Anybody here use Mini-Splits for HVAC?

[hornadylnl]

If you're really getting those r values, I can't see why you can't easily stay under $300 a month on average for the year. I'd have to pull the last year's bills but I'm sure I'm under that. I keep at 70 in winter and 74 now.

 

[IndyGunworks]

I am planning on at least 3 inch's of rigid foam board w/ spray caulk sealing everything. that's an r of 21. then in the remaining 4.5 inch's of wall space I am going to put r 19 fiberglass batts. Once I derate the wall for the few thermal bridges I have, and derate the fiberglass due to a little compression, I think a whole wall value of R 30 is realistic.

 

[Rookie]

Got a link to what you're talking about?
Please?

 

[hornadylnl]

I am planning on at least 3 inch's of rigid foam board w/ spray caulk sealing everything. that's an r of 21. then in the remaining 4.5 inch's of wall space I am going to put r 19 fiberglass batts. Once I derate the wall for the few thermal bridges I have, and derate the fiberglass due to a little compression, I think a whole wall value of R 30 is realistic.

Looked into spray foam?

 

[IndyGunworks]

the fujitsu

https://www.youtube.com/watch?v=WA7sLtSJmKw

diakin (partially ducted which I would NOT be doing)

part 1
https://www.youtube.com/watch?v=zTKlZ_jY5Jw
part 2
https://www.youtube.com/watch?v=n_5cU5xoQBg&list=UUPj8Xyx6snc0UYvARKobnzQ

another diakin

https://www.youtube.com/watch?v=f8428yIAqpo&list=UUPj8Xyx6snc0UYvARKobnzQ

 

[IndyGunworks]

Looked into spray foam?

Yes, to get the same R value as the rigid board I calculated 45000 board feet. This was when I was planning a sealed sisscor truss type vaulted ceiling. and a garage. open cell to get a cavity fill was .40 cents a board foot. so 18,000 w/out needing any other insulation. if I went closed cell w/ a flash and batt it was was going to be .80 cents a board foot and I would still need the fiberglass. BUT, that was going to limit the ability to detect possible roof leaks, and make repairing them miserable. so I changed to a higher side wall and conventional vented attic design.

Ridig foam has an approx r value of 7 per inch so it compares nicely to closed cell foam. ridig xps foam board is 11.5 cents a board foot, and the fiberglass batts .05 cents per board foot. so MUCH cheaper. It will not be as easy to get the air seal my way as opposed to spray foam, but by redundant taping of the two laters of foam, some spray caulk, and an air tight approach to the drywall I should be able to get just as good of an air seal as long as I pay attention to details.

I left my plans at my parents, but should have them back tomorrow. I plan on sitting down and recalculating the board feet needed now that I have changed the roof design. but just from previous calculations and research I should end up w/ about 15,000 for insulation. that is a 1.5 inch layer of foam board between the purlins. 2 inch's between the posts (this is where I will tape and spray caulk) for a total of 3.5 inchs's or R-24ish. then it will have 6 inch thick 8 foot wide fiberglass batts rated at r 19 that I derated to 15 due to the compression. my estimated cost also includes r-60 of blown in cellulose (after I caulk the drywall between the trusses), and 4 inch's of foam under the concrete slab, and around the peremeter.

My only thermal bridges will be
the small section where the concrete permacolum penetrates through the foam floor under the concrete slab, probably less than 1% of the total surface area
the 1.5x6 inch wide sections where the purlins are nail on probably a 2% total surface area.
where my floor trusses rest on headers for the second floor. there wont be a thermal break here, but it will only have 1.5 inch's of foam between the metal and the edge of the floor truss. the total space will be fully insulated, but that MAY have some small amount of thermal bridging, albeit minimal.

the 18,000 was JUST the spray foam, and didn't include the slab insulation, fiberglass batts, or blown cellulose.

I had a 28x48 attached garage that I had all the walls included in the board feet calculations for the spray foam, that I have since dropped in order to keep the mortage at a certain price point. I would rather save for a few years and pay cash for the garage than be house poor. so I might be high on my ridig foam calculations.

also there is a place on the other side of illinios that sells factory second rigid foam. its about half the price of what I stated above, and I am hoping to use that for my 1.5 inch outer layer, and my 4 inch's under the slab. that will cut costs dramatically as well.

I just got the quote for the shell of my house at 33,000. once I add concrete I will probably be right at 40,000 which gives me a 90,000 dollar budget for everything else.... 130,000 being my target goal when its all said and done. I think its doable, but I still have some pencils to run through before I know for sure.

 

[IndyGunworks]

here is another link

https://www.youtube.com/watch?v=LV71OtqSPgo

 

[HoughMade]

Sounds like a super tight house. Do you have plans for ventilation like an air to air heat exchanger or something?

 

[IndyGunworks]

this house will DEFINATLY need an air exchanger. possibly 2. I have read a few places where its possible to have split ducts on a lot of your appliances, like bathroom exhaust, dryer, range hood. and in the summer you duct them directly outside and let the air exchanger do its thing. but in the winter you duct them through an air exchanger to help salvage even more btu's that you have already paid to create. I don't know if I am quite willing to go to this level of detail during construction though. But at least one 400cfm air exchanger will be needed, although I am not sure how often it will have to run.

 

[hornadylnl]

I'm on an REMC and my rates suck. I just figured my cost per kwh without the access charge figured in but taxes and everything else included and it's 12 cents. Now add a $32 a month access charge on top of that and it's almost 14 cents. That's $32 a month whether I use 1 kwh or 10,000. Here's my last 12 bills.

7/14 - $244
6/14 - $254
5/14 - $227
4/14 - $212
3/14 - $255
2/14 - $276
1/14 - $310
12/13 - $297
11/13 - $222
10/13 - $230
9/13 - $230
8/13 - $268

My house is roughly 1800sf basement with 9' ceilings, 1800 sf first floor with 600 sf 18' ceilings and the rest 9', and 800 sf upstairs with 8' ceilings. I have a significantly higher amount of air volume than a conventional all 8' ceiling house. It is all electric with a 3 ton (IIRC) geo, standard electric water heater, electric range, dryer, etc. I keep my strip heat breakers off year round. With the extreme cold we had last winter, I did see the thermostat call for back up heat but I was able to maintain fine.

My energy star rating said my house should cost a total of $1900 a year for electric. Not sure what kwh rate they used and what temperatures they figured for heating and cooling.

 

[IndyGunworks]

Sounds pretty close to what I am trying to do. With gas being used for hot water and cooking though. my rates are 10 cents per kw as well with a 35 dollar facility maintanence fee. so I will be right around where you are as well. I think I can get this thing done w/ one four ton unit and 8 heads. or if its not too much more expensive two two ton units each with 4 heads. If I go two units that will allow me to run just one unit off solar and decrease my overall demand. say run the bedrooms off solar at night, then run the main area during the day. with one unit even though its a variable speed compressor I am not sure if the start up loads would be the same. all food for thought as I dive deeper into my research. also, we are not sure if 4 tons will cover the whole house comfortably either.

you are on geothermal correct?

I will have 1760 first floor, with 400 square feet open to above so an 18' ceiling there. and a 1360 square foot upstairs, however 320 square feet of that will be an 8 foot wide by 40 foot long storage area and not have to be kept with the rest of the house.... the bleed through of heat and cold should keep that space somewhat conditioned. I may add a vent in it to help some of the heat or cold get through.... that room is on an exterior wall as well so that should help lower my demand as that space is 320 square feet that wont require anywhere near the same amount of BTU's

 

[looney2ns]

Indy, couple of points. My current home I had built in 1984. After reading some before building, I knew I wanted, tight house, good insulation and good but minimal windows. Builder thought I was insane.

Your plan sounds excellent and I believe will surpass your expectations on all levels, comfort and cost.

I used high tech at the time for my house. 1" foil faced foam board for sheathing. Joints taped. R 13 batts In the out side walls, then I built a second wall inside that was thermal breaked from the outside wall by air space. Studs staggered from the outside wall studs as much as possible. I added R19 batts in this new additional wall. So the R19, was against the R13 in the outside wall.
So I have in the neighbor hood of better then R30 in the walls. I did the insulation myself, and caulked, taped and sealed in all gaps I could find along the way.

In the ceiling I put in R30 batts, with R40 blown in cellulose on top of that.

I have a Tempstar heat pump that is 19 yrs old. Nothing fancy. My highest electric bill this past winter was $192.00. My heat pump will cycle on/off all the way down to 5 degrees, without any backup heat kicking on. House is 2200sf. Air temp at register is 85 with it 5 outdoors. Thermostat setting 71 in winter, 74 summer.

It's on a crawl space, but floors are insulated with r19 batts. The telling aspect of all this is, I can lay on the floor in my living room back in Jan with it near 0 outdoors, and the wind hollowing at 20mph outdoors, and it feels no different then than it does today at 80 outdoors.

Set in the house with bare feet in the winter time....no problem. No drafts to deal with.

I think you will be ecstatic with your plan for comfort and cost. Mini splits been around for many years, and used extensively in most places outside of the us.

From watching my electric bills, for months like April & Oct which are my lowest bill months and we have the windows open a lot during that time, my heating cost's come to about $40-$45 per month additional in the winter months.

I think the mini splits are great, I've know several that have them, including a restaurant here in town, they all love em.

You won't miss the gas fired furnace and it's higher register temps.

 

[IndyGunworks]

Also, is your basement conditioned year round off that same 3 ton system?

 

[IndyGunworks]

Indy, couple of points. My current home I had built in 1984. After reading some before building, I knew I wanted, tight house, good insulation and good but minimal windows. Builder thought I was insane.

Your plan sounds excellent and I believe will surpass your expectations on all levels, comfort and cost.

I used high tech at the time for my house. 1" foil faced foam board for sheathing. Joints taped. R 13 batts In the out side walls, then I built a second wall inside that was thermal breaked from the outside wall by air space. Studs staggered from the outside wall studs as much as possible. I added R19 batts in this new additional wall. So the R19, was against the R13 in the outside wall.
So I have in the neighbor hood of better then R30 in the walls. I did the insulation myself, and caulked, taped and sealed in all gaps I could find along the way.

In the ceiling I put in R30 batts, with R40 blown in cellulose on top of that.

I have a Tempstar heat pump that is 19 yrs old. Nothing fancy. My highest electric bill this past winter was $192.00. My heat pump will cycle on/off all the way down to 5 degrees, without any backup heat kicking on. House is 2200sf. Air temp at register is 85 with it 5 outdoors. Thermostat setting 71 in winter, 74 summer.

It's on a crawl space, but floors are insulated with r19 batts. The telling aspect of all this is, I can lay on the floor in my living room back in Jan with it near 0 outdoors, and the wind hollowing at 20mph outdoors, and it feels no different then than it does today at 80 outdoors.

Set in the house with bare feet in the winter time....no problem. No drafts to deal with.

I think you will be ecstatic with your plan for comfort and cost. Mini splits been around for many years, and used extensively in most places outside of the us.

From watching my electric bills, for months like April & Oct which are my lowest bill months and we have the windows open a lot during that time, my heating cost's come to about $40-$45 per month additional in the winter months.

I think the mini splits are great, I've know several that have them, including a restaurant here in town, they all love em.

You won't miss the gas fired furnace and it's higher register temps.

what ton system do you have?

 

[hornadylnl]

Also, is your basement conditioned year round off that same 3 ton system?

Yes, it's a geo with 2 zones. 1 zone controls basement and other zone controls upstairs. I close the basement vents down a little to help force more of the air into the first floor vents.

My ICF walls are supposed to be equivalent of r30.

 

[sig-guy]

HP's work when they are sized and installed properly. Don't let the haters steer you away from the savings and comfort of such a system.

Mitsubishi is the leader in mini-splits.
Multiple heads connected to a single outdoor unit. MXZ series:
Mitsubishi Electric US, Inc. Cooling & Heating | HVAC

Indoor wall mounted unit:
Mitsubishi Electric US, Inc. Cooling & Heating | HVAC

Check out their units. They're quiet, yet very efficient and effective.

 

[IndyGunworks]

I like some of that stuff.

Mitsubishi Electric US, Inc. Cooling & Heating | HVAC?

two of those 2.5 ton units would still give me almost 40,000 btu's an hour at 17 degrees with a COP of over 2.5 and allow for 4 heads on each unit... that's pretty impressive.

 

[churchmouse]

I like some of that stuff.

Mitsubishi Electric US, Inc. Cooling & Heating | HVAC?

two of those 2.5 ton units would still give me almost 40,000 btu's an hour at 17 degrees with a COP of over 2.5 and allow for 4 heads on each unit... that's pretty impressive.

If you remember our conversation I mentioned these systems. I lean towards these as they have good local support and have shown reliability.
2.5 tons X 2 units will give you about all you will require if you hold to your plan.

 

[churchmouse]

HP's work when they are sized and installed properly. Don't let the haters steer you away from the savings and comfort of such a system.

Mitsubishi is the leader in mini-splits.
Multiple heads connected to a single outdoor unit. MXZ series:
Mitsubishi Electric US, Inc. Cooling & Heating | HVAC

Indoor wall mounted unit:
Mitsubishi Electric US, Inc. Cooling & Heating | HVAC

Check out their units. They're quiet, yet very efficient and effective.

I know you will be amazed but I am on board with this idea. It will fit his plans very well. Having seen the layout there was concern about duct work and getting good return. This will eliminate all of that and give good local area control.

 

[IndyGunworks]

I know you will be amazed but I am on board with this idea. It will fit his plans very well. Having seen the layout there was concern about duct work and getting good return. This will eliminate all of that and give good local area control.

sounds like we are on the same page. It just took me 15 hours of research to fully understand what you were mentioning. I was a bit concerned about the extra cost of two outside units, but it sounds like its a marginal cost considering the extra efficiency I would get since the smaller units are more efficient. it also looks like the mitsubishi's have a low enough amperage draw that they could be ran off a battery bank at night. I don't know how much storage it would require but in that situation it would be to just keep the house above freezing. I am sure it would have to be at least a 12 battery bank, but those precise calculations are still several years from being needed. I just want to set myself up for success should that become a real possibility.

are we having lunch tomorrow?