help picking out the MS

dablack · 01-12-15, 03:48 PM

So I'm on ACwholesalers trying to pick out a minisplit. The problem is I'm not sure what I need as far as capacity. I'm looking at one large area that is 900 sqft and another small room that is 100 sqft.

This is the 1st floor of a 2 story house. Large porch on the south side so the front door and two front windows will never see direct sun light. No west windows and only a small 3x3' north window. On the east is a glass door and a 3x5' window. 2x6 tight construction with rigid foam board on the outside of the house R11.25. I might be adding spray foam or fiberglass between the studs but I'm not sure right now. Remember there is a 2nd floor that will also be conditioned so no attic heat being added to the 1st floor.

How much AC do I need. 1 ton?

thanks
Austin

ecomodded · 01-12-15, 04:00 PM

Your asking a lot from a one ton , might be better to go with a 1.5 ton / 18000Btu's and use three indoor units.

Just my opinion , I would use a 1 ton for 1 floor only.

How many Heating Btu's are you using now in the winter ? that number will help you size your mini split

dablack · 01-12-15, 05:15 PM

Yes, the 1 ton would be for one floor only. The 1st floor is about 1000sqft. That is where I'm wanting to use the MS. So does every think 1 ton will cool 1000sqft of well insulated, shaded 1st floor?

It is a new build so I don't have an existing heat requirement. I'm not really worried about heat. It doesn't really get cold here.

Thanks
Austin

dablack · 01-12-15, 05:21 PM

This is for east tx. Zip 75785. 97f and crazy humid in the summer.

dablack · 01-13-15, 02:13 PM

OK guys. I did a little more research and it looks like in my climate, 1.5 tons is required for 1000sqft. Using various calculators online gave me 17k to 19k BTUs of cooling.

gtojohn · 01-14-15, 01:45 AM

With tight construction and no attic heat load you should be able to get away 1.5 ton. A 2 ton might cost just a little more, use just a little more power but give you a buffer for 100f heat waves. The cost and efficiency on the multi zone units isn't as good as the single zones systems. Personally I would rather buy 2 single zone systems than one multi zone if anything for the redundancy of 2 separate systems.

jeff5may · 01-14-15, 04:13 AM

Quote:

Originally Posted by dablack

OK guys. I did a little more research and it looks like in my climate, 1.5 tons is required for 1000sqft. Using various calculators online gave me 17k to 19k BTUs of cooling.

It really depends on your comfort and zone control needs. A high efficiency 1 to 1 1/2 ton single-zone unit would be the most efficient, as it would literally run constantly during those days of extreme temperature. However, if your living space is very compartmentalized, the comfort will not just leak into the closed off areas. A couple or three of 3/4 to 1 ton units would be nearly as efficient, and offer better zone control (maybe better if unused zones were shut off or set back) and would dehumidify better. They would most likely cost more than a single unit.

A mini-multi zone unit sized to meet your design heat load or better would be a compromise all the way around. Installation would be complex, both with lineset plumbing and electrical control wiring. Zone control would vary with the load and balance of zones demanding heat. Efficiency would also vary with the overall load. Cost would most likely fall in between the other two options.

The main thing to remember is to purchase a name brand unit! Do not be lured into buying some off brand system to save a few dollars. When and if something goes wrong in the future, you want to be able to get service and parts to complete a repair. The knock off manufacturers all have terrible reputations in this department.

dablack · 01-14-15, 03:29 PM

GTOJohn,
Are you thinking maybe two 3/4 ton systems?

Jeff5may,
I'm not sure where to put the two units if I did go that way.

Layout is attached.

I was thinking of putting the 1.5 ton over the kitchen windown. This is the north side of the house.

dablack · 01-14-15, 03:41 PM

Looks like I can get two Gree 22 SEER 9000 BTU units for 834 each (total of $1668)

or one Gree 21 SEER 18000 BTU unit for $1516.

If I went with two units, I would put one over the hutch and one to the right of the sink.

Thoughts?

ecomodded · 01-14-15, 09:27 PM

I like the idea of having 2 units.

Then you can run 1 unit in the less demanding times and 2 units when the weather calls for it.

I would put both my indoor units on a outside wall rather then above the hutch.
My reason being that it would be easier to mount it with the line ,and run the drain.

01-12-15, 03:48 PM	#1
dablack Helper EcoRenovator Join Date: Jan 2010 Posts: 65 Thanks: 0 Thanked 13 Times in 6 Posts	help picking out the MS So I'm on ACwholesalers trying to pick out a minisplit. The problem is I'm not sure what I need as far as capacity. I'm looking at one large area that is 900 sqft and another small room that is 100 sqft. This is the 1st floor of a 2 story house. Large porch on the south side so the front door and two front windows will never see direct sun light. No west windows and only a small 3x3' north window. On the east is a glass door and a 3x5' window. 2x6 tight construction with rigid foam board on the outside of the house R11.25. I might be adding spray foam or fiberglass between the studs but I'm not sure right now. Remember there is a 2nd floor that will also be conditioned so no attic heat being added to the 1st floor. How much AC do I need. 1 ton? thanks Austin

01-14-15, 03:29 PM	#8
dablack Helper EcoRenovator Join Date: Jan 2010 Posts: 65 Thanks: 0 Thanked 13 Times in 6 Posts	GTOJohn, Are you thinking maybe two 3/4 ton systems? Jeff5may, I'm not sure where to put the two units if I did go that way. Layout is attached. I was thinking of putting the 1.5 ton over the kitchen windown. This is the north side of the house. Attached Thumbnails Last edited by Daox; 01-14-15 at 03:33 PM.. Reason: more info

01-12-15, 04:00 PM	#2
ecomodded Supreme EcoRenovator Join Date: Sep 2012 Location: Vancouver Island,Canada. Posts: 1,037 Thanks: 116 Thanked 100 Times in 87 Posts	Your asking a lot from a one ton , might be better to go with a 1.5 ton / 18000Btu's and use three indoor units. Just my opinion , I would use a 1 ton for 1 floor only. How many Heating Btu's are you using now in the winter ? that number will help you size your mini split

01-12-15, 05:15 PM	#3
dablack Helper EcoRenovator Join Date: Jan 2010 Posts: 65 Thanks: 0 Thanked 13 Times in 6 Posts	Yes, the 1 ton would be for one floor only. The 1st floor is about 1000sqft. That is where I'm wanting to use the MS. So does every think 1 ton will cool 1000sqft of well insulated, shaded 1st floor? It is a new build so I don't have an existing heat requirement. I'm not really worried about heat. It doesn't really get cold here. Thanks Austin

01-12-15, 05:21 PM	#4
dablack Helper EcoRenovator Join Date: Jan 2010 Posts: 65 Thanks: 0 Thanked 13 Times in 6 Posts	This is for east tx. Zip 75785. 97f and crazy humid in the summer.

01-13-15, 02:13 PM	#5
dablack Helper EcoRenovator Join Date: Jan 2010 Posts: 65 Thanks: 0 Thanked 13 Times in 6 Posts	OK guys. I did a little more research and it looks like in my climate, 1.5 tons is required for 1000sqft. Using various calculators online gave me 17k to 19k BTUs of cooling.

01-14-15, 01:45 AM	#6
gtojohn Journeyman EcoRenovator Join Date: Jul 2014 Location: Austin, TX Posts: 314 Thanks: 39 Thanked 50 Times in 45 Posts	With tight construction and no attic heat load you should be able to get away 1.5 ton. A 2 ton might cost just a little more, use just a little more power but give you a buffer for 100f heat waves. The cost and efficiency on the multi zone units isn't as good as the single zones systems. Personally I would rather buy 2 single zone systems than one multi zone if anything for the redundancy of 2 separate systems.

01-14-15, 03:41 PM	#9
dablack Helper EcoRenovator Join Date: Jan 2010 Posts: 65 Thanks: 0 Thanked 13 Times in 6 Posts	Looks like I can get two Gree 22 SEER 9000 BTU units for 834 each (total of $1668) or one Gree 21 SEER 18000 BTU unit for $1516. If I went with two units, I would put one over the hutch and one to the right of the sink. Thoughts?

01-14-15, 09:27 PM	#10
ecomodded Supreme EcoRenovator Join Date: Sep 2012 Location: Vancouver Island,Canada. Posts: 1,037 Thanks: 116 Thanked 100 Times in 87 Posts	I like the idea of having 2 units. Then you can run 1 unit in the less demanding times and 2 units when the weather calls for it. I would put both my indoor units on a outside wall rather then above the hutch. My reason being that it would be easier to mount it with the line ,and run the drain.