Next A/C: how big?

oil pan 4 · 09-18-16, 12:01 AM

Does efficiency not scale up or what?
With the small 1 ton and smaller split units they go all the way up to 30 SEER, with 23~25 SEER being fairly common.
Then when I go to look for big split units such as the 2 ton I am only finding up to 20 SEER, I am assuming there are ones that go higher than 20 made by the big name brands but I am sure there is a pretty high premium for that higher efficiency.

I was thinking about getting a 2 ton split for the kitchen and dining room area and the living room to some degree.
The kitchen and dining room are kind of small 1960s era, only about 250 square feet The living room adds about another 150 or so square feet. So a "1,200 to 1,500" square feet air conditioner sounds kind of like over kill.
The kitchen and dining room has a fridge. The fridge is pretty much always giving off heat. And a stove that really heats up the house when cooking.
Should I stick with a smaller unit, say a 1 ton or 1.5 ton?
We rarely use the oven and if we do its always in cooler months.

So unless anything changes I am going to buy the system next spring (unless I can get a killer deal in the A/C off season).
I think I will buy a 2 ton 19 or 20 SEER, 230v powered unit. Unless you guys talk me out of it.
Looks like the out door unit on these 2 ton units weighs around 140lb.
Or is 2 ton just too much? Should I get a smaller unit?

Does anyone think I should hold out 5 or 6 months for higher efficiency units to come available?
Or should I try and catch a deal on a current unit in the A/C off season, in the dead of winter here in the next 2 or 3 months?
If I can save $100 or $200 on the air conditioner that's 2 or 3 summer power bills.

jeff5may · 09-18-16, 09:26 AM

With most mini-split units, especially electronic expansion valve, inverter-driven compressor types, the outdoor unit is not much different (if at all) in the lower capacity ranges. When matched up with the smaller-capacity indoor units, the outdoor unit just runs slower throughout its useful range. This puts the outdoor unit in its high-efficiency mode and HSPF and EER values are heavenly. The main difference between outdoor units is how many indoor units can be plumbed into and operated off of one outdoor unit...at least up into the two-ton range.

Naturally, the price of a more capable unit will be more expensive than one that can only be rigged to one indoor unit. It would be wrong for the marketing professionals not to jack up the price considerably. In some cases, it is not much more expensive to buy two smaller single-zone units rather than one multi-zone unit of comparable maximum capacity. I am still wondering what a dual-capacity, variable-speed compressor really is on the inside...

The longer you wait, the more savings you are passing up...good deals come and go every day. Plus, installing stuff in the winter is cold and miserable. I would rather invest sweat equity than frostbite equity myself.

In general, mini-split units are more conservatively rated when compared to portable or window units as to raw BTU-moving ability, especially in heating mode. You testified to this difference yourself in another thread, comparing a window unit with a mini-split installed in a bedroom. In your case, I might only buy one unit of smaller capacity first and see if it fulfills the need sufficiently. After the first unit has changed the "comfort profile" of the home, it would be much easier to decide how big and where to install another one if necessary. I'm not you, though, and am much more tolerant of temperature swings in "fringe zone", less occupied areas, if it saves me some bucks.

From a capitalist perspective, the two smaller units would pay themselves back much sooner than the one larger unit, due to the energy efficiency advantage. The downside risk is also minimized, as there are now two points of possible failure rather than one. If one of the small outdoor units failed, not both, you still have half of the system running. Ask Xringer about that one. He thinks he's still in it for the money. The newer, digital microprocessor controlled units are inherently less resistant to power line dirt than the old-school "dumber" cap tube and TXV metered units. With higher ultimate efficiency comes the risk of control module failure.

oil pan 4 · 09-18-16, 11:59 AM

Yes I noticed the out door unit's condenser coil on the split units run much cooler than a window units condenser coils.
Lower pressure should mean less power to drive the compressor.

09-18-16, 12:01 AM	#1
oil pan 4 Land owner Join Date: Nov 2012 Location: NM Posts: 1,026 Thanks: 12 Thanked 127 Times in 107 Posts	Next A/C: how big? Does efficiency not scale up or what? With the small 1 ton and smaller split units they go all the way up to 30 SEER, with 23~25 SEER being fairly common. Then when I go to look for big split units such as the 2 ton I am only finding up to 20 SEER, I am assuming there are ones that go higher than 20 made by the big name brands but I am sure there is a pretty high premium for that higher efficiency. I was thinking about getting a 2 ton split for the kitchen and dining room area and the living room to some degree. The kitchen and dining room are kind of small 1960s era, only about 250 square feet The living room adds about another 150 or so square feet. So a "1,200 to 1,500" square feet air conditioner sounds kind of like over kill. The kitchen and dining room has a fridge. The fridge is pretty much always giving off heat. And a stove that really heats up the house when cooking. Should I stick with a smaller unit, say a 1 ton or 1.5 ton? We rarely use the oven and if we do its always in cooler months. So unless anything changes I am going to buy the system next spring (unless I can get a killer deal in the A/C off season). I think I will buy a 2 ton 19 or 20 SEER, 230v powered unit. Unless you guys talk me out of it. Looks like the out door unit on these 2 ton units weighs around 140lb. Or is 2 ton just too much? Should I get a smaller unit? Does anyone think I should hold out 5 or 6 months for higher efficiency units to come available? Or should I try and catch a deal on a current unit in the A/C off season, in the dead of winter here in the next 2 or 3 months? If I can save $100 or $200 on the air conditioner that's 2 or 3 summer power bills.

09-18-16, 09:26 AM	#2
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	With most mini-split units, especially electronic expansion valve, inverter-driven compressor types, the outdoor unit is not much different (if at all) in the lower capacity ranges. When matched up with the smaller-capacity indoor units, the outdoor unit just runs slower throughout its useful range. This puts the outdoor unit in its high-efficiency mode and HSPF and EER values are heavenly. The main difference between outdoor units is how many indoor units can be plumbed into and operated off of one outdoor unit...at least up into the two-ton range. Naturally, the price of a more capable unit will be more expensive than one that can only be rigged to one indoor unit. It would be wrong for the marketing professionals not to jack up the price considerably. In some cases, it is not much more expensive to buy two smaller single-zone units rather than one multi-zone unit of comparable maximum capacity. I am still wondering what a dual-capacity, variable-speed compressor really is on the inside... The longer you wait, the more savings you are passing up...good deals come and go every day. Plus, installing stuff in the winter is cold and miserable. I would rather invest sweat equity than frostbite equity myself. In general, mini-split units are more conservatively rated when compared to portable or window units as to raw BTU-moving ability, especially in heating mode. You testified to this difference yourself in another thread, comparing a window unit with a mini-split installed in a bedroom. In your case, I might only buy one unit of smaller capacity first and see if it fulfills the need sufficiently. After the first unit has changed the "comfort profile" of the home, it would be much easier to decide how big and where to install another one if necessary. I'm not you, though, and am much more tolerant of temperature swings in "fringe zone", less occupied areas, if it saves me some bucks. From a capitalist perspective, the two smaller units would pay themselves back much sooner than the one larger unit, due to the energy efficiency advantage. The downside risk is also minimized, as there are now two points of possible failure rather than one. If one of the small outdoor units failed, not both, you still have half of the system running. Ask Xringer about that one. He thinks he's still in it for the money. The newer, digital microprocessor controlled units are inherently less resistant to power line dirt than the old-school "dumber" cap tube and TXV metered units. With higher ultimate efficiency comes the risk of control module failure. Last edited by jeff5may; 09-18-16 at 10:33 AM.. Reason: elaborating on ideas

09-18-16, 11:59 AM	#3
oil pan 4 Land owner Join Date: Nov 2012 Location: NM Posts: 1,026 Thanks: 12 Thanked 127 Times in 107 Posts	Yes I noticed the out door unit's condenser coil on the split units run much cooler than a window units condenser coils. Lower pressure should mean less power to drive the compressor.