Code Tidbit - October, 2011 By: Douglas A. Page, PE, MPA, LEED AP, CEM, CPD
I've been researching and thinking about balancing of domestic hot water systems for years now. Ultimately, I plan on writing an article on this topic. Let me let one part of the proverbial cat out of the bag.
The Plumbing Code states:
§P607.2 Hot water supply temperature maintenance. Where the developed length of hot water piping from the source of hot water supply to the farthest fixture exceeds 100 feet (30 480 mm), the hot water supply system shall be provided with a method of maintaining the temperature in accordance with the Energy Conservation Construction Code of New York State.
Although we might use a temperature maintenance cable, we most often maintain hot water with recirculation loops. Flow rates for the loops are determined by one of several methods - such as ASPE Plumbing Engineering Design Handbook Volume 2, Chapter 6. We balance the loops using balancing valves to the design flow rates.
The plumbing system valves, including the balancing valves, are regulated by the Plumbing Code. It states:
§P605.7 Valves. All valves shall be of an approved type and compatible with the type of piping material installed in the system. Ball valves, gate valves, globe valves and plug valves intended to supply drinking water shall meet the requirements of NSF 61.
You could argue that hot water balancing valves are not intended to "supply drinking water". However, per the ICC Code Commentary for the 2006 IPC, "…Valves used in the water supply system that come into contact with the potable water source must conform to the requirements of NSF-61.
The balancing valves used in hot water return systems must meet NSF-61. So what's the problem? Succinctly, there aren't any that comply. I spoke with many manufacturers of balancing valves over the years. Some are more open about their non-compliance than others. One manufacturer of say, a blue balancing valve, point-blank responded to my inquiry and stated they did not comply and had no current plans to have the valve comply. Although I would rather have valves I can use in this application, I can respect their honesty on the matter.
There are other manufacturers that, well, are more misleading on the issue. One manufacturer that has balancing valves that are red in color, markets their valve to the plumbing industry. They advertise in their catalog cut "CSA Certified… ANSI/NSF-61 Annex G Compliant". They are not listed on NSF's website. They are not listed on CSA's website. They could provide no test data demonstrating compliance.
Per Annex G and discussions with NSF International, to comply with Annex G the valve must first be tested to NSF-61. Per discussions with the manufacturer, if the valve was tested by others he was confident the valve would pass NSF-61. Needless to say, our chat was not productive. Aren't manufacturers supposed to have devices tested BEFORE the make claims of compliance with industry standards? If you are an unsuspecting designer, wouldn't you assume the valve complies with NSF-61?
So what's the answer here? Since you read this column, you now know specifying and installing balancing valves in domestic water systems is violating the Code. The real answer is for manufacturers to stop dancing around the issue and get their valves tested and approved to the NSF-61 standard. I bet the first manufacturer to do so would rapidly grow their market share. Perhaps temperature maintenance cable manufacturers should just post this column in their lobbies and include it in their advertisement literature.