[mjhaston]

If you had an unfinished second floor that you were now going to finish. Would you run traditional ductwork or mini-split the entire house, upstairs and down?

 

[roughneck]

Depends on a lot of factors.
Do you have cooling now on the first floor?
What is the climate in your area?

 

[mjhaston]

I'm using window and wall units on the first floor. I'm near Philly. I think you're Delaware? So you know it can get soupy.

 

[roughneck]

In that case, either would work well.
Most important thing is it’s sized well. To deal with humidity.
Could even do a VRF heat pump for both floors.

 

[mjhaston]

I've got 3 estimates for mini-splits. 2 of them call for 1 outdoor condenser. Why would the other call for 2 outdoor units?


#1
Outdoor 1 (Right): 20,000 Btu Multi Zone Hyper Heat Pump Model: MXZ-2C20NAHZ
Indoor 1 (2nd Floor BR): 9,000 Btu Air Handler Model: MSZ-GL09NAU1

Indoor 2 (2nd Floor): 15,000 Btu Air Handler Model: MSZ-GL15NAU1
Outdoor 2 (Right): 18,000 Btu Single Zone Heat Pump Model: MUZ-GL18NA
Indoor 3 (Living Rm): 18,000 Btu Air Handler Model: MSZ-GL18NAU1


----------

#2
Condenser - Supply and install one (1) Mitsubishi® high efficiency MXZ suitcase style side
discharge outdoor condensing unit. The MXZ-3C30NAHZ outdoor unit uses Inverter Technology (Variable Frequency Drive) to provide exceptional indoor cooling and heating comfort. By responding to indoor temperature changes, this system reduces power consumption by varying the compressor speed for extra energy savings. The system performs only to the levels needed to maintain a constant and comfortable indoor environment. To be installed on a stand at the back of home.


----------

#3
Install Bryant Heat Pump 3 indoor wall mount unit with 1 outdoor. 2 up stairs in the
attic space( 12,000 btu, 24,000btu). 1 down stairs on the main floor (24,000btu).


Indoor Units - Supply and install two (2) Mitsubishi® high wall mount indoor evaporator units.
One MSZ-FH12NA to be installed in the living room, and one (1) MSZ-FH18NA to be installed in
the 2nd floor back living room. Computerized control removes excess moisture without lowering
the temperature, providing healthier, more comfortable air conditioning with greater economy.

 

[user_12345a]

If ductwork can only be run in the attic and you don't want to insulate the roof deck, go mini-split. it's worth it just to reduce efficiency loss.

Do keep in mind mini-splits are loaded with proprietary electronic components and maintenance costs can be very high out of warranty.

If a circuit board goes bad when the unit is 12+ years old and costs $1000, it can make more sense to just replace.

Wheres a gas furnace has relatively cheap parts unless you buy a high end unit.

This is also applicable to inverter central heatpumps - but if you don't have natural gas available and want to heat with a heatpump, having proprietary expensive components can be worth it to get full heating capacity down at low outdoor temps and avoid using aux heat.

 

[Old Thomas]

I like mini-splits but I have a ducted system because it is quieter.

 

[mjhaston]

I'm tearing off the old siding and sheathing of my exterior. I can have the walls open to the studs. Could mini-split drains and whatever else be run inside the walls so I don't have those large covers all over the outside of the house?

 

[roughneck]

Yes they can.
Just avoid joints on refrigeration piping within the wall if possible.

 

[user_12345a]

the lines will have to be well protected from screws/nails.

 

[mjhaston]

Yes they can.
Just avoid joints on refrigeration piping within the wall if possible.

So are you saying the drain can go in the wall, but not the refrigeration line? Does that go to the outside unit? I'm hoping all could be hidden, but if not I guess it's ok. I'm just using some nice Hardie Plank siding and would like to keep it pretty clean looking.

 

[mjhaston]

Everyday I seem to go back and forth with ducts vs ductless. If I go the duct route I'm looking at $10k and $3k for additional baseboard heat tied into the existing. I just got a quote of $14k for Mitsubishi all around. 6 indoor (2 of them hyper heat) and then 3 outside units.

I'm told I could run all the mini splits for heat as well and save on my oil, until it gets below 35 and then only my hypers will work. That's a plus.

Some have suggested a duct system is cheaper to maintain down the road.

I have to make up my mind soon!

 

[roughneck]

Refrigerant lines can go in the wall.

 

[mjhaston]

Refrigerant lines can go in the wall.

I misread your post. Thanks.

 

[roughneck]

What user was saying was make sure the utilities going on the wall are protected from nails and fasteners.
Trying to find a refrigerant leak in a wall caused by an errant nail is extremely difficult. And time consuming.
It’s also a fairly common problem.

 

[user_12345a]

I'm told I could run all the mini splits for heat as well and save on my oil, until it gets below 35 and then only my hypers will work. That's a plus.

Depends on how they're sized - when the units are inverter they can be sized more for heating.

All heatpumps sold now can heat well below 35, it's a question of capacity.

Cold climate mini-split models can maintain full capacity down to 0F and below. But wise to still install electric or hydronic baseboards just in case you have breakdowns.



Going heatpump instead of a/c when you have oil is a no-brainer unless you pay like 20+ cents per kwh.

If you get a ducted forced air, you can get a conventional non-cold climate heatpump which looses capacity at it gets colder and have a hydronic coil fed by the oil boiler for aux/supplemental heat.

 

[mjhaston]

What user was saying was make sure the utilities going on the wall are protected from nails and fasteners.
Trying to find a refrigerant leak in a wall caused by an errant nail is extremely difficult. And time consuming.
It’s also a fairly common problem.

Will do. I'll be hanging the sheetrock and the siding, so I'll steer clear.

 

[mjhaston]

A final question on this subject. A friend works for a large HVAC company that does a lot of commercial work. He can get me great prices on the mini split equipment. He can't do the work though. How open do you think an HVAC contractor would be to just getting the labor? All the equipment would come from a certified Mitsubishi dealer.

I think I know the answer!

 

[roughneck]

A lot of contractors will not do it. They don’t want the headache.
Many times the ones that will do the work are the ones you don’t want.
Doing an install that way, you may get no warranty. And you’ll likely get no labor warranty.
Having a contractor that’s 100% knowledgeable on the product is mandatory.
A quick story-
Apartment complex hires a company to install Samsung VRF (big brother to minisplit). Contractor has lots of problems because they don’t know the product. Install done but units still have lots of problems. Contractor has no idea how to fix the issues. Basically stops answering the phone. Apartment goes 1 year trying to find someone to fix the problems. They find our number, I find and fix lots and lots of various problems. Cost the apartment about $25,000 to get everything running as it should. Apartment very happy because the systems are now running as they should. I now have a customer for life that trusts my advice and they have even started calling me directly.
Moral of the story-Minisplit technology is very advanced and very proprietary. If the install/service company doesn’t have the tools or knowledge on the product, the outcome likely isn’t going to be good.

 

[DIYOkie]

I have my own story on mini splits and contractors that don't know the technology. I blew a couple hundred bucks on an idiot that didn't know mini splits. Never again.