Last week on our 2-part blog series, we have talked about the renovation of Hot Water System for Snack Food Manufacturer.
After hours of compiling information relative to the application and evaluating Snak King’s goals for its rebuilding project, considering its future capacity goals, Ponce proposed the following hot water system:
Manufacturing plant hot water demand load requirement — 120 GPM with long term plant capacity increases to 165 GPM for up to four-hour intervals; 7,200 to 9,900 gallons per hour; and
Hot water system design operating temperature — 120° F; temperature rise: 65° F.
Other relative criteria:
- Endless hot water supply;
- Limited available space;
- Energy efficiency required;
- Redundancy needed;
- Serviceability without any down time;
- Capacity expandability of the hot water system; and
- Cost effective solution
Based on the above criteria, Ponce proposed specifying for this application a multi-unit system of 28 WaiWela (pronounced “Vi-vela”) PH-28COF outdoor commercial tankless water heaters, manufactured by Paloma Industries. WaiWela means “hot water” in the Hawaiian language. The unit is rated with an input of 199,900 Btu/hr, so the 28-unit system could modulate from the minimum input of a single unit, just 19,000 Btu/hr, up to 5.6 million Btu/hr with all heaters firing. With each unit capable of continuously producing 5.2 GPM hot water at the 120 set point, the system is capable of continuously producing 145.6 GPM, or 8,736 gallons per hour.
Space is limited inside the Snak King manufacturing plant so Ponce proposed mounting the 28 PH-28COFs on two skids in different locations on the roof of the plant. Coast Aerospace in Huntington Beach, Calif. fabricated two galvanized steel skids at grade.
One skid has 16 units plumbed in parallel with a 1/8 HP circulator pump to deliver immediate hot water to one area. The second skid has 12 units plumbed in parallel with a 1/8 HP circulator to deliver hot water to another area at the plant. The light weight of this system allowed for installation without increasing the roof’s load capacity.
The WaiWela water heater has an energy factor of 0.82. The units are particularly energy efficient in this application because they modulate continuously to produce only the amount of additional heat needed by current demand in the system. These high-efficiency units also qualified for rebates from the local gas company and federal tax credits.
Each WaiWela bank is controlled by a MIC-180 multi-unit system controller, also produced by Paloma. The controller modulates the firing of each WaiWela heater in the system, and rotates the sequence of firing to even out usage of all units over the lifetime of the system.
In what is to be the largest tankless water heater installation in the United States to date, Snak King recently leveraged its innovative spirit in the implementation of a new hot water system for production processing.
The water heaters were plumbed in parallel to provide redundancy and each was installed with an isolation valve kit by Webstone to allow for individual servicing without disrupting hot water service to the manufacturing plant below. Tru-Flex Metal Hose Corporation’s Home-Flex high volume gas connectors were installed to allow for the high Btu/hr volume required for a tankless water heater. This allowed the installing mechanical engineer to eliminate using rigid gas pipe to each unit. Falcon Stainless Steel water connectors were also installed to eliminate plumbing rigid copper pipe from the 4″ manifolds to each water heater.
Another advantage of this system was to allow for future expandability. The skid holding 12 units is expandable to 16 units for increased future manufacturing capacity.
Finally, the cost of each commercial WaiWela tankless system was significantly less than a comparable boiler system. Each WaiWela tankless water heater, with input below 200,000 Btu/hr, did not require the ASME approval that can effectively raise the cost of larger systems.