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#64423 - 04/07/06 12:59 PM Large Residential HVAC Services
rad74ss Offline
Member
Registered: 04/19/04
Posts: 154
Loc: Pryor, OK USA
I am currently working on a series of Residential HVAC Chillers with integral pump packages. Our largest unit has the following stats. RLA=499, MCA=509, Max Fuse =600 (HACR breaker can be higher). 240/1/60 main 115/1/60 and 24/1/60 control.

Has anyone worked on residential HVAC Services this size?

We are mounting the Fused Disconnect on our unit for ease of customer installation as well.
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#64424 - 04/07/06 05:08 PM Re: Large Residential HVAC Services
resqcapt19 Offline
Member
Registered: 11/10/00
Posts: 2209
Loc: IL
Rad,
Quote:
Max Fuse =600 (HACR breaker can be higher).

If the label only say Max Fuse, and doesn't list a breaker size, you must use a fuse as the overcurrent protective device. The use of a breaker would be a code violation.
Don
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#64425 - 04/08/06 05:55 AM Re: Large Residential HVAC Services
rad74ss Offline
Member
Registered: 04/19/04
Posts: 154
Loc: Pryor, OK USA
I should have been more clear. The label says Max Fuse/Breaker*. There is a side note saying a HACR breaker must be used if compressor protection is not provided.

On these particular units we will provide both compressor fusing and a unit fused disconnect.

Some of our customers try to trim as much cost off the unit price as possible and make up for it on the service end. These units are so large and are sectional that we are going to catalog them with all the protection we can provide.
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#64426 - 04/08/06 10:41 AM Re: Large Residential HVAC Services
Larry Fine Offline
Member
Registered: 02/18/05
Posts: 684
Loc: Richmond, VA
"Residential" and "Max Fuse =600"?????

Could this have said "60a"?
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Larry Fine
Fine Electric Co.
fineelectricco.com
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#64427 - 04/08/06 10:42 AM Re: Large Residential HVAC Services
Larry Fine Offline
Member
Registered: 02/18/05
Posts: 684
Loc: Richmond, VA
Or do you mean multi-family buildings?
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Larry Fine
Fine Electric Co.
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#64428 - 04/10/06 05:56 AM Re: Large Residential HVAC Services
rad74ss Offline
Member
Registered: 04/19/04
Posts: 154
Loc: Pryor, OK USA
600 Amps is correct.

The units will be cataloged as "Estate Chiller" and are for large single residences. If it helps to narrow things down the rep is in Connecticut. We have also built several for ski lodges and wineries.

They range in capacity from twenty to sixty tons with an integral dual pump package and a DDC controller.

Personally I thought that if they can afford that, then they can afford to get a three phase connection. The upper management people who designed the theory of the unit wanted to be able to install it on pre-existing 240 single phase hookups and let the customer worry about the electric bill.
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#64429 - 04/10/06 10:30 AM Re: Large Residential HVAC Services
Bob Offline
Member
Registered: 02/05/02
Posts: 182
Loc: Mobile, AL, USA
"Our largest unit has the following stats. RLA=499, MCA=509, Max Fuse =600 (HACR breaker can be higher). 240/1/60 main 115/1/60 and 24/1/60 control."

Does this unit have a soft start? I was looking at a RLA = 499 and a 600 amp breaker.
Also the MCA = 509 amps is too low if the
FLA is 499 amps.
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#64430 - 04/10/06 10:56 AM Re: Large Residential HVAC Services
rad74ss Offline
Member
Registered: 04/19/04
Posts: 154
Loc: Pryor, OK USA
All the units except the 20HP unit are modular. Each module has a tandem set of scroll compressors and two fans. The individual compressor amps are only around 32 amps. That is why the RLA and MCA are so close. On the largest unit the pump is the largest load at 40 amps. All of the heat trace for the water piping, the GFCI outlet and pumphouse service light are on a seperate generator back up service.

The small modular scroll compressor layout saves on start up amp draw and also gets around the requirement for a full time manager. Larger screw compressors and some recips require a full time manager under some city codes.
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