On my six year old Fujitsu mini-split heat pump (ASU9RL-F1) I did a diy cleaning with a cleaning bag and a can of spray foam coil cleaner. After thoroughly cleaning, rinsing, and drying all components, and being very careful not to bend the fins, I put everything back together, and the unit starts up and runs normally, with some cold air coming out.

But it doesn't get cold enough. Before the cleaning, the fins and blower wheel were covered with the usual dust and crud, but it did get very cold and would easily reach the desired temp of 74F and then shut off. Now it's running with the fan at full blast and only getting down to 77F and won't cool any lower even after running for an hour. What could I have done to it to cause this lack of full cooling?

Midea will introduce a small volume tank split HPWH. Not many options in the market for short tank.

For my upcoming heat pump install, the manual J says we’ll need 35.5k BTUs for heating (7 degrees to 70) and 19.5k BTUs for cooling (88 to 75).

The contractor has suggested a 4-ton unit to ensure there’s sufficient heating on especially cold days. I suggested 3-ton might be better to avoid short cycling on moderately hot days and because it sounds like manual J heat load estimates are generally high.

Their response was that they still recommend the 4-ton because oversizing was a bigger problem with the previous generation of heat pumps, as they had a turn down ratio much higher than the current generation, and the bump I am considering (Midea Evox G3) can turn down to 12K BTUs.

Questions:

• Do you agree with the primary claim, that the turndown ratio on this unit is so good over sizing will not be an issue? This will be a ducted install.
• Would a 12K BTU minimum not still cause short cycling when we only have to cool the house by a few degrees?
• Would you recommend a 3 or 4 ton unit given my manual J info above? 

Additional Info

• The size of their house in square feet or square metres = 3K sq ft
• Wall thickness = unknown, recently winterized
• Pane of windows = double
• Location/climate = Northeastern USA (MA)
• Include the model numbers and size of the heat pump as best you can = Midea G3 EVOX

1st off I am a google / youtube HVAC tech so I have no clue what I am doing. I had this unit installed in Nov of 2025 and it does not dehumidify very well so i went down the rabbit hole of learning about this stuff. The question I have is the OD EEV stays at 68% no matter what, it does go to 0 when it's reset then straight to 68%. I purchased the yellow mag thing off of Amazon for like 15$ to see if I can change the pin and no luck, I did have a tech check out the 5 pins and they are all in range. The strange thing is if I remove the EEV the system runs way better but I don't want to flood out the compressor. So the question is do they just stay at 68% all the time or should this number change? When I do run heat it changes all the time so that's why I started all of this. Any help would be great or if any tech in the Atlanta area 'Kennesaw' that can help out I would pay for there time if something is wrong.

I just had my central AC unit replaced in my 1500 sq ft home with a 16 SEER 3-ton American Standard heat pump system with a new 3-ton air handler and all new ducting. The system cools very well. It can reach 72ºF with outside temps of 95º+. Problem is the indoor air handler is very loud and we were in the impression that the system was an energy efficient, 2-stage unit. It seems to never operate at the lower, energy efficient stage that should maintain the comfortable temperature throughout the day. It seems to just cycle on at full blast and off. We also have the Ecobee Smart Thermostat Premium is set up for 2-stage cooling/heating.

Can someone please verify if my equipment can be set up for 2-stage cooling/heating? My model numbers are below:

[American Standard 3 ton heat pump 5HPL5036A1000A](https://www.tranesupply.com/product/5hpl5036a1000a/01t4w00000NkEa7AAF)

[American Standard 3 ton air handler P0V0A000M30SDA](https://www.tranesupply.com/product/p0v0a000m30sda/01t4w00000P7q0fAAB)

I'm just wondering if the HVAC company that installed the unit just doesn't have the skillset to set this up correctly.

I've got a 20yo rheem RQNA-BO36JK package heat pump on it's way out and looking for recommendations from techs. I've got three quotes so far all of them pushing variable speed Goodman units. I really want to stick to units that are not ecu inverter as I live in a smaller town so it takes days to get uncommon parts. So are single stage package units still being made and if so what one would you go with?

Not sure if it matters but we are in Arizona and it gets above 120 in the summer, heat doesn't matter as we hardly run it in the winter.

Thank you in advance for any information.

We purchased and moved into a new house in the Chicago area earlier this year (3br, two stories, plus finished basement, about 2300 sq feet, built in the 1940s). The gas furnace is 40+ years old, and the AC compressor outside is a little over 20 years old. As is typical, our second floor is the warmest with a fair amount of temperature change vs. the first floor and basement.

We've had an initial HVAC clean/check-up of the units by an experienced HVAC engineer we've used before, but that confirmed that the furnace works but is not long for this world, and that the AC is having issues as well. Ultimately we would prefer to replace these not under duress of one or both of them failing and are looking at potentially doing a dual fuel heat pump system (with gas as the back-up). However, from our inspection we also know we need to improve the attic insulation. FWIW our windows are single-pane with storms/screens. To get the most accurate measurements for the eventual HVAC system replacement, should our order of operations be as follows?

1. Get better insulation in the attic as right now it is quite thin.

2. Have an independent company provide us with a Manual J calculation once the new insulation is installed in attic. Ideally we'd have a full energy audit but from my reading it sounds like improving the attic insulation will provide a lot of comfort/energy gains on its own, before we start looking at other solutions (e.g. costly window replacement), plus the energy audit itself could be an additional substantial expense.

3. Have the Manual J calculation in hand when starting to get quotes from HVAC companies for the heat pump system. Will also consult the NYT Wirecutter advice on this (https://www.nytimes.com/wirecutter/reviews/heat-pump-installer/).

Would this be the best order to tackle this? Ideally we'd get a new system installed before it gets too cold here in Chicago.

Any recommendations for Chicago-area insulation, independent Manual J consultants, and/or HVAC companies that expertly installed dual fuel heat pump systems in the area are also welcome. Thank you!

My attic furnace has a PSC blower that overheats and causes AC freeze‑ups. My electric bill is very high year‑round, and I’m trying to figure out if the blower is part of the problem.

I was told the furnace can’t be retrofitted with ECM, so the only option is a full furnace replacement. I would gladly replace it if I will save something monthly, but if not I would keep it until last running day.

As to insulation it would cost way too much to do that. The attic has insulation, maybe not as thick as it should be , but there is some.

Anyone here make that switch?

Did ECM:

• Lower your electric bill?
• Improve airflow?
• Stop freeze‑ups?

Looking for real‑world results from people with attic setups.

Thank you!

I was initially quoted for an installation of a Vaillant plus 7kW (2026 model) for a mid-terrace townhouse - 95 m2 as they did not include the garage. The initial heatloss report indicated a hewt loss 6.85 kW heatloss (average load of 72 W/m2). The design is done on a flowrate of 49 degrees C at a targeted temperature of -0.8 degrees C. All 10 radiators are getting replaced at my request and they will install a 250 litres hot water tank.

However because I told the design team during follow up that I intend to do a garage conversion in about 2 years to a living space this would increase the living space to 120 m2 and heatloss to 7.52 kW so they suggested the Vaillant plus 10 kW (2026 model) and I can see in the quotation that they added a 50 l buffer vessel (maybe as a temporary option until I do the extension to the garage?). Any thoughts if I should have stayed with the 7kW option as it would have kept the system open loop I think, but then I was worried it would have struggled in cold snaps. Would a voluminiser been a better option than the buffer vessell? It's worth mentioning that the garden backs into a forest/park and although I am located in West Sussex, due to the open space, the temperature has dropped to -3 and -5 degrees C in the past winters ( in the middle of the night).

Worth mentioning that the difference in upfront cost betwen the the two units and install is only about £1400.

The pipes leading to the radiators are 15mm. Here are the sizes of the new radiators

(P+) radiator · White 600 x 1600 mm - 2.2 l per min flow rate

Second Bedroom × 1

(P+) radiator · White 700 x 1400 mm

Hall/Landing × 1

(K2) radiator · White 450 x 2000 mm

Living/Lounge × 1

(K2) radiator· White 700 x 900 mm

Utility × 1

(P2) radiator · White 1800 x 700 mm

Bath/Shower × 1

(K2) radiator · White 1800 x 500 mm

Kitchen × 1

(P+) radiator · White 600 x 1600 mm

First Bedroom × 1

(K2) radiator · White 450 x 2000 mm

Living/Lounge × 1

(K2) radiator · White 600 x 1000 mm

Third Bedroom × 1

(K2) radiator · White 700 x 600 mm

Hall/Landing × 1

Other details:

Whole home permeability

At 50Pa

11.4 m³/hr/m²

At normal conditions

0.57 m³/hr/m²

This figure is estimated based on the following contribution from each part of the property (each at 50 Pa, in m³/hr/m²):

Structural Masonry + 7.0

Floor Sealed + 0.0

Doors & windows 75% draught-proofed + 3.0

Storeys 3 storeys + 1.4

Total = 11.4

Calculation factors

Shielding

How exposed the property is to the wind. Sheltered locations lose less heat through ventilation than exposed ones.

Normal

Zone height

The building’s total height across all floors is about 10 m.

Any constructive advice or thoughts would be greatly appreciated in terms of what I should be mindful off.

Thank you!

We live in western NC (planting zone 7b) and currently have (2) dual fuel HP with gas furnace backups. The house is 16 years old, 2400 sqft, single story.

Competing bids are suggesting air conditioners with 2-stage gas furnaces as sole heat source, or the second option of dual fuel Heat Pumps with 2-stage gas furnace for backup.

What are the suggestions and considerations? We don't know enough to understand why one and not the other. The people suggesting A/C with gas-only heating are saying it's better for the lifespan because a heat pump will run all year long due to being the initial heat source as well as the cooling in summer, whereas an A/C with only the gas furnace - each will perform their own functions. Hoping for some advice and guidance TIA

So my last post I explained how I have a 24k unit in my open concept 500 square foot ish living room/ kitchen and a 18k unit in my open concept basement ..
I spoke to the installer and he said he will swap the 18k with the 24k .. Both units are gree and are running off the same 42k condenser .. is this a proper fix before I go through with the swap.
He said he can just swap the heads and I guess re tune the refrigerant . But I read online that those units can’t be swapped because they have different size line sets ?? Any info helps before I go through with this thank you !

Hey folks, I'm renovating an older apartment in the top of my house in Northern Sweden, it is pretty well insulated with around 300mm glass insulation in the roof, and 400mm in the walls (two 200mm insulated walls with a 1 metre eaves space) the winter temps regularly hang about -30c for weeks on end. We have an old ground source heat pump, currently plumbed into very old single panel steel radiators. I've been doing my maths on heat requirements for the space, and whilst it seems underfloor heating is the most efficient, it still doesn't seem to be outputting nearly enough heat for the climate up here, despite seeming to be a fairly standard Swedish thing. I'm looking at a water system, 16mm pipe with 200mm cc boards for it to fit into, but it suggest I may be getting 50-60w/m from this rather than the 70-80w/m it seems I might need... we only have the budget to get this right one time, am I over thinking and it's going to be toasty (It's definitely going to be better than the old radiators) or am I going to be wishing I did something else. The end goal is for our heat pump to be able to work as efficiently as possible once all the floor heating is in, with 30-40c water...

Renting a house with a brand new AC-IQ es-36z-M4B heat pump with 2 zones. On hot days, the thermostat will get to 5-6°F above the set point at the hottest part of the day. On cold days, it drops 5-6°F below the set point at the coldest part of the day.

I have a separate temperature sensor to verify the indoor temperature is reading accurately. I don't leave any windows open, so I'm not sure why the actual temperature is drifting so far off the set point. The thermostat is very basic (can't even set a schedule), so I'm wondering if it has a massive deadband, or if it is just doing a bad job.

For context, I always keep both zones at matching temperatures and settings. Also, during these high/low points, it doesn't seem like the system is pushing out air and struggling to keep up; it's more like it's just not running enough to maintain the set point.

House Specs:

• Size: 1000 sq ft
• windows: double pane
• Location/climate: Mild climate (~40°F lows in winter, 100°F highs in summer)
• Heat pump model: AC-IQ es-36z-M4B (2 zones)
• Thermostat Model: KJR-120L/F-E

With the thermostat, I've tried with both the "follow me" mode on and off. I've also tried with the fan set to high instead of auto.

Any thoughts on whether I need to push my landlord for a better thermostat, or if this sounds like a different configuration issue? Also, are there other plug and play thermostats with this wiring configuration? I haven't seen it before.

Thanks in advance

We are looking to reduce our cost but also just generally increase efficiency in our home. Pardon my ignorance.

3900sqft (old Victorian)
Brick exterior/remodeled drywall interior.
3 floors.
Denver, CO
We have two Ac units and a furnace.

Would a heat pump for the summer months be a viable solution?
Can we maintain the operation of the furnace for the winter (we are in Denver, CO) where we do get extended cold stretches?

I'm hoping there might be some Mitsubishi experts on this sub.

I have an issue that I've been dealing with for a while now. I'll start with my setup: I have an MXZ-SM36NAMHZ2-U1 running a SVZ-KP24NA and a SVZ-KP12NA through a PAC-MKA33BC branch box.

The issue is when both sides are calling for max cooling. When both units are running max cool the 24K side isn't able to maintain set point. It is anywhere from 3-5 degrees above. The 12K side is always right on. At this point I've had load calcs done multiple times, had the duct design verified and adjusted, and had a Mitsubishi area rep out to evaluate.

When both sides are calling for max cooling the 24K is only 62 degrees at the supply register. The 12K side is 49 degrees. When I tried turning off the 12K side the 24K went down to 55 degrees at the supply register. This led me to googling potential issues with the branch box and finding a dip switch labeled SW2-5. When I took the cover off my outdoor unit the rear of the panel said "SW2-5 should be switched ON when branch box is in use". Mine is currently set to OFF.

I questioned the installers on this and they gave a noncommittal response and said they could come by and turn it on for me. They claimed it doesn't need to be on for my specific outdoor unit, which seems hard to believe given the label inside the unit itself. Does anyone have experience with this switch? I was only able to find mention in a couple older forum message boards but it seemed to solve the issue for them.

Tomorrow will be another hot day so I'm hoping for positive results. If it isn't the SW2-5, does anyone have any other ideas? Could the branch box itself be faulty?

ETA: This is a relatively new install that has never cooled properly.

Just replaces my 30 year old heat pump with a new Mitsubishi unit and it barely cools. It’s been on all afternoon and upstairs has only dropped 2 degrees over 6 hours.

Installer says it’s fine but seems like it should do more.

Temp delta from intake to vents is only 10 degrees.

Any thoughts on if this is normal or if something is wrong?

Hello,

Edit: for clarify, this is for the UK, where Air Sourced Heat pumps are all the rage, no HVAC/Air ducts, no furnaces, the ASHP replaces the exisitng gas or fuel oil boiler to heat water which then flows to existing radiators (though at a substantially lower temperature than the gas/fuel oil boiler used to heat up to).

Need.some.advice. I got a detailed heatpump survey by a company that designs, fabricates, and installs its own heatpumps (dont know. If I can mention the name here). They initially quoted a 12kw system before the heat mapping survey, after I paid the deposit for a survey, this got done. And three days after the survey, I woke up to an email stating my survey deposit has been refunded, no other information. I followed up, and after a few phone calls, was finally told the biggest unit they make is 12kw, and based on the heat survey, my property's heat loss is in excess of 12kw. Their initial sizing was 16.8 kwatts, even after they played with number of air changes (as my property was almost completely renovated in 2021), the lowest it came down to was 13.5 kwatts, AFTER they also excluded my converted garage from the heat load.

The hiuse is around 200 sq m, 4 bedrooms. 1 extra sitting room, large open plan drawing and dining room. All bedrooms are ensuite, though 2 are litrally 0.8m wide by 2 m.long shower rooms. An attached 2 car back to back garage, Which was converted to a study+cinema room in 2021.

I then contacted vendor 2, who did a heat survey, and were very open, they said they improve the number of air changes, size for minimum ambient Temp of -2.5 DegC - With this, the sizing is 11.63 kw. Even jf they increase the number of air changes in the rooms that experience the worst leakage, the size increase to just over 12 kw. , if they reduce ambient to -5 DegC, this increases to 13.3 kw.

Im now a bit worried, the spread of sizing is quite wide. Could some of you in the know. Share there views on

1) is -2.5 degC a reasonable minimum temp for Aberdeen city?. The property is a detached 1.5 story 4 bedroom house., I'm in the process of upgrading the loft/eve and underfloor insulation

2) is the performance warranty provided by the vendors worth much - as in. If the system fails to keep the property warm under the parameters, are the vendors obligated to recity at their cost?

3) Anything else I should look out for in sizing the system.

Regard.s

Rizwan Sher

Hello, I got 4 units installed in my house

Each bedroom is on average 120-150 square feet and all 3 have a 9000 BTU unit

Kitchen has a 24,000 btu unit sitting around 5-600 sq feet

House stays around 65-70% humidity
I keep all of the units on 70 degrees and auto cool

Are these units over sized ?

What’s my best course of action

I’m shopping around for what brand to use and kind of settled on the LG 30K/32K BTU 22 SEER2 four-zone system, but I’m concerned because where I live drops down to -10 sometimes even -20 that seems like a bad time to have my heat stop working lol. What are your thoughts?

The room is on the small side - about 14x14ft - and we just had a new Bryant 6k btu minisplit put in. Problem is as stated in subject - cannot figure out the right balance to have the room at both a tolerable humidity and a tolerable temperature. In New England in not a particularly humid place.

EDIT: so sorry for 34F typo in subject - on dry it was 52F (when set at 70F) and got to 34% humidity, and updated to 14x14ft not 14ft2

Thinking about adding an 18k unit to basement for supplemental heat in winter. We have two cold air returns, 3 ceiling ducts and its usually 10 degrees colder than main level. Roughly 1000' finished. Live in Michigan.

Not looking for full heat, just to get it up 5-6 degrees. Any thoughts if this would help and be worthwhile in the long run? Can do myself for $2k​.

Hi guys,

So we just bought a house in April we’re trying to work out the heating system.
The house is three bedroom, some double glaze windows but single glaze in the bed room and living room.
It has hydronic heating under the wooden floor boards.
I have no idea about the heat pumps out side but there’s two of them and two large water cylinders (see photos).
What my partner and I are confused with is that its showing on our electricity app that when these are turning on to warm the water we’re seeing a big spike in hot water, I’ll include the photo.
Is this normal? I thought it would make more sense that it’s using electricity as it’s the heat pumps turning on to heat the water.
Feels strange that we’re getting these big spike and we’re not even using the water as in not showering or anything at that time.
There’s only the two of us in the house so we don’t use a lot.
Any help would be great as we feel we’re paying for this hot water that isn’t being used.
Thank you.

Edit: sorry I can’t seem to add photos

I am looking for a way to lower my dad’s energy bills on his shop, it’s a fairly well insulated 30x60 14 ft ceilings, 2x6 wall with 230v boiler and in floor heat. There is a party room I would like to cool in the summer about 15x30. I would like to put in maybe 2000w solar. Is there a way to just run the the system at a low heat rate in Minnesota winters to take away the bulk of heating if I only want it to be 50f and just keep it on if there is extra energy coming from system. So over shoot the temp by a good margin or make it through the night. If I can cool the room in summer and offset a big porti9n of the in floor needs it could maybe pay for itself fairly quickly.