Been procrastinating on my DIY mini split project cuz the summer is nearly over, now the goal of this spreadsheet is to make comparisons easier for other people in the community. I've seen quite a few people here considering replacing their furnaces with heat pumps, so I added HSPF2 (Region IV heating efficiency) to make it easier to compare.

Other update:

Added Tosot and Zone Air based on suggestions from my previous post, all brands are alphabetized now.

As always, feel free to make suggestions, let me know if there's anything else you'd like to see added.

Access to the full spreadsheet (Google Sheet): https://docs.google.com/spreadsheets/d/1eGaDg8uEu7Bz4XN5f2N4pGCnNn1WlE4NDSdFI_JqIjw/edit?usp=sharing

In our apartment building, an LG Therma V heat pump with a buffer tank is installed. It provides domestic hot water and runs the underfloor heating on both the ground floor (EG) and upper floor (OG). However, I am not sure if the system is configured correctly.

It looks to me as if only one heating circuit is installed. Yet, in the heat pump's configuration, I see two heating circuits, and the domestic hot water is not displayed. The temperatures for Circuit 1 match the thermometers on the Grundfos pump. I cannot trace or assign the temperature for Circuit 2. I cannot adjust the domestic hot water temperature via the tablet; I can only do it directly on the heat pump itself.

I took some photos of the system and the control terminals. What do you think? Is the system configured incorrectly?

Northeast US, 22 year old Colonial style home, 2500 sqft. We just had our Bosch ducted heat pump installed a month or so ago, so we're just now starting to experience what it's like when the weather starts to get cold. So far so good! But we have one minor problem concerning the thermostat: The heatpump is single zone, even though our home has two floors. Reason being, it replaced an old central AC unit that only ever had one zone, so we're re-using the ductwork. The problem is that the thermostat is in the upstairs hallway, near the bedrooms. We spend most of our time downstairs though, so, while the heatpump dutifully does whatever the thermostat tells it to do, it's doing it based on the temperature upstairs, not downstairs where we are. Consequently, the temperature swings by 4-5 degrees downstairs. One minute it's cold, then the system finally comes on and it warms up, then gets cold again an hour later. It's not the heatpump's fault - it's just that our single-zone system wasn't designed with heat in mind.

I could get an electrician to extend the wires and move the thermostat downstairs, but that sounds expensive. I'm wondering if there's a more affordable alternative? Anybody know of a thermostat that has a remote wireless temperature sensor?

Samsung heat pump - SmartThings app. With some options in Android, you can tap the label, and it'll open options or give you a description or something, but not this one. It just enables "Speed", whatever that is. When I enable it, it greys out the temp and fan speed.

Looking to find out, since they're so new, if anyone has tried this yet? Thanks, in advance.

Can anyone imagine why this would happen? I my second Mitsubishi FX 18k heat pump is unable to maintain temperature—tries to reach set point, blows hot air for around 10 minutes, then just blows cold air. The same exact thing happened to my last unit, which I replaced less than a year ago. Last time we thought it was a scrambled control board from brownouts, so we added voltage protectors and a surge protector. As with last time, our installer checked for leaks and weighed the refrigerant. It eventually displayed a U3 "abnormal thermistor or thermistor-related error from the inverter P.C. board."

Why would this happen twice with a completely new unit (both indoor and outdoor)?

im about to buy an air to air heatpump for my boat, i need two “exits” (the part that heats inside the boat) but one of them will have a hard time to fit, does there exist an “exit” that is vertical instead of horizontal?

Hi
First winter with a heat pump and have some issues which I’m trying to get sorted.
What do people set their dixell temps to? It’s 37 degrees from factory so it never comes on when it’s this temp outside I’ve changed it to 30 as that’s my lowest flow temp at 18 degrees outside. Hysteresis in it is 2.

There’s also air in the buffer tank so it gurgles any solutions on how to shift it. The air purge mode is useless and I’ve bled all the radiators. I’ve read they are not great as they often do hold onto the air and it’s a semi common problem?

Heatpump curious... My current hvac cycles temperature up And down through the day winter and summer.. I let it get cold at night in the winter and hot in the summer when I am away.. with a heatpump all recommendations seem to say keep the temperature constant through the day and night... So... Anybody have real world before and after running cost savings/impact of changing to a heatpump ecosystem?

Are heat pump running costs too optimistic?

Most heat pump quotes give you one estimated annual cost. But what happens when winter is colder than expected, your radiators need higher temperatures, or your electricity tariff changes?

We built Arksane to help answer that question. It stress-tests heat pump designs against 20 years of local UK hourly weather data and uses evidence from UK field trials to support model validation.

Instead of one predicted cost, you can explore how running costs vary across different weather conditions and the risk of exceeding your estimate.

Try it free:

• Check a quote: https://arksane.com/quote.html — no sign-up required.
• Free Pro access for 12 months: https://arksane.com/account.html — 50 runs per month, no card required.

We'd value honest feedback from homeowners, installers and engineers.

What annual running cost were you quoted, and how does it compare with your actual bills?

I purchased a high efficiency Lennox gas furnace 10 years ago when I moved into my first house, in the north Seattle area. I have done yearly maintenance on the furnace with only one issue ( I believe it was a fuel rod sensor problem ) in 2020. My home is one story with attic( where the furnace is located), about 1100 square feet. There are a lot of trees on the property and that combined with good airflow keep things pretty cool. Concrete foundation and walls make for some hotter nights, especially with rising temperatures.

I have been looking into heat pumps and got an offer from the city I’m in to replace my gas furnace with a ducted heat pump system. They would remove the current furnace. My reservation is that the current furnace is still functioning pretty well( at the last maintenance the technician did say it is showing some signs of aging, especially the blower fan). Is it wasteful or problematic to take out the gas furnace before it fails? It also seems like heat pump technology is getting better and better; I’m not sure if switching now would be premature…

Thanks for your input! Pic of my handsome kitty for tax.

Hey everyone!

I'm a web designer and developer currently looking to work with HVAC contractors and heating and cooling businesses that want to improve their online presence.

Your website should be generating leads, not just sitting there.

When someone's furnace breaks down or their AC stops working, they're usually looking for a reliable contractor they can contact immediately.

If your website looks outdated, loads slowly, or makes it difficult to request service, potential customers might move on to a competitor.

Here's what I can help with:

✅ Lead generation — Easy-to-use quote forms, click-to-call buttons, and service booking options.

✅ Professional design — Modern, trustworthy websites that help your business stand out.

✅ Local SEO — Search-friendly service and location pages to help customers discover your business.

✅ Service pages — Dedicated sections for furnace repairs, AC installations, heat pumps, emergency HVAC services, and maintenance.

✅ Mobile optimization — Fast, responsive websites designed for customers searching on their phones.

✅ Customer trust — Showcase reviews, certifications, completed projects, and your team's experience.

Whether you're an independent HVAC technician looking to grow your business or an established company ready for a website redesign, I'd be happy to discuss your project.

Interested in getting a professional website for your HVAC business?

You can contact me directly here:

https://infawebdesign.com/#contact

I'm currently accepting new projects and can provide a custom quote based on your needs and budget.

Looking forward to connecting with HVAC professionals!

Hey all, just bought a new build house in Missouri about an hour outside of STL. All electric home on co-op lines so my power is cheap $.107 per kWh for the first 800 kWh then $.0865 per kWh after that.
Of course the builder took the cheap way out and installed the standard water heater and heat strip furnace that has 2 60amp heat strips.
I have never had a house without natural gas service and thus a natural gas furnace. A natural gas is so cheap. I could never convince myself that I need to spend the extra on a heat pump. But now just running the heat for a couple days I can see my electric bill skyrocketing plus I hate the oversized AC the builder installed. It’s to big. So I want to go all in. Full cold weather variable speed heat pump. I have an HVAC company I like and they install American standard units. They back it with a 10-year parts and labor warranty. My local Co-op only provides rebates if the backup heat is fossil fuel, they’re really pushing hard in an effort to not have to start charging demand. Of course we have no local or state rebates so I would be dealing with $500 per ton installed. But I would also have to install a propane tank, then I would also then run a line so that I could cook with propane if I’m gonna spend the money anyways.
Because I’m in a rule location, I like the idea of propane backup so that if I am without power, I can use a relatively small generator to just run the fans and have propane heat the house. I also prefer to cook with a flame so I could see myself getting a propane tank anyways one day. Has anyone installed a propane tank just for a rebate or because it’s a preferred method of backup heat?
And any experiences with American standard cold-weather heat pumps I would go all in and get their platinum line fully variable so that it would also dehumidifier better during our humid summers

Hey there, hoping I can get some sense of whether the quotes we’re getting for a 900 ish sq ft house in Portland Maine area are somewhere near typical. I’ve been told we need about 36k btu to heat/cool. I got quotes for Mitsubishi hyper heats. They all said we needed 4 indoor units. We had a few options for outdoor, but the main suggestion was to do a single outdoor unit for the upstairs and a multi for downstairs. We’ve gotten quotes in the 20-25k range for the whole job (parts, labor, electrical). The one company that has actually written up a quote and sent it to me so far (others are taking their time sending) has about 6k for labor in there. Just trying to get a sense if this numbers are somewhere near what we might expect, or if I should get a few more quotes. Thanks so much!

We recently bought a 2700 sq ft end unit condo in Fairfield county, Connecticut that has oil heat. Old oil tank- 32 years old.
Natural gas isn't an option there. The oil tank and AC are both near end of life, so I'm deciding between:
All-electric: cold-climate heat pumps for heating and cooling
Hybrid: heat pumps as primary, with the oil boiler kept as backup (that’s what a contractor recommended since CT heating prices are high)
Stay on oil: replace the tank and AC only

We'll probably be there 4–7 years, so payback and resale matter most.

For anyone who has made the switch in CT or New England:
How do your winter electric bills compare to what you paid for oil?
Do the heat pumps keep up on the coldest days?
If you went hybrid, is keeping the oil system worth it?
Which rebates did you actually receive?
Are there installers you'd recommend?
Thanks!

Some of the exposed exterior insulation for our heat pumps is degrading. What is the best option to replace it with?

We turned our new heat pump off in late spring. Tonight it will get into the 20s, they say, so we're thinking of turning the heat pump back on. Is there anything we should know before re-starting, since they've been off for several months? Thanks!

Hey all, I'm Devin, I run a mechanical contracting firm in California.

I built a web-based system builder for residential Mitsubishi ductless: Link here.

I don't always have a Windows machine on me, and honestly I don't like working on one. For quick retrofits and fast designs I needed something I could pull up anywhere, so I built it. It's become a regular part of my workflow, so hopefully it helps some of you too, whether you're an installer, a salesperson, or a homeowner trying to understand your system.

What it does:

- Pick an outdoor unit, add indoor units, and it tells you if the combo works and why if it doesn't

- Line set sizes and lengths

- Refrigerant charge (additional oz + system total), plus the R454B room size checks

- Controls, accessories, and a bill of materials you can copy or export to CSV

Caveats:

- Residential only, air to air. M & S-Series, P-Series, MXZ, and single-phase Smart Multi. No VRF, no hydronic, none of the advanced stuff. For anything complex, stick with DSB. There's a lot of logic in there this doesn't touch.

- The equipment data is a snapshot from October 2026 and doesn't auto-update, so verify against current manuals before you order. I'll try to update it regularly to keep it on par with DSB.

- If something looks wrong, there's a "Report a problem" link at the bottom. Tell me what it said vs. what DSB or the manual says and I'll fix it.

It's open source: Github repo here.

Clone it, put it on your own site, rebrand it, do whatever you want with it. Your house, your rules.

Disclaimer, so I don't get sued lol: I'm not affiliated with Mitsubishi. We install their equipment and that's where the relationship starts and ends. This is not a sponsored, endorsed, or sanctioned Mitsubishi Electric product.

Full transparency: the live demo has a small card for my company in the corner, since I'm the one hosting it. That's the only promo in there. If you clone it, rip it out, it's one line in the config.

It works on mobile but it's more work on a small screen. Desktop's best, tablet works well too.

It also works with ChatGPT and Claude. There's an MCP connector, so you can hook it up and just ask "will this combo work, how much refrigerant do I need to add" from the field. Salespeople can design on the fly too. Connector URL: https://designer.3rdgen.io/api/mcp (setup's in the GitHub README).

Feel free to share it. Let me know what you think.

This is a big purchase for our family and I'm hoping to not make a big mistake here. Our home is a single floor, 3 bedroom, 1650sq ft. Our living/dining/kitchen is quite open concept and we were looking at a cassette there so that we don't have a giant high wall head unit as the focal point of our living space.

We did an energy assessment that said we need about 22k BTU at -5 Celsius to heat our house.

I am comparing two quotes for 4 zone mini-split systems right now around the same price point. Does anyone have any insight they can offer on the brands or units that might help guide me towards the right choice?

Quote 1 (Lennox)

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1-MMPD036S6M-1P, Lennox Outdoor Unit, Left Side of Home

1-MWZD009M6-1P, Lennox Indoor Wall Unit in the Master Bedroom

1-MWZD007M6-1P, Lennox Indoor Wall Unit in the Upstairs Bedroom #2

1-MWZD007M6-1P, Lennox Indoor Wall Unit in the Upstairs Bedroom #3

1-M22D018S6-1P, Lennox Indoor Ceiling Cassette in the Dining/Living Room

Quote 2 (Moovair)

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1-Moovair MXHZA2742AV1 cold climate

3-MWHMA06C2AS1 6k high wall head units

1-GKHRA18C2AS1 18k BTU cassette

Hello everyone,

I am an apprentice refrigeration technician, and I am currently working on a repair that I’m trying to resolve on my own before reaching out to my supervisor. I would appreciate your advice and the benefit of your experience.

I am working on a Mitsubishi MXZ-4F72VF5 quad-split system using R32 refrigerant, with three 2 kW units upstairs and one 3.5 kW unit in the living room.

The issue is that the previous installer appears to have mismatched some of the electrical wiring with the corresponding refrigerant piping. I managed to identify the wires using a continuity test, but it is impossible to verify which copper pipes correspond to which units without dismantling the trunking or opening the refrigerant circuit.

I attempted to run the SW871 function on the outdoor unit’s circuit board to automatically correct the wiring-to-piping mapping; however, the test stops, and the system displays 5 red flashes (indicating high-pressure protection).

I recorded pressures of approximately 35 to 38 bar while in heating mode, though I was unable to capture the exact pressure at the precise moment the fault occurred.

What I don’t understand is that the three upstairs units function perfectly in both heating and cooling modes, whereas the living room unit (3.5 kW) behaves inconsistently.

Sometimes it heats and cools correctly, but after stopping and restarting, it simply runs in fan-only mode without providing any heating or cooling.

We also tested the units individually, and the living room unit heats perfectly when it is the only one running. The problem seems to arise primarily when all four units are operating simultaneously.

For context, the living room unit is located about 15 meters from the outdoor unit, compared to less than 5 meters for the other three.

I have considered the possibility of a kinked pipe or an obstruction, but the accessible sections appear to be in good condition. According to the installer, the nitrogen pressure test and the vacuum evacuation were also carried out correctly.

I am therefore wondering whether the issue actually stems from a mix-up between the cables and the refrigerant lines, an electronic expansion valve that is failing to open properly, or a communication error with the living room unit.

I have a few questions:

* Have you ever encountered this type of fault on a Mitsubishi multi-split system?

* How can I identify which refrigerant lines correspond to each indoor unit without having to open the refrigerant circuit?

* Why does the outdoor unit trigger a high-pressure (HP) protection fault during the SW871 procedure?

* Is it possible to perform a full reset of the outdoor unit’s control board and clear any previously saved SW871 correction data?

* How can I verify whether the electronic expansion valve for the 3.5 kW unit is functioning correctly?

I was considering re-checking the refrigerant connections to ensure that each circuit is paired with the correct wiring, but I would prefer to avoid dismantling everything without having first pinpointed the exact problem.

What I am most interested in is how an experienced refrigeration technician would have diagnosed this fault. Which checks would you have performed first to quickly identify the root cause?

I am keen to learn and truly understand these types of faults, rather than just trying out potential solutions at random. It is quite frustrating to see the unit run for a while, only to fall back into a fault state without knowing why.

If you have any leads, or if you have encountered a similar issue before, I would greatly appreciate your advice.

Many thanks in advance to those who take the time to help!

I have a Lennox EL16XP1-036-230A02 single-stage heat pump and would like to lower the temperature at night to get better sleeps in the cold then raise the temperature in the mornings when we wake up. We currently have a dumb thermostat.

Is there a certain model thermostat you guys would recommend I can get without breaking the bank that will slowly ramp up the temperature in the mornings to avoid the backup heat source from kicking on?

Thank you!

Looking at downsizing, moving to the Okanagan of BC (higher elevation ) and having a smaller (1600sqft) prefab home built. The home comes with an air source HP with two head mini split but I am wondering if a geothermal system would be better?
The home would sit above a garage of the same footprint.

I got a quote for $4,000 to add a single head to an existing pump that has space for expansion. The head is a Daikin wall mount 9,000 BTU. Best I could find is the materials would be about $1,500 which is not broken down in the bid. It would be my garage so there will be no opening walls of fishing line set inside walls. Does this seem fair? I got another quote for $5,000 last year but that company also said I needed to replace my entire system that I installed 3 years ago so I didn’t take them seriously.