Design Question / Opinion

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Chamuit

Chamuit

Grumpy Old Man
Location
Texas
Occupation
Electrician
To the engineers here / or anyone else with knowledge. I'd just like to hear other opinions.

I went today and looked at a set-up for special ed school. They have an old natural gas a/c system that used to do the cooling and heating. The unit provided the electrical needs for the whole system, so, there isn't any electrical nearby.

They want to change this old system out to a (total electric) heat pump set-up. 15 tons is required for the space. There is available an empty 120/240 single phase 200 amp panel. (I could make this into a disconnect . . . or whatever.) Condensing Units have to sit on the ground.

Would you:

A - run 6 seperate HR's to three 5-ton units on the ground and three AHU.

B - set a phase converter to get 3 phase to feed a 15-ton unit.

C - something else I haven't thought of.

This will ultimately get engineered, drawn, permitted and so forth but would like to tell my client which way to go.
 
Run three 5 ton single phase units. A no-brainer, to me. Keep the phase converter out of the situation. Not only will this keep the initial install cost down, but this will also greatly reduce MRO costs into the future. It will also assure some heating and air conditioning should one of the 5-ton units go down. If a single 15 unit went down, they're SOL.
 
mdshunk said:
Run three 5 ton single phase units. A no-brainer, to me. Keep the phase converter out of the situation. Not only will this keep the initial install cost down, but this will also greatly reduce MRO costs into the future. It will also assure some heating and air conditioning should one of the 5-ton units go down. If a single 15 unit went down, they're SOL.
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Absolutely. The phase converter will also cost you in lost efficiency on a constant basis, which you will not regain by using 3 phase and a larger unit.
 
Jraef said:
. . . The phase converter will also cost you in lost efficiency on a . . .
Click to expand...

My helper and I discussed/wondered that as we drove away. Thanks for your inpuut about that.
 
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