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Evaluating Heat and Moisture Load from Commercial Dishroom Appliances and Equipment

ASHRAE Research Project 1778

Evaluating Heat and Moisture Load from Commercial Dishroom Appliances and Equipment

From ASHRAE Journal Newsletter, September 22, 2020

Existing data relating to the heat gain and moisture load from dishroom equipment has been limited, but this type of information could assist HVAC designers in making better design decisions.

In ASHRAE Research Project 1778, Heat and Moisture Load from Commercial Dishroom Appliances and Equipment, researchers tested and collected data to analyze the heat gain to space for commercial foodservice equipment as it applies to the dishroom space. Denis Livchak, P.E., LEED AP, Associate Member ASHRAE, and Rich Swierczyna, Member ASHRAE, discuss the research.

1. What is the significance of this research?

This research will allow HVAC designers to properly size ventilation and space conditioning equipment for commercial dishrooms and improve thermal comfort for dishroom staff that typically operate in very hot and humid conditions.

2. How does this research further the industry's knowledge on this topic?

There is very little data on heat gain or moisture loading from dishroom equipment, so this research doubled the available information for dishroom HVAC designers and will enable them to make better HVAC design decisions.

3. What lessons, facts, and/or guidance can an engineer working in the field take away from this research?

A hood over a dishwasher does not mitigate all the heat and moisture issues in the dishroom. Engineers must take into account heat and moisture loads from all equipment that uses hot water in the dishroom, especially pre-rinse equipment.

4. Were there any surprises or unforeseen challenges for you when preparing this research?

It is more difficult to accurately quantify heat and moisture loads from smaller equipment than large dishwashers. Racks of washed dishes coming out of the dishwasher may generate more heat and moisture than the dishwasher itself. A small pre-rinse spray valve may generate more heat and moisture than an upright dishwasher. A dishwasher under a hood can capture as little as 40% of the heat coming off the machine. A high-temperature dishwasher with heat recovery generates as little heat load as a low-temperature dishwasher.

5. What are the next steps to further this research?

This research covered only generic product categories. Every dishwasher is designed differently and results in different heat gains (such as glass washers), so the heat gain database can be expanded. With hooded dishwashers, heat and moisture mitigation is a balance between exhaust airflow and space cooling; more research needs to be conducted on whether it is more cost-effective to mitigate that heat with exhaust airflow or space cooling for different climate zones in the U.S.