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cmui

Mind sharing some details of your install - equipment model/size, controls, and cost of install?

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I'm looking at this 36,000 BTU/h unit for $3,750. Pre-charged line sets make it accessible to homeowners

https://www.amazon.com/dp/B08FGLMZB8?_encoding=UTF8&aaxitk=e...

I installed a MrCool mini split a few years ago and it's still running great in both summer and winter.

Installing one of these is a pretty advanced project for a typical home owner though. You have one chance to get those pre-charged linesets connected perfectly, and if you screw it up, good luck finding an HVAC contractor that will come and help you recover your botched installation of an off-brand heat pump.

That said, there are certainly homeowners who are experienced enough to pull it off, and I'm glad these DIY products exist. I could see potential for further innovation from ElectricAir to make this sort of thing accessible to more people (at a higher cost, obviously, to pay for that sweet sweet design)

The size ratings are confusing. This is really a ~19kbtu unit at 5F. Most homeowners do not want a DIY solution, they want it professionally installed. And this system lacks air quality features (HEPA, fresh air intake, humidifier) and the thermostat.

That really isn't the same product, as I understand this is an HRV combined with heat pump system where they are software integrated to PID controls that optimize the level of fresh air and weather aware energy utilization, with a system like this and a startup I'm sure optimizations like this https://youtu.be/0f9GpMWdvWI?t=432 should be possible - this is like Dropbox, can't expect people to roll their own - and you need a fully integrated system to really make this work well without comfort, even simpler if cooling/heating is more efficient via bringing in fresh air this system could choose to do that vs running the heat pump at all!

Looking at these US prices with envy. Heat pumps are just becoming a thing in Europe and currently installers are looking to earn a quick buck. I've not seen an install under 20k in the UK lately, bolting on to existing radiators. Also Europe seems to be heavily into air-to-water systems.

My wife paid 4000 euros for a heatpump in Finland, last year. Mostly to be used for cooling during the summer, rather than for heating in the winters (since there is "district heating" available for that).

Seemed pretty cheap, and the installation only took a day.

Air-to-air is much cheaper than connecting to water flow radiator system. Radiators aren't that great for cooling anyway.

US (attempted) buyers of air-to-water look with envy to the Nordics, Northern EU, and the UK. My quote in the US was almost double that figure (for an installed system). The parts prices you’re looking at are indeed cheap. The labor is moderate. The profit margins are high.

>are just becoming a thing

where do you life? in germany they are available for years already. friends built new homes with them 5-6 years ago and back then it was already established

in all differen varities. air or with geothermal pipes in your yard (either surface or drilled)

Often you can get EPA certification and all the tools for less. But that system does get good reviews.

Is there a straightforward way to estimate whether a small (24 kbtu), medium (36 kbtu), or large (48 kbtu) unit would be most appropriate for a given home?

For reference for international users, 24 kbtu is 7kW, 36 is 10kW and 48 is 14kW

I'm not a heatpump export, but if that's continuous output, with an SCOP of say 3.8 (what I had quoted in the UK for an airsource -> water -- UK heating is typically hot water run from a boiler through radiators in each room rather than pumping hot (or cool) air direct to the romm via ducted which seems common in the US, perhaps because of the historical desire/need for aircon)

That would require 1.8/2.6/3.7kW of electricity to run. In the UK at 35p/kWh that would mean 91p to generate 10kWh of heat. For reference my oil boiler at 95% efficency and current prices is about 6p/kWh, but we have had insanely high electricity charges this year. Back in September my oil heating approached 10p/kWh -- about £1 a litre.

I hear a lot of horror stories from the UK about this, that people pay upwards of £500 and still cold in their homes. There are a lot of cowboy installers going around but even those who are qualified can't be reached for aftercare/handoff etc. Fiddling with settings at 50p/kWh is not a great experience. On that note I think biopropane will be the solution for Europe.

> I hear a lot of horror stories from the UK about this, that people pay upwards of £500

£500 for what? Total cost for a month? A year? The monthly average of a full year of costs. The monthly average cost thing is common in NL; people often have no clue other than knowing the monthly average cost. And it's often estimated beforehand by the energy company. It's assumed to be correct.

Anyway, people need to check the SCOP instead of figuring out if it is efficient (COP) at a certain temperature.

> On that note I think biopropane will be the solution for Europe.

Oh please no.

On UK, I was in Scotland. I thought the homes in NL are often terrible quality. Scotland was another level. Pretty much no insulation, terrible windows. Really drafty. Yet the media (as a result the public as well) hates the "Insulate Britain" movement.

Why no? Biopropane is fully renewable from biomass but on the other hand people think heating with electricity is somehow cleaner than other methods. Well, electricity production in Europe is not very clean at the moment and not will be (and can't be) renewable-based unless wind and solar conditions change drastically. Large-scale geothermal production is a pipe dream within our lifetimes. So while most homes in Europe are already connected to a pipeline we are demolishing that and figuring out from scratch how to heat drafty homes with heat pumps. I'm just saying maybe, we shouldn't throw out 50+ years of boiler knowledge just like that.

A great deal of the problem is the inability to understand basic maths. This whole nonsense about a £2000 a year cap or whatever, rather than something nice and simple like a 35p/kWh electric cap, or a 7p/kWh gas cap, is both a symptom and the cause.

The number of homes that could have improvements in insulation for tiny costs is astounding, but somehow insulating a home is some lefty woke thing.

I think the proper method used by HVAC companies is called the manual J method. I found a simplified version below but the real thing involved a whole book.

https://www.indeed.com/career-advice/career-development/manu...

This page does the full Manual J, but it is challenging to do and understand. I used it to confirm the estimates that my installer did without a full J workup, and it was helpful.

https://loadcalc.net/

If you have a Nest thermostat, some of the newer models give a usage display of how many minutes per hour they are running. This will tell you how much of your furnace's capacity is running at. For example, if I have a 40kbtu furnace, and I see a maximum of 15 minutes per hour usage on the furnace during a heating season, that means my usage maxes out at roughly 10kbtu. I might choose my heat pump based on that capacity; if I got a 10kbtu heat pump, I would expect it to be running continuously during the maximum usage time.

Not at the moment, working on a tool like this for the preorder site! There are btu/sq.ft. rules of thumbs that are not appropriate for heat pumps (you can easily oversize by 100%).

10-20 W/m2 is modern warm house, 30-40 - modernish house or well insulated old house, 60 - barely insulated, 100 - no insulation. Roughly.

Assuming they mean kbtu/h continuous and not kbtu, 12kbtu/h is ~3.5kW. So, 7, 10, 14 KW units.

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