Pulling my hair out.....mini-split sizing

[Rosco]

I have been researching mini-splits for my bonus room and using every calculator I can find to get the right size. I am hoping someone can help me narrow it down. I have the 18000 BTU Ramsond ( http://www.ramsond.com/proddetail.php?prod=R55GW&cat=Ductless Mini Split AC Systems ) as the top choice right now, but do not want to pull the trigger until the knowledgable ones on here tell me it is the right size.


Bonus Room is 26 feet long by 18 feet wide (knee wall)(468 sq. ft.)

Cieling is 8 feet high and 8 feet wide in the center (cieling slopes from 8 foot width to the 18 foot width knee wall......11/12 pitch)

I have 2 dormers with 8 foot high cielings, 8 foot wide (adds 128 sq. ft. to the cieling space, only 64 sq. ft. to the floor space)

I will have a working kitchen (fridge,microwave, stove, dishwasher) but will not be used continuously

One of the dormers has a 3/4 bathroom (4' shower, toilet, sink) within the above square footage.

It is a bonus room in the south, therefore it will get extremely hot. It will be well insulated, but I only list it as average insulation in the calculators since it is a bonus room. I am more worried about A/C than Heat.

I have gotten everything from 8,000 BTU to 15,000 BTU from the calculators I have used.

Any advice?

 

[f365gtb4]

Rule of thumb is 1 ton per 400 SQ ft, 1 ton = 12,000 btu so 18000 btu = 1.5 ton.

Have the same unit in my garage, 26 x 20, 10 ft high non insulated and keeps it constant 72 with outside ambient at 95 and high RH

When you buy get extra remote, you break loose one you got problems

 

[Rosco]

Thanks! I take it that I am in the ballpark with 18000 BTU.......

good advice on the remote. Do you mind if I ask where you got yours from?

 

[mpire]

Think this would work in my garage? Its 27' x 20' x 10'h with insulated doors, ceiling, and shares a wall with the house. Other two walls are concrete block.

 

[Rosco]

Think this would work in my garage? Its 27' x 20' x 10'h with insulated doors, ceiling, and shares a wall with the house. Other two walls are concrete block.

Based on everything I have read and the different BTU calculators available I would say yes. Unless someone chimes in that I am way off-base, the unit I posted is the one I will go with.

 

[BoilermakerNate]

Rule of thumb is 1 ton per 400 SQ ft, 1 ton = 12,000 btu so 18000 btu = 1.5 ton.

Have the same unit in my garage, 26 x 20, 10 ft high non insulated and keeps it constant 72 with outside ambient at 95 and high RH

When you buy get extra remote, you break loose one you got problems

Right on the money...you should be right between 300 and 400 sq.ft. per ton from what you have described, so 18000 btu gets you right on the high side of that range. A little extra capacity never hurts as long as you don't really over do it, like going up to 30000 btu. A greatly oversized unit like that will short cycle and cause humidity problems.

 

[mpire]

Its a shame that you can't split a mini-split up very far. The only two rooms in my house that I use are the master bedroom and the garage. If I could air condition those two rooms then I wouldn't have to run the whole house A/C. Whats the max distance you can go between a mini-split indoor and outdoor unit?

 

[Falcon67]

Whats the max distance you can go between a mini-split indoor and outdoor unit?

Have to read the mfg specs - I've been looking, most have different maximums.

 

[Rosco]

Usually 16' maximum, but as just posted, some are different. If the difference is too far, then you can put the compressor up higher on a bracket.

Check out the mini-splits installed on "the shrine's" build thread.

 

[MikeLawrence]

Its a shame that you can't split a mini-split up very far. The only two rooms in my house that I use are the master bedroom and the garage. If I could air condition those two rooms then I wouldn't have to run the whole house A/C. Whats the max distance you can go between a mini-split indoor and outdoor unit?

How much money do you want to throw at the situation?

A Fujitsu Halcyon system could EASILY cover a whole house (can do 8 story buildings actually) can have between 2 and 8 (really) internal ports and uses something called a hybrid flex inverter which is marketing juju but basically it means that if your garage needed say 18k and your bedroom needed like say 9k then instead of the one that set the thermostat first getting comfort and the other room either being a sauna or an ice box, both rooms get to be pretty well comfortable. So, funny name, but amazing functionality.

It's all about getting the right system for the job.

Michael Lawrence, LISSCO
www.thruwalls.com