[JohnDS1]

Hey guys, I have a 1 bedroom basement apartment(about 500sqft) that has the option for a 2nd bedroom(additional 144sqft).

I'm planning to get:
- MXZ-2C20NAHZ2 condenser
- 9k btu unit for the 1 bedroom
- 12k btu unit for the living room
(If the apartment is rented as a 2 bed, I believe with both these running, it would be fine to cool and heat the extra bedroom, especially being a basement and well insulated)

My question refers to the seer rating for the different style residential indoor units. According to Mitsubishi's website, the seer rating is highest for the wall mounted unit, next is the floor mounted unit, then the lowest seer is the ez fit ceiling cassette.

Unfortunately, I dont like how the wall mounted units look so I plan to go with 2 of the next highest seer units, which would be the floor mounted units(9k and 12k). However, being that the living room is pretty far from where the condensate drain would terminate, I wont have the height for the pitch by the time it gets there. I'm not looking to add a condensate pump because I dont need or want another maintenance item, so I may go with an ez fit ceiling cassette for the living room instead.

That being said, ideally, I like the ez fit ceiling cassettes the best and wish I could do both rooms with these because I can just simply run the condensate out at ground level, but I'm worried that these units being the lowest of the seer rating, would make that much of a difference in energy costs in comparison to the floor units.

What do you guys think? Would it make a huge difference in running cost or would this be something not so noticeable? I just dont want to hurt the tenant since they'd be paying their own electric bill.

Thanks for the help.

I believe Mitsubishi lists the units as follows:

Wall mounted:
Capacities: 6,000 to 18,000 BTU/H
Sound: as low as 20 dB(A)
SEER: up to 33.1
HSPF: up to 13.5
COP: up to 4.68
ENERGY STAR®: Yes

Floor mounted:
Capacities: 9,000 to 18,000 BTU/H
Sound: as low as 21 dB(A)
SEER: up to 28.2
HSPF: up to 13.0
COP: up to 4.3
ENERGY STAR®: Yes

Ez fit ceiling mounted:
Capacities: 6,000 to 18,000 BTU/H (top image 06, bottom image 9/12/18)
(6,000 model is mulit-zone only)
Sound: as low as 21 dB(A)
SEER: up to 22.3
HSPF: up to 13.3
COP: up to 4.1
ENERGY STAR®: Yes

 

[BALloyd]

Who sized this equipment?? Likely massively oversized and you are going to have massive overheating problems in the winter set up like that.

 

[JohnDS1]

Who sized this equipment?? Likely massively oversized and you are going to have massive overheating problems in the winter set up like that.

Thank you for the reply. I understand you believe what's listed is oversized.

1) Can you be more specific as to what you mean when you say "set up like that". Are you referring to btu size, having 2 indoor units in general, or the type of indoor units?

2) What will have massive overheating problems in winter? Are you referring to the system overheating the rooms or are you talking about overheating the units/condenser?

 

[pecmsg]

A 6000 BTU/h wall unit will take care of a large room. Yes they can ramp down but humidity removal suffers. I’d rather see a properly sized duct system than multiple indoor with one outdoor unit.

 

[JohnDS1]

A 6000 BTU/h wall unit will take care of a large room. Yes they can ramp down but humidity removal suffers. I’d rather see a properly sized duct system than multiple indoor with one outdoor unit.

Thank you. Unfortunately, ductwork is not an option in this case. This is a basement one bed apartment with kitchen, living room, bath, and laundry room. Approx 500sqft. The 2nd bed would make it 644sqft, but the 2nd bed probably wont be happening any time soon if at all.

From what I'm gathering is that multiple units will be fighting with eachother if doors are left open. Maybe I should continue to get the 2 zone condenser, and just do one 12k btu indoor unit for the whole place?

 

[FlyersFan]

Are you sizing these indoor units for cooling or heating? If you're sizing for heating you're going to be battling basement humidity all summer long and will likely need a dehumidifier to keep the space comfortable. 21K BTU sounds like a lot for 644 square feet, let alone 500 square feet without the second BR, unless we're talking terrible building construction.

Has anyone done any kind of load calculation to see what the heating and cooling requirements are going to be?

Also check out this app note from Mitsubishi on using multizone equipment and how important proper sizing is. If it's not done right it's going to be an expensive learning experience.

 

[JohnDS1]

Are you sizing these indoor units for cooling or heating? If you're sizing for heating you're going to be battling basement humidity all summer long and will likely need a dehumidifier to keep the space comfortable. 21K BTU sounds like a lot for 644 square feet, let alone 500 square feet without the second BR, unless we're talking terrible building construction.

Has anyone done any kind of load calculation to see what the heating and cooling requirements are going to be?

Also check out this app note from Mitsubishi on using multizone equipment and how important proper sizing is. If it's not done right it's going to be an expensive learning experience.

Well cooling is priority. I actually have a hydronic heating loop ran as a backup. The heat pump side of these mini split units was an added bonus and simplifies things, so I wouldnt have to use my boiler to heat the apartment.

A load calculation? Not professionally. I was looking to install myself and did not want to waste anyones time. I'm not sure how many HVAC contractors would be willing to just come by for a load calculation, let alone care enough if its accurate or not, if they know they are not doing the work.

I agree. The btus do sound high.

As for the humidity, the concrete walls behind 3 sides of the apartment's 2x4 walls will be spray foamed with closed cell foam. This apartment is half my basement, so the adjoining wall in the middle is just a double 2x4 wall spaced 3½" apart with 3 layers of rockwool safe and sound inside. I dont see an option to post the drawings for the apartment.

I'll check that out the link. Thanks.

 

[BALloyd]

Well cooling is priority. I actually have a hydronic heating loop ran as a backup. The heat pump side of these mini split units was an added bonus and simplifies things, so I wouldnt have to use my boiler to heat the apartment.

A load calculation? Not professionally. I was looking to install myself and did not want to waste anyones time. I'm not sure how many HVAC contractors would be willing to just come by for a load calculation, let alone care enough if its accurate or not, if they know they are not doing the work.

I agree. The btus do sound high.

As for the humidity, the concrete walls behind 3 sides of the apartment's 2x4 walls will be spray foamed with closed cell foam. This apartment is half my basement, so the adjoining wall in the middle is just a double 2x4 wall spaced 3½" apart with 3 layers of rockwool safe and sound inside. I dont see an option to post the drawings for the apartment.

I'll check that out the link. Thanks.

So you know you will get zero warranty installing Mitsubishi equipment yourself right? You cannot even register it unless you are a contractor. Where are you going to get the equipment? At one point there was some counterfeit Mitsubishi units being sold.

 

[JohnDS1]

So you know you will get zero warranty installing Mitsubishi equipment yourself right? You cannot even register it unless you are a contractor. Where are you going to get the equipment? At one point there was some counterfeit Mitsubishi units being sold.

I was looking to get from Ferguson or some other HVAC supply house. Whats weird is, I can find the indoor units when I search on Ferguson, but the condenser is showing as "discontinued". I called Mitsubishi and asked if they discontinued it and they said no. They said they are seeing in their system that its just out of stock.

I did not know that about the warranty. It's probably worth me taking my chances on something eventually breaking and paying for repairs rather that getting hosed by someone to install. We do install these at work all the time and I have all the equipment. In fact, I have my EPA license. The thing is, I dont usually size them at work. The so-called engineer does this, but he doesnt do a manual-j or anything fancy. Where I work, it's just city buildings where they dont care if they estimate wrong, otherwise I would ask him to size this equipment.

Anyway, I am in the process of having a company size it. Hopefully it goes well.

 

[kdean1]

We do not provide assistance to homeowners for DIY. Since you have some certifications you can apply for pro membership. Thread closed.