Potable Water Questions
04_42 Can polyethylene water pipe be used underground in a distribution system downstream of the polyethylene water service? Reference 7.2.5.5.(2), Table 7.2.11.2.and Appendix on page A-20?
Answer: (On. Reg. 403/97)
At first glance, we could not understand why someone would ask a question to which he already knew the answer unless it was his way of making us aware of a discrepancy in the code. We concur with your findings; ie. Code says in 7.2.5.5.(1) and in Table 7.2.11.2. PE for service pipe and in Sentence 7.2.5.5.(2) it allows PE pipe in underground cold distribution system only but the Appendix did not recognize Sentence (2). Knowing that the Appendix is only for explanatory material and not forming part of the code, it is easily dismissed. But, the Ministry has acknowledged the discrepancy and in the future OBC the wording will change if the scope of the Standard or the NPC wording has changed to say what the Appendix is referencing now. However, as it stands now, 7.2.5.5.(2) clearly states that PE pipe can be used underground in the COLD water distribution system.
04_43 Is the pipe manufactured by Wirsbo for distribution systems? What type of pipe is it and where is it referenced in the code?
Answer: (On. Reg. 403/97)
Wirsbo tubing is manufactured for distribution systems and is referred to as Aquapex. The name gives away the type of pipe and that is PEX which stands for Cross-linked polyethylene (PE...polyethylene and X...cross-linked). The references in the code are in 7.2.5.5.(4) and 7.2.11.2. You should also check the Appendix for additional information A-21 and for a quick summary A-22. It must be certified to CAN/CSA-B137.5. Note: Be careful of other Wirsbo product designed for radiant floor heating called HePex. That product is NOT approved for potable water.
05_02 I’ve inspected an installation using the potable hot water as a heat source. The cold water passes through a ATakagi T-KD20"" instantaneous water heater, to supply the hot water for the radiant heat loop, and has a branch just downstream of the heater to supply potable water to the house. This branch has a thermostatic mixing valve on it to bring the water down to the code required temperature. The concern I have is that the water in the heating loop will become contaminated, especially over the summer, and that it is not separated from the potable water available to the occupants. The manufacturer recommends that the recirculating pump run for 60 seconds every 6 hours, and that a priority switch be installed on the cold water inlet to temporarily shut down the pump when water is drawn by the occupant, but is that enough? As an example, the water has been sitting in the heating loop all summer, and has been doing its loops through the heater every 6 hours. Part way through the cycle the occupant draws off hot water to add to soup. The water that is present in the heater at that time could have been trapped in the heat loop all summer. This water would then be supplied to the occupant through the potable water system. Do you agree with my concern? Should I request a separate system?
Answer: (On. Reg. 403/97)
1. According to the OBC requirement, the proposed installation may render the potable water and becomes non-potable. Therefore, such a connection is prohibited in accordance with Sentence 7.6.2.1. of the OBC. 2. Authority having jurisdiction can always accept other design or installation methods based on Section 2.7 of the OBC if warranted. Authority can reject or accept a design proposal if the CSA B214 Standard is being used with a double wall heat exchanger, or by re-circulating water within the heating loop even during summer time and complete with all components/piping which will meet the NSF 61 criteria and potable water piping required by the OBC.
05_18 What is an acceptable backflow prevention valve for an underground sprinkler system at a residence?
Answer: (On. Reg. 403/97)
If it is determined from the installation of the lawn sprinkler system that the hazard is moderate and that protection is against back siphonage only, then the device required would be an Atmospheric Vacuum Breaker, a Double Check Valve Assembly or a Pressure Vacuum Breaker. However, if the degree of hazard is assessed at severe (ie. chemical systems included), then a Reduced Pressure Principle Backflow Preventer or a Pressure Vacuum Breaker would be required. An example of a moderate hazard submitted by one of the committee members was that sprinkler heads were raised above adjacent ground and another member suggested that it was dependant on which side of the solenoid the backflow preventer was located under pressure or not?
05_19 How does Sentence 7.6.2.3.(8) apply to Article 7.6.2.3. and what is the intent?
Answer: (On. Reg. 403/97)
As the title of the Sub-section would suggest, the intent of the Articles are to protect the potable water systems from contamination. The various Sentences in Article 7.6.2.3. go on telling us where and how to protect the water system. Sentence (5) is giving us the requirement for premise isolation as stipulated in the CAN/CSA- B64.10. Like most requirements, there are exceptions and you should note that Sentences (4) and (8) form part of those exceptions. Sentence (8) is a clarification that Part 9 buildings of residential occupancy do not need to be isolated UNLESS they have access to an auxiliary water supply.
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