Need some guidance...10-15 ton package unit

[developerx]

Folks,

I am a building owner. I have several rooftop package units and one of them is past it's design life. I have decided to replace it, rather than continue to bandaid it. This is a 2 stage heat and 2 stage cool application, side discharge, on rails. The application is on Long Island (northeast zone temps).

The existing unit is a York model #D1SS180G26517FDB. I am under the impression this is a 15 ton unit, but I can't find any details at all. York does not give access to older manuals and documentation that I can get to.

The space it handles is 5000 sf, less about 500 sf of hallway covered by another 5 ton unit which covers all hallways. Excluding non-ac areas like closets and such, I figure the net area is 4,250 and that is open and intermingles with force air from another unit doing 5000 sf, so a portion of the load is shared. This space is however, all under the flat roof (top floor).

This being the case, I have been told (and it makes sense), that a modern, high-efficiency 10 ton unit will suffice. Based upon what I've read here, the smaller ac rating may result in a longer runtime on high demand days, but that will do a better job of dehumidification due to more airtime over the coil. As far as heat goes, there is a perimeter hydronic loop in the area, so btu output on a 10 ton will be plenty.

Now, to replace this unit, a Coleman model #RKNB120CM has been proposed.

I know that York makes the unit for Coleman, but to be frank, I can't find any information on this model # either. This is supposed to be a high-efficiency, 2 stage heat - 2 stage cool, with an economizer.

So, the questions I'm throwing out there are:

1. Does anyone have any info on either of these units (old and/or new)?
2. Does anyone have experience good or bad with the branded Coleman units?
3. Does sizing sound ok?
4. Any thoughts or recommendations on equipment, brands, etc for this application?

Thanks in advance for any guidance!

AJ

[coolwhip]

I dont think I have ever seen a Coleman RTU. Must not be popular here in The D.
Be sure to get some other quotes and ask for a commercial load calc on the space involved.

[Sleuth]

I would ask about the warranty and availability of parts.

I couldn't say I've seen a Coleman on a commercial roof ... it could happen.

[BaldLoonie]

Coleman RTUs are just Yorkies rebadged. So guess it boils down to how well a person likes a York unit.

RKNB is a Rheem unit which would be good as well.

[Sleuth]

Coleman RTUs are just Yorkies rebadged. So guess it boils down to how well a person likes a York unit.

RKNB is a Rheem unit which would be good as well.

Some people have learning curves, I run into shear cliffs.

[developerx]

So the proposal is presented as a Coleman (York) and the model # is actually a Rheem. Not getting the warm and fuzzy at the moment... Any other pointers? It would really help if I knew what the original York model was sized at. Thanks!

[Airmechanical]

yes the old one appears to be a 15 ton



.

[Sleuth]

So the proposal is presented as a Coleman (York) and the model # is actually a Rheem. Not getting the warm and fuzzy at the moment... Any other pointers? It would really help if I knew what the original York model was sized at. Thanks!

It's a york/Coleman ... a Rheem model #

???

D1SS180 is 15 ton/cooling

[developerx]

Ok, sounds like I've got some good info going here. Thank you!

[kdocsr05]

Your load calculation needs to include a 15% minimum outside air requirement at 95f

4,250 X 40 btu / 12,000 puts your calculated load at 14 tons then run the unit at 375 cfm per ton cooling and let the staging handle the dehumidification. I think the 15-ton unit was a good size for the loads you will expect during the summer cooling season and the 10-ton unit is under sized for maximum loads.

[flange]

the off brands(york, luxaire) are only allowed to sell to a certain tonnage, and are not supposed to replace a unit that is existing as york. that being said, you definately have a 15 tonner there, and to reduce to a ten, your contractor better be damn sure. the biggest reason tenants move out of commercial spaces is heating/cooling issues. do you want to keep yours? be sure of what you need by doing a real load calc, and KNOWING what you are buying. guessing hurts.

[BaldLoonie]

York is an off brand?

[timebuilder]

Coleman RTUs are just Yorkies rebadged. So guess it boils down to how well a person likes a York unit.

RKNB is a Rheem unit which would be good as well.

I was told that it was the other way around. The Yorks like this are made on the Coleman assembly line.