Advice on mini-splits

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What DBoon said!! Really.

If you wanted to ditch oil, you would need an expensive system to cover your full heating needs and would need to worry about distribution to bedrooms and all that.

But you are keeping the oil, and just looking to take a big bite out of the oil man's bill. One big mini downstairs will do that. Maximum ROI. You will have all the AC you ever need downstairs, and if a bedroom needs a small window unit, no bigs. Its not like trying to AC a whole house with giant window units or an army of smaller ones.

I also second the 2X mark-up. If you're in a HCOL area, 2x equipment price is pretty much the bottom line for someone doing it for a living. If you want to save money, you could do a lot of the install DIY, but it sounds like that is not your bag.
 
I think I get the financial logic of installing just 1 unit and making sure it's an efficient one. I'm trying to figure out how it would work practically. If I install 1 unit downstairs to heat that floor to a comfortable temperature, wouldn't that prevent the house thermostat (also downstairs) from kicking on? Without the boiler turning on, I'd get no heat upstairs save for what limited amount rose naturally from the first floor. I'd have to turn the thermostat up pretty high to get sufficient heat upstairs, which seems counterproductive.

Given how much more time I spend upstairs (office, bed, bath, workout space) than down, does it make sense to buy only 1 unit but have it installed upstairs?

Thanks for continuing to provide advice.
 
I think we are assuming that warm air rises, so the upstairs would not freeze. Might run a couple degrees cooler than downstairs, not a huge worry.

Even IF it was a problem, you would have multiple simple options....
1. You can stuff towels or foam pipe insulation in 50% of your downstairs hydronic baseboards (or close their flappers) to reduce their output, sending more heat upstairs. You might have two loops even in a one zone system, and can turn off the lower story loop by closing a valve??
2. You could move the thermostat upstairs, and get effectively 2 zones...the mini one downstairs and the stat/oil one upstairs (running much lower output due to warm air rising).
3. You could set up a fan for circulation, either box type on a landing or a ceiling fan in the stairwell.
4. some combination of these.
 
Hi Wear More Layers,

You are going to find that the heat travels upstairs pretty well if the heat source is located downstairs. I would just make sure that your minimize the heat loss upstairs as part of your install, so make sure you windows are well-sealed upstairs, and that you have good attic insulation so as to keep the upstairs temperature more constant. You will find that you need to keep the downstairs five degrees warmer or so to keep the upstairs at a comfortable temperature. The advice above is depending on the room layout, of course...

It is slightly problematic to have your thermostat for the oil furnace on the first floor. Is there a way to move it to the upstairs? Alternatively, you could look at zoning the furnace distribution, but that is probably more expensive than just moving the thermostat.
 
I have only 1 zone, with the thermostat in the one room which all of the companies targeted for the downstairs unit. I don't think there's a straightforward way to move the thermostat upstairs.

There's only 1 loop running through the house to all of the radiators. None of the radiators has a shut-off valve that I can discern. I'd be reluctant to gum up the radiators with foam insulation. Fans may be my one way of redirecting the heat upstairs.

I think I need to step away for a little while. Maybe taking a break will help regain some perspective.
 
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Wear More Layers said:
I'd be reluctant to gum up the radiators with foam insulation. Fans may be my one way of redirecting the heat upstairs.
Click to expand...

Sorry, I thought you had baseboards that are easy to close off or (reversibly) stop up with foam. Then I saw you had cast iron.

My hydronic system was a single zone and a single pump hooked up to two loops (each with a sep shutoff valve), you'd never know without tracing the plumbing. Have you done that? Maybe you used to be gravity fed steam?

Moving the stat, if you don't want to just use Dave's wireless idea is not that bad. You just need to snake a new low voltage cable....they're thin and you can take a circuitous route...follow the plumbing vent up from the basement to the attic, then drop it down from the attic where you want it, etc. A handyman could to do it for you in <1 hour probably.
 
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Hi Wear More Layers,

Having a single-zone cast iron radiant system definitely complicates things a little bit. I had a single zone system with home run lines (direct lines) to each radiator. The home runs all began in one of two pipes, and I split the system there. In the process, the big old pump was replaced by two smaller Taco pumps and I am likely saving about 50 to 60 kWh per month in the heating system (I saw my bills go down immediately). Cost was about $1200. Well worth it. Now, the bedrooms and bathroom (which are farthest away from the woodstove) are on a separate zone. This makes the wife happy.

FYI, the Fujitsu mini-split I speak of was put in a different house that I am just starting to renovate....

But even before I zoned my cast iron heating system, I still got a lot of benefit from the woodstove. Now I am just getting more. Your setup is a little different - heat does rise pretty remarkably well. I would still go forward with a mini-split, but now I would mostly definitely just start with one downstairs and run it as much as you can and see how the heat flow works. It is quite likely that 50% of the time the mini-split will take the full heat load for you (like in Spring and Fall) which is when they are most efficient and the heat loss in the upstairs will not be as great. Then, you would just run your oil boiler in the deep winter (and you could still run your mini-split in the winter overnights or at some baseload temperature to moderate the need for the boiler).

I say "go for it" - get the one downstairs to start. Once you do, you are going to wonder why it took you so long to get it.
 
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If you have an open stairwell to the upstairs, you will be fine with heat rising. If the indoor head is close to the stairs you might get more heat upstairs than down (I am not recommending you put it that close, just saying). Warm air pools on the lower level ceiling, and flows horizontally until it reaches the stairwell and pours up the stairs. Cool air from upstairs returns at tread level.

If we were talking wood or pellet stoves....we would want to see a floorplan. You did say your downstairs was open plan...
 
For what its worth, I am heating half my second floor with a one ton unit located on the first floor. The heat runs up an enclosed stairwell in the center of the house. I have to run my heat pump at around 69 degrees to maintain 65 in the office. Its good down to about 20 degrees but takes a long time to warm up if I close the doors. I have 12" of insulation between the main floor and the second floor. I also run a ceiling fan running upwards in the second floor office as the heat tends to stratify near the ceiling.
 
This thread all sounds similar to my setup, only I have a thermostat upstairs. A/C would be nice for less than 10 days a year and so far we've been heating mostly with wood: the insert is kind of acting like the heat pump, and oil (and/or electric space heaters) heating the upstairs.

Has anyone heard anything good about the Toshiba/Carrier units? I might be able to get a deal on the equipment.
 
Happy New Year. Thank you for all of the advice you offered me last year. I took a break and am now trying to finalize my heating plan as one of my goals for 2014. Based on your combined wisdom, the suggested most cost-effective plan is:
1. buy 1 downstairs unit
2. move the thermostat upstairs (= $170 for a wireless unit)
3. buy a room air conditioner for upstairs (= $300 for a 12,000 BTU window unit)

I've looked into single mini split units and came up with the table of choices below. I hope the table format is legible. I did not include the Mitsubishi Hyperheat because the indoor unit is too long to fit on my wall.

BrandUnitBTU/47FHSPF/47FCOP/47FBTU/17FCOP/17FcoolingSEERCost
Fujitsu15RLS218,000120.99??14,50021.5$1,757
Fujitsu15RLS2H18,00010.33.91??14,50021.5$1,910
MitsubishiMSZ-GE18NA21,600103.3313,4002.7117,20019.2$2,021
MitsubishiMSZ-GE24NA27,600103.4616,0002.6422,50019$2,260


Notes:
- Mitsubishi lists data for 47 F and 17 F. I couldn't find comparable 17 F data for Fujitsu.
- I calculated COP by hand for several units when I couldn't find published data and was surprised by the 15RLS2 COP of 0.99.
- Costs are for online purchase only. I'm assuming that installation costs will be the same independent of brand or unit.

My questions:
- Given all of the above info, what are the most important factors I should be considering? Total heat output? HSPF? COP?
- Does a lower COP mean higher operating costs? Connecticut (and NY) boasts the highest elec rates in the continental US, so I need to keep an eye on the cost to run the unit.
 
Wear More Layers said:
Happy New Year. Thank you for all of the advice you offered me last year. I took a break and am now trying to finalize my

BrandUnitBTU/47FHSPF/47FCOP/47FBTU/17FCOP/17FcoolingSEERCost
Fujitsu15RLS218,000120.99??14,50021.5$1,757
Fujitsu15RLS2H18,00010.33.91??14,50021.5$1,910
MitsubishiMSZ-GE18NA21,600103.3313,4002.7117,20019.2$2,021
MitsubishiMSZ-GE24NA27,600103.4616,0002.6422,50019$2,260
/quote]

I see that the table format got all screwed up. Sorry about that. Here's another attempt:

Brand Unit BTU/47F HSPF/47F COP/47F BTU/17F COP/17F cooling SEER Cost
Fujitsu 15RLS2 18,000 12 0.99 ? ? 14,500 21.5 $1,757
Fujitsu 15RLS2H 18,000 10.3 3.91 ? ? 14,500 21.5 $1,910
Mitsubishi MSZ-GE18NA 21,600 10 3.33 13,400 2.71 17,200 19.2 $2,021
Mitsubishi MSZ-GE24NA 27,600 1 0 3.46 16,000 2.64 22,500 19 $2,260
Click to expand...
 
Well that's annoying. If you have a suggestion for how to show a table of data, please let me know. Copying an excel table didn't work. Manually spacing columns of data didn't work, either.
 
Its easy to minimize heat coming from cast iron radiators. Each one has a valve you can adjust in a feed and return system. In a loop type system just put an old blanket one the ones you DONT want heat from. If its baseboard cast iron , block the air vents.
 
Floydian said:
Happy New Year!

This is the info you want for the Fujitsu 15RLS2: http://m.master.ca/documents/4Fujitsu_Technical_Manual_9_12_15RLS2.pdf

Page 8 has the basic specs and page 15 has a table with more in depth specs on total capacity and input power at given outdoor temps. Even at -5::F you should still see a COP of 2+.
Click to expand...

Thanks very much, Noah. The 15RLS2 looks like a good performer, and it's the least expensive model ($1,760) I've seen for its size. One question: If you know, what's the difference between this one and the 15RLS2H? The latter is more expensive yet has a lower HSPF and identical COP, SEER.

So do people think an 18,000 BTU (at 47F) downstairs unit sounds reasonable? Fujitsu doesn't go bigger, so the alternatives are Mitsubishi MSZ-GE18NA ($2,000, HSPF=10, COP=3.33) or 24NA ($2,260, HSPF=10, COP=3.46).
 
Seasoned Oak said:
Its easy to minimize heat coming from cast iron radiators. Each one has a valve you can adjust in a feed and return system. In a loop type system just put an old blanket one the ones you DONT want heat from. If its baseboard cast iron , block the air vents.
Click to expand...

I can't seem to locate any valves for closing individual radiators. Once the cold snap breaks I can try wrapping a radiator in a blanket to see what happens. It's safe to do this?
 
Wear More Layers said:
Well that's annoying. If you have a suggestion for how to show a table of data, please let me know. Copying an excel table didn't work. Manually spacing columns of data didn't work, either.
Click to expand...
Include it as a graphic (image) rather than tabular text.
Excel allows copying as a "picture" directly.
 
Wear More Layers said:
If you know, what's the difference between this one and the 15RLS2H? The latter is more expensive yet has a lower HSPF and identical COP, SEER.
Click to expand...

The 15RLS2H is Fujitsu's equivalent to the Hyper Heat from Mitsubishi. It provides heat down to -15::F and has a heated base. I am not sure why the HSPF is lower but it my be rated for a colder climate than the 15RLS2 series. That is all I can think of but I have not looked into the H models much.

I think the 15RLS2 is a good fit for what you want to accomplish.

A couple of things to keep in mind: 1.Fujitsu does not warranty online sales, period. 2. Local installers are likely paying more for the units than they are selling for online because the online units are not going through regional distributors.

Noah
 
Wear More Layers said:
I can't seem to locate any valves for closing individual radiators. Once the cold snap breaks I can try wrapping a radiator in a blanket to see what happens. It's safe to do this?
Click to expand...
Theres no safety issue. You are simply blocking the airflow over the cast iron surface.
 
Yeah. With an electric radiator, it wold get a lot hotter if you blocked it. A hydronic radiator will just rise to the temp of the water and no further.

For a cosmetic solution, you could have those wooden/lattice 'radiator covers' made by a local outfit for not too much money, and put a little insulation under them to knock down their output by the desired amount.
 
semipro said:
Include it as a graphic (image) rather than tabular text.
Excel allows copying as a "picture" directly.
Click to expand...

Just trying an experiment with coding the table in HTML. Ignore this post if it looks like a mess.

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  <td class=xl77>Unit</td>
  <td class=xl87>heat at 47</td>
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  <td class=xl87>COP at 47</td>
  <td class=xl77>heat at 17</td>
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  <td height=15 class=xl89 style='height:15.0pt'>Fujitsu</td>
  <td class=xl79 style='border-left:none'>15RLS2</td>
  <td class=xl90 style='border-left:none'>18,000</td>
  <td class=xl79 style='border-left:none'>12</td>
  <td class=xl91 style='border-left:none'>3.91</td>
  <td class=xl79 style='border-left:none'>?</td>
  <td class=xl91 style='border-left:none'>~2.7</td>
  <td class=xl80 style='border-left:none'>14,500</td>
  <td class=xl91 style='border-left:none'>21.5</td>
  <td class=xl81 style='border-left:none'>$1,757</td>
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  <td class=xl90 style='border-top:none;border-left:none'>18,000</td>
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  <td class=xl91 style='border-top:none;border-left:none'>3.91</td>
  <td class=xl79 style='border-top:none;border-left:none'>?</td>
  <td class=xl91 style='border-top:none;border-left:none'>?</td>
  <td class=xl80 style='border-top:none;border-left:none'>14,500</td>
  <td class=xl91 style='border-top:none;border-left:none'>21.5</td>
  <td class=xl81 style='border-top:none;border-left:none'>$1,910</td>
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  <td height=15 class=xl89 style='height:15.0pt;border-top:none'>Mitsubishi</td>
  <td class=xl79 style='border-top:none;border-left:none'>MSZ-GE18NA</td>
  <td class=xl90 style='border-top:none;border-left:none'>21,600</td>
  <td class=xl79 style='border-top:none;border-left:none'>10</td>
  <td class=xl91 style='border-top:none;border-left:none'>3.33</td>
  <td class=xl80 style='border-top:none;border-left:none'>13,400</td>
  <td class=xl91 style='border-top:none;border-left:none'>2.71</td>
  <td class=xl80 style='border-top:none;border-left:none'>17,200</td>
  <td class=xl91 style='border-top:none;border-left:none'>19.2</td>
  <td class=xl81 style='border-top:none;border-left:none'>$2,021</td>
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  <td class=xl79 style='border-top:none;border-left:none'>MSZ-GE24NA</td>
  <td class=xl90 style='border-top:none;border-left:none'>27,600</td>
  <td class=xl79 style='border-top:none;border-left:none'>10</td>
  <td class=xl91 style='border-top:none;border-left:none'>3.46</td>
  <td class=xl80 style='border-top:none;border-left:none'>16,000</td>
  <td class=xl91 style='border-top:none;border-left:none'>2.64</td>
  <td class=xl80 style='border-top:none;border-left:none'>22,500</td>
  <td class=xl91 style='border-top:none;border-left:none'>19</td>
  <td class=xl81 style='border-top:none;border-left:none'>$2,260</td>
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