ICF Hybrid,
What brand of mini-splits do your friends have that have never needed a service call.  I have heard that the mean time between failure rates is best for Daikin.  That is the only company that will tell me their percentanges of failure.  In fact, they are quite proud of their rate.  Other companies that I have talked to treat this data as a trade secret.  I have also heard that LG costs less than other brands but will require more maintenance.  I have no way of knowing which brand is the best or which brand buys the most per dollar.

I am trying to learn more about mini-splits simply because some of my clients want them instead of a ducted system.

What brand of mini-splits do your friends have

I don't know. I don't pay much attention to brand. I'm pretty sure I remember some Mitsubishis and Fujitsus. And, I think one of the first ones was actually a Sanyo. I saw a number of the owners at a Pi Day party last night and had the opportunity to ask whether or not they had any maintenance issues. The answer was no. Everyone likes them regardless of brand.

Daikin is proud of their quality and they are proud of delivering more than their marketing claims. That comes out when you talk to the engineers much.

I think I said in another thread that I got a bunch of ductless mini quotes and they all came in within 10% of each other and that included the Daikin.

We work with another firm that does a lot of mini-split maintenance. It seems Mitsubishi and Fujitsu come in first and are quite reliable, but Daikin is new or unknown to most. We are thinking of one for the shop/office since some buildings require duct-work.

Posted By ICFHybrid on 14 Mar 2014 10:41 AM

Who the heck would want to clean 7000 sf of house?

Who wants to clean 1400 sf of house? ;-)

hheeeheee

Two questions: 1. Is it okay to have outdoor unit installed under a deck that's 6 feet high? 2. If the outdoor unit is installed 4 feet from a bedroom window, with the window shut is the noise barely audible?

Each manufacturer has published clearances for the installation of their outdoor units. You can look those up and go from there, but it seems pretty good as long as the deck is not enclosed and there is circulation. Protects it from snowfall, too.

Noise is very much dependent on the manufacturer, although they are all substantially "quiet". It would also be dependent on your window quality, too. With average windows and a unit on the noisier end of the scale, the noise could be an issue for someone like a student who has to study there. With better windows and a moderately quiet unit, you are probably okay with all but finicky room inhabitants. A certain amount of noise comes through the wall structure it is mounted on, so make sure you get sound isolating bushings for the mount.

I didn't like the wall mount because of vibration and resonance. If I place the unit on a pad, plastic is better than concrete in terms of the sound reflected right? Is there anything else I can do to minimize noise? I am not sure if the sound isolating bushings is applicable for pad mount.

Wall mounts are nice because your units are off the ground and away from precipitation and snowfall and animals. If I mounted the units on the ground, I'd put them up on some sort of a pedestal at the least, but it's true that isolating them from the house will reduce your noise concerns.

Isolation mounts aren't too costly, whatever installation you choose. Usually well worth it.

Posted By seiyafan on 17 Mar 2014 02:13 PM
I didn't like the wall mount because of vibration and resonance. If I place the unit on a pad, plastic is better than concrete in terms of the sound reflected right? Is there anything else I can do to minimize noise? I am not sure if the sound isolating bushings is applicable for pad mount.

What vibration & resonance?  What sound?

Mini-split units have VERY little of the vibe & sound compared to reciprocating air-conditioner compressor/fan units. Even no-name mini-splits are using scroll compressors these days, but "inverter drive" name brand units all use variable speed DC motors and scroll compressors. It's more of a "whoosh" than a vibe, but there will be some very-low frequency stuff from the fan blades to be damped using the rubbery bushings on the wall-racks.

On a pad mount you won't be able to hear the outdoor unit from indoors, even at full blast with the windows shut. Even standing next to outdoors it can be hard to hear in a 5 mph wind.  Standing next to it there may be a low audible 60hertz (powerline frequency) from the primary side of the inverter, but the rest of it is ghostly-quiet compared to what you may be used to with air-conditioners.

The better 3/4-1.25 ton outdoor units at full speed put out about 50-55 dbA at full speed (read the specs), which is about as loud as a typical home refrigerator.  The interior heads are a bit quieter than that. 

If having that level of noise outside your window is too bothersome to sleep you may need to move to Patagonia, live in a cave, and wear earplugs.

Thanks, I will use something like this (http://www.amazon.com/gp/product/B004HGEPB8/ref=s9_simh_gw_p469_d0_i1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=1P46C9VX7X7Y93DDRH9X&pf_rd_t=101&pf_rd_p=1688200382&pf_rd_i=507846) to go under the mount.

Vibration isn't an issue with the outdoor units .... the compressors already have damping isolators.

If you must, what you need to use is vibration mount grommets....

How do you secure the grommet to the pad? Super glue? screw through it?

If your using an mini split outdoor compressor, you have no option, you have to bolt it down to a pad of some sorts. I prefer a concrete pad as most do, with concrete wedge anchors.



I would recommend not using rubber pads. Reason being if they deteriorate prematurely, or unit is bumped hard it could jar the refrigerant lines and cause a leak.

The anchor bolt solution would be bad, since it traps the bottom pan of the unit to the pad where it can collect crud, wick moisture from the pad to the bottom of the unit and eventually rust it out from the bottom up.

Hard-bolting it to two blocks instead of a slab to provide more clearance below puts mechanical stress on the unit as one or the other block settles or frost-heaves.

If not bracket-mounted to the wall, a slab is really the right approach, but like anything else there are good/better/best approaches. Better pad installations would use leveling-foot anchors that also provide more clearance under the compressor unit:

http://goingductless.com/sites/default/files/resources/ContractorsGuide.pdf

And on a pad mount there's little point to going with the low-durometer bushings- there isn't enough vibe to matter.

Bracket mounting on walls under the protection of roof rake overhangs is really best practice in snowy areas.

All units I have ever seen come standard with stand off brackets to elevate the system off the pad.



If your in a heavy snow zone, of course you need to form a riser.

Right, what I meant was to place a vibration pad between the riser and slab to further reduce vibration noise.

Again there are no vibrations to be concerned about if you mount it on a concrete slab. I would NOT recommend using rubber grommets. Reason being if they deteriorate prematurely, or unit is bumped hard the unit might give depending on the rubber density, and jar the refrigerant lines causing a refrigerant leak. The odds of that happening is rather slim, but the grommets are not needed.

I came with an idea about getting cooler air from the master bedroom to the second bedroom. What if I cut a hole in the wall between these two rooms and put a fan to draw air in? Is there something like that I can implement with?

s there something like that I can implement with?

Sure. Google "through wall fan" or even "Thruwall fan" which is the name of one of them. The fan doesn't have to move much air. You might want to consider one of the superquiet and efficient bathroom exhaust fans. Some models mount on the wall and would be ideal for this. They might be more expensive up front, but you would get a quieter fan with a longer life and lower operating cost.

OK similar question. We are building a very tight, Well insulated home in Central Oregon, Zone 5. Wall r37, ceiling r-58, slab r-20. High perofrmance windows. Looking to use Hyper heat unit. HVAC guy is recommending placement of unit in red circle above door. We are planning a small circulation duct from the center of the building to the rear three areas. Do you agree with the placement or would you locate it more towards the center?