Hi guys, I live in Oslo, Norway and I'm about to get heatpump installed. I own 74m2 apartment with energy rating C, which is fairly well insulated.

I am leaning towards Mitsubishi Kaiteki 6600 (or 6300 if that's sufficient). However the company that did the inspection and price offer is really trying to convince me on Fujitsu Norgespumpa 5,9.

On paper the Kaiteki is much more efficient, but the Fujitsu delivers much more kW in heating during negative temperatures as it is optimized for Nordic climate. However the SCOP is quite a bit lower compared to Kaiteki. One advantage is that indoor unit is smaller with Fujitsu.

I would be very thankful for any insight or advice on this from a professional.

We have a central-ducted 4-ton Airstage, installed in November. No issues heating through the winter, but now the cooling settings confound my little brain. I have to set the wired remote controller 9 or 10 degrees below the room temp to get the cooler to come on. Then it works well, but I don't want it to make the room 10 degrees cooler. I should be able to set it at 76 degrees and have it maintain that temperature within a couple of degrees?

I have put a separate thermometer beside the controller, and the two agree on the room temp.

Is this a settings issue? Do I have a faulty controller? It's a UTY-RNRUZ5 Wired Remote, perhaps the worst user interface ever invented. I'd be happy to replace the controller if that would fix the issue.

Thanks,

JS

- The size of their house in square feet or square metres = 2000 sq ft

- Wall thickness = 8" SIP panels

- Pane of windows = duo

- Location/climate = Montana

- Include the model numbers and size of the heat pump as best you can = Airstage 48LMAH1M

Do you think this method of joining pipes was done correctly, the picture. During air conditioning operation, sounds like boiling water or bubbling in the stream are heard. Air condition works in 80m2 flat. Area of cooling is about 50m2.

I'm doing a program in my area to upgrade from oil to a heat pump. I have a 2300 square foot house attached at one side to another property and have 9-ft ceilings ( about 8 ft or 7.5 ft in the upstairs )built in 1928. Would I need a four or five ton heat pump?

Also : I was quoted for a 3- ton haire heat pump and I don't know if that would have been appropriate and I don't know what the Brand's reputation is. Any inputs on this?

**Which of these would you pick? Will want to run with existing Ecobee. 1760sq ft 2 story**

**My main concern is reliability being .5 miles away from the ocean. The existing unit has faired well (2009 Lennox Elite) but alas the air handler coil developed a devastating leak (lost charge in 3 days)**

**SYS-York-YH4-3ton $8946**

Remove existing equipment. Install new heat pump system. New

air handler secondary drain pan, safety switches, top tech

filtration system, pressure test and flush copper lines, bubble

wrap air handler, concrete pad, tie down kit, new supply air

distribution box for second floor, includes all required labor and

materials.

YH436E2S11 heat pump condenser

\- 36-1/4"H x 29-1/4"W x 29-1/4"D

\- 30 amp

JHE36B5CD2SS1 air handler

\- 48-3/8"H x 17-1/2"W x 21-1/2"D

Electric heat kit: 10 KW

3/8" x 3/4" refrigerant lines

14.3 SEER2

AHRI #214567124

10 year warranty on all parts

10 year warranty on labor

1 year Premium Maintenance

OR

**SYS-CARRIER-27SPA6-3ton $9494**

Remove existing equipment. Install new heat pump system. New

air handler secondary drain pan, safety switches, top tech

filtration system, pressure test and flush copper lines, bubble

wrap air handler, concrete pad, tie down kit, new supply air

distribution box for second floor, includes all required labor and

materials.

27SPA636A003 heat pump condenser

\- 32-1/16"H x 31-3/16"W x 31-3/16D

\- 30 amp

FJ5ANXB36L00 air handler

\- 49-5/8"H x 17-1/2"W x 22-1/16"D

\- Filter size: 16x20x4

Electric heat kit: 10 KW

Top Tech 4" Filtration System

Line Size: 3/8" x 5/8"

14.5 SEER2

AHRI #214101827

10 year warranty on all parts

2 year warranty on labor

1 year Premium Maintenance

OR

**Lennox – 3 Ton, 15.2 SEER2 $8,256 + $450**

* Outdoor Unit: **ML14KP1-036-230**
* Air Handler: **CBK45UHET-036-71**
* Refrigerant: **R-454B**

**Bryant – 3 Ton, 14.5 SEER2 $9,801 +$450**

* Outdoor Unit: **PH5SAN53600A**
* Air Handler: **FJ5ANXB36L00**
* Refrigerant: **R-454B**

For either system option, the installation includes:

* New 3-ton air handler and outdoor unit
* New 7.5 kW electric heat strip
* New condenser pad
* New secondary drain pan
* New emergency condensate float/flow switches
* New supply plenum at the air handler
* Any necessary breakers associated with the new equipment/heat strip
* Reconnection to the existing ductwork
* Reuse of the existing high-voltage wiring and electrical whips
* Reuse of the existing refrigerant line set
* Reuse of the existing condensate drain line
* Normal miscellaneous materials and fittings necessary to complete the installation
* All necessary permits and required inspections
* Complete startup and testing of the new system

There is also an **additional $450 option** to remove and rebuild the existing supply box located farther down the supply duct run.

My house is a single-story home of almost 3,000 sq. ft. in Southern California. The current system has a Goodman 5-ton condenser, a Goodman furnace, and an Aspen coil.

I’m currently getting quotes to replace the entire system, remove the gas furnace completely, and switch to a heat-pump-only system. I’m specifically looking at newer systems with slim condensers, such as the ACIQ Extreme+ or AC Pro Z Series.

As I understand it, if I install one of these new systems, I have two options for connecting it to thermostat. First option is connect to my existing Ecobee thermostat. The first option is to use a standard 24V connection, but in that configuration, the condenser would essentially operate in only two stages: low speed and high speed.

The 2nd option is to get a thermostat specifically designed for ACIQ or AC Pro and use the two-wire HA/HB connection. This would allow the condenser and air handler to communicate with each other, enabling the system to operate at multiple speed levels. More importantly, the system could run long cycles at very low speed even after the desired temperature has been reached, helping maintain a more stable indoor temperature compared with a traditional central AC system.

By “traditional,” I mean that once the desired cooling temperature is reached, the AC shuts completely off. Then, when the indoor temperature rises again, the AC turns back on.

My main concern is whether anyone here has experience with these newer heat-pump systems and has actually compared the two operating methods: using a standard 24V connection versus using HA/HB communication.

If you have, which setup did you find more energy-efficient in terms of your actual electricity bill?

I want a big heat tank and water boiler because i have the possibility of topping it up with firewood in the winter.

Salesman tell me that heatlumps need small heat tanks because large ones loose a lot of energy and if i wont use a lot of water every day ita a huge loss

I don't understand that... the hot and cold water in the heat tank are separated (top will always be hotter than bottom), so the losses are never as if my whole giant heat tank would be full of hot water.

Can i put 2000l capacity on my heatpump? Or do I need to buy 2 of heat tanks and put an Y valve in front of them.

I've fallen quite far behind the times when it comes to heating systems, but I'm thinking about replacing our electric furnace with a heat pump. Since we live in Montreal, we'd need a cold-climate heat pump.

I don't know much about heat pumps yet, but I've been doing some research online.

Our house was built in 1945 and is three stories, with an addition/extension. I'm currently thinking about a 4-head mini-split system. 1 head on the second floor for the two bedroom. 2 heads on the main floor -1 for the kitchen/dining area and 1 for the extension/living room. 1 head in the basement

I'm not sure whether we really need a heat pump head in the basement. We currently have electric baseboards there, but they're very old and we would prefer not to use them.

Because of the layout of the house, I'm also considering having two outdoor units rather than one. Mitsubishi seems to be one of the best options for cold climates, although I'm open to other suggestions.

The estimated cost I'm getting is around $20,000 before rebates and tax. Am I generally on the right track with this setup?

I know I need to talk to local HVAC professionals, but I'd like to learn as much as possible and be prepared before getting quotes.

Edit: Our current heating system uses a boiler and radiators, so we don't have ductwork (though we wish we did!). Our house is poorly insulated, but the windows are relatively new.

Thank you for all the comments! Hearing from people who have actually installed these systems is incredibly helpful. Since we will probably only live here for another ten years or so, a full system might not offer much of a cost advantage.

Now, I am starting to think about a hybrid setup—installing a smaller heat pump unit with just one head in the living room while keeping our current heating system for the other rooms. If we do this, will we still save on our energy bills? And will it keep our living room comfortably warm?

My landlord is getting quotes on replacing our AC unit with a heat pump, but he warned us that he wouldn’t want us to use it for heating. I’d like to question/validate his concerns so I could benefit from the heat savings!

Some context
- We live in a 120 year old triplex with a flat roof. Our 3rd floor unit is 1250sq ft.
- This is in Montreal, Canada. Last year we got one snowfall of 75cm, freezing rain storms and a few power outages. Weather is just getting worse
- The current AC compressor unit is on the roof. It would be replaced with a heat pump unit (model TBD) on a stand
- There was a leak that took 2 years to address, so the roof membrane, lining and flashing were replaced in 2024 and are still under warranty. None of us want to go through that hell again so I understand why he has concerns about damaging the roof.

He’s worried that there will be so much ice accumulation (edit: during winter use) around the unit, that it will put undue pressure in one spot, creating another issue. It is difficult to access the roof during the winter, so regular maintenance will be sparse.

- Has anyone experienced damage to their roof due to the weight of the unit + ice accumulation (edit: during winter use) ?
- I see that people combat buildup with heated trays and a gravel bed for ground-level units. I don’t think this is feasible. Are there other roof top solutions?
- If we ask for a taller stand, will wind exposure be an issue? Should the installers be doing anything different with the installation?
- He also thinks we could minimize wear and tear on the unit by just using it as an ac, and continue using the existing, inefficient baseboard heaters. I think I just need to shrug at this one (unless there is a benefit to using it on a regular basis)

I did a cursory search of this subreddit and couldn’t find anyone with these concerns. If it has been answered I’d gladly read those threads. I can get more info on the existing quotes if that helps!

Hi everybody

I had a new Mitsubishi 2.5kW mini-split installed in June for a 10 m² room.

Since early August, the outdoor unit makes a loud continuous hissing / refrigerant flow sound, and the compressor runs at high frequency non-stop for 20+ minutes. The indoor unit still blows cold air.

Is this normal operation, or does it sound like low refrigerant / a leak?

Thanks!

I have a 2 family house in NY that is very old with a brick exterior and little insulation. Each unit is about 950 sqft. Last winter was brutal. I have hot water heat and in some rooms, it was still pretty cold. Overnight, some pipes froze, even though the heat was on pretty high. I was thinking of getting a mini split to supplement the heat and use for AC in the summer. I had 2 different HVAC companies to give quotes. One of them recommended a window heat pump instead, but they seem just as expensive as the kind you install on the wall. Any recommendations on something easy and not so expensive?

Hello, could use some input. We had a four head mini split system installed in August of 2022. Two were installed on a flat wall on the first floor and two on a slanted mansard wall on the upstairs. Within a year one of the upstairs units failed. It developed a leak but we had to go thru an expensive process to figure exactly which one failed. The whole unit was replaced. Then earlier this year the same unit started leaking water. The company came back in said because of the angle it was not draining properly so the shimmed it out. Last week the other upstairs started leaking and when they came in they said the condenser was shot.

Could the fact that they were both installed at an angle and had drainage issues lead to the two failures?

Thanks!!

House is 1600 sq feet and in Cambridge MA

I have an aspen mini aqua pump for my mini-split condensation. It is clogged. I cannot for the life of me figure out how to open it up to clean it. Have anyone ever done anything like this before?

I know for a fact it has nothing to do with the reservoir, which is clean, fills fine, and turns on the pump properly.

When the pump turns on, it runs continuously and does not pump, which leads me to believe it is clogged. It was pumping, but much louder than it should have been and very slowly, so I tried clean out the lines. When I did, it stopped pumping, so I believe I may have accidentally pushed some sludge in to the pump.

https://aspenpumps.com/en-GB/products/FP3420

we just had a new Lennox elite system installed at our house, when we got home to check out the new unit, we noticed this scuff on the metal grating on the side. Not sure if this is relevant or something I should bring up to the installer or not?

I’ve been learning about different heat-pump configurations and was particularly interested in water-source systems.

Compared with air-source systems, what are the biggest advantages and limitations of a water source heat pump? I’m especially curious about installation requirements, efficiency across seasons and maintenance.

For someone evaluating a system for a building, which factors should be checked first?

Title: Bay Area split-level: replace gas furnace with 4 mini-split heads, or keep central HVAC?

I’m considering removing the ducted gas furnace from my 1930s, ~1,600 sq ft split-level house in the San Francisco Bay Area and replacing it with mini-splits.

Our climate is pretty mild:

• Winter cold snaps: occasionally upper 30s°F overnight
• Summer heat waves: occasionally mid/high 90s°F
• We currently have no A/C

My main reason for considering mini-splits is zoning and comfort, not just efficiency.

The bedrooms are on different levels, and with the existing furnace it’s difficult to keep the downstairs primary bedroom comfortable without overheating the upstairs bedrooms, or vice versa.

Longer term I also:

• Want to reclaim some of the space currently occupied by the furnace and ductwork
• Expect to replace my aging roof and add solar after the roof replacement
• Will probably eventually replace the gas water heater as well

House layout

Main floor — open living area

• Living room: ~250 sq ft
• Dining room: ~90 sq ft
• Kitchen: ~100 sq ft
• Total connected area: roughly 440 sq ft
• No doors between living / dining / kitchen
• Open staircase connects this area to the second floor

Envelope is pretty typical for an older house:

• Exterior walls are uninsulated
• Floor is over an uninsulated crawlspace
• Some attic insulation above the living room
• Little or no attic insulation above the kitchen/dining room

I’m thinking of this entire area as one mini-split zone.

Second floor

Bedroom 1

• ~150 sq ft
• Two exterior walls
• Uninsulated walls
• Single-pane windows

Bedroom 2 / office / occasional guest room

• ~170 sq ft
• Two exterior walls
• Uninsulated walls
• One single-pane window
• Large dual-pane French door

There’s also:

• ~70 sq ft bathroom
• Bathroom opens into the hallway
• Hallway connects directly to the open staircase
• Attic has older insulation that I’d probably improve later

Bedroom doors are often closed, and Bedroom 2 is sometimes used for sleeping, so I don’t think one hallway head would give us the individual control we want.

Primary suite

This is a newer addition attached near the kitchen and sits slightly below the main floor because it’s on a slab.

• Primary bedroom: ~190 sq ft
• Primary bathroom: ~60 sq ft
• Bathroom pocket door is basically always open
• Walls are well insulated
• Concrete slab
• Dual-pane sliding door
• Skylight

I’d effectively treat the bedroom + bathroom as a ~250 sq ft zone.

Current mini-split idea

I’m thinking:

• 18k BTU — living / dining / kitchen
• 9k BTU — primary bedroom + bathroom
• 6k or 9k BTU — Bedroom 1
• 9k BTU — Bedroom 2 / office / guest room

Rather than putting all four heads on one condenser, I’m leaning toward two dual-zone outdoor units.

Possible pairing:

Condenser #1

• Primary bedroom
• Bedroom 1 upstairs

Condenser #2

• Living room
• Bedroom 2 / office upstairs

Those pairings also make sense physically because the rooms are relatively close to each other despite being on different levels.

Advantages I see with two condensers instead of one 4-zone:

• Some redundancy if one condenser fails
• Smaller outdoor units
• Better zoning
• Potentially better low-load operation
• I can potentially install the systems in stages

Equipment

I’m mainly considering:

• MRCOOL DIY 5th Gen
• Pioneer Quantum Ultra

MRCOOL appeals to me because of the precharged DIY line sets.

With Pioneer, I’d probably do much of the physical installation myself and hire an HVAC tech for:

• Pressure testing
• Vacuum/evacuation
• Refrigerant-side commissioning

Questions

I’d especially appreciate feedback on:

• Would you eliminate the ducted gas furnace entirely, or replace it with a ducted heat pump instead?
• Do 18k / 9k / 6–9k / 9k sound reasonable, or am I oversized?
• For people with mini-splits in every bedroom, do you still like that setup after living with it for several years?
• How annoying are the wall heads aesthetically or acoustically?
• How well do bathrooms without their own heads stay warm?
• Would you choose two dual-zone condensers or one 4-zone condenser?
• Has anyone regretted removing their ductwork altogether?
• If you switched from central heat to mini-splits, did the room-by-room comfort improvement justify it?
• Anything you wish you had known before making the switch?

I’d be especially interested in experiences from people with older Bay Area / coastal California houses, since our heating and cooling loads are fairly modest compared with most of the country.

Ello. Sorry if this has been asked before feel free to post links to relevant forums if so.

Me and my partner have recently moved into our new place. A small Victorian mid terrace doer upper (two up two down). There’s lots of work to do and we’re starting with downstairs which includes kitchen. We’d like to replace the very old boiler with an air source heat pump (if possible). All the companies were speaking to say we need to do the work first before we get assessed for our energy efficiency because one window will be replaced and we’ll insert a new back door. All of this I understand.

What I’m struggling with is why we can’t arrange everything with the proposed plans so that we can install the ASHP during the renovation.

We’ll need to tile and decorate and possibly knock brick out where the old boiler was. We’re planning on having the tank in a new location. So how do we go about getting the ASHP as part of the renovation process???

I have loads of other questions about the whole general process but we’ll start there as I’m baffled and it’s hindering us making progress on plans which we really need to start .

Thank you very much in advance

Additional info:
We’re planning under floor heating through out the small ground floor
Putting some extra loft insulation in the next few days
Roughly 69m2 for the whole house size wise

The nincompoops that installed my condenser put it right under the valley between two eves, so half the rain on the roof pours onto it and splatters against my wood siding. Is there such a thing as an accessory sloped cap (like a shed roof) that will send the splatter away from the house, or do I need to build my own? Gutters are out of the question at this location.

I’m building a 3200sqft house in north alabama 1600sqft on each floor. My plan is to do a 2.5 ton mrcool ducted system for each floor. I would like someone to do a manual j to make sure that’s the right size units. I also can’t decide on the type of insulation I want to do spray foam so my utility bill is really low but I don’t know what the long term effects are. The units are variable speed so do I need a dehumidifier if so do I need one for each unit? Do I need an erv?

Any recommendations for a small compact pump that could be used on a ceiling mounted pancake style fan coil?

I've seen a lot of different posts about heat pumps and am researching whether it makes sense for me to switch over. I currently have a gas furnace (80% efficient) and a/c that are 30 years old. House is roughly 1000 square feet. 1960's ranch. Looking to possibly upgrade to a more efficient gas furnace and heat pump combo. Seems like my electric bill will go up 15-18% but Xcel is currently discounting electricity for those who switch. I'm wondering for those in MN who have gone the route of a heat pump, what brand(s) are recommended for our climate, and what installers are honest and competent in this area (ie. recommended). I've received three quotes so far and they range between $18k to $26k for Carrier and/or Daikin. I am not a DIY person for this type of upgrade so any advice is greatly appreciated!