Water Circulation System

[Mech]

2018 Int'l Energy Code

C404.6.1 Circulation systems.
Heated-water circulation systems shall be provided with a circulation pump. The system return pipe shall be a dedicated return pipe or a cold water supply pipe. Gravity and thermo-syphon circulation systems shall be prohibited. Controls for circulating hot water system pumps shall start the pump based on the identification of a demand for hot water within the occupancy. The controls shall automatically turn off the pump when the water in the circulation loop is at the desired temperature and when there is not a demand for hot water. [bolded text mine]

The locker room and toilet room water fixtures in a proposed manufacturing facility will utilize the code required pump system with activation requirements.

The manufacturing facility deals with chemicals and there will be several combination emergency shower / eyewash stations and stand-alone eyewash stations. They have sinks in work rooms where any water heaters installed in the work rooms would need to match the electrical class / division requirements. They have already determined from past experience that using water heaters with the proper class / div requirements is not in their best interest. Their desire is to duplicate the setup at an existing facility and install a bank of tankless water heaters with a storage tank in their boiler room and continuously circulate hot water through-out the plant. Is there an exception for water used in these areas to be exempt from the energy code requirements?

Thanks for any help!

 

[Bryant]

No desire for the energy code amongst us fossil fuel dinosaurs.
First thing I'd want to know is, the manfuacutres specifications for ganging tankless water heaters. Seems to me the point is hot water on demand is to be close as possible to the fixture served for energy conservation.
The other side of storage tanks is capacity, in VA anything over....boilers, water heaters, etc
As to the H2O exception, I do not know if there is. Outside of being in a H use with divisions & classifications, the intent is to keep the water temparture in check with demand with circulation, otherwise not point to the method. Storing it seems doable with the corect commands with on call usage, I dont see an exemption honestly.

 

[Paul Sweet]

I'd say that there is a demand for hot water whenever the building is occupied, especially when there are emergency showers and eyewashes.

 

[steveray]

Note to whoever....2021 IECC want the HW "source" to be within 24" of a public lav....

 

[Paul Sweet]

2 ft. is crazy, as well expensive and a maintenance nightmare! Lavatories are required to be at least 30" O.C., so the only way to meet this is with a point-of-use water heater between each pair of lavs.

 

[Energystar]

I think lavatory faucets only need to be 3/8". Also, the recir. line counts as the "source".

 

[steveray]

I think lavatory faucets only need to be 3/8". Also, the recir. line counts as the "source".

Correct on the source, but generally lavs are fed with 1/2".....

 

[Mech]

2018 IECC C404.5.2 Maximum allowable pipe volume method. The water volume in the piping shall be calculated in accordance with Section C404.5.2.1. Water heaters, circulating water systems and heat trace temperature maintenance systems shall be considered to be sources of heated water. The volume from the nearest source of heated water to the termination of the fixture supply pipe shall be as follows:
1. For a public lavatory faucet: not more than 2 ounces.
2. For other plumbing fixtures or plumbing appliances; not more than 0.5 gallon.