Two minisplit proposals...

[Innovate1]

Looking to put a minisplit system in my 30 x 40 x 14 high shop. 2 x 6 walls with at least R19, R38 in ceiling. R17 OHDs. Slab insulation. Have two slightly different layouts and capacities from two contractors. Right around $10k. Larger system is about $200 more. Have marked the locations and capacities in red.

One concern is heat to the bathroom since it won't have a duct like it would for a ducted system and has two exterior walls.

Please give me some feedback on these, which you think is better, etc...

Was thinking furnace/AC but the minisplit system is about $1000 less and have heard good things about them.

 

[justinjoyal]

Looking to put a minisplit system in my 30 x 40 x 14 high shop. 2 x 6 walls with at least R19, R38 in ceiling. R17 OHDs. Slab insulation. Have two slightly different layouts and capacities from two contractors. Right around $10k. Larger system is about $200 more. Have marked the locations and capacities in red.

One concern is heat to the bathroom since it won't have a duct like it would for a ducted system and has two exterior walls.

Please give me some feedback on these, which you think is better, etc...

Was thinking furnace/AC but the minisplit system is about $1000 less and have heard good things about them.

Layout #1, definitely.

Can’t comment on sizing as I have no load calc to work with.

10k? Geeez.

 

[Innovate1]

Layout #1, definitely.

Can’t comment on sizing as I have no load calc to work with.

10k? Geeez.

Does seem quite high now that I look at some on line pricing. It appears I can buy the same unit (Mitsubishi) on line for around $4500. That was from a Trane dealer. Need to look into what's involved in buying online and getting someone to do charging and startup.

Quick on line sizing I did showed I need about 12k for cooling and 19k for heating but the downloaded summary is wonky. Doesn't even have the right number of windows I entered and other major mismatches from what I entered. So I am not putting any faith in that even though I entered insulation values and other details that should have given a good result.

I have several quotes for a furnace/ac when I was planning to build the same building in a nearby town. It was a big range. The furnace ranged from about 40k to 90k and AC from 2ton to 3.5ton.

 

[Innovate1]

Daikin and LG have similar size units that are quite a bit cheaper on line. About $3500. Do these perform as well at low temps for heating?

 

[yeldogt]

That's actually a decent price for a full 3 head hyper from Mitsubishi ...

What's you heat load and fuel possibilities ?

 

[Innovate1]

No big heat sources in the building if that's what you are asking. Ran natural gas line to the building when running other utilities from the house thinking I would do a furnace so have gas and electric. 100A panel with perhaps 50A available for HVAC.

 

[yeldogt]

What's the electric rate ?..... with NG and space to install a conventional system I think that would be my first loo.

High efficiency furnance -- spiral pipe?

I would think you have a higher heat load vs cooling load

 

[justinjoyal]

Does seem quite high now that I look at some on line pricing. It appears I can buy the same unit (Mitsubishi) on line for around $4500. That was from a Trane dealer. Need to look into what's involved in buying online and getting someone to do charging and startup.

Quick on line sizing I did showed I need about 12k for cooling and 19k for heating but the downloaded summary is wonky. Doesn't even have the right number of windows I entered and other major mismatches from what I entered. So I am not putting any faith in that even though I entered insulation values and other details that should have given a good result.

I have several quotes for a furnace/ac when I was planning to build the same building in a nearby town. It was a big range. The furnace ranged from about 40k to 90k and AC from 2ton to 3.5ton.

2 ton to 3.5 ton. That’s a huge difference.

If you provide me with the number of doors and windows and their respective size, the building front door’s orientation, and insulation r value of the floor I can run a quick load calc.

Edit: ok, windows/doors are on the plan.

 

[Innovate1]

2 ton to 3.5 ton. That’s a huge difference.

If you provide me with the number of doors and windows and their respective size, the building front door’s orientation, and insulation r value of the floor I can run a quick load calc.

Edit: ok, windows/doors are on the plan.

Yeah. The sizing was all over the place. One contractor called out a 100k+ furnace - Maybe he thought I would have the big doors opening repeatedly like a commercial garage. I don't expect to have them open much and a brief temp swing when I do is ok. OHDs face south. Floor has 2" R10 under slab and along inside of foundation wall. I brought the foundation foam up to almost the top of the slab around the edge but the concrete guys cut most of that out so no slab edge insulation. West wall is fairly well shaded by trees. Any other details you need for the load calc?

 

[Black Oak]

with all you've done really well , I'd go back and insulate the edge of the slab . if you can .

 

[theoldwizard1]

It would cost more to install, but 2 separate smaller units would be more efficient.

It would be difficult to calculate the pay back time.

 

[Innovate1]

with all you've done really well , I'd go back and insulate the edge of the slab . if you can .

That seems like a REALLY difficult job. I would have to saw cut the concrete to create a gap between the foundation wall and slab and then fill that with insulation and cover it. The filling and covering part is easy. The removal of concrete is the difficult part. Is there some other method?

My current garage has some slab projection under the OHDs and is partially insulated around the perimeter (all but top 1 to 1.5 inches insulated with R5 insulation as I recall. Heating it isn't bad at all but it is about 2/3 the size and not as tall.

 

[yeldogt]

It would cost more to install, but 2 separate smaller units would be more efficient.

It would be difficult to calculate the pay back time.

Only if both units are running in the optimal zone ... single units are based on short tubing and running at 70 percent . Multi have the ability to provide what's needed and properly sized can be a better fit.

That's not to say that some times two can be a good idea. It's all dependent on load.

 

[rattle_snake]

Option #1.
The best advice I have found on this forum is from the member who responded first.

I have a very similar building (same size & insulation), 36k is more than enough. I went separate units (2x 18k) as they were significantly cheaper. At the time had to get a higher end unit to get multi head. I went with Daikins.

I can run just one and it cools the whole building fine except for max heat load on 115*+ days. I can open overhead door and pull in a hot vehicle to work on lift, 36k BTU is enough for this scenario.

 

[Innovate1]

Option #1.
The best advice I have found on this forum is from the member who responded first.

I have a very similar building (same size & insulation), 36k is more than enough. I went separate units (2x 18k) as they were significantly cheaper. At the time had to get a higher end unit to get multi head. I went with Daikins.

I can run just one and it cools the whole building fine except for max heat load on 115*+ days. I can open overhead door and pull in a hot vehicle to work on lift, 36k BTU is enough for this scenario.

I see your location and we have lots of humidity but not as high of temps here in the summer. Probably similar cooling load. More concerned about heating in the winter which is colder here.

Did you buy them on line? Install them yourself? Get someone else to setup and charge?

 

[Git]

It seems that most of the big manufacturers are trying to distance themselves from internet sales - perhaps to protect their dealer network?

I installed my own dual-zone, 24k Mr Slim going on 6 years now. Purchased everything from eComfort (very pleased with them, they will even do load calcs if you fill out their form). I installed everything myself, lineset, flares, electrical, etc. Then I paid a local Mitsu Dealer to come in and start it up for 'warranty' purposes. Cost was $300, they checked everything over, nitrogen leak test, vacuum, etc

Not sure if that can be done anymore, but what really is the failure rate in the higher end units. At the time, I spent about $140 on specialized tools - Flaring tool was $105 plus cutter, nylog, things like that. For the $300, I could have pretty much-bought everything I needed to start it up on my own

Take a look at the eComfort site - they make it real easy to shop for what your looking for, by zone, by BTU, etc

https://www.ecomfort.com/cooling/mitsubishi-mini-split-systems.html

 

[Black Oak]

Sorry , I was thinking pole barn shop . My mistake on that . Lots of heat lost thru the edge of a slab .

 

[SkeeterZX200]

I have a 30x60x 14. I put in two 18k Pioneer split systems. I too have R-19 in the walls and around R-40 in the ceiling.

I installed the two split systems myself. I have less than 3k into it.

I have only run through a heating season, but I do not see having a problem in the summer here in Kansas City.

I would recommend adding ceiling fans to move the conditioned air around. Also, the hot air is going to want to sit at the ceiling.

 

[Innovate1]

I have a 30x60x 14. I put in two 18k Pioneer split systems. I too have R-19 in the walls and around R-40 in the ceiling.

I installed the two split systems myself. I have less than 3k into it.

I have only run through a heating season, but I do not see having a problem in the summer here in Kansas City.

I would recommend adding ceiling fans to move the conditioned air around. Also, the hot air is going to want to sit at the ceiling.

Self install seems to be an issue with the coolant and warranty. How did you deal with charging the system? Where did you get the units?

 

[SkeeterZX200]

Self install seems to be an issue with the coolant and warranty. How did you deal with charging the system? Where did you get the units?

When it come to warranty I will just have to deal with whatever issues come up.

The condenser comes precharged for the line set length that is provided.

I ordered the units through Amazon.


https://www.amazon.com/dp/B01DVW6FXO/?tag=atomicindus08-20

 

[yeldogt]

The 20 SEER 3rd generation are just over $1300 -- with DIY warranty.

I'm really thinking of going this route.

 

[SkeeterZX200]

The 20 SEER 3rd generation are just over $1300 -- with DIY warranty.

I'm really thinking of going this route.

The only I items I need to buy were gauges and a vacuum pump.

 

[theoldwizard1]

I have a very similar building (same size & insulation), 36k is more than enough. I went separate units (2x 18k) as they were significantly cheaper. At the time had to get a higher end unit to get multi head. I went with Daikins.

While I do know that the multi head units are more expensive, I have never heard that the uplift was more than buying two smaller ones ! VERY INTERESTING !

 

[theoldwizard1]

with all you've done really well , I'd go back and insulate the edge of the slab . if you can .

That seems like a REALLY difficult job. I would have to saw cut the concrete to create a gap between the foundation wall and slab ...

Dig a trench on the outside of the garage next to the foundation. Install at least 2" of rigid foam insulation there.

Depending on how cold your winters are, it may of may not be worth the effort.

 

[theoldwizard1]

Daikin and LG have similar size units that are quite a bit cheaper on line. About $3500. Do these perform as well at low temps for heating?

You are asking the right question, but it is not easy to answer. I am not an HVAC guy, but looking at specs from various manufacturers, you will see that they advertise performance differently so it is difficult to do an "apple to apples" comparison.

First, check for an Energy Star Rating. Only the most efficient models will get that. Second, look for something like "100% heating at X°F" or some type of chart that show how fast the efficiency drops off.

 

[ardpub]

I believe you can get the EPA certification to work on (and buy refrigerant for) mini-splits online in a few hours. Considered doing this for my install but decided it was too much hassle and cost in tools. I was never sure if having that license would be sufficient for warranty.

The labor costs on mini-split installs are serious but I guess its a lot of work and get why they only want to work with a handful of trusted brands.

 

[Notgrownup]

I appreciate the labor costs of installers and like said above and them wanting a brand they can get support...I opted to do my own install and get it commissioned by a pro...Yes I take a chance but playing the odds with positive reviews....
I would do it again, I feel like I got a very high quality unit with the Blueridge 18 seer.
I can say the labor is probably worth it seeing what I had to do to install.

 

[dcg9381]

Self install seems to be an issue with the coolant and warranty. How did you deal with charging the system? Where did you get the units?

This is true that the units may or may not be warrantied when installed "by consumer". There is one manufacturer that will warranty self-installed, but they cost about 10% more.

Systems are typically pre-charged. You need some tools to evaculate the lines and check for leaks.

I did 2 x 2 ton Daikin systems in my shop. About $2400 was my total cost. Like you, I got bids in the $10k range.

 

[Innovate1]

That's a big savings. What is all the labor to install? Seems like placing the units, running the refrigerant lines, the electric. Then check the system for leaks pull a vacuum and charge or release the compressor charge into the lines. Wondering what it would cost to have a local company do the leak check and start up.

 

[yeldogt]

The Mr Cool DIY have a consumer warranty .... they are DIY. Obviously if you have a leak -- now the fix is not DIY. I was looking and they provide $450 for this under some of the plans.

The new 3rd gen are at the 20 seer

having them installed -- do the math. It ends up being most practical to by the better equipment as so much of the cost is labor.

 

[yeldogt]

This is true that the units may or may not be warrantied when installed "by consumer". There is one manufacturer that will warranty self-installed, but they cost about 10% more.

Systems are typically pre-charged. You need some tools to evaculate the lines and check for leaks.

I did 2 x 2 ton Daikin systems in my shop. About $2400 was my total cost. Like you, I got bids in the $10k range.

I'm not sure when you did that .. but, that's going to be hard to hit today w/ linesets .. all equipment. the 24k btu units are a bit more money over the 9 and 12

 

[yeldogt]

While I do know that the multi head units are more expensive, I have never heard that the uplift was more than buying two smaller ones ! VERY INTERESTING !

The multi heads allow for more head vs compressor. So you can add three 12's and only have a 30k BTU compressor. This is great for most applications -- since the heads are not evaporators they work differently. It allows the compressor to work in its sweat spot more of the time.. This is especially valuable in heating. With most applications the single units are not running at full output .. so if you need some extra capacity for setbacks or occasional uses you don't have all of these oversized single systems in a dwelling.

I have a three head in the house where I am currently -- when I entered the room the eye saw me and directed ac my way and I dropped the temp ... the unit has the extra capacity from the compressor. to drop the room a few degrees quickly. With the multi -- you size the load to the compressor -- you don't add up the heads

 

[davo727]

Ive said it before, who cares about waranty if you save so much you could buy all the components 3 more times with the price difference between contractor vs doing it yourself.

 

[Git]

Wondering what it would cost to have a local company do the leak check and start up.

I paid a Mitsubishi dealer $300 to startup my Mr Slim unit about 5 years ago. I did everything - electrical, cut and flared the lines, etc. They looked it over, leak tested, vacuumed, and released the freon charge.

 

[pgray007]

That's a big savings. What is all the labor to install? Seems like placing the units, running the refrigerant lines, the electric. Then check the system for leaks pull a vacuum and charge or release the compressor charge into the lines. Wondering what it would cost to have a local company do the leak check and start up.

Same as many above. I did the install and had a pro connect the lines and check for leaks. I believe it was around $250 for a couple hours on my Daikin with two heads (upstairs and down). Heading performance is great, as is cooling, and it sips electricity on a 20A circuit.

Install is easy. Mount the compressor outside, cut a hole in the wall, mount wall units, power, lines, turn on basically. It probably took me 4 hours and then another 3 with the HVAC guy for the line set stuff and it’s been running like a top for 4 years at this point save for a motor that moves the vanes breaking, which is a $30 part.


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[Innovate1]

Sounds like a good plan to buy and install myself and have an HVAC firm do the leak check and startup.

One thing I am just now thinking about is the drain lines from the heads. I had planned to mount the furnace/AC high and run it to a high trap on the wall to keep all that off the floor. Now that I am thinking of mini-split I am wondering how to deal with the drain lines. Walls are 14' and thinking the heads would be at about 9' - high enough to be out of the way but low enough to easily access for service. That would allow me to run the lines to a trap at about 7.5' I think. Longest drain line would be about 25'. Would run the drain line along the walls. Does that sound about right? Have seen flexible drain line for sale at minisplit sites but thinking PVC would look better and be easier to get constant slope (no dips).

 

[pgray007]

At least in my case there was flexible drain line that we zip tied to the line set and ran outside the wall. I put it all in some nice conduit stuff (I forget the brand, but got it from supplyhouse.com and then hid behind the compressor.


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[Innovate1]

They make lineset covers to make things look neater. will look up some details on that.