Mini-Split Heat Pump

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Mini-Split Heat Pump

Postby Huckleberry on Mon Nov 07, 2011 5:46 pm

Hello folks,

Has anyone here installed a "mini-split" heat pump in their house? I am thinking of going that route for our upstairs bedroom. I have two concerns. Are they quiet enough to be used in a bedroom? Are there any that are small enough for a single 14'x17' room?

Thanks for any help.

Huckleberry
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Re: Mini-Split Heat Pump

Postby chooseopen on Mon Nov 07, 2011 6:00 pm

Forum member rodpaine posted a detailed write-up of his system here:

http://mysite.verizon.net/vze7aq8e/pictures/id7.html
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Re: Mini-Split Heat Pump

Postby Huckleberry on Mon Nov 07, 2011 10:13 pm

Thanks for that link. I did a search for "mini-splits" but that didn't show up. I still haven't found one that will suit a 240 s/f room. The mini-split heat pumps look like a good way to avoid pushing ductwork through old walls and to avoid hanging ugly AC units out of windows as well.

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Re: Mini-Split Heat Pump

Postby shazapple on Tue Nov 08, 2011 9:28 am

A small one in a bedroom would be about as quiet as a fan. Certainly not whisper quiet but something most could sleep over.

I'm not sure you would get your money out of a mini-split that is only in one room. If you have too big of a unit they tend to cool the room before enough moisture is removed, so you end up with a cold damp room. Typically they are installed in a hallway and service the entire floor.

You could look into High velocity mini duct systems. I don't have any experience but they seem well suited for a retrofit situation.
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Re: Mini-Split Heat Pump

Postby triguy128 on Tue Nov 08, 2011 10:39 am

The biggest advantage they have is sizing and you can also have multiple indoor units for a "zoned" system.

Units are offered down to around 5000BTU. THe total surface area of a upstairs bedroom that's 14x17' is 501 sqft with a 8.5' ceiling and 2 outside walls. Assuming an average R value of 4 for outside walls, and 20 for the attic and ignoring air leakage (most drafts upstairs go out anyway due to chimney effect.), assuming a 70F temperature differential in winter (0F design temp), thats 5444 BTU's. Now, fow a single unit, 9000 BTU"s is the smallest they make. But if you have a2nd room that needs AC & heat, you could get a 2 zone system with 2 smaller units.

You can also get indoor modules that are ducted and mount in the attic, as well as units that are flushmounted in the ceiling. The most common just mount on the wall.

I've been told by my HVAC contractor that Mitsubishi and Fujitsu are the better brands. Some of the better units are almost as efficient as a geothermal system when cooling and reach 26 SEER since they are vairable speed not just on and off.
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Re: Mini-Split Heat Pump

Postby Huckleberry on Tue Nov 08, 2011 5:21 pm

Thanks, TriGuy. That's a great reply.

We actually have three bedrooms and a bathroom upstairs, as well as a pretty large hallway space, so we could actually use a four-zone if we had to, but it's just my wife and I, so I was thinking to keep it to one room. I guess we could do a two-zone system with one unit in our room and another in the hallway as Shazapple mentioned?

I've read some interesting things about their efficiency. Basically, I like a system that can be turned on and off as needed and that doesn't require a lot of ductwork. MY HVAC guy doesn't like them because he had trouble with mini-splits he installed many years ago, but they seem to be better now.

I guess I need to find a dealer and get some prices.

Huck
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Re: Mini-Split Heat Pump

Postby Daniel Meyer on Tue Nov 08, 2011 5:44 pm

Huckleberry wrote:
I guess I need to find a dealer and get some prices.



An idea on pricing (I've bought from these folks. Fast/good service)

http://kingersons.com/12000btuminisplitac-inverter.html
CUAgain,
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Re: Mini-Split Heat Pump

Postby triguy128 on Tue Nov 08, 2011 10:36 pm

IN terms of pricing, they are actually a little more expensive equipment wise than conventional split systems... for the better quality mini splits. But the installation costs are much lower.
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Previous home - 1968 single story Ranch/Colonial, 1200sqft - 11 windows
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Re: Mini-Split Heat Pump

Postby Huckleberry on Wed Nov 09, 2011 7:16 pm

Daniel Meyer wrote:
Huckleberry wrote:
I guess I need to find a dealer and get some prices.



An idea on pricing (I've bought from these folks. Fast/good service)

http://kingersons.com/12000btuminisplitac-inverter.html


Were you buying a mini-split? How did you handle the install?

Thanks,

Huckleberry
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Re: Mini-Split Heat Pump

Postby Daniel Meyer on Wed Nov 09, 2011 10:30 pm

They are pre-charged. I installed, then had the local AC guy come out and test for leaks (pressurized with nitrogen I think), then evacuate the lines. Once that's done you just turn two valves. (if you have longer than 20' lines they will have to add extra charge).

You can do all that yourself...guages and pumps to evacuate are not expensive if you are doing several units (and you can buy the charge for this kind).

The AC guy only charged $100 to test/evacuate though, so I had him do it.
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