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robbin
Mod
join:2000-09-21
Leander, TX

robbin to Ken

Mod

to Ken

Re: [HVAC] Manual J and heat pump sizing

You may want to research units that use inverter technology. They keep their efficiency over a wide range. I'm not sure who all makes them but here is an example

"Innovative and Advanced: No other air conditioner operates like an iQ Drive. Its inverter-rotary technology constantly adjusts to exactly offset the cooling demands on the home. This unit modulates from 40% to 118% of capacity."

»www.westinghousehvac.com ··· s4bi.htm

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

Jack_in_VA

Premium Member

A few years ago Trane had a unit using variable frequency drives on the reciprocating compressor. They were expensive so I didn't investigate. Evidently there were many problems as Trane stopped offering them.

Tech told me last year that they were working on the concept so maybe it might come back. There are many VFD's available and have been for years. The problem must be with controlling the pressures of the gas.

The variable speed air handlers have a VFD for the fan motor. I'm surprised Trane isn't throwing out the "Inverter" word to describe it.

Inverter is just the new buzz word manufacturers are now using on clueless consumers.
iknow_t
join:2012-05-03

iknow_t to robbin

Member

to robbin
said by robbin:

You may want to research units that use inverter technology. They keep their efficiency over a wide range. I'm not sure who all makes them but here is an example

"Innovative and Advanced: No other air conditioner operates like an iQ Drive. Its inverter-rotary technology constantly adjusts to exactly offset the cooling demands on the home. This unit modulates from 40% to 118% of capacity."

»www.westinghousehvac.com ··· s4bi.htm

instead of using a VFD they could use a stepper motor, and vary the speed from 0 to thousands of RPM without the motor getting too hot. CNC machines use that. and it works very well.

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

Jack_in_VA

Premium Member

Stepper motors operate much differently That's why they are called stepper motors.
iknow_t
join:2012-05-03

iknow_t

Member

said by Jack_in_VA:

Stepper motors operate much differently That's why they are called stepper motors.

yes of course. but they can be used, and have been, to provide smooth rotary motion. some examples are cooling fans for cars, and computer fans, but they are also used in applications which require many HP.

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

1 edit

Jack_in_VA

Premium Member

Where did you learn your Motor knowledge?

»en.wikipedia.org/wiki/St ··· er_motor

Tex
Dave's not here
Premium Member
join:2012-10-20

Tex to Jack_in_VA

Premium Member

to Jack_in_VA
Looks like they still do offer a variable speed:

»www.trane.com/residentia ··· at-pumps

As well as Carrier:

»www.carrier.com/homecomf ··· -25vna0/

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

Jack_in_VA

Premium Member

Sure does Tex. That would be great but I wonder if it's really going to be worth the cost?

I have a 16i 2-stage condenser and variable air handling unit and that was very expensive.

Tex
Dave's not here
Premium Member
join:2012-10-20

Tex

Premium Member

I don't know what they cost, but I'm sure they are very proud of them. Of course, two-speeds aren't cheap, either. Who knows how many years it would take to reach a break even point.

Ken
MVM
join:2003-06-16
Markle, IN

Ken to robbin

MVM

to robbin
said by robbin:

You may want to research units that use inverter technology.

I am looking at that right now as my #1 choice. The Water Furnace 7 Series looks amazing, but the price might be out of my budget.

tons             cooling           heating
3          13,000 -  38,000   14,000  -  41,000
4          19,200 -  49,000   19,000  -  55,000
5          23,200 -  60,000   23,000  -  65,000
 

The 4 ton unit would be perfect for me, I'm trying to find out prices on any scratch and dent models they might have. The other model I'm looking at is a Daikin Mcquay with variable speed compressor.

tons             cooling           heating
3          15,900 -  38,900    9,900  -  30,100
4          17,200 -  50,900   18,800  -  40,700
 

The heating max btu's are a little deceiving. I believe Water Furnace uses the top capacity possible, such as 118%, as the max number. Daikin on the other hand uses 100% as the max number, even though the unit can go above that. I found a chart that showed the Daikin 4 ton with an actual top of around 53,000, inline with the Water Furnace numbers.
mj3431
join:2003-04-21
STL, MO

mj3431 to Tex

Member

to Tex
I had a Greenspeed 3 ton unit priced for me 2 years ago. They wanted nearly 10k just for the equipment. We do have a 4 ton Greenspeed in one of the offices at work though and it works really well, and is very quiet.