Wall-mounted ductless minisplit vs concealed duct minisplit
Hi GBA group,
Were finalizing our plans for the HVAC and everyone has been helpful. We are now deciding on 2 options and wanted to get all opinions on each.
Option 1: 1 Bedroom/1 Bath Apt Minisplits are widely used in the NYC area and was planning on have a TWO 1 to 1 units wall mounted.
https://www.ecomfort.com/Mitsubishi-MZ-FH06NAH/p79443.html
We would be using 1 in the living room and 1 in the bedroom. They have a low min btu for both heating and cooling so I’d imagine they wouldnt shortcycle.
Cost: $3192.00 for 2 units no need for ducting and will need to connect about 40-50 feet to reach their outdoor units in the roof.
Option 2: Instead of using 2 wall mounted minisplits, we would go for a single zone concealed duct mini split 9K
https://www.ecomfort.com/Mitsubishi-SE-KD09NA.TH/p96641.html
The indoor unit would probably stand inside the ceiling at the entrance of the apartment and then run less than 10 feet of ducting to the living room and less than 10 feet of ducting to the bedroom. This would only be single zone. They would definitely look nicer in my opinion as they feed to a linear slot diffuser for a modern look.
Cost: $2102.00 plus whatever duct word needed to install, cost of linear slot diffusers, plenums, etc.
Comparing them and from the advice, people say:
1) The concealed duct is less maintenance
2) The wall mount offers 2 separate zones of temperature control
3) Cost wise not sure how much the extra cost for the ducting, labor, plenums, and linear slot diffusers but Id imagine it would be more than $1000.00 more which would make it more expensive to begin with than the 2 separate wall mount units.
4) For the Concealed duct, I am only working with 1 outdoor condenser so I save more room on the roof compared to the separate zones which would take up 2 outdoor condensers
5) I have only met with a few installers and GC that are 100% familiar with the wall mounted units but they havent really installed the concealed duct units but they said if its anything like a central air system, shouldnt be problem either.
We are looking for the best optimal solution as this is for luxury rental building so we are looking for reliability, longevity, least maintenance as I will be maintaining the building myself, price difference of 1-2k wont matter to me if the other aspects are a lot greater but a 5k+ difference for at least 7 units will make me start to consider.
Question:
Is it necessary to have them installed by their respective company Mitsubishi in this case their certified “diamond installers” to get the extended 12 year warranties?
-Cody
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
"Is it necessary to have them installed by their respective company Mitsubishi in this case their certified “diamond installers” to get the extended 12 year warranties"
The ecomfort website caters to mostly diy types that are buying and iself installing units knowing they get no warranty. If you want a Mitsubishi installed with the full warranty you will need to have a local authorized Mitsubishi dealer install it. Pretty much no hvac company is going to want to install a unit you bought online. Not worth the risk and they lose alot of money by not selling you a unit they markup.
I would guess your looking at 3 or 4x the price compared to buying one on ecomfort to have one professionally installed in the NYC area.
I prefer ductless units, and you’re going to have a more efficient system using two independent units which can better modulate. That being said, unless your bedroom is enormous, you’re going to be oversized when using even the smallest available 6k head unit. Leaving doors open a lot might help, or incorporating “through-wall” type units to better disperse air and help the units work in tandem. Otherwise that bedroom unit is going to short cycle and you’ll be stuck with higher utility bills, a unit with a shortened life span, and a clammy bedroom in July.
Edit: as far as e-comfort, that’s only going to be a better option if you self install or have access to a handy man type that is especially familiar with mini-split units. Not just any old handy man that’s put in regular split systems. If he/she just throws a vac on the line set for 30 minutes and calls it good, you’re going to have problems. IMHO, they can be diy, but you’ll need to be extremely thorough and well read before attempting. Not a casual project for someone who’s only wired in light switches and done some shiplap.
You can also look into having two heads on one condenser - I dont think you need two condensers for this.
2 heads on one unit, multi split, cause the minimum modulation level to be double what a 1 to 1 unit is. So the bedroom unit would never modulate low enough and would short cycle. I like the Fujitsu 9RLFCD ducted mini split at around $1900. Or LG makes a ductless that modulates down to 1000 Btus, and might work in the bedroom
Thanks for you input everyone. Some things I am still confused on:
1) Is it worth it to get a diamond contractor to get the longer warranty of like 10+ years or is that some BS that is just to bump up the installation price.
2) Eric: My main concern was the short cycling I was researching extensively on here and other forums. By having 2 separate condensers and being able to modulate down to about 1900 BTU for the mitsubishi, we basically eliminate any short cycling for each room or down to 3000 BTU for the single concealed duct mini split that would feed into both rooms and only have 1 zone.
3) David: I saw the LG ductless that modulates down to 1000: I think there were 2:
A) https://www.ecomfort.com/LG-LA090HYV1/p56906.html
B) https://www.ecomfort.com/LG-LS090HSV5/p81403.html
I think the art cool premier is a better option even though 76 dollars more, I get the LGRED option to work below -14 degress AND it has a higher seer rating at 27.5 compared to 23.5 which I am not sure if it is big deal.
in my experience, labor is extremely expensive and the upcharges on these units is several times the material costs you are looking at on ecomfort. If you are looking for the most cost effective solution, you might look into a mr cool DIY unit and install it yourself. Otherwise, the only way to know the cost difference between the ductless and ducted unit is to get direct quotes. I did, and they were dramatic. Then it's just a matter of deciding if the ducted unit is worth the cost difference. How much is the warranty worth? You can probably quantify the value based on the failure rate. The mistubishi ductless units seem to be pretty reliable, so the warranty probably isn't worth that much.
The only thing that makes Mr. Cool DIY are the sealed and pre-charged line sets right? Depending on your states laws, it’s not overly difficult evacuate and charge a mini split. Don’t overestimate your skills, but if you’re a builder of any kind, you can likely figure out how to do so.
I have no experience with charging lines, but after watching youtube videos of people doing it and messing it up, the possibility of decreasing efficiency, and environmental risks of releasing refrigerant, I personally came to the conclusion my time was better spent elsewhere and just use the plug and play diy kit.
Fair enough! Props for making an honest personal assessment. By no means am I advocating anyone take on a project they’re uncomfortable with.