Exhausted all ways of trying to find a suitable mini spit, even second best with Zero success. Fourteen foot ceiling for mini splits seems to be the killer, not to mention dust? So with all the talk here about mini splits here, what's the secret with them? I'm about to give up and go the dreaded propane ceiling unit. Thanks
Mini Split or Propane ceiling uni
- Thread starter Sturgeon
- Start date
justinjoyal
Well-known member
A high dust area is not the best for a mini-split, but a "regular" environnement is not a problem even with 14ft ceilings. You just don't mount the wall unit all the way up there.
You need cooling or heating (or both?)
You need cooling or heating (or both?)
jack stand
Well-known member
Are you being cautioned by someone about the 14' ceilings?
Yes hot air rises but you can direct the airflow towards the floor from an 8' wall height of the inside unit and if necessary a lazy turning ceiling fan will help with the convection.
I'm not a pro but I'm thinking that regardless of what/how you make hot air it's a distribution issue. I'm assuming that when you mention "propane ceiling unit" your talking about a vented "Modine" type not a radiant tube that is more radiation heating than air.
I have one unit that's in a 16' ceiling in living space that's mounted at about 11'-12' and that was cleared and approved with an on site inspection by a mini split only large company during a sales and information meeting. I did happen to have a ceiling fan where it was needed but there's also a 2nd floor to utilize the additional heat also.
Dust, if you're talking wood shop dust, that will probably require an excerated cleaning schedule over normal living space but in the end it's only efficiency that you'd loose and that probably would apply to most heat sources.
Yes hot air rises but you can direct the airflow towards the floor from an 8' wall height of the inside unit and if necessary a lazy turning ceiling fan will help with the convection.
I'm not a pro but I'm thinking that regardless of what/how you make hot air it's a distribution issue. I'm assuming that when you mention "propane ceiling unit" your talking about a vented "Modine" type not a radiant tube that is more radiation heating than air.
I have one unit that's in a 16' ceiling in living space that's mounted at about 11'-12' and that was cleared and approved with an on site inspection by a mini split only large company during a sales and information meeting. I did happen to have a ceiling fan where it was needed but there's also a 2nd floor to utilize the additional heat also.
Dust, if you're talking wood shop dust, that will probably require an excerated cleaning schedule over normal living space but in the end it's only efficiency that you'd loose and that probably would apply to most heat sources.
Not one rep, say anything about the possibly of mounting cassettes lower, maybe just common sense, sounds like a good idea. Fan is a good option either way. They can't get beyond ceiling issue and me being in zone 5. Trust me, It's all been no no no. Yes, ceiling mounted propane power vented, really don't have a issue their other than being under the thumb of propane suppliers.
Many here have installed mini splits in shops with high ceilings. I used to sell and install them too. I have zero issues with it, although you may want a ceiling fan in the heating season to help circulate the air.
Where exactly is their issue? Mounting height? Not being able to heat or cool effectively??
Firebrick43
Well-known member
Does W. Mt mean Wester Montana or western mountains? Because if its western montana that is zone 6 and could possibly have issues with keeping up on the heat.
What is your shop square footage, insulation in walls, in ceiling, large windows or doors, under slab insulation? Any discussion without these is a shot in the dark.
jack stand
Well-known member
I hear "cassettes" and think of the flush in ceiling type that's a fairly expensive alternative to the wall mounted units that are the standard arrangement.
He's upselling you right from the start. (it would seem)
He's upselling you right from the start. (it would seem)
It's a new build, 34x52x14', 1750 sq ft. + -, insulating ceilings to r-38 and walls r-21, floor not insulated. Two 12x12' insulated doors, five 4x4 windows and 2x5' windows plus a man door all insulated. The mini split supplier's, the locale hvac installer said repeatedly no to the 14' cieling and the climate zone. Tried telling them building wouldn't be used when were in the minuses, that I would have back up heat source to no avail, zero. No mention of lowering wall units, fans, just won't work. Last mini split supplier Seville , said it would take at least a 54,000 btu + unit.
jack stand
Well-known member
I've heard of HVAC contractors around the country that have been putting in conventional ductwork systems for their whole careers not fully understanding the M/S and basically rejecting them being more comfortable with very old technology.
Like I touched on earlier, the BTU's required for the space is what it is, period. Weather it's a wood fire or nuclear fusion it the comfortable distribution that I think they have a hard time with. They want to bang a bunch of tin together just like grandpa did.
This mindset is usually reflected in their estimates. The M/S's are wildly popular in housing and small businesses here in Maine and where many things are more expensive, I've witnessed that it's the opposite to many areas. I have to believe that it's the lack of billable labor. You garage is a one day job for 2 men with no "shop work" fabricating ductwork.
Like I touched on earlier, the BTU's required for the space is what it is, period. Weather it's a wood fire or nuclear fusion it the comfortable distribution that I think they have a hard time with. They want to bang a bunch of tin together just like grandpa did.
This mindset is usually reflected in their estimates. The M/S's are wildly popular in housing and small businesses here in Maine and where many things are more expensive, I've witnessed that it's the opposite to many areas. I have to believe that it's the lack of billable labor. You garage is a one day job for 2 men with no "shop work" fabricating ductwork.
I agree with the hvac installers alarm, dyi made simple m/splits,. The hvac person I did contact fiend ignorance on larger sizes of these units and thinking about it there's three mini splits on one large house and two shops down the road. Punch drunk from all the nasayer`s sounds like. Also just one old business out of a bunch will touch home owner installed mini split. Pretty low.
jack stand
Well-known member
My cousin just installed a "Pioneer" DIY 1 head system in a little cabin. He's a licensed electrician and very meticulous but certainly not experienced in any way with this type of work. It's only been a couple of months but no problems so far. He's into it for only about $1500!
Previously I wouldn't consider a DIY system and it's been about 4 years since we had our 2 head unit installed by a large local company that m/s's is there only business. We went into this only looking for a/c due to prior (friends) experience with "heat pumps" in a conventional ducted systems 20 years ago we dismissed using the heating side.
The m/s turned out to be a great addition for the "shoulder seasons" prior to firing up the wood boiler for our radiant heat for the serious cold and of course the a/c.
But in a shop or non living space, his experience (and costs) have changed my mind.... so far. For that money you could buy a 2nd system and just use it for parts and still be way ahead.
Previously I wouldn't consider a DIY system and it's been about 4 years since we had our 2 head unit installed by a large local company that m/s's is there only business. We went into this only looking for a/c due to prior (friends) experience with "heat pumps" in a conventional ducted systems 20 years ago we dismissed using the heating side.
The m/s turned out to be a great addition for the "shoulder seasons" prior to firing up the wood boiler for our radiant heat for the serious cold and of course the a/c.
But in a shop or non living space, his experience (and costs) have changed my mind.... so far. For that money you could buy a 2nd system and just use it for parts and still be way ahead.
Firebrick43
Well-known member
Without doing a manual J that sounds reasonable for the reduced heat output in cold weather.
If you have back up heat I don't know why they are having a tizzy.
14' ceilings is not an issue with a wall mounted traditional head.
The biggest head is about 36000 btu but many are 24000 btu or smaller.
If it was me I would place two separate 24000 btu units. Single head units are more efficient than the multihead units, about the same cost(equipment wise) and then you have some redundancy built in as well. Since you are going to install a back up heat if those two units don't keep up with cooling or heating for 80 percent of the time, add a third smaller unit over the benches or where ever area of the shop you spend most of your time. Shops don't need 24/7 72 degree conditioning like a house.
My 28x32 x12' is handled very nicely by a 18k btu unit. I also have a reznor propane unit (60kbtu) for quick heat up. My insulation is the same as yours. I also have an upstairs using attic trusses. It's 14x32. Your floor area is twice mine. A 36kbtu mini split should work fine. Or for redundancy, put in two 18-24kbtu units.
Really good imformation people, thanks. Going to tear into this again tomorrow, it's getting old. Going to try LG, Gree or Seville and hopefully won't have to yell over salesman's barking dogs or screaming kids, seriously that's what it's been like. Thanks again.
American Locomotive
Well-known member
Mitsubishi is basically the standard, and should not be excluded
I sold mini splits for 10 years for a wholesaler and installed the the previous 12 years. I have no clue why they say no to mini splits.
I would stick a 36,000 BTU wall mount cold weather unit in there and never look back. If it wasn't for the heating capacity I might go with a 24,000 BTU.
If it turned up being a bit short on capacity, then stick in a second unit, based on the experience you have with the first.
I would stick a 36,000 BTU wall mount cold weather unit in there and never look back. If it wasn't for the heating capacity I might go with a 24,000 BTU.
If it turned up being a bit short on capacity, then stick in a second unit, based on the experience you have with the first.
Thanks P Ub , looking at two Seville 24000 btu units, didn't think to mention there's a rv and stuff taking up 25% of building either. Like the for mentioned idea of seperate units for maybe issues or convenience. Forum rocks.
American Locomotive
Well-known member
Be careful, a lot of senville's units have abysmal heating performance at low temps
jack stand
Well-known member
I've heard the same thing about efficiency as firebrick said about single heard units.(sounds like he in the trade)
Firebrick43
Well-known member
You give me to much credit. I am not an HVAC tech, although I have worked on some industrial refrigeration chillers and my own/friends house and auto AC and have tools to do it properly.
While its a trade I have thought about several times I highly dislike crawling on my belly, especially in dark places like crawlspaces.
It was more of an observation when I researched, purchased, and installed my own Mitsubishi mini split that all the seer ratings were higher with single traditional head units compared to multi head units or ducted cassettes.
I would suggest a combination. Get a mini-split sized for your cooling/dehumidifier needs. Oversized it a bit for heat if you want to. Install a Rinnai EX38 in NG or lp. I find the combination to work very well and use it in my home. Fujitsu has a 36kbtu ceiling suspended unit that might work very well for you. I had excellent results with it.
Nothing wrong with mounting the wall units lower than the ceiling. I have 10' ceilings and mounted the six wall units at about 7' so I can clean the filters without standing on anything. I have no interest in paying to cool the area above my head.
The only issue with mounting the cassette units lower than the ceiling is that it reduces the useful height of the ceiling. If you have a drive-through shop with a 14' ceiling, and your cassette unit is hanging in the center at 8', you can't drive anything higher than 8' through. I have only one cassette units, and it's at 8' and works great.
I have a few ceiling fans to help the wall units, but they're a little pointless with the cassette units.
Incidentally, given the configuration of the cassette units, they handle dust much better and requier much less servicing than the wall units.
IMO, but for the extra cost, the cassettes have it all over the wall units. I'll never buy another wall unit unless it's temporary....
The only issue with mounting the cassette units lower than the ceiling is that it reduces the useful height of the ceiling. If you have a drive-through shop with a 14' ceiling, and your cassette unit is hanging in the center at 8', you can't drive anything higher than 8' through. I have only one cassette units, and it's at 8' and works great.
I have a few ceiling fans to help the wall units, but they're a little pointless with the cassette units.
Incidentally, given the configuration of the cassette units, they handle dust much better and requier much less servicing than the wall units.
IMO, but for the extra cost, the cassettes have it all over the wall units. I'll never buy another wall unit unless it's temporary....
Make sure you are aware of the heating capabilities of the unit you are considering. I don't know anything about the Senville brand. Any manufacturer should be able to produce a chart of heating BTU capabilities at what ever outdoor temp. Many units are pretty much done near 0F and in reality the heating output tapers down so they might be near half rated out put at 20 or 30 degrees outdoor temp. If I wanted the unit to heat I would look for a unit that is rated for heating down to -20 or -30F. Sure you might not ever need it to heat thst low of outdoor temp, but a unit rated the low will have near full output at 0F.
Mount the indoor unit 8-10 feet up, put in a ceiling fan to help circulate air and they will do fine. With tall ceilings your warm air will go up and stay there without a ceiling fan to blow it down again. a mini split will not have enough fan to get that stratified air down from the ceiling.
jack stand
Well-known member
I was told (by a salesman at my kitchen table) that sizing was not nearly as critical with m/s as it's not an "on/off" like a traditional system.
It seems to be so, once they hit the set point it seems they throttle back and "maintain" very low speed. As I understand it this is one of the huge efficiencies as previously compressors did not have this "variable speed" ability and the same went for the electric motor.
In less words it's maintaining temperatures all the time and at an idle saving energy vs. a "full on or full off" temperature swing of 10-15* built into the t-stat of a non VFD controlled motor.
(Take my explanation very lightly. I'm a carpenter)
I was told (by a salesman at my kitchen table) that sizing was not nearly as critical with m/s as it's not an "on/off" like a traditional system.
It seems to be so, once they hit the set point it seems they throttle back and "maintain" very low speed. As I understand it this is one of the huge efficiencies as previously compressors did not have this "variable speed" ability and the same went for the electric motor.
In less words it's maintaining temperatures all the time and at an idle saving energy vs. a "full on or full off" temperature swing of 10-15* built into the t-stat of a non VFD controlled motor.
(Take my explanation very lightly. I'm a carpenter)
An "inverter" unit will throttle-back rather than cycle off and on, but not just with mini-splits. Oversizing a unit is less of a concern (assuming you're not concerned with the additional cost), but under-sizing is still a concern.
That is correct Jack. About forever we used 400 sq ft/ton of cooling. When i was in New England, depending upon building orientation I frequently went 6-700 sq ft with no problems, but that is cooling. This past weekend I suspect plenty of ms were pushed pretty hard. My 12k unit will modulate from 3,600-(+/-)15,000 output. another thing ms do is when they do cycle on off, which isn’t very common they have an equalizing valve in the units so the compressor doesn’t have to push against the head pressure of the system to start smoothly and efficiently. A modulating appliance even on low speed in H/C will give better and even temps as it just continues to move the air.
Mrgreen617
Active member
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- Mar 16, 2023
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What height is your unit mounted at?
Gave up, going with 65000 btu + - propane ceiling heater. Mounting it ten feet off the floor with two directional fans centered in building to move air. The shop attic was insulated to r48 Tuesday and the portable furnace and large fan running to dry sheetrock mud is making it pretty toasty. Also mite add just purchased a older Earth wood stove so bring on next winters negatives, pretty sure I will be ready. Wanted a mini split and sure didn't want propane but just to many nay sayers.
My mini split is less than a foot from the ceiling...
Mrgreen617
Active member
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So on a 12’ceiling your mounted at 11’? Interesting. What part of the country you live in?
Mrgreen617
Active member
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That *****. We’ll see if mine works out. Started a thread on it. Maybe it can help you down the road.
theoldwizard1
Well-known member
Mini-split air handlers tend to have smaller (CFM) fans and outlet temperature is less than any gas fired furnace. This means they are slower to heat up a given volume and will have more of a problem distributing their hot/cold air in a large area. 2 air handlers is the solution.
theoldwizard1
Well-known member
Cassettes are less efficient.
Why do you say that?
theoldwizard1
Well-known member
Check with the manufacturer, if they even post specs for cassettes !
fitter30
Well-known member
When using lp check with your supplier for tank size as for as vapor pressure and your input btu's. If power failure is a problem a lp generator might be nice.