Mini-split sizing

[Rand]

Tons of good info in here.

I feel that the suggested btu for a basement room is NUTS. basements are cold naturally.
even if you get a system that can vary between 20-100% it still might not be dehumidified well.
I would undersize.(if it makes sense is it even "undersizing"?)
if it runs 100% of the time at 100% (highly unlikely) you could always help it out with a vent or 2 from the main house A/C as worstcase/last resort for that one week of 110F heat per year.
The basement already stays 5-10f colder than upstairs with the existing cooling. no need to add 2 tons more of A/C to an underground room.


The sun room on the other hand could be all over the place got a decent pic or 2 you could share.
the sunroom is under a porch? so is it mostly shaded? how much actual sun directly shines in the room.. esp between 10am and 6pm.
Will it get any cooling from the basement or be totally separate.
There should be not much heat from above? ie not like sun beating down on a roof above upstairs bedroom.

If you answered any of this earlier I missed it on phone.

 

[brianl703]

When I said most homes are better off with multiple system I didn't mean 1 in attic 1 in basement or garage, that's no good either.

What I meant was a "little place outside the wall where you put the compressor unit of the AC away from bedroom, and a line that goes to the indoor unit of each room for the mini split. If done right it shouldn't be loud, and it should be individual room control.

Still if you want to use natural gas to heat in the winter this may not work, but for area that are better served with heat pump, multiple ductless individual units are better.

For heating, unless these minisplits are grossly oversized, they probably won't keep up on the coldest days unless the house is well insulated and sealed. A regular split system has supplementary heat of some form, either a furnace or electric heating coils.

There was one year it got down to 5F here. My heat pump won't heat the house beyond 60F when it's that cold outside without using aux heat.

Doubt 4 tons worth of minisplits could have done much better.

Oh, and let's talk about air filtration. The filter on minisplits just isn't very good. It's about like a window screen, maybe a little finer.

Here's what the filter on my central air system looks like:

I should also mention the ventilation controller that automatically turns on and brings fresh air into the house which is part of my central air system. You can't do that with a minisplit. Guess you can open the window?

 

[CDX825]

I Wouldn't rely on a mini split alone to dehumidify your basement. A basement doesn't present much load to an AC system. Your run times even on an under sized system probably won't be long enough to pull out the humidity. And as much as everyone loves inverter systems I can tell you they don't dehumidify well when running at low speeds which is what you get when they are over sized.

 

[DuckRyder]

More later, but:

Now my phone compass is saying the 3 windows face 108E ... not going to be any observing sunrise / set or exposure until next week probably...

I did discuss the possibility of zoning the existing system and it is a no go without major reconfiguration and the sun (or actually most would call it a 4 seasons room) would still need something.

 

[Jetronic]

For heating, unless these minisplits are grossly oversized, they probably won't keep up on the coldest days unless the house is well insulated and sealed. A regular split system has supplementary heat of some form, either a furnace or electric heating coils.

There was one year it got down to 5F here. My heat pump won't heat the house beyond 60F when it's that cold outside without using aux heat.

Doubt 4 tons worth of minisplits could have done much better.

Oh, and let's talk about air filtration. The filter on minisplits just isn't very good. It's about like a window screen, maybe a little finer.

Here's what the filter on my central air system looks like:

View attachment 90177
I should also mention the ventilation controller that automatically turns on and brings fresh air into the house which is part of my central air system. You can't do that with a minisplit. Guess you can open the window?

Ground temps are also higher than 5F unless you live in a permafrost area... they don't change much summer or winter when you get a few feet deep. For my area it's like the basement is in a 59F area at all times. It'll be a bit higher in warmer places, a bit lower in colder places

 

[DuckRyder]

So, the gree guy came back with his installation manger, he claims his manual J came up to 19,000 in the sunroom so he went to the next largest 24,000. Install guy said that 18,000 would be fine, they still want to put 24,000 in basement room. So that still puts the outdoor unit at 3.5 tons.

I have not heard from the Dakin guy answering any questions. It is a smaller company and maybe I'm being too needy, I do not know, I will call him next week. He was in the lead before he didn't respond to questions.

Here are some pictures in various states, the window next to the man door is 4 wide 5 tall all the others are 5x5.

Depending on the iPhone and whether the compass is set to true north or not, an iPhone pointed straight out the back compass reads between 98 (on true north) and 110. (I cannot explain why it said south the other day)

 

[Hillbilly Deluxe]

You don’t want Gee. You WANT Daikin.

 

[PimTac]

You don’t want Gee. You WANT Daikin.

I have heard good things about Daikin. They are huge everywhere else in the world.

 

[RhondaHonda]

I’d run a stand-alone dehumidifier in the basement and put a hotel room wall unit in the sunroom and call it good. That size basement isn’t going to need anything other than humidity control.

 

[brianl703]

I have heard good things about Daikin. They are huge everywhere else in the world.

They are Goodman here in the USA.

 

[Hillbilly Deluxe]

They are Goodman here in the USA.

That is 100% incorrect.

Daikin is basically three divisions-

Daikin Applied which is large commercial/industrial products, mainly chillers, built-up air handling units, etc. Everything associated with chilled water VAV type systems.

Daikin VRV/Commercial is VRV/Mini-split systems that range from the inexpensive single-zone ductless/mini-splits to multi-module VRV with/without heat recovery systems that are capable of serving very large buildings. This also includes Daikin Engineered packaged units to include DOAS, packaged gas/electric units, etc.

Then there's the residential line that is Goodman. Daikin bought Goodman several years ago and I can't for the life of me figure out why. Neither can many of their sales people. So yes, Goodman is owned by Daikin and I've heard Daikin has implemented some higher quality standards into the residential line that is Goodman but anyone with real info will tell you it's still Goodman....

 

[brianl703]

That is 100% incorrect.

It is 100% correct that Goodman is a brand of Daiken in the USA. Which is what I meant.

 

[Hillbilly Deluxe]

It is 100% correct that Goodman is a brand of Daiken in the USA. Which is what I meant.

"They are Goodman in the US" means that someone is implying that Goodman makes/oversees Daikin. Daikin bought Goodman and there is nothing Goodman about Daikin.

 

[brianl703]

"They are Goodman in the US" means that someone is implying that Goodman makes/oversees Daikin. Daikin bought Goodman and there is nothing Goodman about Daikin.

I don't think anyone would have come to that conclusion.

 

[DuckRyder]

I do actually want the Daikin if i can get it (i'm being told it might be mid to late summer) ... Still Gotta call the guy, they are killing us at work...

 

[DuckRyder]

Talked to Daikin dealer.

Hes very confident in the 9K in the sunroom he said he would do a 12K if we really wanted but oversizing it will make it short cycle and not dehumidify. He said he needed to talk to the tech who came out about the basement room (this is a smaller company, when you call you get the owner.) They also have very good reviews.

 

[Hillbilly Deluxe]

A Daikin mini-split oversized by 3,000 BTUs is not going to short-cycle. These things operate on a range of variable refrigerant flow and fan speed to match the current load. You might better figure out if he's really a competent dealer/installer now and possibly look for another one. This one sounds like he's in 1998.

 

[Snagglefoot]

Can anyone explain why an AC guy would say "mini-splits put out body temperature"?

Just a rule of thumb. Normal body temp is 98.6 F. When it’s cold outside, near freezing or slightly below, the heat coming out of the duct may be about body temp ( 98.6 F). That doesn’t feel more than luke-warm. When the auxiliary heat (say heating strips) kicks in on a cold day the temp of the air coming out of the duct will be over 100 F and will feel cozy warm to the touch.

 

[DuckRyder]

A Daikin mini-split oversized by 3,000 BTUs is not going to short-cycle. These things operate on a range of variable refrigerant flow and fan speed to match the current load. You might better figure out if he's really a competent dealer/installer now and possibly look for another one. This one sounds like he's in 1998.

I wasn't clear. He did not say oversizing it by 3000 would make it short cycle. He did say if it's oversized it will short cycle and won't dehumidify properly. He did think 18-24 was way too much and says he has several 9Kbtu units in similar spaces that work great.

 

[loneryder]

I have one dealer saying to do two, but have not gotten his quotes yet. this of course increases cost by adding more high voltage wiring, disconnects ETC.

2 of them are trying to sell Mitsubishi, 1 Gree, 1 Dakin. The one selling the gree would prefer Dakin but says he cannot get one, the other guy says he can get one in a week.

The Mitsubishi apparently has an installation issue and will have to use a ceiling cassette because of clearance above the windows, Dakin and Gree both dealers say it is no problem under repeated questioning.

This is a basement Ranch, i know I've sort of described it before but the basement living area is buried on 2 sides one side is the wall that opens to the garage (double layer x code drywall and 4" rock wool insulation, solid steel door) the 2 buried walls and the back wall are concrete block. there are 2 andersen sliders that go into the new sunroom. I'm not sure how to rate this insulation, i put average.

The sunroom is below a upper screened porch. There is a deck all the way across the back and the rear wall faces South / very slightly SW. The sunroom is 6" stud walls with 4 5x5 and 1 4x5 windows and will have 6" insulation, but there is only 24" of it, the area above the windows is all header. 2 of these 5x5 are pretty well below ground and look at a retaining wall.

So far i liked the guy selling the Dakin best, but he is also quoting the smallest units. He was the least salesmany...

Daikin and Fujitsu are the best. Mitsubishi is over priced due to their name. I run an 18k btu Fujitsu outdoor unit with 2 9k indoor units here in SW Florida in an 800Sq ft park home with literally no insulation. It's been in the high 80's here the last month and my highest bill was $48. It costs me $20 a month to leave it on set at 80 in dehumidify mode. I think you could get by with a 24k btu outdoor unit but you would have to figure the indoor unit mix knowing the climate on the porch and in basement.