New Home HVAC System

[Sigarms]

I like the idea of each room/area temperature being controlled independently. I also like the idea of no duct work as well.

With ductless mini splits, generally (and Mitsubishi for certain unless you're using the Kumo cloud which is a whole set of other variables to deal with), the system is either in heating or cooling mode, not both. What sucks is if you have temperature swings in spring and fall (such as I think Tenn would have), the master unit dictates if the system is in heating or cooling, and you either have to shut the system completely off to change the "master" if you want to change the mode or your stuck with the mode it's in. Some other brands do have a auto setting, but in general people complain on how long they take to switch modes (genearlly 15-30 minutes).

I do a lot of mini splits and highly recommend them for certain applications, but doing a complete home isn't one of them for various reasons (service to clean indoor units can add up depending on the quality of indoor air as well).

Ironically enough, I installed a dual fuel system (heat pump with gas furnace) in my own attic when I had to replace the old lennox gas/ac system, and I have a LP fireplace for the living room (straight heat pump for first floor located in basement).

If you're building, try to include a basement with mechanical room, and run the ductwork in the basement for both floors. Point being, even if doing an attic and that's where the equipment is going, give yourself enough room for the equipment access and ductwork. This is where mini splits shine due to space and installation, but for a whole home, genearlly a whole home mini split system will cost more than a standard split system with dutwork.

 

[Sergei1]

We have mini-split system and love it. Our house is small, it costs about $1/day for heating in the winter, until temps get below 20dF then we go to the wood stove. Ours is one of the older Mitsubishi Mini-splits that the efficiency drops off fast below 20dF. New ones are good to below -5dF. In the summer it costs about $0.50/day for cooling. If I was building new, Geothermal would be my first choice, mini splits second, central air heat-pump last. Biggest issue with Mini splits is the WAF of the interior units. At least one of the mini split makers has units that recess into the ceiling and don't look any different than a central air duct.

The Mitsubishi I have install will output 70 degree heat down to -13. Right now ín Iowa been really putting it to a test and so far been great.

 

[Sigarms]

The Mitsubishi I have install will output 70 degree heat down to -13. Right now ín Iowa been really putting it to a test and so far been great.

I'd like to see the indoor remote reading with the outdoor temp side by side with that claim. I'm very familiar with Mitsubishi technical literature, and no where does it state what you just claimed. I just looked, a new FS18 k model (single zone) will give you 17,100 BTU/h of heat at -13.

The question becomes, when it's below 40F outside, what is the remote set to per desired temp and what is the actual temp in the room?

If you want higher heating output with Mitsubishi, you have to use their "hyperheat" system. By the same token, other manufacturers can do the same thing. On the other hand, higher heating performance systems cost much more.

I was lucky enough to have a disgruntled homeowner where I had to get involved because the at the end of the day, the installing contractor screwed up and didn't do a load calc for the basement. To most, he had "plenty" size of system, but anytime it got below 30F, his system couldn't keep up with a 70F setting. Because the homeowner was an engineer by trade, I was lucky enough to make a deal with him to get me actual readings, which made him giddy like a kid on Christmas morning LOL

I only point this out because some mini splits have a "high heating performance", but at the end of the day, most homeowners don't know what to ask, and they assume they are getting a system sized appropriately for thier home for heating. AC is generally not the problem because thats what the nomenclatuer represents, cooling at 95F outside air temp. The issue with mini splits has always been heating.

 

[Sergei1]

I'd like to see the indoor remote reading with the outdoor temp side by side with that claim. I'm very familiar with Mitsubishi technical literature, and no where does it state what you just claimed. I just looked, a new FS18 k model (single zone) will give you 17,100 BTU/h of heat at -13.

The question becomes, when it's below 40F outside, what is the remote set to per desired temp and what is the actual temp in the room?

If you want higher heating output with Mitsubishi, you have to use their "hyperheat" system. By the same token, other manufacturers can do the same thing. On the other hand, higher heating performance systems cost much more.

I was lucky enough to have a disgruntled homeowner where I had to get involved because the at the end of the day, the installing contractor screwed up and didn't do a load calc for the basement. To most, he had "plenty" size of system, but anytime it got below 30F, his system couldn't keep up with a 70F setting. Because the homeowner was an engineer by trade, I was lucky enough to make a deal with him to get me actual readings, which made him giddy like a kid on Christmas morning LOL

I only point this out because some mini splits have a "high heating performance", but at the end of the day, most homeowners don't know what to ask, and they assume they are getting a system sized appropriately for thier home for heating. AC is generally not the problem because thats what the nomenclatuer represents, cooling at 95F outside air temp. The issue with mini splits has always been heating.

Checkout the MsZ-FE12na. When it's been minus outside temperature the bedroom remote is set for 68 , fan at low and the unit keeps it at 68. We keep it at 68 becaúse of wife. Besides using a thermometer that's in the room AIso I've my Flir camera to check the output temperature of the unit. If you check Iowa temperature you'll see that were in the minus most of February.

 

[Sergei1]

Right now outside temperature is 2 degrees and you can see the pictures. I'll post another when it down in the minus range
Check out KCRG weather.

 

[kenmac]

You'll never get the efficiency with a ducted system compared to a ductless system

 

[Sigarms]

You'll never get the efficiency with a ducted system compared to a ductless system

A 2-4 indoor zone ductless multi zone system (by Mitsubishi and everyone else) will get you about 18 SEER.

A zoned Geothermal system is a whole heck of a lot more efficient, and even ducted inverter systems by most unitary split HVAC manufacturers (Trane, York, Lennox, Rheem...) are pushing a higher SEER/EER/HSPF rating than ductless multi zone systems.

The simple reason single zone mini split systems have such higher efficiency ratings is because there is no ductwork involved.

Take a look at ductless systems which use their ducted indoor units and the efficiency drops like a rock.

Don't take my comments as being negative towards ductless, because I do like mini splits for what they are designed for, not having to use ductwork. Just laid out a 2 system 9 indoor head system because at the end of the day, it's the only thing that really will work without having to do some major structural work.

That said Ken, I know you love your multi zone system. But I do think you had an advantage over most of the general population Found something new the other day, a "electronic air cleaner" designed for ductless. Just put one in on a job that has some indoor air quality issues that needs the indoor serviced annually and curious to see how it helps the blower wheel.

 

[Sigarms]

Right now outside temperature is 2 degrees and you can see the pictures. I'll post another when it down in the minus range
Check out KCRG weather.View attachment 686159View attachment 686160

Got to ask, what kind of FLIR unit are you using? I bought one that I can use off my phone and like it a lot for the price point.

Honestly, wasn't trying to be a smart butt by asking to see a picture, and the truth is I mis read your post. I thought you refering to keep the indoor temp at 70 not the discharge air temp.

If homeowner spends good coin on a heating system, they need to understand how hot or cold they can get it indoors. My father who lives in the basement with us generally keeps the t-stat set on a minimum of 75/77F with the forced air system in the basement (and that's with a gas furnace). When he had his oil fired boiler up north, 70F was more than fine for him (when I went up to sell his house couple years ago in the winter, I forgot how comfortable hydronic heat feels compared to force air). We do keep the first floor around 70F in the winter, and I need to turn it up for dinner time or he freezes his butt off at 70 with a forced air heat pump LOL).

Even in my area of NC, a 3 ton AC system may be enough for cooling, but most people don't realize that a house requiring 3 ton of cooling can easily require 40,000-60,000 BTU/h of heat.

The only way to ensure you have enough heat using a ductless system is either to do a load set to a indoor design temp vs what outdoor temp the homeowner is looking for, or oversize the unit on the AC side (where you do have a a lot of leeway with a inventer mini split at least). The issue is most contractors think a 18k mini split will give you 18k of heat at 17F, 14F or 5F outside air temp (which is generally not the case, because everyone looks at price as well), and only worry about the efficeny ratings on the ductless system from my experiences.

A standard 3 ton mitsubishi multi zone system will give you around 23,000 BTU/h of heat at a 5F outside air temp (genearlly not a issue in Texas or Florida, but even an issue in west part of NC). A Mitsubishi "Hyperheat" 3 ton multi zone system will give you 45,000 BTU/h of heat at 5F. Thing is, I prefer another line because with the Mitsubishi hyperheat multi zone system, you have to use a indoor branch box which can cause a whole of other PITA factors which affects price.

The only place I can think of a mini split for my own home is in my fathers bedroom. I'd put a high temp unit in to offset having to run the gas furnace for him at night when he's sleeping, but he tells me he will disown me if I put one in his bedroom just because he's living there LOL

 

[Sigarms]

Checkout the MsZ-FE12na. When it's been minus outside temperature the bedroom remote is set for 68 , fan at low and the unit keeps it at 68. We keep it at 68 beca?e of wife. Besides using a thermometer that's in the room AIso I've my Flir camera to check the output temperature of the unit. If you check Iowa temperature you'll see that were in the minus most of February.

Missed this one, apologies.

Very familiar with the FE series. It's the older hyperheat single zone system from Mitsubishi that's been replaced by two different models at this point in time. It's a GREAT unit, their top of the line at the time.

Thing to remember is with a "whole house" multi zone system, the capacity can change dramatically sepnding on size/capacity (it's kind of unfair to compare a single zone ductless vrs a multi zone ductless for various reasons).

What I would sincerely be curious about is if you changed the t-stat to 71F indoor, would it keep it at 71F indoor when the outdoor temp was in the negative range? I honetsly don't know.

Now, that said, 68F indoor temp would freeze my fathers butt off LOL This is the part where the contractor has to know their customer, the customers expectations, and what they can provide at what price point.

Even though I don't think highly of ductless mini splits for whole house applications, I do think one aspect they are great for is bedrooms (particularly the master, and if applicable, where the master t-stat is located for the whole home if there is an existing split ducted system).

 

[Sigarms]

If you are planning on living in this house the rest of your life, I would still factor in what resale value will be if something comes up in your life that you never imagined happening. It happens a lot. How much money will you lose when selling the house because of the mini split systems over a central HVAC system?

Agreed. Also, if a ductless mini split is over 10 years old, depending on the brand, you may be lucky to find a part in stock in the United States, which means if it's a critical service part to keep the system running, you may end up replacing the system. Generally with unitary split systems, you have about 15-20 years before you run out of "expired parts" vs 5-15 years on mini splits depending on brand name. Back around 1998 I still remember having to track a compressor from Japan on a "slow boat" that took about 6 months to get in (off a boat in california is no fun tracking is something else I remember) LOL

Long time ago sold a CHEAP Chinese system, and needed a new remote control 12 years later. Ended up dealing litterally with a guy with a Chinese email signature line in his e-mail, and when I called, I would be lucky to get someone who spoke English. NEVER will I go through that again.

Daikin, Fujitsu, Mitsubishi. 3 of the original Japanese units sold decades ago in the US, good support, and wouldn't look at anything else in the US. If someone is going to have a old part available for sale, it will be one of those 3.

The issue is the United States is the one country in the world that doesn't use ductless as "standard equipment", and every manufacturer is trying to now capitilize in the US market now because they see the market share increasing.