Grocery Store HVAC Design Tips 1

[PatBethea]

I've been asked to provide a quote to design the HVAC system for a new grocery store. This project is just different enough that I thought I'd see if I could garner any tips. There's a small section on "supermarkets" in the ASHRAE Applications Handbook (2007 - Ch. 2). Does anyone have any other references on the subject they'd like to share? Any design tips/things to avoid? What's the preferred method of humidity control?

Some site-specific info: Located in southwest GA. At this point, I assume I'll be spec-ing air-cooled condensing equipment. The floor plan I've been given shows open refrigerated display cases around 3-1/3 sides and closed freezers running down the center aisles. The (potential) client has stated that he prefers to have air returns just above the refrigerated cases - which runs counter to what ASHRAE seems to recommend (floor returns).

Thank you.

 

[AbbyNormal]

recalim heat from the refrigeration, probably heat a store in a georgia winter, get reheat in summer to control humidity

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[DonPhillips]

Depending on the size of the store and the type of entry doors, you may want to consider a zone around the main entry to better control the temperature near the doors, especially if there is staff near them - like for cash registers.


Don Phillips

http://worthingtonengineering.com

 

[gepman]

As AbbyNormal says you should reclaim heat from the refrigeration systems for the display freezers and refrigerators. You should probably also subcool the liquid refrigerant in the MT (Medium Temperature) refrigeration system. The MT system is probably subcooling the liquid for the LT (Low Temperature) system.

You should integrate your design with the display case refrigeration system so the overall efficiency of the refrigeration systems is optimized.

 

[AbbyNormal]

the refrigeration manufacturers will usually tell you how much heat they feel you can reclaim from the racks

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[ChrisConley]

Don't forget the bakery fan...

Few designs we done have included a transfer fan that exhausts from the bakery and discharges above the entrance.

I scratched my head for quite a while trying to figure out the purpose.... which is that bakery smells make people hungry, hungry people buy more.

 

[AbbyNormal]

never heard that one about a bakery fan Chris, makes sense though

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[Wareagl487]

Don't forget the bakery fan...

Yep - Did a Whole Foods here in Atlanta - That is part of their design criteria.

Andy W.

 

[therockinks]

From a refrigeration service engineer's view
I know you have to follow customers spec for top
of case returns
High returns just above the cases?
All case manufacturers strongly recommend
Do not allow any hvac airflow patterns of supply or return
near cases that can disrupt inside case airflow patterns

Most mid sized stores run 60 to 100 hp on refrigeration
We have to assume that 100 hp is falling directly
on the floor
Why not take advantage of that 100 hp to cool the building
with low returns?
Under floor tunnels have been used here in the midwest
for return air, refrigeration piping, electrical & plumbing

Check the temperatures in a supermarket with high returns
I think you'll find
40F floor temp, 72F at thermostat height and 100F+ roof height

Air statifies in supermarkets due to cold air falling off
cases, freezer doors opening and open freezer cases
With 8Ft high or higher returns your heat stays against
the roof (assuming no dropped ceilings) and the cold air
stays on the floor
The customer stops buying when their feet get cold ask them

If you have a 100hp central rack type refrigeration
why not pull that 100 hp off the floor run it through
heat reclaim pick up another 50HP of refrigeration motor
heat and heat of compression
=150HP for heat and 100 HP cooling the building on July 4th
You'll have to work with the rack equipment manufacturers to
get BTUs,hp, cfms for heat reclaim coils and air handlers
add destratification or a second roof height return to pull
heat off the ceiling and you have just about eliminated
heat and a/c units and cold isle complaints
Damper off high returns in the summer
Let that heat stay up there

If you're pulling 100hp out of a building with
refrigeration what kind of heat
load do you have remaining for a/cs?
What is your remaining load if any?
If the store closes will the hvac be required to serve
a new non-grocery tenant without refrigeration?

On July 4th I have watched many high return stores with
rooftop furnaces running steady until 12:00 noon then
shifting to a/c in the afternoon
You have to sell allot of hamburger to make that back

Why is it that when it comes time to trim fat off the
budget they usually chop off the return ductwork then
they pay for it for the rest of the life of the building?
Ductwork and insulation are items that increase in value
every time energy rates go up

I hope I have helped you with some views from the service
side of the industry

John R

 

[PatBethea]

Thanks for all the replies. I didn't get the job, though - I was unable to commit to the desired timetable. Next time . . .

 

[AbbyNormal]

That is honourable and professional to disclose you culd not meet what could have been an unreasonable time frame.

9 times out of 10 the entity who takes on the project does not meet the deadline either.

Take the "V" out of HVAC and you are left with a HAC(k) job.