Owner Building installing Mini Splits in New Construction, Help Please.

[MaryS]

Originally Posted by AC_Hacker

As you plan your system, also consider your axillary heating sources. I'm not sure what axillary sources you have available to you, so that must influence your thinking.
-AC_Hacker

ACHacker,
Regarding the need for backup heat - I would like to discuss this further. Our site has no access to natural gas, but your posted direct vent heater looks interesting for those that do have natural gas.

I'm not trying to be argumentative or anything, I just want to better understand your position. You're not the only person that has mentioned this to me, although the others were local HVAC contractors who were also trying to talk me out of the mini splits ... so it was harder to evaluate their comments minus a potential bias. But you're a mini split advocate AND also mentioning aux backup heat - so you have my attention.

I was thinking two things in terms of aux heat:

- In the short term, like our first two winters in the ho
use, if we're chilly 'cause the mini(s) aren't keeping up with the load then we'll have limited use of electric heat from some cheap (to buy, not to operate) electric blower/heater that you set on the floor. I'm thinking this would be in the bathrooms only and used for only a brief time, say a 45 min/day. If we're chilly at night, heated blanket should help. And during the day, thermal undies and layers, keep moving or while sitting down to do work, use a throw blanket.

- I have a keen interest in DIY solar and have planned to design/build a solar HW system aka BuildItSolar; large home made tank in basement for storage, ground mount panels (we have lots of space). I would like to use this for HW and try to design it for enough heat capacity/storage to supplement in the bathrooms and possibly the office. The success (or not) of this system of course remains to be seen and I've not done any real design work yet. Gotta finish the house first, right?

If the electric goes out, that would be a problem. Neither of my options above would provide heat in that situation (even the solar needs pumps, unless I could use solar operate pumps, which remains to be seen). To tell you the truth, I didn't consider total loss of electric service much of an issue as I've really never had an outage that lasted more than a few hours (in all my adult life) and even those are very rare. But then Oct 29 this year and the mess they had up in CT with longer term winter outages. That incident did make me take notice. Hmm, what would I do in that situation? It's possible ... and maybe I should plan something for that. We have the ability to add a generator to our electric panel, and manually select the house loads we want to run. We don't own a generator yet, no plans on the near horizon to get one either - it's pretty far down on the list right now.

In our initial design I had thought about a wood burning stove, and I was temporarily in love with the idea of it - even looked at those ones you can bake bread in. Nice! But in the end I cut it out due to cost and somewhat to IAQ, espeically since I was going for a very tight house. Also we have very limited trees and would need to buy wood.

ACHacker, from your POV on the need for aux heat, are you saying:
- aux heat is needed for possible extreme cold snaps where the mini splits can't keep up or even shut down
- aux heat is needed for potential longer term power outages during cold weather (in which case any electric based system would be out)

Given that I don't have access to NG, any other ideas/thoughts/comments? I appreciate your willingness to discuss these issues - as I sometimes feel 'out on the limb' with no one local doing what I am and contractors/builders scoffing at the very idea of min splits. It's good to be able to get some input from those who've been there, done that.

Thanks
Mary

PS Thanks to everyone for their input, it is very valuable. I have some other follow-up questions on the posts above, but I'm running very late and should already be that site working ... so it'll have to wait 'till later.

[AC_Hacker]

Originally Posted by MaryS

ACHacker, from your POV on the need for aux heat, are you saying:
- aux heat is needed for possible extreme cold snaps where the mini splits can't keep up or even shut down
- aux heat is needed for potential longer term power outages during cold weather (in which case any electric based system would be out)

[* Actually I am very influenced by the Passive House concept and methodology, so my true bias is for the most energy efficient, least environmentally damaging solution to house comfort that is available. The best solution I see is to radically minimize infiltration (.35 to .5 ACH), to utilize a very high-efficiency (> 85%) HRV or ERV best coupled with earth tempered air-intake, to optimize proper solar orientation and solar gain, to radically maximize insulation and fenestration, and then, lastly to consider the heating option... if it is even required. My personal preference for heating efficiency is a ground source heat pump combined with radiant floor heating. I have come to realize that if the house is properly built, an expensive GSHP and radiant floor, as efficient as they are, may not be needed at all. I am upgrading a house that was built in the 1880's, so I'll never reach the insulation/infiltration goals I am shooting for, and I am building my own very small GSHP to meet my anticipated insulation/infiltration levels. I purchased a small (9k) mini-split to get me by while the GSHP evolves, and I have been amazed at how well it works... I have also come to realize that with the nature of the climate here (Portland, Oregon), that there are significant periods in the winter when an ASHP would actually out-perform a GSHP. (my thread, Home Made Heat Pump Manifesto tells the whole story in all it's agonizing detail.*]

You have implied that your house will be well insulated, and rather tight... However tight and well-insulated it is, Manual-J will indicate the heating required to maintain a comfortable temperature level for you.

I think that one of the reasons that the heating contractors shy away from mini-splits is that there is less profit to be made from them, since there is no ducting work, not hydronic layout & integration, no integrated inside climate control system to install.

You seem to be worried that the mini-splits may not be able to pull the grade, and keep you warm, but if your Manual-J was done correctly, you should have no worry... in fact, evolving heat pump technology is being applied to mini-splits before it creeps into (if ever) whole house heating... so your mini-split should operate more efficiently, and at lower temperature that it's whole house counterpart.

Originally Posted by MaryS

Given that I don't have access to NG, any other ideas/thoughts/comments?

Well, the direct-vent unit I linked to before has a propane adapter kit available. Also, there are pellet stove options available... The problem might be finding one that is small enough and is able to run off of battery. Wood stoves... hmmm. If you could find a good used axillary source, much the better, since it will be used so seldom... save the money and take a trip to Brazil in the winter.

Regarding the reasoning behind axillary heat, there are heat pump considerations, and infrastructure considerations.

Heat pumps run most efficiently at or near maximum output. Additionally there is a period during startup when the heat pump is 'warming up' for lack of a better word, when it is not operating optimally. I have watched and measured this on units I have built. Inverter heat pumps can throttle themselves down, and avoid on/off cycling, so they are better than single-speed units. But still, the best efficiency is had with the unit running at or near full capacity, that is why it is better to choose a unit that is slightly smaller than required, and fill in the minor (2%) days when the mini-split falls short.

Then there is the infrastructure part. I'm glad that you have never experienced a serious power outage, I can tell you that it is distressing if you are not prepared, and can be fun if you are prepared... an experience comes to mind, about 30 years ago, when we were hit by a 5 degree F sustained 'blue norther' that was accompanied by a two day power outage. We experienced several burst water pipes, and saw every plant in the house die... But just down the street a few houses from me were some old-timers who had food and fuel set aside for such times, and they had their friends over for a very enjoyable week in the cellar, getting caught up and reminiscing about old times, while my young family and I suffered... Experiences like that imprint pretty vividly in you memory.

Also to consider about infrastructure, is that the US is not maintaining and upgrading infrastructure like it used to, so power outages are likely to become more common in the future.

Another approach I am taking is that I don't think it is vital to heat my whole house all the time, since I came across this very interesting quote:

...an incredible amount of wood is really squandered in this country for fuel, day and night, all winter, for nearly half a year in all rooms, a fire is kept going.
-letter from a European visitor to America in the late 1600s

So I heat the room I am usually in all day, the living room... and my mini-split drops that down to 60F at night. The other rooms I don't heat at all unless I'm going to be there working for a while, and I have noticed that heat from the living room 'leaks' into the other rooms, and since they are well insulated, the heat takes its sweet time before it finally goes back to the sky.

Best,

-AC_Hacker

[S-F]

I know a fellow who has been installing those Mitsu's for a year or so and he's sold. He says that even in the New England mountains they always put out good heat in the winter compared to every other brand.

[MaryS]

Originally Posted by Xringer

I would not use wall mounted outdoor units, put them on a ground pad.
It might be okay to use wall brackets, if the wall was remote from
the active areas of the home. Like the far side of a garage.
Wall mounts have appeal for those of us living in snowy areas.
They are very common in upper floor installs in Europe.

Hi Xringer, thanks for detailing how you've used your mini splits, very interesting. Question for you, on your comment above - What do you see as the problem with wall (or sometimes even wall bracket) mounts? Is it noise in the interior, vibration? Other?

Actually I planned a spot on the far side of the garage for two mini splits (back when I was thinking of multiple indoor heads for one of the units). It will be tight for three outdoor units, but I think I can still make it work. Since it is on the north side I was thinking of putting the units on wall brackets to get them up at least 2' - just to give allowance for snow. I'll also definately need to build a wind break fence - a strong one. I have plans for an evergreen tree wind break, but that's gonna take some time. Can't rush Mother Nature.

Another idea is to install some sturdy fence posts with a few cross pieces of lumber and mount the units to those, totally removed from the structural framing, a foot or so from the garage wall. I kind of like that idea, but since the soil was recently distrurbed (ie backfilled this past August), I'm doubtful about setting a fence post in that backfilled ground.

Thanks for your time,
Mary

[Xringer]

IDU:
The indoor unit has a small motor, and the noise it does make is mostly
low amplitude and low frequency. Since the blower is moving (and filtering)
air there is a soft hissing White-Noise type sound. Like a nice breeze sound.

It's hard to hear that white-noise, if you are more than 10-15 feet from the IDU.
In our house, the refrigerator noise covers up any sound made by the Sanyos.
Since we've been running the Sanyos, we've found out how loud,
and irritating the refrigerator and dishwasher noise is..

The IDU blower runs at H, M, L and super slow. On this model, it's not
continuously variable.

OUD:
But, the ODU motors are continuously variable. That means they need
a lot of internal anti-vibration dampers built in.
Both the compressor and the big fan can run at variable random speeds.

This means the ODU can find the resonate frequency of objects it's in contact with.
So, a wall mounted unit can conduct a low frequency 'hum' vibration into the structure of your house.
If the conducted sound hits the resonate frequency of your wall etc,
it can get pretty loud, during that time.

I knew about this induction, but I still wanted a small rain/snow shield on Sanyo #2.
This temporary coroplas roof works pretty well (after some mods),
but it can induce a good bit of low freq vibration into the bathroom wall.
(It's a bit like having the refrigerator in the bathroom with me).
So, I can imagine what it would sound like, if it was a wall mounted unit..


Because of the low duty cycle of Sanyo #2, I rarely hear the ODU rumble.
Plus, it has to be running at high speed, which is not often.
It's a bit like the rumble of jets going into the nearby airport..

My guess is a wall mount back there would be very similar to
the sound/vibes you get from a 6,000 BTU window AC, (Wallshaker).

I do like your idea of building a stand-alone Frame to hold the ODUs.
When I built the little 'H' frame for Sanyo #2, I considered putting some legs on it.

I think building a 4x8 foot 'Table' mount would work for two ODUs.
Kinda like this old deck, that I use for solar stuff.
http://i46.photobucket.com/albums/f1...arrayhoist.jpg
If you built a 4'x8' deck and put in 4"x4" cross sections for the ODU's 'feet'
to rest on (lag-bolted).
And left the flooring out, so snow wouldn't build up.. Sounds alright...

Overall, the sound from the ODU will not be noticeable by your neighbors.
They makes very little noise when compared to regular central air compressors.

[RKA]

Mary, if it's any help, I can post feedback (I hope) later this week on my wall mounted Fujitsu. It's mounted to concrete block at the base of my garage. We're getting close to turning it on thanks to the help of the guys in this thread and my friendly neighbor.

BTW, Fujitsu will not honor any warranty on a homeowner installed unit OR any unit purchased over the internet. I chose it for it's efficiency and reliability, and the savings going DIY more than made up for any lack of warranty.

[Xringer]

If buying a Fujitsu from a web vendor, it might be a good idea to make sure
they will accept returns on anything damaged by UPS..

It would be pretty rotten, if you got a DOA unit and couldn't return it.

[MaryS]

ACHacker, thanks for the thoughtful discussion on aux heating sources and the reasons behind them. I will continue to think on this topic for what we want to do in our home.

XRinger, thanks for the ideas on how to mount the ODU. We decided to go with your "table" idea. I'll post photos when we get to that point. Also, I gave the link of your install thread to my Hubby so he can look over it for background.

RKA, good luck with your system! I hear you on the warranty vs DIY and we'll see how the details of our install shake out. I know that my husband is skilled and very fussy with stuff like this - as opposed to hanging a picture on the wall, which he claims has no functional requirements :-) LOL.

I made our first purchase, a MSZFE-09NA Heat Pump (the hyper heat one). I didn't get any of the accessories on-line because Hubby thought we could do better (price wise) locally and also we wanted to review the complete documentation and see it before we bought the other items.

We will need three units for the entire house, so we are starting with this one unit to see how it goes. I understand the Fujitsu has a better (heating) operation efficency with an HSPF of 12 compared to the 10 of the Mistu I ordered. However the Mitsu will produce more heat at lower outside temperatures, if I understand correctly. And if I don't, well - it is already ordered so no going back now. It might not be the decision someone else would have made, but I think it is a resonable choice, and WAY more efficent than a typical whole house heat pump (which I've lived with for some 20 yrs), and way less cost than a contractor installed GSHP.

So, let the adventure begin.

THANKS TO EVERYONE for your time and help!!

[Xringer]

Sounds like you are on the right track there!

But, before you go.. There is a pretty neat way to wall mount.. Check it out..
Just came in this morning!

http://ecorenovator.org/forum/geothe...roject-46.html

[AC_Hacker]

Originally Posted by Xringer

There is a pretty neat way to wall mount.. Check it out.. Just came in this morning!

Yeah, it does look good...

A friend of mine recently did a wall mount of a LG mini-split, and the local Oregon code inspector made him increase the distance between the unit & the wall. They said that even though he had hit the manufacturer's minimum spec on that distance, it was still not enough for optimum functioning of the ODU.

I would consider the inspector's objection to be a wise decision, and would advise DIY folks to consider the manufacturer's minimum distance to be insufficient.

-AC_Hacker

P.S.: Regarding my friend's wall mount, he said that the compressor and fan noise is being conducted through the framing, and into the house, which is otherwise VERY quite, due to 6" dense pack in the walls and 2" XPS wrap. I see that the Fujitsu mini-split you are referring to, is bolted to the foundation, which is much better than the wall... But I think a separate pad (or other structure) would be better yet.

* * *