, why spend $10k+ on a heat pump?

You shouldn't spend that much. If you need an air conditioning system, making it a bidirectional heat pump is negligible unless people are trying to rip you off. (They are)

Are you one of the grifters or just confused?

Comparing a cold-climate AC to a cold climate heat pump shows how confused YOU are.

ACs in cold climates are cheap. Cooling a house down 20 degrees doesnt take a lot of BTUs. Plus they’re just cheaper per-BTU and a typical northeast homeowner is going to be comfortable installing a cheap brand because it’s not life-or-death if your AC goes out.

When you start talking about having a heat pump being the primary heat source in a cold climate home, that’s a different ball game. First you need WAY more BTUs to heat a house in winter lows — even NYC hits single-digits most winters, that’s a 60 degree temperature differential. And you need to be prepared for the worst temperatures which basically necessitates a top-end brand like Mitsubishi which is rated down to historic-ish lows.

Not to mention that many homes don’t have central ducts, so converting to a heat pump means ductwork or mini splits..

All in all it’s not really a negligible thing.

No, the difference in cost between central air conditioning (a heat pump that works in one direction) and a heat pump that works in both directions is negligable unless you're being ripped off.

Just saying something doesn’t make it true.

Here’s a concrete example that took 5 minutes to find. Two condensers from the same company, same seller, same SEER, same series, same tonnage, except the second does heat. The heat pump is 29% more expensive.

2 Ton 14.3 SEER2 Trane Air Conditioner Condenser - RT Series. $1615

2 Ton 14.3 SEER2 Trane Heat Pump Condenser - RT Series. $2090

https://hvacdirect.com/trane-a4ac4024d1-2-ton-14-3-seer2-air...

https://hvacdirect.com/trane-a4hp4024d1-2-ton-14-3-seer2-hea...

That very quickly pays for itself.

Goalposts movin’ like crazy

Goalposts haven't moved. Refer to my first post and stop spreading FUD about heat pumps.

You’re spreading the FUD

There's a green trend in much of central-north europe to use electric heating, mainly by promoting air heat pumps.

And despite the handwringing, air source heat pumps can work fine in pretty cold places (eg Norway).

You can, right now, buy air source heat pumps rated to -28C (-14F). While not enough for record lows in, say, Chicago or Toronto, it's plenty for places like New York, Seattle, and Vancouver.

Rated to -14F doesn’t really bring a lot of comfort. NYC has reached that temperature; NJ has reached -34. In a typical winter you might stay above zero every minute of every day. But when that big arctic blast comes through and your heat pump efficiency tanks, right at the same time your house is bleeding its heat faster than ever, that could be pretty dangerous. So, every heat pump installer recommends a having a backup (at least the dozen I’ve talked to in the Northeast US). it’s hard to convince regular people that heat pumps are the future when you’re also told to have a backup.

This year I installed a heat pump with a 10kW auxiliary heater for my home in southern Ontario. With an appropriate air handler, both the heat pump and auxiliary heater can run at the same time. The setup seems fine to me.

If anything having a backup heat source makes me feel secure. A lot of things can go wrong with a gas furnace; some things can go wrong with a heat pump; but 10kW of electric restive heat is dead simple and just by itself it can provide 34000 BTU/h, which is 60% of the output of my old gas furnace. I don't think the duty cycle of my gas furnace ever exceeded 60% running time.

The auxiliary heater consists of two 5kW heaters, so even if one fails, there is still the other.

Do you worry about losing electricity though? A bad blizzard that knocks out power could be dangerous.

That is a worry. Of course a power outage would also knock out my old gas furnace too. Without the blower running, etc. the gas furnace wouldn't run.

True, but you could always have a battery back up for the blower and such.

Do you have a wood burning back up? At my house in Massachusetts, we had a wood-burning stove that we could always fire up in a pinch. It never came to that, but it felt good knowing that we can always just burn a super hot fire and not freeze to death.

While I could have had a battery backup for the blower, I never did, so I guess I'm not missing out. :)

I live in an urban environment, so I'm not too worried about losing power for an extended period of time, and if I do I would probably just leave temporarily.

In my rural living fantasy I have a Ford F150 Lightning which I use as a "portable" backup battery that can be recharged by driving it to a Level 3 charging station. That and either a pellet stove and/or a Masonry Heater fireplace that sits opposite to a large equator (south) facing window.

It sounds like you're suffering from the typical grift where contractors over-charge because they don't want to do the work you're asking for. This is common but its a problem with contractors. The standard way to build in the US involves illegal immigrants doing poor quality work.

If there is a heat pump rated to -14F and an area has historic lows of -34F it sounds like a bit more than just grifting going on. These people are setting up a system where, if everything works to spec, the customer may well freeze to death one winter.

I don't know much about how heat pump performance degrades, but going in to a life-and-death situation where the main heat system is operating outside rated performance seems like poor planning.

No one is going to install a system that puts you in a life or death situation. Worst case is it uses resistive heating to deal with extreme cold. Systems like that are widespread and still save people money.

Sounds like a grift

Despite being effective at low temperatures when properly sized, and with traditional heating when needed, they aren't efficient during the coldest days when you have a leaky house. That's where ground source systems clean up.

My main issue with GS is the complexity. gas furnaces are pretty bulletproof; in my experience they are really reliable and east to fix (or just replace in a one-day job) if there are issues. Air source is a little more complicated to fix but not too bad. Ground source though, part of the system is literally buried underground!

The buried part will never need fixing unless you build it on a fault line or elon musk tries to dig a hyperloop under your house.

> But in sunnier, warmer parts of the world

Though solar panels prefer if it isn't too hot. Still, any such inefficiencies are easily outweighed by their low cost. In Netherlands it is common to install practice (and advised) more Wp than the inverter can handle. Maybe also a solution if it gets too hot, make it up by having more panels.

Reply on news.ycombinator.com