Carrier is in my opinion weird when you get into an Inverter 5 speed or more type systems. This one (Green Speed) they talk about noise albeit differently in other documents... they mention it as a 'purring type' noise. LOL.

Lastly they don't want you running the heat pump in slightly chilly weather (66 degrees F. and above)

Competing manufacturer's from what I have seen, don't have these odd ball things mentioned in any literature I can put my hands on.

If noise is a concern I wouldn't use any Carrier or ICP 5 speed machine. They all mention odd noises coming from outdoor condenser, whether it's a heat pump or straight cool only model.

It seems the noise issue has been resolved. See http://hvac-talk.com/vbb/showthread.php?2231371-Carrier-Greenspeed-(Bryant)-or-the-5-stage-25VNA8-(Bryant-288BNV)&p=26048031#post26048031

Nope. The sound issue noted in my first post comes from the manual of the unit in question. These are odd noises by DESIGN or I guess you could say a flaw of engineering.

As I said before, if noise is a concern I would not install a Carrier 5 speed or ICP model. (If noise is of no concern, then your options are wide open.)

I haven't seen any other competing manufacturer's 5 speed inverter systems with such concerns listed, noises due to installation problems is completely different animal.

You stated you want to replace your AC with a heat pump. Do you currently have a heat pump? If not what is your plan for heating and what is that you are hoping to accomplish with buying a high end inverter type heat pump?

In the past there was a Carrier service bulletin about installing a muffler at the time of installation. I don't know if the latest Carrier Greenspeed models still recommend this as part of the installation.

I know that Carrier has been selected for some reason, but does Mitsubishi use their Flash Technology in central systems and how does cost and efficiency compare?

I pulled the trigger on an 25VNA03 greenspeed (3 ton) this summer. i live in the northeast and had all electric baseboards. My upstairs main level is 1250 sq ft.i needed a heating solution and didn’t want to go with an oil boiler or oil forced air. Yesterday it was a high of 26F and a low of 21F. My useage was $7.50 (12 cent electric rate for both supplier and delivery)

for the day keeping my place at a toasty 73F. Yes i keep it very warm due to health condition.

Heat pumps these days are very efficient compared to electric strip heating. The higher the efficiency of the heat pump the cheaper it will be on operational costs and the technology (heat pump) is a vast improvement from heat pumps of old.

I know I was kind of hard on Carrier over the hissing sounds on off cycle but those things need to be known if you place this near a bedroom window.

With that said and given your climate, have you had any problems with defrost on this machine?

I'm sure Tiger might be interested to hear it. LOL.

Competitors models noise at 100% would be roughly the same, minus the hissing sound when it shuts off.

Given how your unit is situated you may not hear the hissing sound on off cycle. It doesn't last that long maybe 5 seconds and may be more of a swooshing sound in winter at colder temps. I've only heard it after running in cooling cycle in warm weather.

You might be able to get better 'rough' estimates in terms of performance via amp draws. Find out how many heat strips you have. Typically these are strung in 5kw sizing strings. If this system is large you may have 3 or 4 strips.

A 5kw strip pulls about 20 amps. 4 x 20 = 80 amps. That is one heck of a load.

Your Heat Pump may pull as low as 5amps up to maybe 15amps in high. For this reason, lower temps, moisture in air and ultimately how much defrost is required would be the wild card(s) of a heat pump system. I don't know that you'll ever know for sure what the breakeven point is because OAT conditions change. Humidity, rain, snow etc. can change your performance meters... when only considering temperature alone. Meaning if the unit is buried in snow at 25 degrees, is likely not the same running at 25 degrees not buried in snow.

FYI -- The 5 speed is quieter vs the greenspeed .. The inverter noise is greater on the greenspeed. That's what you hear .... The efficiencies are greater with the Greenspeed. I don't think you will ever get the price difference back. The 5 speed will go down to 25 % -- greenspeed is only 40% ... that's a big win for the 5 speed. Also, the 5 speed will not start if temps are under 10 -- and will not operated under 2 ... the greenspeed will go down to -15. I get single digit temps -- more in the last 5 years. Unit never missed a beat -- it's never off in those temps -- going up and down all day. Mine was spinning along at 2 degrees w/o issue .. but if you get really cold temps -- have to get the greenspeed. Unless the unit is on 5 --- it's silent ... even on 5 it's a very quiet unit.. I have two of the units in different houses -- both with zoning, The Carrier zoning is really slick

Well, that’s what an arced control board looks like on a 2 year old Carrier 25VNA848… it took out the control board of the air handler as well. $3k and on back order.