# Water Heater Sizing



## Mech (May 24, 2011)

2009 code series

I thought some codebook somewhere in the ICC arsenal stated that water heaters must be sized by the manufacturer. Am I remembering correctly? Where does it state this?

Thanks


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## mtlogcabin (May 24, 2011)

2009 IPC

Chapter 5 Water Heaters. Chapter 5 regulates the design, approval and installation of water heaters and related safety devices. The intent is to minimize the hazards associated with the installation and operation of water heaters. Although this code does not regulate the size of a water heater, it does regulate all other aspects of the water heater installation such as temperature and pressure relief valves, safety drip pans, installation and connections. Where a water heater also supplies water for space heating, this chapter regulates the maximum water temperature supplied to the water distribution system.

2009 IRC

Chapter 28 Water Heaters. Chapter 28 regulates the design, approval and installation of water heaters and related safety devices. The intent is to minimize the hazards associated with the installation and operation of water heaters. Although this chapter does not regulate the size of a water heater, it does regulate all other aspects of the water heater installation such as temperature and pressure relief valves, safety drip pans and connections. Where a water heater also supplies water for space heating, this chapter regulates the maximum water temperature supplied to the water distribution system.


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## steveray (May 24, 2011)

Mech...

Did you mean listed and labelled type "sizing"?


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## Mech (May 24, 2011)

I was thinking more along the lines of: I am designing an office building for 50 people with two lavatories and one kitchen sink.  What size water heater and input (gph oil, kW electric, cfh gas) do we need for a one hour recovery?  I cannot find anything in the IPC nor in the IECC that requires the manufacturer to size the water heater.  Maybe I read something wrong or was misinformed.


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## rshuey (May 24, 2011)

I would put in tankless and be done.


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## mtlogcabin (May 24, 2011)

UPC Table 5.1 has a first hour rating based on bedrooms and baths

Check this link

http://www.consumerreports.org/cro/appliances/heating-cooling-and-air/water-heaters/how-to-size-a-water-heater/overview/sizing-hot-water-heaters-ov.htm

and this one

http://www.daviddarling.info/encyclopedia/W/AE_water_heater_size.html

Even a tankless needs to be properly sized and may require more than one


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## peach (May 24, 2011)

don't even know that hot water is required.  I believe the code calls for tempered water in commercial uses.  No minimum or maximum temp.


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## cda (May 25, 2011)

I guess the question is why would the maker get involved and be required to size it????


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## Pappy Code dog (Aug 12, 2011)

No min, just what ever tempered means, Max dependant on fixture.


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## Builder Bob (Aug 15, 2011)

Pappy Code dog said:
			
		

> No min, just what ever tempered means, Max dependant on fixture.


IPC defintion :

TEMPERED WATER. Water having a temperature range

between 85°F (29°C) and 110°F (43°C).


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## north star (Aug 16, 2011)

*& & & &*

Mech,

Water heater sizing is not [ yet ] required by the I-codes, however,

there are some formulas and "guidelines" that can be applied.....The

following link is just one example:



http://www.burtonandsons.com/webapp/GetPage?pid=197

See if the example will help you.   



*& & & &*


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## peach (Aug 17, 2011)

depends on how much hot water a building needs... and... if water conservation is a concern, some places are limiting the amount of water that can be left in the hot water lines is 87 ounces (about 11 cups)... you'll have to design the plumbing system and include insta hots even in some homes.  (Which means the plan review needs to ask for more than a domestic water riser diagram).


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## Pappy Code dog (Jan 27, 2012)

I stand corrected, thank you Bob!!!!!!!


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