Ductless minisplit brands, options, info

ChrisJ

Tim said:

My brother in law & sister in law from STL (super hot & super muggy) have an early 1900's 3 layer brick house with steam heat. They had their a/c system installed 20 years ago, & the setup very similar to how you describe your concept. AH in the attic, all ducts & returns through ceiling, main floor drops through closets, the open stairway is the return from the main floor to the upstairs big return air grill in the hallway. I can't say I've ever been in a house that is more comfortable in the summer, it works great. The only recurring problem they have is the condensate pump clogs occasionally, & is located in a hard to get place in the attic, so make sure you have the best access possible for service. & of course, DONT OVERSIZE or your humidity control & comfort suffers greatly.

Good luck,

Tim

Seems a bit odd to need a condensate pump in the attic, no?

Agreed on making easy access possible. What I'm picturing is the air handler in the center of the attic, plenty of height and easy to get to.


The small bedroom is to the left in this picture, another gable end that can't be seen. The air handler would in theory, go between me and the B vent with the return right there.

Harvey Ramer

It definitely is. It will save on the install as well as provide excellent comfort to the whole house as a single zone. I would still use the ecobee thermostat with a wireless sensor. The thermostat serves as one occupancy sensor and will come with one additional sensor. You can have one upstairs and one downstairs. the latest sensor to sense occupancy will command setpoint to about a 75% deviation of the temp split between the 2 sensors.

You can easily run drops down through closets or build a chase on the second story.

ChrisJ

Harvey Ramer said:

It definitely is. It will save on the install as well as provide excellent comfort to the whole house as a single zone. I would still use the ecobee thermostat with a wireless sensor. The thermostat serves as one occupancy sensor and will come with one additional sensor. You can have one upstairs and one downstairs. the latest sensor to sense occupancy will command setpoint to about a 75% deviation of the temp split between the 2 sensors.

You can easily run drops down through closets or build a chase on the second story.

I was just thinking whether or not someone made a thermostat that did this. I know with the VisionPro you can use multiple thermisters, but it's very limited in what it can do, and very ridiculous in that you need to keep the resistance the same. I think you need a minimum of like 4 or 8 sensors if you want to do more than one area.

Jack

Register as a contractor on Fujitsu's site and the world opens up to you informationally. I was going to go multi heads in my system, but SWEI's comment on the turn down is a big factor and for me the biggest factor was how I was going to actually use the space. A triple or quad system was going to get pretty pricey and was not as efficient as the singles. I ended up going with a dual for the upstairs bedrooms and a much higher efficiency single for the downstairs. Cost came out close to the trip/quad system I was looking at. As it is I get better zoning and efficiency out of two systems.
I have had success on jobs using Tjernlund Air-Share transfer fans as well. Put the fan on a switched outlet and you can move air to adjoining rooms without having to add another evaporator. I would not put them in at first, but would find out areas where you might need them.
For your residence you can go with the branch box set-ups but it is a level of complication that I don't think you need to accept...or pay for. They are cool, but they are pricey.

Bob Bona_4

It's going to be a tight job for sure, but doable. Try to keep the returns long, sound attenuation. It will likely be close to a spider system

Harvey Ramer

If you do a central return, pay close attention to the face velocity of the return air filter/grill. If you stay low enough, you won't hear a whisper.

You'll want your duct system designed via manual d. No rules of thumb. I generally try to not go over 100 and 130 cfm per Supply register and space them for even air distribution. You'll be doing ceiling vents with a central return likely, so you'll want to keep the registers close enough to the perimeter to enhance equal distribution.

I would install duct takeoffs with Balance dampers. There again you have the opportunity to spend a chunk of change. The wizards at Belmo have built an electronic Balance damper that also measures airflow and readjusts automatically. I believe they even have feedback sensors for the respective rooms. Anyway, they are blue tooth and you access the actuator with your smartphone and set the cfm and so forth. If you want to do it manually, I could rent you a flow hood and give you the charts and formula to balance the system. You'll have to come pick it up of course and bring it back.

TonyS

Hi Chris, I have been installing these things for many years pre inverter and post. I have them in my own home after removing my central attic system. Started with Sanyo then Fujitsu and now Comfort Star. I have a Samsung Vivace downstairs because my wife made me match it to the black TV. I have taken all these units into my shop and disassembled them from top to bottom. I am anal like that but I would prefer to do it in a well lit shop than on a ladder in a customers home. What I have found is these units are almost all the same, they are manufactured in China, they use the same fan motors and reversing valves and txv's and someone else's compressor. If someone tell you one is better than the other...ask why with mechanical facts please. I have installed one early Samsung DMV with branch boxes and cassettes ...cassettes were not available on residential multi units till a few years later. Make a long story short, Samsung teamed up with Copeland and used a non variable motor to drive a variable displacement scroll...it sounds like a truck shifting.
The scroll compressor does not like to vary speed so all your new inverter units use rotary compressors, even the new variable central units. 25 years of tooling up to make scrolls out the window lol. Branch boxes end up in the attic...exactly the place I dont want to be. Next question..pre made line sets..NEVER.
Pre insulated linesets have been in a race to the bottom as to how thin they can make their tubing. Anyone who has put this garbage in a tube bender knows what I am saying. On ductless we dont only have to bend this garbage, we have to flare it. Buy regular acr tubing and insulate it yourself. Again you can verify this with a metal thickness gauge..inexpensive from Harbor Freight. Some of the features that I like on the Comfort Star are.
follow me..you have the choice of integral temp monitoring or you can use the remote as the thermostat..works well on high ceilings. Able to shut off all LEDs while still operating! MUlti units now have master low and high valves, you can vac down all branches at once. This makes it much easier to properly vac down system...vac...nitrogen..vac...nitrogen..vac...nitrogen...finish.
As far as servicing goes they all operate on a similar inverter system..incoming ac rectified to DC then inverted back to a simulated 3 phase to run the compressor. The condenser fan motor is controlled differently on different models..some ac multi speeds and others dc variable. There are no hard starts and I am sure this extends compressor life greatly. All manufacturers have different boards and test points so you need to have individual schooling and support on each one.

As far as comfort there is no comparison to anything else. These units constantly vary their speed to match the load..they know what the temperature is inside and out and they just work. Everyone has their own remote and sets their own comfort level and dehumidification keeps everything nice and dry. Comparing ductless to a brainless central system isnt even an argument. It would be like comparing an old cast iron boiler with no zone valves to a modulating boiler with outdoor reset and everything zoned.

These things work very trouble free and the simple fact they sell them in grocery stores in Mexico attest to this fact. Yea they dont even vac them down, just blow a little freon out the lines and they work for years and years. Also when you see how inexpensive they are there (same manufacturers as here) you tend to tighten your **** a little. Good luck

Techman

The only problem I have w/ Ductless/Inverter is the indoor section gets moldy/dirty/not nice ,but all it takes is some cleaning/cleaning/cleaning. On a couple of comm units I set up a plastic tarp taped AROUND the entire unit and funnel the tarp into a 55gal container,and go to work w/ a full fledged garden hose and a wet vac.

BobC

For about 50 cents per unit they could humiseal the boards so they wouldn't be affected by moisture or dirt - except for the dirt maybe leading to overheating the parts that aren't rated for that environment in the first place.

We all know that 50 cents would just destroy the insignificant profit margin they have to live with on these units.

Bob

ChrisJ

Techman said:

The only problem I have w/ Ductless/Inverter is the indoor section gets moldy/dirty/not nice ,but all it takes is some cleaning/cleaning/cleaning. On a couple of comm units I set up a plastic tarp taped AROUND the entire unit and funnel the tarp into a 55gal container,and go to work w/ a full fledged garden hose and a wet vac.

That sounds fun to do on multiple units in your house..........

TonyS

Cleaning isnt bad at all..I use the rectorseal kit and a self contained 135 psi rechargable sprayer. http://www.rectorseal.com/desolv-cleaning-kit/

TonyS

Dont use a regular sprayer shown in the video..here is what I use.It has enough pressure to really clean the long squirrel cage...https://www.amazon.com/Ivation-Multipurpose-Portable-Spray-Washer/dp/B00R0GBKR4/ref=pd_yo_rr_bia_t_2?ie=UTF8&psc=1&refRID=146119HMPH37K6HHSG2C

JUGHNE

So if you are looking at a different budget then a standard air handler in your attic might be the option. However 3.5 ton really sounds over the top for AC. I did a 90 year old house with about 1200 on the ground floor and 975 on the upper floor. A 2.5 heat pump cools the entire house and heats it most of the time. It is a 1 1/2 story with knee walls and valleys that are more prone to air infiltration then yours which looks to be full 2 stories.
We are all certain you will do a heat gain survey for your house. (Your attic floor looks a little thin for R value unless there is something we don't see) My gut tells me you would need only a 2 ton.....2.5 would be the most.....and probably over cool the upstairs. The house I mention above has 4 bd rms and bath upstairs. 4 more 8" runs were run down thru closets to the first floor. The largest single filter grill available was put in the central 2nd floor hallway just at the top of the open stairwell.....it is somewhat noisy.
The 2nd unit I installed 30 years after the first.....I added another 12" flex to that return box (which quieted it down) and Up graded some flex sized. 30 years ago I and many others were unaware of the reduced CFM capacity of flex compared to solid round pipe. The new AH has a variable speed fan motor which will correct duct sizing sins to a certain degree.
You have only 5 SA runs (so far) to get rid of the air. 5 8" flex runs will get rid of only about 825 CFM......2 tons by my shoot from the hip guess.
I believe you or someone mentioned houses with a single system in the basement trying to push cool up to the second floor and freezing the lower floor. It is the difference of day and night to have most of the SA on the second floor with open stairwell.
Also with variable speed motor you could run fan "on" in the heating season (1/2 speed) and recapture some of the gravity flow going upstairs from the steam.

Techman

TonyS, Some don't do ,but ,they ALL do,at least they do around here,LI,NY.

ChrisJ

JUGHNE said:

So if you are looking at a different budget then a standard air handler in your attic might be the option. However 3.5 ton really sounds over the top for AC. I did a 90 year old house with about 1200 on the ground floor and 975 on the upper floor. A 2.5 heat pump cools the entire house and heats it most of the time. It is a 1 1/2 story with knee walls and valleys that are more prone to air infiltration then yours which looks to be full 2 stories.
We are all certain you will do a heat gain survey for your house. (Your attic floor looks a little thin for R value unless there is something we don't see) My gut tells me you would need only a 2 ton.....2.5 would be the most.....and probably over cool the upstairs. The house I mention above has 4 bd rms and bath upstairs. 4 more 8" runs were run down thru closets to the first floor. The largest single filter grill available was put in the central 2nd floor hallway just at the top of the open stairwell.....it is somewhat noisy.
The 2nd unit I installed 30 years after the first.....I added another 12" flex to that return box (which quieted it down) and Up graded some flex sized. 30 years ago I and many others were unaware of the reduced CFM capacity of flex compared to solid round pipe. The new AH has a variable speed fan motor which will correct duct sizing sins to a certain degree.
You have only 5 SA runs (so far) to get rid of the air. 5 8" flex runs will get rid of only about 825 CFM......2 tons by my shoot from the hip guess.
I believe you or someone mentioned houses with a single system in the basement trying to push cool up to the second floor and freezing the lower floor. It is the difference of day and night to have most of the SA on the second floor with open stairwell.
Also with variable speed motor you could run fan "on" in the heating season (1/2 speed) and recapture some of the gravity flow going upstairs from the steam.

Things have been changing, yes 3.5 ton is overkill but 3 ton seems to be about spot on. I've had a few trying to push me down to 2.5 ton but the problem is I don't maintain 78F, I generally am closer to 70-72F but 75F is tolerable. Outdoor design temp is 89F here.


Here's my current ideas.
3 ton 2 stage unit with variable speed air handler. 3" insulation over metal duct and very short flex runs to drops.

I am concerned about the return noise as I know it's going to be very loud. Perhaps it should be split between two in that area?

I know some are against it, but so far I really like the idea of a single return in this setup.


Go easy on me, I knew zero about duct sizing a few days ago and have been getting help and doing an awful lot of reading.

I'm trying.

Bob Bona_4

I'm thinking 2-2.5 ton max, variable speed, zoned, with an 8" bypass. 14 or 16 SEER cond. NJ utility offering rebates?

3 ton too big. What are you gonna do with all that air when upstairs only calls and you only have 3-7" and 1-5". That's 1200 cfm and you have maybe 530 cfm capable ductwork at an acceptable static pressure? Probs

ChrisJ

Bob Bona said:

I'm thinking 2-2.5 ton max, variable speed, zoned, with an 8" bypass. 14 or 16 SEER cond. NJ utility offering rebates?



3 ton too big. What are you gonna do with all that air when upstairs only calls and you only have 3-7" and 1-5". That's 1200 cfm and you have maybe 530 cfm capable ductwork at an acceptable static pressure? Probs

Yep, they are I'm just not sure how it would work out with me doing the work.


You bring up a good point, what exactly controls the variable speed on an air handler such as this? What determines when the compressor runs on low, and high?

I was looking at 16 or 18 SEER 2 stage.
What's a bypass? Sounds like a feedback loop?

JUGHNE

I am wondering if material costs, due to the minor complexity of this zoning & control, are approaching the multi mini split unit costs.
Also see the labor time tripling for plaster/lath cutting (repairs ) and ductwork insulation work. But I think you enjoy that.
Also with AC AH only, in attic you lose the benefit of having cheap heat pump heat for the shoulder seasons.

Decisions.....decisions.....decisions!

ChrisJ

JUGHNE said:

I am wondering if material costs, due to the minor complexity of this zoning & control, are approaching the multi mini split unit costs.
Also see the labor time tripling for plaster/lath cutting (repairs ) and ductwork insulation work. But I think you enjoy that.
Also with AC AH only, in attic you lose the benefit of having cheap heat pump heat for the shoulder seasons.

Decisions.....decisions.....decisions!

That's the fun part! Figuring out what to do.

The cleaning BS with the mini-splits has me off that. Some may say it's worth it, but no thanks. I know me, and I know I'll keep one coil clean but doing it to 4 or more of them in livingspaces? No thanks.

Won't be much plaster repair, the ductwork for first floor is going through two closets, plenty of room and some drywall to close it in afterwards will be easy. Will be plenty of labor involved in everything though, no doubt about that. The other huge benefit is I won't have a bunch of linesets running up the sides of the house all over. A few years back I spent 4 hours running cable tv coax through the wall to one room, instead of going up the outside of the house like most would. If I had gone up the outside it would've been a 30 minute job tops.

The zoning may, or may not happen. In fact it probably won't at first until I end up with an issue, manual dampers are cheap and easy. If the system can be set manually and just let run without a problem, why mess with it? Perhaps only one automatic damper on the livingroom side will be needed as that's the shady side of the house.


What really has me concerned is multiple people saying 2 to 2.5 tons. And not just any "people" but people that actually know what they're talking about unlike me. I spent most of the weekend trying to figure out why this is. Why is this so far away from what I came up with using my window units? Is it because I keep my house colder than the equipment is designed for? Is it because window unit ratings are wrong?

One thing I know without a doubt is an oversized A\C system sucks. It's a damp, expensive to run nightmare so I understand the importance in getting it right.


Are there any easy to use manual J programs out there?

JUGHNE

Your window AC may not put out their claims. Also you don't get the even air distribution you can have with central ducting.

Another point is that return air filter grills that I have seen only give you a 1" thick filter. You may want to go with a single 4-5" thick filter rack at the unit, as your attic looks to have a lot of head room. (change perhaps once a year).

Think about the standard basement duct system trying to push cool up to 2nd floor. Too cold on first floor and barely comfortable on 2nd. With oversized attic AC you would reverse that situation. That cool air will walk down the stairwell and your warm 1st floor air will float above the stairs. Think of it as getting second hand residual cooling from above.

SWEI

ChrisJ said:

Are there any easy to use manual J programs out there?

LoopCAD/HeatCAD have a 30-day trial.

JUGHNE

Here is easy to use, needs pencil and tape measure.....
has worked for me for a long time. If you would please try this and compare it with a high tech LoopCAD etc and post the differences so I learn how wrong I have been for 35 years.

JUGHNE

Well that is the back side, see if I can get the front posted.
Old as dirt and twice as simple!

ChrisJ

JUGHNE said:

Well that is the back side, see if I can get the front posted.
Old as dirt and twice as simple!

How would you treat single pane loose windows with cheesy storms? As single pane, or two pane?

JUGHNE

Judgment call on your part......just like guess on the ACH with other programs. You could average the R factor between 1 & 2 panes. Unless you do a blower door test which will cut into your budget even more.....and you know where the major leaks are already.
On an old rental I had I found some aluminum tracks for double hungs that were DIY projects. They tightened up the sides and then adding weather striping on the bottom, top and the junction of the 2 sashes, adding maybe 2 window locks to pull them together tightly.....all this helped.
This also points out the diminishing return on a lot of factors; such as the difference between double and triple pane.

If your house has the same area and wall R value on the first floor and 2nd floor, you could just ignore the ceiling/floor between and figure one big box with 16-18' side walls. KISS.

This form will slightly over heat & cool as it assumes a fair amount of ACH with each R value.
Please compare and let us know.
Thank you.

Jack

TonyS said:

Dont use a regular sprayer shown in the video..here is what I use.It has enough pressure to really clean the long squirrel cage...https://www.amazon.com/Ivation-Multipurpose-Portable-Spray-Washer/dp/B00R0GBKR4/ref=pd_yo_rr_bia_t_2?ie=UTF8&psc=1&refRID=146119HMPH37K6HHSG2C

Thanks for the lead on this Tony. I've been looking for a better way to clean mshp evaps. This should speed it up considerably.

SWEI

If you decide to use LoopCAD/HeatCAD (MJ8 Edition) be sure to get all the window details right. It will use the height above floor and overhang numbers to calculate solar gain from those windows.

MikeG

If you want info on Mitsubishi go to MyLinkDrive.com. Their actual web site leaves a lot to be desired but this site has a lot of the tech stuff. I installed my second one the end of June. It was a 30 SEER 9k hyper heat pump. For an upstairs beadroom in a remodeled farmhouse with hot water heat. The first one I put in 5 years ago was cool only 12K in the master bedroom. I did look at the multihead option 5 years ago. I was advised that if the outside unit went bad I would have nothing. I believe the multihead units also have lower ratings. This site gives you all kinds of options if you wade through it. My wife loves them. Some dont like the looks but they are super quiet. I did all the install, electrical, runing the line sets, concrete pad, set the outdoor unit etc. I then paid a HVAC contractor friend to connect the lineset, purge, leaktest and pull the vacumn. I bought a premade insulated 25' lineset. The flares were junk, which I accounted for. We reflared to R410A specs. It was still cheaper than getting bulk material. The units I put in come with R410a for up to 25' of line, over that and you have to add, I don't think you recover refrigerant for under 25'. Just my experience

SWEI

The better preinsulated lines have a skin over their insulation that is orders of magnitude tougher than the standard EPDM foam stuff. Works great as a solar thermal line as well. We buy it in 50 meter rolls to minimize waste.

ChrisJ

@JUGHNE
Using your forms I came up with 2.6 tons for an indoor temp of 75F at 90F outside.

Question is, what would 2.5 tons give me, in theory, with an outdoor temp of say 85F? Would I be able to do 70-72F?

Techman

ChrisJ, what is the design degree temp where you live.? The typical design temp diff of indoor/outdoor temp was 20*,so on a 92* day the house was 72*,then if 95* out it was 75* inside the house. Hydronic heat is the same way,just opposite.

Then the energy situation showed up the weather change a little and now for my area(LI,NY) the 20* TD is figured at 15*F,depending.

ChrisJ

Techman said:

ChrisJ, what is the design degree temp where you live.? The typical design temp diff of indoor/outdoor temp was 20*,so on a 92* day the house was 72*,then if 95* out it was 75* inside the house. Hydronic heat is the same way,just opposite.

Then the energy situation showed up the weather change a little and now for my area(LI,NY) the 20* TD is figured at 15*F,depending.

Design temp is 89F for my area.
I used 90F on Jughne's papers.

20F sounds far more reasonable to me than 15.

JUGHNE

Do you have a lot of east-west glass?
What ceiling (attic floor) R value do you have?

Gone all day.

ChrisJ

JUGHNE said:

Do you have a lot of east-west glass?
What ceiling (attic floor) R value do you have?

Gone all day.

Decent amount of glass on all sides of the house.
R value in attic is low, non-existent in some areas.

I know that needs to be fixed, but it hasn't happened yet.

ChrisJ

Does anyone make a 2 stage condenser smaller than 3 ton?
That's the smallest I've been able to find.

TonyS

Jack said:

TonyS said:

Dont use a regular sprayer shown in the video..here is what I use.It has enough pressure to really clean the long squirrel cage...https://www.amazon.com/Ivation-Multipurpose-Portable-Spray-Washer/dp/B00R0GBKR4/ref=pd_yo_rr_bia_t_2?ie=UTF8&psc=1&refRID=146119HMPH37K6HHSG2C

Thanks for the lead on this Tony. I've been looking for a better way to clean mshp evaps. This should speed it up considerably.

Jack..this item has also made working on splits a pleasure..full step to stand on and a little tool holder and divider tray on rail...love it!..https://www.amazon.com/gp/product/B00005V5MF/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

JUGHNE

As I thought about leaky windows today and had suggested for you to use an average of 1.5 glazing's, however I might use that for the heating calc. But cooling I would go for the 2 glazings, you may not have the wind factor in the summer and also we are only talking of 15 to 20 TD inside to outside.

Attic insulation is the lowest hanging fruit, biggest bang for the buck. If you go for AH in attic with a return near the stairwell, that opening would be the opportunity to slid some 2 X 6 lumber up there to double the height of the floor if you wanted that. Or remove existing floor boards, build up 2x6 platform and raised walkway and blow in your choice after AC is complete.
I would caulk any penetrations in the ceiling first.
Reduces the heat loss more than heat gain.

ChrisJ

I had assistance with this from one of the best in the industry.

JUGHNE

That is quite a TD for cooling, 25 degrees.
If I set my end of the house for 74 I get the mild brain freeze effect from the AC. I have some high wall supplies for the cooling, those are on inside walls of course. The result of the cooler air being delivered from above is more obvious than other parts of the house with traditional floor supplies. FWIW

From past experience, I believe that "old school" paper form of the 60-70's would always guarantee that the equipment was safely oversized.

Also back to the RA hole in the ceiling, for me all the equipment and myself went up that way until finished. The last RA flex/grill box put in place when finished and then travel thru the attic access for service/start up only.

ChrisJ

JUGHNE said:

That is quite a TD for cooling, 25 degrees.
If I set my end of the house for 74 I get the mild brain freeze effect from the AC. I have some high wall supplies for the cooling, those are on inside walls of course. The result of the cooler air being delivered from above is more obvious than other parts of the house with traditional floor supplies. FWIW

From past experience, I believe that "old school" paper form of the 60-70's would always guarantee that the equipment was safely oversized.

Also back to the RA hole in the ceiling, for me all the equipment and myself went up that way until finished. The last RA flex/grill box put in place when finished and then travel thru the attic access for service/start up only.

I have a set of winder stairs with a standard interior door to go up to the attic which is nice. Should make bringing stuff up easy alone.

@JUGHNE Keep in mind, with your paper I had a TD of only 15 degrees and it said 2.6 tons so it's not surprising for 25° to be 3 tons.

I've had our bedroom window unit set to 68F for a while now and a fan running.

I told you, I like it cold.
I run my refrigerator at 32F as well. Love ice cold drinks, has to be almost frozen.