HVAC "Advice"

Messages
750
Location
MN
I put in a 20seer mini split this year (high end residential stuff, not commercial). Those inverter drives really are something else, pretty sure the unit almost never shuts off, it just varies the output of the system to just barely keep up with cooling/heat load. I was pretty surprised to see that my power bill actually went down this fall when the system was cooling during the day and heating at night. All summer long I never even noticed a bump in my bill compared to my December through March bills from the previous year. Best part is I was able to cut a full month of my primary hydronic heating season and about 30% off my fuel useage as long as the outdoor temps stayed above 0F
 
Messages
10,906
Location
Nokesville, VA
The Daikin VRV-S system I had installed will produce 100°F discharge air at 0°F ambient. You're not going to see that with your Bryant, Carrier, Trane, Goodman or Lennox heat pump.

That doesn't matter. Heat pumps are not rated by discharge air temperature. What does matter is BTU output and COP. You could probably get your Bryant, Carrier, Trane or Goodman heatpump to produce 100F discharge air at 0F ambient if you lower the indoor fan speed enough. Which, I'll guarantee you, is what your mini-split does to achieve a 100F discharge air temp.

At some cost in energy efficiency, I might add. Higher discharge temperatures lead to higher head pressures which leads to higher energy consumption. All things being equal, it's better for a heat pump to have sufficient airflow to have a lower discharge temperature.
 
Last edited:
Messages
17,387
Location
Silicon Valley
I have seen TV advertisement in Taiwan (on business trip) of variable speed / flow AC that advertise 10 year warranty on inverter, and something even longer for the rest of the system. It may not be good enough for the US market because how much it cost to install here and how much central unit is, but if you can just swap them out with low labor cost like most of the rest of the world, 10 year is good enough for a good price.

The typical US warranty on central furnance / AC / HVAC covers parts when installed by certified tech. I think this is the reason why some tech refuse to do repair on an old system because they may get blamed for something else breaking that they don't get paid for. If they are making good money installing new system and warranty paid for their labor for a certain period of time + parts for even longer, there is no incentive for them to repair a system with minor problem and take the risk of having to fix someone else's problem.

For home owners, having to pay $400 a visit to replace a sensor here and a motor there under warranty is ridiculous. This IMO is what set apart the high end vs low end when they are all the same parts. This also set apart the reason to go precharge mini split that you just throw away or swap out if they break, and the $400 per visit and $5000 per installation labor central unit. IMO having AC and gas furnace mixed into the same unit and needing the same license to repair and install is what doom this industry to begin with. Why do I need to pay so much more to install a furnace (even more ridiculously an AC) when a water heater is so easy to install by a plumber? It make no sense to me.
 
Messages
552
Location
illinois, usa
I'll address some posts-

1. Regarding complexity and break-downs/repairs with this system- I know anything mechanical and surely nowadays with everything computer-controlled, anything can and will break down and need repair. I am extremely confident in the Daikin products (I mean real "legacy" Daikin, not the Goodman line being re-vamped slowly) in that their stuff is extremely high-quality and built to perform as well as last as you would expect. Daikin is not equal to most other "mini-splits" or VRV/VRF type systems other than Mitsubishi. Most manufacturers have brought something to market in the mini-split line and it is showing that they didn't want to fund R&D or be real proud of their product line. It's sad because all the cheaper made stuff will probably give the newer technology a bad name over time. I only considered Daikin and Mitsubishi. I also have a pretty good relationship with a large number of people at Daikin, I feel that they would help me in a time of need should something major arise with a repair.

2. No, you can't install a mini-split/VRV coil over a gas furnace and cassettes/high-wall/fan coils elsewhere. Just no.

3. I wasn't concerned with payback, although my mother will probably live long enough in that house to see the payback of the additional cost over a sub-par, typical residential equipment change out with the energy savings she will see with this system. Payback with a VRV/VRF type system (not a "mini-split") might look like 15 years but when you factor in your comfort and other performance into the equation, payback is a lost thought and you realize how poor performing typical single and two-speed equipment really is.

4. The mini-split and VRV/VRF lines of equipment from most manufacturers have indoor units that look, feel and operate just like your current indoor air handling unit that is in a closet, attic or crawl space with ductwork attached. The installers can remove your existing air handling units and put in new air handling units matched with the condensing unit from the mini-split manufacturer. It's going to be a LOT quieter, tho. Strip heat is not normally needed, even in colder climates. While the condensing units do operate a defrost cycle, many manufacturers have methods to combat the introduction of cold air into the space. Daikin shuts down the evaporator (indoor) fan during defrost. The Daikin VRV-S system I had installed will produce 100°F discharge air at 0°F ambient. You're not going to see that with your Bryant, Carrier, Trane, Goodman or Lennox heat pump.

5. Nobody is getting any HVAC system that is a permanent installation (not a PTAC/Window unit) for $1700. The equipment cost of a simple 2-ton split system is $2,000. You won't get a contractor to show up for less than $2,000. The equipment cost for a 1.5 ton mini-split with a ductless high-wall unit from any reputable manufacturer is $1500+.

6. Yes, repair/etc., with this particular commercial-based system is going to be limited to certain contractors in our area. Out of the 4 contractors that I had show up (I actually sent out invitations/calls to 7, 3 did not respond), only ONE had installed this type of system previously (my friend). All perform commercial as well as residential work ( the same crews with any contractor do not cross-pollenate. There's commercial crews and residential crews. A commercial crew performed my installation.) I am not worried about repair. The contractor that I used, I have developed a relationship with and they are now more eager to try to sell these systems after this installation and actually seeing the performance themselves. With that said, I don't want just any HVAC contractor showing up at one of my properties to perform work because I'm in a tight spot. I want highly experienced and trained people.

As I stated in my OP and stressed, not many people will have much desire to spend the money necessary for a system like this, but anyone who does and can realize all the benefits will certainly say it's worth every penny when done. I'm not trying to sell anything, I'm not getting a kickback nor do I care what you do at your property. I'm simply throwing out some advice and experience to anyone wanting to listen. I have learned over the years that not many people really understand HVAC and that's an understatement. Even the people that try to sound like they do don't understand it all and don't think about many factors.

One of the biggest benefits of a system like this is the unlimited part-load capacity and the real variable speed of the compressor, condensing fan and indoor fan as well as the metering of the refrigerant, which provides minute part-load capacity. I can't stress enough how great this is. Your weather is never the same day to day and hour by hour at times, neither is the heat gain/loss of your structure.

And yes, I eat this stuff up. I'll never consider myself a nerd, but I get all nerded up in HVAC stuff. I love it.
Thanks for info regarding my question.
 
Messages
201
Location
WA
I didn't see this thread when it first posted.

I just switched out to a ductless mini split last summer. I'd researched all options, including replacing the typical ac system that had been in the house prior to me buying it. For some reason the prior owner got ride of the outdoor condenser and used window units.

The bids were ridiculously high for a 3 ton 3 zone Mitsubishi system, one contractor wanted $20,000 installed, and that didn't include electrical.

My cost on the same system was just under $6,000.

I ended up buying a more DIY friendly unit, bought all the equipment, did my research and installed it myself, it was much easier than I expected.

The total cost was so low, and the system so simple, that replacing parts, or a whole unit would cost less than a service call. And because I bought all the tools needed, I can troubleshoot and repair any component.

I'm all electrical and the temps here range from -8F to a little over 100F.

My electric bill dropped about $50 per month in the summer, and up to $300 in the winter. Our same bill for that month the prior year was about $590. Our old central electrical forced air system was that bad.

We now keep the house at about 72 day and night, and the cost is still that much lower. Plus I don't use the wood stove much at all, previously I used it a great deal.

It worked so well I bought a 9000 btu for the shop, which I now keep at 65 and then warm it up when I work out there.

It's extremely quiet, and you don't notice any fluctuations in temperature, so the comfort level is high.

I'm going to buy another unit for the house to improve heating below 10F, and as a backup. I want to remove the wood stove completely, it's the backup now.

Because the system draws so much less power I can now run everything in the house off of a 7,000 watt generator.

I'd do this again immediately without hesitation.

Sounds like a sales pitch, but I'm not in the industry and didn't know much about this stuff prior to this project. It was just far better than I expected.
 
Messages
3,403
Location
Chicago
Yeah. My neighbor just installed an instantaneous water heating system, all electric, which required an entrance panel upgrade. She also installed a water conditioning system, since someone told her that hard water (which we don't have) will hurt the system.
She's 80 years old.
This was all done to "save electricity".
Her payoff will be about 38 years.
Yeh but that hot water temp will be perfect...
 

Hillbilly Deluxe

Thread starter
Messages
105
Location
South of Metro Atlanta
My cost on the same system was just under $6,000.

My cost for the Daikin 4-ton multiport condensing unit, the 3-ton indoor air handler, 1.5-ton indoor air handler, branch Y-connectors, and other required Daikin accessories was $6200.

Other parts/materials/ductwork was about $2200, the rest was labor.

3 men worked for 4 days on the change out.
 

Hillbilly Deluxe

Thread starter
Messages
105
Location
South of Metro Atlanta
Just an update.

I analyzed the power bills from Dec, Jan and Feb to date.
The bill for Dec was ~$360. Jan was ~$415.

I’m estimating the Next Bill will be about $160. Yes, we’ve had some warmer weather but still had pretty cold weather the first 14 days after install.
 

Hillbilly Deluxe

Thread starter
Messages
105
Location
South of Metro Atlanta
Well I was right on the money....no pun intended. Latest power bill was $185, but the reading was for 33 days, so about 4 days longer than the normal previous reading cycles.

I was sold on the Daikin technology and performance before this, now I am simply blown away.

For those of you who need or are considering changing your HVAC system and plan on staying put for a decent length of time or are desiring ultimate comfort and lower bills, I can't recommend these systems enough. But please understand there is a world of difference between inexpensive "ductless splits", "Mini-splits", etc., and the better brand name systems, especially the VRV technology from Daikin. You truly do get what you pay for.
 
Top