MRCOOL Ceiling Cassette

[Zwy]

Have a link to the ducted unit you bought?
It does seem like a good solution to a structure that already has ducting.

Although Ductwork definitely has loss and can have leaks. Especially old sheet metal ductwork.

It is more than that. From this page.

"It also should be noted that reviewing SEER and COP ratings for both unitary central and ductless HVAC systems isn’t necessarily an apples-to-apples comparison. With centralized air-conditioning systems, the air handlers are tested without ductwork attached. When installed in a home, the SEER and COP ratings are negatively impacted by the added ductwork, up to a 35% reduction in performance. Since ductless units are installed within the zone they serve, their performance is 100% reflective of their SEER and COP rating."

Conditioning zones is always more efficient than non zoned.

I’ve never seen a copper line carring anything fail anywhere other than the connectors unless it was impacted or crushed by something, or corrosion is present.
That goes for fuel lines, water, and refrigerant.

I work on refrigerant systems. For copper lines, what you stated is true.

 

[Rocksnsalt]

It is more than that. From this page.

"It also should be noted that reviewing SEER and COP ratings for both unitary central and ductless HVAC systems isn’t necessarily an apples-to-apples comparison. With centralized air-conditioning systems, the air handlers are tested without ductwork attached. When installed in a home, the SEER and COP ratings are negatively impacted by the added ductwork, up to a 35% reduction in performance. Since ductless units are installed within the zone they serve, their performance is 100% reflective of their SEER and COP rating."

Conditioning zones is always more efficient than non zoned.


I work on refrigerant systems. For copper lines, what you stated is true.

100% agree re zone conditioning and duct loss.
Since our upstairs is only used for sleepy time, I see no need to heat or cool it until shortly before that time occurs.

That said, since ducting is already in place, it’s tempting to use a ducted unit vs the placing the obtrusive air handlers, running lines and power etc for multiple mini splits.
A tradeoff to be considered, and in my case using 2 units would make sense, though would require modifying upstairs/downstairs ductwork which would take some doing and extra cost. Otherwise it’s 6 units or air handlers which is getting nutty, and there would be location issues.

 

[Zwy]

More from Carrier:

Mini split efficiency: Pros​

• Higher SEER and HSPF ratings: With mini split heat pumps and air conditioners, you’ll find higher SEER (cooling efficiency) and HSPF (heating efficiency) ratings. For example, a Carrier Infinity® system mini split air conditioner offers a published rating of up to 42 SEER cooling efficiency compared to a top-of-the-line Carrier Infinity split system air conditioner that provides up to 26 SEER cooling efficiency. Keep in mind that, just like miles-per-gallon for your car, a higher SEER number means higher fuel efficiency.
• Targeted comfort: Mini split systems can provide more targeted comfort. They are perfect for adding comfort to a room addition or to a room in the house that your central air system can’t seem to keep comfortable. Or, you can create a zoned system for your home by adding a mini split indoor unit in every room. In terms of energy savings and efficiency, you can save money on utility bills by setting the temperature for comfort in rooms you are using, and either turning off or setting back temperatures in the rooms that are unoccupied.
• Avoid energy lost through ductwork: Because ductless systems deliver comfort directly from the source to the room, they eliminate the energy – and money – lost by central air systems as cooled or heated air travels through ductwork into your living spaces. In an average house, you can lose 25% or more of your energy through the ducts.*
• Easy system installation: While installation costs don’t necessarily affect the system’s energy efficiency, they do add to the overall cost of ownership. Installing a ductless mini split system in a room or home without ductwork can save on costs associated with installing new ductwork and connecting to existing duct systems.

 

[Solar Guppy]

Have a link to the ducted unit you bought?

Yes, here it is The Mrcool 2/3 Ton universal

I used conventional brazed lines, a generic MrCool Air Handler ( any 410a coil will work ) as I wrote replaced the PSC motor with ECM one and controller as standard PSC uses the near same energy regardless of the speed setting

 

[Browneye]

Thanks for the info on the heat mode energy use.
Happen to know what generation and seer rating your mr cool units are?
I see they have gen 4 out now at costco.

Also are your units running on 220 or 120vac?

I don't know how they designate their 'generations', but I think the first one I bought was a gen2, and perhaps the second one. The third one, the 9K one is their budget series and I think it's gen3. They aren't the real high seer rated ones, but they are all heat pumps, are super quiet, and kick out a LOT of cool air.

The two smaller ones are 120V, the bigger one is 240V.
The bigger one runs off a garage circuit that was originally for an electric dryer and central air condenser - fed from a 45A breaker in the main panel. I connected to a new sub panel with 25A breakers per spec for the split unit, with a switched disconnect at the unit.
The second one I ran a feed off a 20A receptacle circuit for the back bedrooms, to a switched disconnect. You're supposed to have a dedicated circuit, but it works fine - there's nothing else plugged into that circuit. I think the 12K btu unit pulls about 9 amps running.
The third one is right below the main panel so I was able to pull wire to an empty 20A breaker, with a switched disconnect.
The smaller units all call for a 20A breaker, the bigger ones are based on how big they are - the 24K is 25A.

My middle daughter is a commercial electrician, so I have a built in NEC guide. Not only does she know all the codes but the reasons for them. ?There was a long argument on another forum about fused disconnects - what the install manual calls for. That's the way they used to do them, but virtually all breakers today are AC rated and sufficient for fusing them. They can be in the unit disconnect box or the main panel - either is fine.

 

[Rocksnsalt]

I don't know how they designate their 'generations', but I think the first one I bought was a gen2, and perhaps the second one. The third one, the 9K one is their budget series and I think it's gen3. They aren't the real high seer rated ones, but they are all heat pumps, are super quiet, and kick out a LOT of cool air.

The two smaller ones are 120V, the bigger one is 240V.
The bigger one runs off a garage circuit that was originally for an electric dryer and central air condenser - fed from a 45A breaker in the main panel. I connected to a new sub panel with 25A breakers per spec for the split unit, with a switched disconnect at the unit.
The second one I ran a feed off a 20A receptacle circuit for the back bedrooms, to a switched disconnect. You're supposed to have a dedicated circuit, but it works fine - there's nothing else plugged into that circuit. I think the 12K btu unit pulls about 9 amps running.
The third one is right below the main panel so I was able to pull wire to an empty 20A breaker, with a switched disconnect.
The smaller units all call for a 20A breaker, the bigger ones are based on how big they are - the 24K is 25A.

My middle daughter is a commercial electrician, so I have a built in NEC guide. Not only does she know all the codes but the reasons for them. ?There was a long argument on another forum about fused disconnects - what the install manual calls for. That's the way they used to do them, but virtually all breakers today are AC rated and sufficient for fusing them. They can be in the unit disconnect box or the main panel - either is fine.

Thanks for that info.
Must be nice to have an electrician in the family!

 

[timselectric]

I'm installing a Pioneer floor model in my living room now. Too many windows and I think the floor model will work better for the install and cleaning.

I've been looking into the concealed units. You mount them out of sight. And run a short duct to a standard register. And I assume also a return.

 

[Zwy]

I've been looking into the concealed units. You mount them out of sight. And run a short duct to a standard register. And I assume also a return.

I went with this one. https://www.pioneerminisplit.com/co...lit-air-conditioner-heat-pump-system-full-set

Did not have studs in the right places in this old house so used an oak cleat top and bottom fastened to studs and the unit to the cleats. Wall wasn't straight anyway so it all worked out. Cleats are mainly hidden, just the last 1/2" on the ends show. I had an outlet under where it needed to go so I didn't set it on the floor. Hole for lines, drain and power/comm cable goes straight out the back which I hope to get done this weekend.

 

[teal95]

I have the one of the early Mr Cool minisplits in the in law suite above my shop. At the time they only had one size and one line set length for DIY. For the first year it was heating and cooling, but no one lived in it so it was just keeping things from freezing. After that I finally got the water heating system in (heated floor in shop and radiatora upstairs). It's worked well up there.

Last year my wife got a sunroom added on to our house and I knew the a/c probably wasn't going to keep up and we would want it zoned. We also have issues with the house only being on a single thermostat and to keep it comfortable upstairs for sleeping the basement (my office) turns into a freezer. Our upstairs is basically all gable so there's minimal wall space so I wanted ceiling cassettes. At the time Mr Cool didn't have any ceiling mounts. So I ended up purchasing a Pioneer with a wall mount for the sunroom and ceiling mounts for the bedroom. It took some convincing but the HVAC guy has agreed to commission them when I'm ready. It helped that I did most of the grunt work on installing the heated floor in the sunroom with him.