[ultra-jeremyx]

Cold climate mini-split heat pumps * I live in northern New England and used to heat exclusively with wood in the winter time. Very cozy, but hard to maintain a consistent temp throughout the house. The new cold-climate models can operate at 100% capacity down to an ambient temp of -13F outdoors. One in each bedroom, the living area, and home office makes it easy to dial in the optimal temp for the space. No more loading the woodstove overnight when everyone is in a bedroom with the door closed!

For the summer, the heat pumps have replaced our terribly inefficient whole-house central AC. We have a PV solar electric system, so we can use the electricity we produce to run them, and once I started paying attention to energy use in our home it was clear that the old central AC had to go.

The modern mini-splits are pretty much maintenance-free, and are warrantied for 12 years. Best off all? The compressors are very quiet. You can have a normal conversation standing right next to them.

[wccrawford]

A word of warning, though: Get someone to install them that is used to installing minisplits.

We didn't know the AC company we chose didn't normally do them. They told us about it, sold us on it, and then royally screwed up the installation. We had them fix it a few times, then they had to basically replace all the inside heads. And even after that, they still aren't right. Some of it is simple incompetence, but some of it had to do with knowing how to install a minisplit in particular.

We're now paying another company to completely replace it, just 2-3 years later. The manufacturer's warranty is gone (Don't buy Lennox! 2 year warranty and garbage hardware!) and the free (warranty) labor from the AC company isn't worth the time and hassle.

[yojo]

I researched the heck out of this before getting one for a rental. Mitsubishi is the way to go if money is no object and you want the most reliable/lowest hassle system.

If you want to save a little money, Daikin is almost as good and a little cheaper. Below that you’re rolling the dice on service calls.

[wccrawford]

Glad to hear you say that. We're getting Mitsubishi this time. It's actually going to replace our downstairs AC and the minisplit.

[Wistar]

Plus, the mini-split recessed in-ceiling cassettes from Mitsubishi are wondrous. No goofy unit hanging on the wall.

[ultra-jeremyx]

We went the Mitsubishi units (I see these and Fuji everywhere) and a certified installer. They add two years to the warranty if you have one of their certified installers do the work. I have high confidence in Mitsubishi being around to honor the warranty.

[awillen]

Same here - Mitsubishi Diamond installer for mini splits that do heat and A/C. Almost two years in and still working perfectly. I believe I have a ten year warranty against most issues.

[wccrawford]

We're getting Mitsubishi this time, so I'm glad to hear that.

[reedjosh]

I installed my own import brand dual minisplit vacuum pump and all. Sounds like you just got a terrible HVAC co the first go round.

[benwilson-512]

I recently installed two MrCool DIY minisplits which worked out great. They come with pre-charged quick connect coolant lines so you can install them without the need for flushing coolant or soldering the lines.

If you're comfortable putting a hole in your house for the line and running power, it can really save a lot of money.

[leadbase0]

Can't stress this enough, especially the hyper heat models: caulked compressors (very high pressure) with phase control injector, not only it runs at very low temps but the performance and COP is linear down to -15C.

Insulation matters more with heat pumps, especially ceiling for cold starts (for descending heat build up from the top) as low temp air heating is not as radiative as IR from traditional heating appliances, or the conventional oil radiators that move air passively.

CO² heat pumps are less impacted due to the much higher air temperature but they are very uncommon for split system (dangerous), and usually used for water heating in AIO unit in a basement.

Had a house electrical failure recently with solar, ran one 18k BTU unit for 60m² on a tiny 5hp Diesel generator sipping 0.4L/hr. (2-4L for Diesel burner in comparison)

These models need proper installation as they use a synthetic proprietary lubricant compared to the commonly used mineral oil, moisture or contamination during tubing installation is a big deal for twin rotary compressors which may reduce service life.

[elric]

This is the first time I've heard that CO2 heat pumps might be dangerous. Can you elaborate on why that is?

[throwaway00127]

Whole-house centralized variable speed heat-pump with zones is actually the most efficient way to heat/cool your home. Also better at circulating air, filtering, dehumidifying, etc.

HVAC companies push multiple mini-splits these days because they're faster to install, and have better margins, even though they're technically not the best solution versus centralized air.

[acconrad]

So if i already have duct work from an old AC I can use that duct work for something like this Mitsubishi Zuba?

[g8oz]

The Mitsubishi Zuba system is a good example of this type.

[PenguinCoder]

So the heat pumps can also do cooling during the summer? What was the ballpark range for three of those, installed?

[gilbetron]

Not the OP, but we had 5 installed last May for $15k US, and they are awesome. Also a big chunk of our cost was due to the fact that two of them required a lot of exterior piping work because they were on the opposite side of the house from the base unit.

Work fantastic in the summer, quiet, work really fast, and pull humidity out as well. In the winter they are great because they allow each room to be its own temp, key for pandemic months where my wife, son, and I all like specific temps.

[ultra-jeremyx]

We had three 6k BTU units, one 12k BTU unit, and one 18k BTU unit and the total cost was ~$18k. We got $1,600 in rebates from the utility for the energy efficiency program.

I am very impressed with how little electricity they use!

[coldpie]

> So the heat pumps can also do cooling during the summer?

Here's a pair of really great videos about heat pumps and what they can (and could, in the future) do:

https://www.youtube.com/watch?v=7J52mDjZzto

https://www.youtube.com/watch?v=7zrx-b2sLUs

[elric]

What do you use for heating water? I'm tempted to switch to mini-split heat pumps for heating, but I'd also like to have hot water. My house is very small and there's basically no room a big hot water tank.

[darksensei]

I have a heat pump (Fujitsu Waterstage) that does central heating via hydronic radiators and can also heat hot water. Annual heating costs are a lot lower than when we had oil based heating. You can also just get hot water heat pumps that are basically heat pumps integrated into a big tank of water.

[Glench]

Ooh which mini-split heat pumps did you end up getting?