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C404.5 Efficient heated water supply piping.

Discussion in 'Commercial Energy Codes' started by Jamie Holmes, Oct 10, 2018.

  1. Jamie Holmes

    Jamie Holmes Registered User

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    I was introduced to this section of the code for the first time in a recent plan review. I'm still scratching my head. Our plumbing specialist and I read and re read this and the subsequent sections many times. The official stated that since we were using 1/2" NP pipe (Which was fully insulated) from the instant water heater to the check valve below the public lavatories (2 men's and 2 women's) in a park restroom building, that this tempered water supply pipe could only be 2' in length. In order to make the corrections to the plans as he indicated we ended up adding a second instant water heater, because the restrooms are divided by a 6' wide mechanical chase and there was no other way to reach all 4 lavs with 2' of pipe. Fast forward to this moment> same type of building but the state this building is going to requires tempered water supply pipe to be a minimum of 3/4" NP. According to Table C404.5.1 I have 6" of pipe to go from the water heater outlet to the angle stop for 4 public lavatories from a mechanical chase which is separated from the restrooms by a 4" thick CMU wall. If this officials interpretation is correct, I would need to install a water heater under each lavatory where it would be subject to the vandalism we all know happens in public park restrooms or install a circulation system. Customers don't choose the expensive way to meet the code when we hit a wall like this. They would rather put a 2.5 gallon storage water heater at each sink rather than pay to put in a circulation system because they can buy these little water heaters cheap. I wonder where the energy conservation is in this method.
    So, my question; Is the interpretation we were given by the code official how you interpret this code? I feel like we're missing something.
     
  2. mp25

    mp25 Registered User

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    The distances in the table are maximum pipe lengths from the source of heated water (the tap off from a circulation system or a heat trace tape system) to the termination of the fixture supply pipe. It does not give you a lot of room to work with for public lavs and I agree with the lengths that you described. If a circulation system is not a feasible option, you can heat trace tape it, or install water heaters close by as you suggested.
    My personal opinion on this section is that it seems like there is a lot of work that is being done for little benefit for small projects. My guess is that it takes more energy to produce those extra water heaters than the energy that will be saved. Water might be saved, but that is not the purpose of the energy codes. I will have a copy of the commentary version of the code next week, so I will read some of the reasoning behind this section.
     
  3. Francis Vineyard

    Francis Vineyard Sawhorse

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    Assuming 2015 edition and new construction, if not then Chapter 5 would be applicable. To my knowledge ASHRAE is more flexible. Hope this helps.

    C401.2 Application.
    Commercial buildings shall comply with one of the following:

    1. The requirements of ANSI/ASHRAE/IESNA 90.1.

    2. The requirements of Sections C402 through C405. In addition, commercial buildings shall comply with Section C406 and tenant spaces shall comply with Section C406.1.1

    3. The requirements of Section C402.5, C403.2, C404, C404, C405.2, C405.5, C405.6 and C405.7. The building energy cost shall be equal to or less than 85 percent of the standard reference design building.
     
  4. Jamie Holmes

    Jamie Holmes Registered User

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    Thank you for your reply. I finally was able to get a technical opinion from ICC and the interpretation from the BO is correct. Basically the energy code is written to force the use of a circulating system or heat trace as you mentioned. We are currently redesigning our system with the circulating pump and utilizing the lighting occupancy sensors and relays so that the water will be tempering as the occupant enters the building whether or not they choose to use the water. This seamed to be the most conservative energy option between circulating and the heat trace. We feel the client will accept this as opposed to the installation costs of 4 water heaters and dealing with the accessibility issues.
     
  5. Jamie Holmes

    Jamie Holmes Registered User

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    Thank you for this. I read 2013 ANSI/ASHRAE/IESNA 90.1 section 7. Is it just me, or are these same requirements not even touched on?
     
  6. Francis Vineyard

    Francis Vineyard Sawhorse

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    That's my understanding (though we're still on the 2012 IBC & 2010 ASHRAE).
     
  7. Yikes

    Yikes Gold Member

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    Just checking another option - - for a park restroom, could you simply forego the tempered/hot water in the lavs altogether?
    I'm currently doing a park project in so Cal where the city and their building official have determined that tempered or hot water is undesirable; it is making sanitation worse, not better, because the homeless population strips down and uses the lav as their personal bathing facility.

    They cited UPC 601.2 Hot and Cold Water Required. "Except where not deemed necessary for safety or sanitation by the Authority Having Jurisdiction, ..."
     
    Francis Vineyard likes this.
  8. Francis Vineyard

    Francis Vineyard Sawhorse

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    Does sanitation and safety include health?
    OSHA is against IECC hot water recirculation as it promotes Legionella.
     

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