3 phase energy consumption?

[bill a]

I was wondering where to get objective information on energy cost comparison between the same device (air conditioner) in 3 phase vs single phase. I will be getting a new condenser next season (maybe 3.5 to 5 ton), and 3 phase is available, but I would need to justify putting in a panel for it. I already have adequate panel space in single phase. Natural gas has gone up quite a bit here, and I might consider an all electric heat pump, as well. I'd would like to have 3ph anyway for machinery, etc, but it would help the decision if the a/c would actually run cheaper. Someone was telling me that electric meters are more weighted towards amperage, than just wattage, but I have my doubts on that. Thanks Bill

[SQLit]

I know where I live 3 phase for a residence is an act of god or produce load calculations for something like 100 kw demand. If I were you I would look into what it will cost for an phase service then look at the cost of an single phase air conditioner. I seriously doubt that there is any payback. You must contact your utility to see what the rate differences are. 3 phase will no doubt have an demand charge maybe more. Unless you have an machine shop that runs 18 hours a day your probably tilting at windmills.

An 3 phase motor does draw less amps but the kwh is about the same. An horse power is still an horse power whether it be 3 phase or single phase. Wire sizes are smaller with 3 phase and all of the protective devices are smaller in size and usually more in initial cost.

[RBM]

[TURTLE]

This is Turtle.

The ideal you have is full of holes as to try to burn less electric as cost goes by having a 3 phase hvac system. Most all 3 phase equipment has a SEER rating of

7 to 9 seer and just a few have 9.8 seer rating but really rare. Let's say you buy the highest seer rating they make 10 seer in a 3 phase hvac system and it cost you $100.00 a month to run it. If you would buy a 14 seer in single phase hvac system and the 3 phase will cost you $100.00 a month to run it. The 14 SEER single phase hvac system will cost you $60.00 a month to run it.

3 phase 10 seer hvac system = $100.00 a month to run it.

Single phase 14 seer hvac system = $60.00 a month to run it.

Now Try this out !

Single phase 16 seer hvac system = $40.00 a month to run it.

Which one sounds better to pay for ''''' $100.00 a month '''''' or ''''' $40.00 a month '''''' to cool your building?

TURTLE

[bill a]

[bill a]

I wasn't aware that the higher seer units were unavailable in 3 ph. That would make a considerable difference in the decision.

Bill

[bill a]

here's an article that seems to imply that 3ph motors are inherently more efficient and that 3ph compressors do run more cheaply

bill

[TURTLE]

This is Turtle.

The 3 phase compressor may run very cheaply but the compressor is what that is rated here and the system as a whole is not rated. Cost to operate is rated in seer and not in the out put of A compressor but the system as a whole.

The highest seer rating of any 3 phase system know to man today is a 10 seer rating and single phase systems have rating of 16 seer + .

No matter how you look at it 3 phase is a electric hog made to even run on low voltage where a single phase will not run on low voltage!

TURTLE