Specific advice on Mitsubishi mini-split system in region 5
Have had several local companies provide quotes on Mitsubishi mini split systems for my home. Have seen wildly different Manual J calculations, as well as different recommendations on equipment, some conflicting. Can give more info if requested.
Recommendations on units for different rooms have varied between GE6000 to FE or FH9000. And between FE or FH9000 and FE or FH12000. So only off by 3000BTU or so. I’ve been told that these units don’t have the traditional problem associated with oversizing (other than initial investment) because of the variable output, they can ramp down to fit the room they are in. But that having the extra headroom provides more output in colder temperatures in winter. I am in zone 5, in Northeast PA. Can GE, FE, FH units all be mix and matched on a single outdoor unit (ie the MXZ-4C36NAHZ). If so I’d consider putting GE6000’s on 2 mixed use guest bedrooms which we don’t use too much.
One suggested FH series head units, but another said that the FH units are only used for single zone systems, and that there was no benefit over the FE units, other than an additional filter which was expensive to replace. The contractor who suggested FH said it has a 3d i-sensor that takes a profile of the room and located hot and cold spots in the space to push air to that area. Comments?
Also, most have suggested putting the basement as a 4th head onto the same outdoor unit that will support my 3 upstairs bedrooms. One though suggested putting a separate indoor and outdoor unit for the basement. “It is a design flaw with these units, when you put a head in a basement location with multiple heads on a different floor; the upstairs will over heat because the basement system will be calling more than the upstairs and it will send the hot refrigerant through the other heads and over heat the space. I do not recommend putting the basement zone on the same outdoor as any other floor. There is a fix for it per Mitsubishi tech support but the fix will significantly lower the efficiency of the system.” Comments on this? Our basement is below grade and we are planning to have it spray foamed with 2″ closed cell which I’d think would make it call for heat less.
Also most seem to dissect the quote into my 2 floors (w/ the basement added onto the 2nd), but this seems largely a pricing/marketing consideration, making the cost seem more palatable, whereas it doesn’t appear to be logical installation wise. I’d think putting one unit covering one side of the home (1 basement, 2 downstairs, 1 upstairs MBR), with shorter linesets to each. And then the other unit could either run a single line to the other side of the home and mount the branch box there, with shorter runs to the other 2 downstairs rooms and 2 upstairs bedrooms, or else just mount the outdoor unit on the other side of the home entirely, and just have a longer electrical run. Again, any logical principles on how to break up which rooms/floors to put on the same outdoor unit?
My kitchen doesn’t really have space for a head unit, but most have suggested not putting a unit in the kitchen anyway, and allowing the surrounding rooms to condition it. The flow is relatively open. One contractor though suggested the opposite, that it’s important to condition the kitchen directly. Who’s right?
What is the benefit to using disconnect switches? Won’t a circuit breaker take care of this? Is it just to simplify servicing the unit by not having to go inside and turn off the breaker? Are all the head units powered off this main unit? So the disconnect will also kill power for all those units? I’ve read some suggest disconnects also for each head unit, but it’s unsightly.
What clearances are required on the GE/FE/FH series head units from walls and other obstructions above, in front and on the sides? Some have suggested I needed 5″ minimum above to ceiling, but another said it could be only 1″. Is there any drawback to installing a unit over our bed? I’ve been told we can direct the grills away from blowing right on us.
What is the latest on control / automation? I see info on MHK1 and MCCH1, but the implementations seem to leave something to be desired. Is the PAC-US444CN-1 solid? I’d like the option to implement control via CoolMasterNet, Proliphix IMT550c/w series, Venstar Colortouch, Radio CT or Filtrete series. I’m into home automation and it would be nice to have options to integrate it into an automation system. However, many have suggested that it’s ideal with this system to just set it and forget it. Don’t try to save energy by adjusting the temps at different times or days when we’re not around. And that I really only have the option to adjust different heads on the same outdoor unit by about 2 degrees F. Kind of seems like I’m not really getting the advertised mixed zone control in that case? So there’s no benefit to leaving certain rooms off? Or reducing output while we’re away? Can we program it to be cooler during sleep times and warmer upon waking, then cooler again while we’re gone (or vice versa in summer)?
Thanks!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Those who worry about keeping the kitchen cool enough will want to condition the kitchen.
Get your own room by room Manual-J performed by a certified energy nerd, not an HVAC contractor. Seriously- there's a lot of "garbage in= garbage out" type Manual-Js performed by HVAC contractors, but those who are only selling the accuracy of their calculations usually hit it pretty close.
To avoid oversizing, for calculation purposes onle use only 68F as the heating interior design temp, and 76F for the cooling interior design temp, and use the 99% and 1% outside design temps, not the 99.7% or 0.4%. A selection of ASHRAE design temp numbers can be found in the appendix here:
http://www.ewp.rpi.edu/hartford/~scarzm/MANE6980/Other/ASHRAE_References/2009%20ASHRAE%20HANDBOOK%20FUNDAMENTALS%20-CHP14_Climates.pdf
A selection of ACCA Manual-J design temps can be found here:
https://articles.extension.org/sites/default/files/7.%20Outdoor_Design_Conditions_508.pdf
The modulation range of these systems is not infinite, particularly the compressors on multi-splits. If the minimum-modulated output of the compressor at +47F is much higher than your heat load @ +47F even the compressors won't modulate much.
The minimum output of the MXZ-4C36NAHZ @ +47F is 7,200 BTU/hr, which happens to be the MAXIMUM output of the GE06NA. That means if only a single GE06NA head is calling for heat it has to cycle on/off, not modulate. But the heat load of a typical current code-min bedroom is less than 5000 BTU/hr @ 0F, and at 47F it's under 1500 BTU/hr.
Ideally you'd want to both the compressors and the heads to be modulating at least most of the season, but the 1-head per room approach usually leads to only modulating when it's below freezing out, and sometimes not even then.
The list of compatible heads & cassettes for the MXZ-4C36NAHZ is found here (and it includes almost all FE, FH, and GE heads)
http://usa.mylinkdrive.com/categories/3/product_types/5/series/42/models/372/products/show/2416.html
So, get some accurate numbers, do your own math, and TELL the contractors what you want, don't ASK them. About 19 out of 20 are pretty clueless about what it takes to get them running in an efficient mode.
The clearance specs for the heads are all available online, but in a heating dominated climate you don't want to be anywhere NEAR min-clearance at the ceiling. The ceiling is where the warmer air pools, and the efficiency specifications assume 67F incoming air, which is only found near the floor, never the ceiling in a 70F room. Having intake air at the head 5F warmer than the test specifications means both lower heating capacity and lower efficiency than the test numbers indicate. Mounting close to the ceiling makes sense for air conditioners, not heaters.
Thank you for the reply. I actually did have an independent Manual J calculation made which I paid for. I will attach the PDF. I also have it in Right Suite Universal format.
I also just received a 3rd quote from a different contractor. He suggested a single outdoor unit, the MXZ-8C48NAHZ. He said my house BTU requirement was only about 36,000. He also spec'd the FH units. 3 12NA's (TV Room, MBR, and Fireplace room), and 5 09NA's all other rooms including basement.
He said I would need backup electric baseboard when it gets down to 5F or below. But he said most of the time this would be sufficient and it wouldn't even fully draw on the outdoor unit. Does this make sense? I thought I shouldn't put indoor units in that go above (81,000 vs 48,000!) what the outdoor unit can produce.
It does make for a cheaper install, though. Just wondering if it would be worth the extra $5-7K to just put in 2 MXZ-4C36NAHZ's instead of the one 8C unit.
When researching I've also noticed there appears to be -8th and -9th generation models on the indoor units. Does it make much of a difference on whether I receive the newest 9th generation models? Most of my quotes seem to include the -8th generation models.
Unfortunately I don't find the Manual J calculation provided very convincing. For one thing, it includes 5000 btu/h allocated to a humidifier. That's generally a bad idea. It says it calculates infiltration based on a blower door test result of 2500 CFM_50 which is s suspiciously round number which I suspect is a made-up number not a test result. And I don't see the assumptions about the insulation and window U factors documented anywhere.
I'm afraid I can't offer useful advice on the particulars of configurations of different units, or the differences in 8th or 9th generation units.
How many thumbs are on the scale?
**An air leakage rate that exceeds current code-max. Using their volume and cfm estimates that's about 7 ACH/50, whereas code-max is 3 ACH/50- a number that is usually retrofittable.
**Using +70F as the indoor design temp as the indoor design temp instead of the code-minimum +68F, along with using +4F as the outside design temp when the 99% temperature bin for Scranton/Wilkes-Barre is +7F. See:
https://articles.extension.org/sites/default/files/7.%20Outdoor_Design_Conditions_508.pdf
The temperature selections alone adds 6F to the design temperature difference, which is adding about 9-10% to the total. The load associated with air infiltration should be cut in half to be closer to reality. All told I suspect the above overestimates reality by about 15-20%, maybe more.
Even using their numbers, after adjustments for the known thumbs on the scale any individual room could be heated with a GE06 head, but an FH head with the i-see sensor may be more useful for larger open areas served by a single head. You might opt for an FH09 head for some of the bigger room loads but not the FH12. The FH09 has a huge turn-down ratio, capable of throttling back to 1600 BTU/hr, which minimizes cycling even if it's max output is oversized for the load at design temp. The individual room loads for most rooms are too small for even a GE06. A mini-duct cassette serving multiple adjacent or nearby rooms sized for the combined load would be more efficient than multiple oversized wall-coil heads.
Under no circumstances would you be better off with two 3-ton compressors, since you'd then have a minimum compressor output of 7,200 BTU/hr + 7,200 BTU/hr = 14,400 BTU/hr, which is something half the real whole-house heat load, which means even the compressors would be cycling on/off rather than modulating any time it's warmer than ~35-38F outside. The binned hourly average outdoor temperature over the coolest 10 weeks of the year in Scranton/Wilkes-Barre is about 35F, which means with two compressors there would be doing a lot of cycling rather than modulating throughout the winter, which is lousy for efficiency. Though the single 4 ton -8C unit is oversized for your peak load, it can throttle back to the same 7,200 BTU/hr as the 3-tonners which moves the outdoor temp at which the compressor begins cycling well north of 40F. The oversized outdoor coil is also good for efficiency, since it'll be idling along at part load nearly always.
Without more detail it's hard to vet the U-factors used in the load calculations, or estimate how much you'll be able to peel off the load by insulating the foundation.
Be your own judge on how open adjacent rooms are to one another, and how likely they would be capable of sharing a wall-coil head, and be mindful of the minimum modulation of the heads/cassettes as well as the maximum capacity.
I had to break the PDF in 2 as it exceeded the max size for uploads.
That's excellent information, thank you for the detailed replies. I've asked the person I paid for that Manual J report about the things you both mentioned so we'll see what he says.
Of the 3 HVAC companies that I received quotes from, only one gave me their Manual J report. For your reference I just scanned that one in and I'll attach it to compare. He seemed a lot more thorough in the measurements that he took, however his load calculations are way higher. The difference of course is that he was trying to sell me equipment, and his quote was *by far* the highest of any company I contacted. I'm disappointed with the Manual J report that I paid $200 for, because there *shouldn't* be any thumbs on the scale with his report.
Unfortunately I have too many other pressing responsibilities to have time to become an expert in this field in the coming weeks. I want to make as educated a decision as possible, but I need to enlist the help of some experts / nerds to help me make a decision.
FYI, my windows in the original portion of my house are all old bottom of the barrel single pane windows, 18 of them. There are 5 single pane basement windows. And then the "Fireplace room" is part of an addition, along with the garage. Those rooms have double pane windows. I'm actually in the process of typing up a similarly detailed question about my insulation project I'm simultaneously trying to become educated with. But presently I have minimal fiberglass batting. It's a 1968 cape cod with typical dormers / knee walls in the bedrooms upstairs. I'll have a series of questions on the insulation posted shortly.
Well, right off the bat we see that on that one he used 72 as the interior winter temperature, and 70 as the interior summer temperature. I guess that's based on the assumption that you'll be wearing shorts inside in the winter and sweaters in the summer? And a 0 F outdoor design temperature, perhaps planning ahead for if you move to Vermont and bring your house along with you.
In other words, your suspicion that he's trying to sell expensive oversized equipment rather than trying to do accurate calculations seems to be justified.
I think we can all agree that the reports are not tailored to the best of my interests. Unfortunately I don't have access to a Manual J calc software to tinker with the #'s. Unless there's a free option? Is there anything useful in these reports that I can use to tweak the #'s and derive accurate info?
How "bottom of the barrel" are those single panes? Are we talking wood sash double-hungs, or crummy aluminum sliders that leak air like a wind tunnel?
Wood sash double-hungs can be reasonably affordably tightened up. Tightening them up and installing a better-grade low-E storm window over them is usually cheaper than code-min replacement windows, and will perform comparably.
Leaky metal-sash windows should be considered ripe for full replacement.
Without going over the contractor's load calc in detail, right off the top he's starting with an outdoor design temp of 0F, fully 7F colder than Manual-J for that location, and an indoor design temp of +72F, which is 4F warmer than code-min, for a delta-T of 72F, fully 11F larger than an aggressive calc using the 99th percentile temperature bin of +7F and 68F, a 61F delta. Even if the rest of the calculation is perfect (not likely!), that's already an 18% upsizing, and from there the next equipment step-sizing makes for even crazier oversizing. This wouldn't have a serious efficiency hit if this were a condensing gas hot air furnace, but it's absolutely the wrong way to go about sizing a modulating heat pump.
As a general rule of thumb you don't want the compressor to be more than 50% oversized for it's actual 99% load, but 25% oversizing is better than 15% undersizing, and can more efficient than if it were dead-on the money for capacity at design temp conditions. The same is true for the max output of the heads relative to the load it's serving. There are exceptions to prove the rule, of course- the very low minimum modulation an FH09 head is one of those exceptions. An FH09 head can deliver about 11,000 BTU/hr at your +7F outside design temp, but modulates slightly lower than a GE06 (140 cfm at lowest blower speed on the FH09 vs. 145 cfm for the GE06). Either would be efficient serving peak load in the 5000 BTU/hr range, even though the max capacity of the FH09 is twice that. IIRC the SEZ-KDxx series mini-duct cassettes all modulate down to 4800 BTU/hr, independent of size, and given the wimpy air-handlers power oversizing those by a step-size wouldn't be a disaster. (FWIW: Fujitsu's mini-duct cassettes have better blowers than the SEZ-KDxx and can modulate down to 3100 BTU/hr, independent of size.)
@Ryan, there is free software such as BeOpt and Hot2000, though you would need training on using them correctly and you would have to take some measurements on your house's construction and current insulation level.
Mini-duct cassettes can often be mounted at ceiling level in closets between bedrooms, serving both rooms with only a foot or so of duct. It's sometimes possible to serve other nearby rooms on the same level by threading ducts inside joist bays with a closet ceiling mount. What you DON'T want to do is mount them in the attic, unless it's an unvented attic with the insulation and air-pressure boundary at the roof deck. (FWIW: Unlike the SEZ-KD cassettes, Fujitsu's RLFCD units can also be mounted vertically, which is sometimes useful in tight conditions.)
I'm really not sure what happens to an -8C48 when there is more head capacity than compressor capacity- never had reason to really go there. It's more than enough compressor for your "after" picture loads, and it's the post-upgrades loads that you should be looking at when designing the mechanical systems, not the where-is-as-is load of the house as it exists right now. If it's undersized for the house in it's current condition it doesn't mean you'll be cold all winter, but it may lose ground on the coldest nights unless you use some auxilliary heating sources.
Yes it's possible to determine if an FH09 per room would work (probably does), but that's not to say it's the best solution even if it does work. Oversizing the compressor capacity by a lot just to have a head per room is usually more expensive and less efficient than a more modestly oversized compressor using more appropriately sized mini-duct cassettes to combine multiple small-load rooms into a single zone should be cheaper and work better. If a doored-off room's design load is under 2000 BTU/hr it's reasonable to consider not heating that room directly if it can't be combined onto a mini-duct zone.
Designing the heating system before the final loads are really known is fraught with risk. When upgrading the building envelope including windows and insulatoin it can make a dramatic affect on the system sizing requirements. Nailing down an aggressive load calculation on the AFTER picture of the planned upgrades is where it makes the most sense to start.
Thanks Alan. I'll check out the software. Although I expect I have quite some learning to do to know what I'm doing with it, as I don't even what Wet Bulb, Dry Bulb and Design Grains mean. Nor do I really understand yet how to tweak reports or plans based on air leakage, insulation values, windows, doors, etc.
Dana looking back to your first post I noticed you mentioned "the 1-head per room approach usually leads to only modulating when it's below freezing out, and sometimes not even then." I started wondering if I should remove heads from some of the rooms and allow the conditioned air from adjacent areas to seep in. But the last couple of posts you've mentinoed mini-duct cassettes, which I wasn't at all familiar with, so I will look into them. This would be an independent system or does it tie in to the ductless outdoor unit? Are there options for Mitsubishi? Or would this only be an option for the Fujitsu and others?
I just received a response from the person who I hired to independently perform my Manual J calculation (the first one I posted) and who also did my energy audit.
--------------------------------------------------------------------------------
In response to Charlie Sullivan's comment:
--------------------------------------------------------------------------------
Since you were thinking about a ducted system to the 1st floor and basement area, humidification is very common on ducted systems. It helps to keep the house on proper humidity level during the heating season. Do I think there are other options to control humidity in your home? Absolutely, but this is a very common process. Wrightsoft Man J software is very specific about the humidification. I have an option to mark or unmark it in the input phase. Humidifiers work with evaporating water into the ducts. This evaporation (like all other evaporations) requires heat, that is the reason why the software adjust the heating load with 4,994 Btu.
I am still not sure about what Charlie thinks under "that's generally a bad idea"? Humidification works and actually it is required in most homes during heating season, this is a fact.
Blower door number 2500 CFM @ 50 Pa. Infiltration is about 30% of the total load at any residential construction. You know we measured your home with the blower door, it was 3260 CFM @ 50 PA. As we discussed the whole Man J load is based on projected insulation and infiltration levels after you upgraded the house. 2,500 CFM is too much or not enough? Who knows, this is a projected number. If you or Charlie knows what will be your infiltration number after the air sealing job is done, please tell me and I will replace the projected number to an actual CFM rate. 2,500 CFM is much better than 3,260 CFM, it is 20% air leakage reduction. I hope you will get that number. You are looking to apply spray foam to the basement walls and to the roof. We assume it will be a great reduction but unfortunately your exterior walls are still T 1-11, and they leak, a lot. So I made my best guess and picked 2,500 CFM. You can judge me on that.
The window U-value, SHGC and the insulation levels are all available in the software. Maybe it is not in the report, but if he works with the software he could open it and see them.
Windows U-value: 0.30; SHGC 0.30 - These are average new window performance numbers
Attic insulation level (based on the thickness of the rafters with open cell) R-28
Exterior walls R-13
--------------------------------------------------------------------------------
And response to Dana's first 2 comments:
--------------------------------------------------------------------------------
Code 3 ACH/50 is not a code in State of PA. It is a requirement for new home construction in IRC 2012, but your home is not a new construction and again State of PA still uses IRC 2009.
"N1102.4.2.1 Testing option
Tested air leakage is less than 7 ACH when tested with a blower door at a pressure of 50 pascals"
Maybe he lives in another state where they adopted the new code already.
He is almost right about the temperature settings. The required ACCA indoor design temperatures are 68 degrees for heating and 75 degrees for cooling - not 76. He is right about ACCA recommends to use the 99%-1% method however the Man J calculation needs to be converted to a Man S equipment selection method.
The units we talked about (and you were asking for) are modulating units with 30% oversize allowance based on ACCA Man S.
The reason why I design 70 degrees indoor instead of 68? Based on my 20 years of personal experience families with children keep indoor temperature around 69-70 degrees, older people (over age of 70) keep it even higher 70-72 degrees. This is depends of your personal comfort feeling. Is it screws up the calculation significantly? Absolutely not.
Outdoor design temperature. ACCA 99%-1% process recommends +8 degrees (not 7) for outdoor temperature design in Wilkes-Barre/Scranton area. I always pick +4 degrees. Why? Because in your case when you want to design a heating system with no auxiliary heat source you should get better coverage. You should know that most of the HVAC contractors in the area are using -5--10 degrees as a design temperature. Do I think they are crazy? Absolutely not. Do I agree with them? Sure not, but instead of telling them that they are not professionals I try to teach them and show them what they should do differently. They are the people who has to be responsible for all the emergency calls if the installed system doesn't perform as designed because of the outdoor temperature design. For example outdoor temperature was -15 degrees in certain areas in the Poconos last year. You should ask Dana how the outdoor compressor runs under these conditions? Again mini-split units has no auxiliary heat source, when the refrigerant cycle doesn't work it has no backup. When you design with new system like this, you have to consider with some safety factor.
The load factors on different size heads are something you should discuss with the engineering department of the brand. They will tell you what is your best option based on the room-by room loads.
--------------------------------------------------------------------------------
Please excuse the defensive tone I am somewhat responsible for there, didn't mean to necessarily pit everyone against each other, but just trying to make sense of all this. Does this clarify anything or are there still any glaring red lights? For what it's worth I have the original Right Suite Universal file if anyone wants to view that, I just don't have the software. Didn't realize that file contained other useful variables and info not shown in the PDF.
Wood sash double hungs. Maybe your suggestion isn't a bad way to go. I think the energy auditor that was here said storm windows weren't an option in my case, but I'll have to double check why. This year, we were just planning to tape plastic over them from the hardware store, and hope to replace them next year. But I'm def open to a better more inexpensive solution.
FWIW, I also have a friend who is an HVAC contractor, but I've been trying to avoid using him because like many contractors he has a certain way of doing things and I don't want to offend him or affect the relationship by disagreeing with him. But he has offered to get me equipment at cost under warranty and even offer some help with the install if I do the majority of it. But he doesn't really do Manual J, he's not up on building science, and I want to take full responsibility on the overall design plans, hence my questions and research. I'm not sure I'm up to the task, but it's an option. I may just end up hiring a contractor if I can find one that I actually trust for a reasonable price. Anyway the reason I mention it is that he seems to push the Fujitsu products as they are easier for him to get. But everything I've read otherwise suggests the Mitsubishi hyper heat units would be best for me, because they are nearly as good with heating, and way better with cooling.
I had eliminated any ducted designs from consideration on the basis that it would be impossible to extend ductwork between floors without an unacceptable amount of vertical soffit buildouts in one or more rooms. Plus with 6.5' ceilings in the basement, and me being 6', it would make a large part of the basement much less useable. The attic is also very small, and will get smaller after I figure out my insulation plans. If it's considerably more efficient and cheaper, it's certainly worthy of consideration, but I'm partial to FH09's if they can indeed work for my room sizes.
Is it possible to determine if FH09's would work in all my rooms? Also, going back to my initial question, if I used a single 8C48NAHZ outdoor unit, but ended up using say 6 FH09's and 2 GE06's, would it be a problem to have 66,000 BTU in indoor units attached to a 48,000 BTU outdoor unit?
Well I answered my own initial question with a little research. The SEZ-KD is a Mitsubishi unit, and compatible with the H2i outdoor units. If it will indeed perform better in my 2 smaller upstairs bedrooms, then I'll have to see if perhaps my daughters room and the spare bedroom upstairs could share one of these units. The MBR should be fine with an FH09 then. And perhaps the Dining Room and Office on the main floor could share an SEZ-KD as well. I can't yet visualize the installation and how it would work. You've mentioned the Fujitsu units a few times, Dana. How is the cooling? My understanding was that the Mitsubishi's greatly outshined them in the summer time.
The reason we decided to try and estimate my air infiltration after performing some planned spray foam work was because once the spray foam is in place, it will be impossible to run the linesets through the soffits into the attic to reach some of the rooms in the house the way that we planned on running them. So perhaps it's backwards but I can't figure a better way on doing it without then tearing out the spray foam and having to patch it again afterwards.
For what it's worth I'd been strongly leaning towards 6'5" open cell spray foam in my roof system creating an unvented roof. From the soffit up to the ridge. But the closets between my knee walls and attic area would be filled with 6'5" open cell injection foam. However I've read some articles on this site lately that highlight problems with wood sheathing rot above the open cell foam. Also 6.5" open cell would provide under R30, not even enough for my local energy company's rebate (R38 required).
I could instead do closed cell, I believe 6.5" would achieve just over R38. But I'm not aware of a closed cell injection product for above the closet (sloped drywall ceiling) between the knee wall and the attic. Plus I wouldn't be alerted to any issues with roof leaks as I would with open cell. Further my understanding is that over time, closed cell loses it's R-value and becomes close to open cell in R-value, as it loses it's gases.
Similarly we are planning to spray foam the basement and crawl space. 3" closed cell in the band joist and 2" closed cell on the block wall. However, I have decisions that need to be made down there first as well. I intended to create a separate post about that but I prob won't get around to it until tomorrow or Sunday.
Ryan, I am building and am hashing over spray foams and firmly wish to stay in the open cell category for environmental issues, AS WELL AS the fact that open cell is more flexible and responds better to shrinking, drying new lumber. Closed cell has no give and as framing members dry and shrink, air gaps may open. I spoke to someone who has been in the industry for 15 years and he said that here in the Albany, NY area he did not experience one failure with open cell foam in either roof decks or in walls. No OSB rot, moisture issues, nothing. His product is Icynene and he has varying density open cell products which Dana listed in a thread recently including MD-R210 which is a class two vapor barrier at a certain depth. I think they call it pro seal or something else now. I would urge you to stay with open cell products if you can, based on everything that I have researched both here and in the field. Also on basement walls, you are stuck with closed cell, however if you are not going to dry wall over and finish, then look for a rigid foam product that you can attach that has a foil or cover. I forget what that is called st the moment, but there are a few brands. As a side note to AJ Builder if he is reading this-Doug K. Is now at Advanced Spray Foam in Ballston Spa, no longer at Northeast.
Thanks for the input. In my case the house was built in 1968 so the lumber is all dried out and shrunk already. One contractor proposed 6'5" Lapolla 4G open cell up in the roof system. And 2" closed cell on the basement block wall, 3" in the band joist. We hadn't really explored rigid foam in the basement because a full sheet won't fit, I imagine it would be a hassle forming it tightly around the space. I suppose it's better for removal if necessary. I don't like that spray foam is permanent. I'm going to post another thread on insulation now so it doesn't take over from my questions on HVAC here.
Just because 3ACH/50 isn't a current code requriem in PA doesn't mean that the house isn't that tight, or can't/shouldn't be retrofitted to that level during the extensive insulation retrofitting and window tightening.
It's also simply not true that air infiltration is "...about 30% of the total load at any residential construction...", and even less true of houses that have undergone extensive retrofit air sealing & insulation.
It's also not true that Mitsubishi greatly outshines Fujitsu in cooling efficiency or capacity (or conversely). Some of the highest SEER mini-splits on the market today is the Fujitsu _ _ RLS3 series (the 3/4 tonner has an SEER of 33!) :
http://www.fujitsugeneral.com/PDF_06/9-12-15RLS3%20Sell%20Sheet.pdf
But the 9RLS3 only modulates down to 3100 BTU/hr in heating mode, whereas the FH09NA can idle along a 1700BTU/hr out, making it a much better choice in those low-load rooms. No matter what the HSPF test numbers say, if it's not modulating, it's not delivering modulating efficiency.
But on the mini-duct cassette end of the product line Fujitsu has the advantage on installation flexibility, capacity, efficiency and duct drive. (It wouldn't hurt my feelings if Mitsubishi updated the SEZ-KDs... :-) )
The Icynene MD-R-200 and MD-R-210 would both be greener and better products than most 2lb pours, and either would have an appropriate vapor permeance at 6.5" depth (The more vapor-open MD-R-200 would be preferable, and it's higher-R too. At 6.5" it's well into class-II vapor retardency.) But they don't come in pourable forms, only sprayed. Aloha Energy (a small time foam manufacturer out of Albany NY) has a water-blown 1.6 lb pour that would work though:
http://aloha-energy.com/injection-foan/
The problem there is finding a local installer for their products. Start here:
http://aloha-energy.com/spray-foam-installers/
I'm looking at the Icynene site and I don't see MD-R-200 or 210, only MD-C.200. ProSeal is also a closed cell foam. Which of their currently available products should I be looking at? I contacted Aloha for info on any local installers.