Thermal Expansion Control on Storage Water Heater with Circulating Pump

[jar546]

What is your answer?

 

[ICE]

yes

Is it me or is it you?

 

[jar546]

Is it me or is it you?

It's you.

 

[wwhitney]

For the UPC, looks like expansion control is only required when (608.2) a pressure regulator is installed or (608.3) there is a "check valve, backflow preventer, or other normally closed device that prevents dissipation of building pressure back into the water main". I see no blanket requirement that a circulation pump triggers a requirement for expansion control.

606.9 does require a check valve whenever a circulation pump is installed, "to ensure the direction of flow." However, as long as there is only one check valve on the recirculation loop (counting the pump itself if it has a check valve or functions as a check valve), 608.3 would not be triggered by that. That is, the recirculation loop provides two distinct paths for expansion back to the water heater cold supply, so a single check valve on the recirculation loop will only block one of those paths.

Cheers, Wayne

 

[jar546]

For the UPC, looks like expansion control is only required when (608.2) a pressure regulator is installed or (608.3) there is a "check valve, backflow preventer, or other normally closed device that prevents dissipation of building pressure back into the water main". I see no blanket requirement that a circulation pump triggers a requirement for expansion control.

606.9 does require a check valve whenever a circulation pump is installed, "to ensure the direction of flow." However, as long as there is only one check valve on the recirculation loop (counting the pump itself if it has a check valve or functions as a check valve), 608.3 would not be triggered by that. That is, the recirculation loop provides two distinct paths for expansion back to the water heater cold supply, so a single check valve on the recirculation loop will only block one of those paths.

Cheers, Wayne

It's amazing how the IPC and UPC differ. Here is the IPC

607.3Thermal expansion control.​

Where a storage water heater is supplied with cold water that passes through a check valve, pressure reducing valve or backflow preventer, a thermal expansion control device shall be connected to the water heater cold water supply pipe at a point that is downstream of all check valves, pressure reducing valves and backflow preventers. Thermal expansion control devices shall be sized in accordance with the manufacturer’s instructions and shall be sized such that the pressure in the water distribution system shall not exceed that required by Section 604.8.

 

[wwhitney]

It's amazing how the IPC and UPC differ. Here is the IPC

If there's just one recirculation check valve, and the recirculation loop goes from the hot water outlet back to a tee on the cold water inlet, then to avoid triggering IPC 607.3, all you need to do is install the check valve somewhere other than the cold water pipe between the tee and water heater. The language in UPC 608.3 is a bit more general and I would say recognizes that even with a single check valve in that location, there's a path for expansion back to the water main via the recirculation loop itself.

Cheers, Wayne

 

[ICE]

Commercial buildings almost always have a back flow preventer at the main line.

 

[jar546]

Commercial buildings almost always have a back flow preventer at the main line.

Yes, agree.