Mini-split ductless question..

[Forty Two]

Something I just thought of as I looked through the mini-splits on ebay.... many are only Seer 13, and these don't seem to function at temps below 15 degrees F. Make sure you get something in the SEER 18-20 or with a HPSF(?) that's as close to 10 as possible. These seem to be the ones that function best in cold weather.
I saw a 24000 BTU mini split on ebay for only $1000 but it was only a SEER 13 and couldn't function well at low temps.

I LOVE the idea of using earth tubes to feed the outdoor compressor on an air source heat pump. You get rid of any issues of mold, and in really cold environments you only have to get the temp up to around zero. Plus, you wouldn't need to trench it as far- probably a regular trencher would do the trick instead of a backhoe. Around here you have to go pretty low to avoid frost for water lines- but in this application you only need to raise the temp up to a good operating range for the heat pump. Even if you don't do it right away, keep that in mind when you mount the outdoor unit. You might want to add something like that later. I know I'm thinking about it.

[psmithrt]

Originally Posted by Nevyn

Thanks, that's got a lot of what I wanted to hear in it. it's rare to see temps that low here, but it does happen occasionally. I'd be mounting the compressor in front of the dryer vent, which I figure should help with air temps for it to work against a little bit. My area to heat/cool is ~588 square feet, which is kind of on the line. I'd love to oversize, but I'm also looking to minimize cost.

If it halved my oil bill then it might pay for itself by springtime. That's a MAJOR bargain! I just have to be sure to get one that is inverter powered, correct?

Placing the outdoor unit near the dryer vent might be asking for problems,
with little micro fibers of lint building up in the coil.

I second the warning, not only lint, but humidity.

[Nevyn]

I do thank you for your concerns, they were things that I hadn't really thought of in a large way. I was looking at it a little more over the weekend, and I won't be putting it RIGHT in front like I thought was a good idea. It'll be near it by necessity, but I'll put it next to my basement doors instead - about 3 feet to the left of the vent. The vent points towards the backyard, and I'll be mounting the unit on the front side, so it'll actually be blowing away from the unit.

I wonder if I can move my dryer vent underground and heat my garage with it....?

[psmithrt]

Originally Posted by Nevyn

I do thank you for your concerns, they were things that I hadn't really thought of in a large way. I was looking at it a little more over the weekend, and I won't be putting it RIGHT in front like I thought was a good idea. It'll be near it by necessity, but I'll put it next to my basement doors instead - about 3 feet to the left of the vent. The vent points towards the backyard, and I'll be mounting the unit on the front side, so it'll actually be blowing away from the unit.

I wonder if I can move my dryer vent underground and heat my garage with it....?

I wish I could come up with a positive reply. Under ground would not be good either. I'm afraid we are getting too far off subject for this thread. If you know how to PM then leave me one and I will try to explain something I did that seemed to help utilize a little of the heat. Otherwise you would be asking for trouble again by putting it under ground. The cool ground would condense the humidity, leaving the inside walls very wet and cause a lint trap and a probable blockage. NOT GOOD. Not to mention, there probably wouldn't be much heat left to exit anyways.

Paul

[Nevyn]

That's why I mentioned it - I figured there was SOME problem I'd forget about.

Anyway, we're looking at going with a 12,000 BTU unit over the 18,000. It says the 12k is for 300 to 500 square feet.

We're more concerned with heat than cooling. Would putting that in a space around 550 square feet be over-taxing to the unit? It's job wouldn't be primary heat, but merely to help hold temperature once the furnace has the area up to temp (from overnight low).

[psmithrt]

Originally Posted by Nevyn

That's why I mentioned it - I figured there was SOME problem I'd forget about.

Anyway, we're looking at going with a 12,000 BTU unit over the 18,000. It says the 12k is for 300 to 500 square feet.

We're more concerned with heat than cooling. Would putting that in a space around 550 square feet be over-taxing to the unit? It's job wouldn't be primary heat, but merely to help hold temperature once the furnace has the area up to temp (from overnight low).

I really hate to see people waste their money sooo.

People often discount or totally ignore stratification of air when heating/cooling two story homes. As silly as this may sound, (IF!) you have an open (no door at the bottom of) stairway and you are considering only one unit (mini split) and are looking purely at saving money as opposed to requiring more comfort (as was 42's initial concern) you may be better off putting the unit upstairs in as open an area as possible. Over heat the upstairs a few degrees with the combined output of your boiler and this unit set a few degrees higher which would in effect cause an insulating buffer zone akin to adding more insulation in your attic. I can only guess that is why 42 is so happy with his. Well that and it was quite a find as far as specs and price are concerned.. (KUDOS to 42 for the find) I would buy three of those separately over a three zone multi split.
Excuse the over explaining but, my Mother owns a over under duplex. My brother currently rents the upstairs and keeps his heat at 62 all the time. They both have the same make and efficiency furnaces except for size. Hers being forced air gas 93% AFUE 75000 btu out. His the same , but 48000 btu out. She needs to keep hers set at 70-72 to keep it comfortable downstairs. Last month (DEC) here in central NY was cold as usual. He used exactly half the therms gas as her 92 his vs 184 hers. These apts are not open to each other so I can only surmise that the 8-10 degrees delta T and the fact that he has some insulation over head in attic where as there is none in her ceiling between apts that her heat is indeed supplementing his. They are both same sq ft same layout.
My mother saves everything and I was able to prove this with old bills when previous tenants lived there and kept a much more reasonable 70-72. The difference was only 67% on average as opposed to 100%.
Now this can be used for A/C as well. At my previous house (I am currently back home with Mom) I was able to cool one upstairs bedroom and the whole downstairs from 88in 92out to 66in bedroom 78downstairs all with one 6000BTU window unit running max. I covered all the registers, supply and return with cardboard and tape. Placed a box fan at the bottom of the stairway in a fashion that blew the cool air in a complete circle around the downstairs. I watched in amazement with a lit cigarette as the heat was brought around and went up the stairway with an almost chimney like draw as the cool air flowed down the stairs like a waterfall.
NEVYN.
This is why if you use only one unit (and I would buy 42's 12000btu Amcor) I would suggest an upstairs open area with room doors open if possible over downstairs. At least for the first unit. Who knows, maybe next year another for downstairs!! and No boiler.
One thing I thought of, but have no answer to is if it would be cost effective to have your boiler kick down (setback) overnight as I am not familiar with how quickly one pipe systems can recoup. If your bedrooms are upstairs this may be another money saving option we use in CNY with forced air. I do know that with boilers and radiant floors it doesn't work well.
Anyways I just have this feeling that if you put the indoor unit downstairs as you propose, you will not only be asking a 12000BTU unit to heat your 588sq ft downstairs, but also effectively half of your upstairs through convection. In which case YES you would be over taxing it. In which case I believe you would be better off taking the $1500 (per 42's install) and renting a blow in cellulose machine and putting as much as feasible in you attic. Caulk any infiltration areas. It would be money better spent.
As always my opinion is just that. I always appreciate any feedback as that is how I learn. With the exception of the statement about resistant heats efficiency vs heat pumps JMags has been (in my opinion) spot on and maybe he can add or subtract from all I've suggested.
As the great philosopher Forest Gump said, "That's all I got to say about that, I think I'll go for a run."

PAUL

[Nevyn]

Thanks, there's a lot of info there.

My upstairs is very oddly shaped - see the slideshow in my first post. There's a small foyer area, a bedroom, and the computer room that sit above the two downstairs rooms I want to put the unit in for. Above them is a crawlspace, no real attic. It's full of R-38 insulation ON TOP OF some R-13/R-19 that was there. We had to add the insulation to be able to get a gov't grant for first time home buyers. The rooms upstairs often hold heat 3 to 5 degrees warmer than downstairs.

The floors downstairs have R-19 between them and the basement.

I'll get some better pics and measurements over the weekend, but I hope that this info helps. I'd feel better with the 18,000; maybe we should just scrimp the extra $500 together for it?

[psmithrt]

Originally Posted by Nevyn

Thanks, there's a lot of info there.

My upstairs is very oddly shaped - see the slideshow in my first post. There's a small foyer area, a bedroom, and the computer room that sit above the two downstairs rooms I want to put the unit in for. Above them is a crawlspace, no real attic. It's full of R-38 insulation ON TOP OF some R-13/R-19 that was there. We had to add the insulation to be able to get a gov't grant for first time home buyers. The rooms upstairs often hold heat 3 to 5 degrees warmer than downstairs.

The floors downstairs have R-19 between them and the basement.

I'll get some better pics and measurements over the weekend, but I hope that this info helps. I'd feel better with the 18,000; maybe we should just scrimp the extra $500 together for it?

Excellent and yes it helps. How serious are you about this and have you thought the total costs through. Are you thinking of the Amcor or looking elsewhere. I keep trying to see how serious you are. I spend way too much time trying to help people and they end up doing something totally different or end up cheaping out a couple dollars and unhappy. Then somehow blame me so let me know if this is just a thought or a goal because I think if you do what I propose you could save quite a bit over oil. Payback definitely. How long, can't say. Do it wrong, never, plus waste of your up front money.

PAUL

[psmithrt]

Sorry about that, just had something happen before I sat down previously. Anyhow. This Amcor deal looks too good to pass up. You can find what looks cheaper to start, then add in all the other stuff that this one includes and it is more expensive with worse specs.
NEVYN:

I would go with nothing less than this...

mini split air conditioner - ductless split system

For many reasons. Look at it and the price and if your still with me tell me what you think. Also I found this...

http://www.youtube.com/watch?v=PdMRVO_NOz4

How much of this do you think you can do on your own?

Also try as I might I can't find the room pictures at your link. I find pictures, but not of rooms.

PAUL

[Nevyn]

Kingerson's what where I planned on ordering from, and the Amcor was my plan too. I'll post the link again, if it doesn't get you to the "House!" photos PM me and I'll direct link you.

Picasa Web Albums - Nevyn - House!

We're highly serious about this. My wife and I agree that we *NEED* to do something to reduce what we spend on oil, and this looks to be the best bet.

I have no trouble doing, well, just about anything for a home. I grew up in a DIY house, and with an extended family that gave me all the opportunities a boy could wish for (My mom's side runs a farm - and they have a sawmill + full woodworking shop, AND a full machine shop for equipment repairs). I have no problems with household wiring, piping, plumbing, ducting, etc.

We are looking to use the mini-split for several reasons:

1. Save money by buying less oil.

2. Provide an alternate source to the oil furnace for maintaining the temperature of the main two rooms downstairs (rest of the house is not important). The furnace will boost the temperature once in the mornings throughout the whole house, and then be turned back down and the mini-split will heat only the rooms that are occupied.

3. Provide small to moderate cooling in the summer. We're not looking for something that will cool 90 down to 70, but for something that would be able to take 85 down to 75 in the "main occupancy rooms."