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Launch HN: Electric Air (YC W23) – Heat pump sold directly to homeowners

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Re: Launch HN: Electric Air (YC W23) – Heat pump sold directly to homeowners

#401

Post by raisedbyninjas »

coryrc wrote: post #363
vladgur wrote: post #234

Earlier quoted context omitted.

I agree. Use standardized wiring and let me control it from a $100 smart thermostat that i can replace if it becomes obsolete. If i want HomeAssistant integration, ill buy an HA-compatible thermostat. I dont want an expensive HVAC system to be in a walled garden of its own.

You lose about 30% efficiency using "standardized wiring" with an inverter heat pump instead of a communicating thermostat, because running a heat pump at 33% power continuously instead of 100% power 20 minutes of every hour results in a COP about 30% higher.

Why do inverter heat pump need proprietary wiring? Everything I've seen indicates inverter and dual stage heat pumps can use standard wiring.

Re: Launch HN: Electric Air (YC W23) – Heat pump sold directly to homeowners

#402

Post by sosodev »

cmui wrote: post #337
sosodev wrote: post #151

Earlier quoted context omitted.

When you say it's rated at 47F do you mean its efficiency is measured at 47F? If so, does that matter much? The unit linked in the post you're replying to states that it can operate as low as -13F.

Talking about capacity for heat pumps is tricky, their available heating power changes continuously as a function of outdoor temperature. The convention is to refer to the available capacity at 47F for 'normal' heat pump and the capacity at 5F for a cold climate heat pump.

Makes sense. How much does their capacity typically change over their operating temperature range?

Re: Launch HN: Electric Air (YC W23) – Heat pump sold directly to homeowners

#403

Post by pkulak »

cmui wrote: post #195
ukd1 wrote: post #165

Earlier quoted context omitted.

HA user here as well, having a non-locked down API at minimum (i.e. not actively trying to stop folks using it), through to an open and documented api (would be great), through to open firmware (would be best) and or releasing your own integration for HA would likely get you those kinda customers.

If people have a preferred way of integrating their devices, like home assistant, I'd want to make that possible for people to do with Electric Air. Re the sizing question - this is a part of the site that needs improvement. 12kbtu is 1 ton. The 48kbtu system is a 4ton system, but rated at 5F, if you're in a more temperate climate, two of these will likely have plenty of capacity for you. It's also likely that your c…

The good news, at least, is that almost anything will work. You don't need full Matter support for Home Assistant folks to be happy. The bare-minimum, local REST api built on a Monday by an intern will do it. Someone will write the Python code to fully integrate it. I get that there would be some security concerns there, but you get my drift.

Re: Launch HN: Electric Air (YC W23) – Heat pump sold directly to homeowners

#404

Post by tgtweak »

jakedata wrote: post #370

You should give some thought to offering an AC-DC power supply. Being able to dedicate several solar panels directly to heating or cooling might get people out of a regulatory bind with crazy interconnect fees and local regulations. The trick would be to supply supplemental DC solar power in a manner that would not be considered grid-tied. That would eliminate a whole level of installation costs, permitting fees and…

Most ultra high efficiency heat pumps are already using DC inverter technology which allows the compressor, fans and pumps to run on fully variable speed. If Electric Air is planning on using DC components for their heat pumps, they could make it DC powered as well. The issue is that it would increase cost substantially for people who don't necessarily need it since a 5KW class DC controller (to run the aforementioned off of solar) would add a good chunk to the bill of materials. It would also add a lot of complexity to the system. Lastly, it is only really practical in hotter summer climates for cooling where your cooling demand and sunshine line up nicely. In heating applications, you need the most power when it is cold out (in the middle of the night) and so the demand and generation is almost fully inverted.

One feature that would be great (and universally practical) is using the heat pump to heat water with the waste heat from air conditioning in the summer (or when any time the house doesn't need the air heated). Add to this the fact that heat-pump water heaters are in the $2000 range, and eligible for many credits - it could be a great add-on.

Re: Launch HN: Electric Air (YC W23) – Heat pump sold directly to homeowners

#406

Post by izolate »

hunter2_ wrote: post #328
izolate wrote: post #152

I live in Buffalo NY, and from the recent record-breaking snowstorms, I've concluded that the push for electrification of home appliances may not be the best solution. Although gas furnaces still require electricity, they can operate for a more extended period on a generator, and gas stoves are a crucial backup option for staying warm during a power outage. Until our electricity grid becomes more reliable, I would he…

> gas stoves are a crucial backup option for staying warm during a power outage Isn't CO (and other combustion byproducts) an issue? When cooking a meal the duration is short enough to not matter much, but at extended durations to provide heat I would think this is a bad idea, unless you monitor air quality enough to run a vented range hood at the optimization point between unhealthy and wasting most of the heat you'…

I agree that these byproducts can be an issue. However, in the context of a life-threatening situation like a power blackout in a blizzard, where the alternative is death from exposure to the cold, running a gas stove for a long duration may be an acceptable risk.

Re: Launch HN: Electric Air (YC W23) – Heat pump sold directly to homeowners

#409

Post by surfmike »

itake wrote: post #298
thehappypm wrote: post #143

Earlier quoted context omitted.

Counterpoint — I have an app for my Mitsubishi heat pump and use it all the time. It’s way more convenient and lets me hyper optimize my house. I actually don’t even use the physical ones at all anymore

What is your plan if Mitsubishi cuts off access in 20 years or updates in a way that you're not comfortable with (like add advertisements to the panels)?

You can replace the thermostats with dumb versions.

Re: Launch HN: Electric Air (YC W23) – Heat pump sold directly to homeowners

#410

Post by tgtweak »

rcme wrote: post #55
signaturefish wrote: post #37

Earlier quoted context omitted.

In the context of heat pumps, a "backup heating strip" is a resistive heating element - electricity goes in, heat comes out just like an old electric heater. They're generally used during defrost cycles for the external air handler in cold weather, or to provide a temporary thermal boost when the heat pump is having performance trouble e.g. when the exterior temperature is near the bottom of the heat pump's operating…

Whole-house heating with resistive electric heating is going to get expensive, quickly. If they're serious about installing these in cold weather climates, they should have more information about the cut over temperature and the efficiency of the heat pumps at those temperatures. Just for context, my heat pumps cut over around 40-45 degrees to gas-based heat.

High efficiency heat pumps with built-in defrosters (or "heating strips") can often provide full heating capacity (ie: 48,000btu for a 4 ton unit) down to -12f, with reduced output at even lower temps. The COP efficiency drops quite a bit though and it will eventually get to a point where it is essentially as energy efficient as a resistive heater. Whether it's more efficient than using gas or not is a difficult calculation based on your gas price, heat pump COP temperature curve and electricity price. If you expect to see <-20f temperatures regularly, you'll want/need a backup heat source anyway.
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