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Originally Posted by icemeister

So in a nutshell Powell, yes...a Btu is still a Btu, but the published case load ratings for the parallel racks are the "actual" or steady state BTU load for that case whereas the BTU ratings for the cases applied with conventional units have been kicked up a notch to account for the post defrost and cycling loads.

icemeister,

"Steady" was the thought process I was pondering.

Thanks..........I'm mo smarter now.

Originally Posted by mccool

I concur with chilly on the btuh/door, most older CRH, RCA, NRC are approx, the same BTUH 1650/door on FF. (-5 F discharge temp required for FF -12 for ice cream)

What refrigerant are the cases rated for as per nameplate??
What are they running on?
Have all required mods been made?

What is the specific problem??

Thanks. No problems...yet.

My customer bought 10 doors of "remanufactured" Hussmann NRC and 24 ft of Hill/Phoenix OHPH with conventional condensing units for each. I just saw the cases briefly the other day when I was at the store to cut loose and wave bye-bye to 24 ft of "ancient" WIZ wide island FF.

The units didn't get delivered until yesterday. I just want to see what this reman outfit gives us for compressors and how they match up. The customer bought those H/P OHPH cases as multideck meat cases. I told them that the OHPH is a produce case.

The fun is just beginning.

I concur with chilly on the btuh/door, most older CRH, RCA, NRC are approx, the same BTUH 1650/door on FF. (-5 F discharge temp required for FF -12 for ice cream)

What refrigerant are the cases rated for as per nameplate??
What are they running on?
Have all required mods been made?

What is the specific problem??

Conventional Unit vs. Parallel System Capacities...

Originally Posted by powell

You know, I've always questioned this rack vs. single system btuh rating for supermarket type equipment. If the btuh is 1650 for rack, why is it 1750 for a single? A btuh is a btuh. Is it because the ambient conditions change and a single loses capacity? If so, then is it really 1750 that is required and the rack system can adjust for this.

What am I missing?

It has to to with what Hussmann called system "diversity" in parallel, or what they called them, "mixed multiplexed" rack systems.

Here's their explanation of diversity taken from the Hussmann New System Planning Manual from 1976:

Conventional Units Versus Mixed Multiplexing Capacities

"There is a basic difference between the actual capacity of a conventional unit must have for a particular case versus a mixed multiplexed unit operating the same case. When the conventional unit is applied, the unit must handle the case balanced load, pulldown load after defrost, along with a cycling ability to maintain temperature in the case with a pressure control or thermostat. When the same refrigerator becomes a part of a total load on mixed multiplexing, there is a certain diversity that the unit can handle due to normal defrosts, load variations, etc. on the system. Because of this diversity the capacity for the case can be applied without the pulldown, cycling requirement."

So in a nutshell Powell, yes...a Btu is still a Btu, but the published case load ratings for the parallel racks are the "actual" or steady state BTU load for that case whereas the BTU ratings for the cases applied with conventional units have been kicked up a notch to account for the post defrost and cycling loads.

Originally Posted by icemeister

Was that job a parallel rack system or conventional singles? The Btuh/Door rating is usually about 10% higher for singles, which is what I'm going to be dealing with.

You know, I've always questioned this rack vs. single system btuh rating for supermarket type equipment. If the btuh is 1650 for rack, why is it 1750 for a single? A btuh is a btuh. Is it because the ambient conditions change and a single loses capacity? If so, then is it really 1750 that is required and the rack system can adjust for this.

What am I missing?

Thanks again!

that would be -19. this was a parallel rack, for conventional unit use 1750 btu's. the loads are the same as the same as the classic line RFA. I still have the case cuts on these.

Originally Posted by chilly123

the magical # you are looking for is 1650 btu's per door. pulled this from a set of prints on a job a few years back on some NRCV's which are the same as NRC5L, your fronts are lower.

Thanks chilly.

You didn't happen to note what the evap temp was on those did you?

Was that job a parallel rack system or conventional singles? The Btuh/Door rating is usually about 10% higher for singles, which is what I'm going to be dealing with.

the magical # you are looking for is 1650 btu's per door. pulled this from a set of prints on a job a few years back on some NRCV's which are the same as NRC5L, your fronts are lower.

Originally Posted by powell

Same here ice, My books don't list that model. Hussmann want help anymore either, which I'm sure you know.

Yes I know....Those Bass-Turds.

...and to think that my father, who was a Hussmann distributor back in the 1950's into the mid 1970's, was personal friends with the then president of Hussmann (Gordon Gary ?) who also retired to Vero Beach.

If Pop were still around, I'd have that info in a heartbeat.

Same here ice, My books don't list that model. Hussmann want help anymore either, which I'm sure you know.

Originally Posted by icemeister

Do any of you market guys have the case load (Btuh/Door) and evap temp for this case? for both FF and ice cream? (I assume from the model number this is an ice cream case, but it'll be used for frozen food.)

My Hussmann data doesn't cover that one.

Sorry ice I couldnt fine any info on it.

Hussmann NRC5L Info Needed...

Do any of you market guys have the case load (Btuh/Door) and evap temp for this case? for both FF and ice cream? (I assume from the model number this is an ice cream case, but it'll be used for frozen food.)

My Hussmann data doesn't cover that one.