Hot Water Heater's Overflow Pipe - Plumbing - DIY Home Improvement | DIYChatroom

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Old 08-11-2009, 05:11 PM   #1
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Hot water heater's overflow pipe

I've looked in the instructions, but couldn't find out how far the overflow pipe should be from the floor. What's the typical clearance for this pipe from the floor? Thanks.


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Old 08-11-2009, 06:17 PM   #2
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Random google search came up with this; likely would be acceptable most places (should check with your local authority if there is one). I think somewhere between 6 and 12" off the floor but in an attic, etc... may need to be discharged outside. See below or a plumber will check in.

Frisco Texas Water Heater Installation Requirements:
The City Frisco Texas follows the 2006 International Plumbing Code. Local amendments listed: Water heaters installed above ground or floor. When the attic, roof, mezzanine or platform in which a water heater is installed is more than eight (8) feet above the ground or floor level, it shall be made accessible by a stairway or permanent ladder with a minimum 300 pound capacity fastened to the building, or an access door from an upper floor level. Exception: a max 10 gallon water heater (or larger with approval) is installed is not more than ten (10) feet above the ground or floor level and may be reached with a portable ladder.
Requirements for discharge pipe: The discharge piping serving a pressure-relief valve, temperature relief valve or combinations valve shall: not be directly connected to the drainage system. Discharge through an air gap located in the same room as the water heater. Not be smaller than the diameter of the outlet of the valve served and shall discharge full size to the air gap. Serve a single relief device and shall not connect to piping serving any other relief device or equipment. Discharge to an indirect waste receptor or to the outdoors. When discharging outside the building, the point of discharge shall be with the end of the pipe six (6) inches above the ground or the floor level of the area receiving the discharge and pointing downward. Discharge in a manner that does not cause personal injury or structural damage. Discharge to a termination point that is readily observable by the building occupants. Not be trapped. Be installed to flow by gravity. Not terminate more than 6 inches above the floor or waste receptor. Not have a threaded connection at the end of the piping. Not have valves or tee fittings. Be constructed of those materials listed in Section P2904.5 or materials tested, rated and approved for such use in accordance with ASME A112.4.1. Not discharge into a pan required in Section 2801.5. T & P discharge line requires a union.
Where water heaters or hot water storage tanks are installed in attics or furred spaces, in an approved location within the occupied area of a building or in a garage adjacent to the common wall with an occupied area where leakage of the tanks or connection will cause damage, the tank or water heater shall be installed in a galvanized steel pan having a minimum thickness of 24 gage or other pans approved for such use.


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Old 08-12-2009, 09:47 AM   #3
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Most areas require no more than 6" from the floor. Florida, required they be piped outside the house, with a tee, one end facing upwards so leaks could be seen, and a 6" pipe, with stone inside, a distance of 16" into the ground. In units I have installed, if the T/P valve made the discharge pipe be towards a door, I installed an elbow facing towards the rear so no one got scalded if it opened. Check your Local Codes.
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Old 08-12-2009, 10:50 PM   #4
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2-3" off the floor is where I put them. By the way...that IS NOT an overflow pipe. It is the discharge from your temperature and pressure (T&P) valve. A water heater doesnt have an overflow.
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Old 08-13-2009, 06:59 AM   #5
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as some of the others have said 6'' from the floor.. This is from watts t&p instructions..
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Old 08-13-2009, 05:23 PM   #6
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Well, it sounds like it should be anywhere between 3 to 6 inches off the floor. I appreciate the information.
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Old 08-13-2009, 10:28 PM   #7
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There's no code for it in the International Plumbing Code. Local rules that require it be piped outside are nothing short of ridiculous! It should be piped to a conspicuous location so the homeowner can see it leaking should the valve ever start to leak or should there ever be a T&P blowoff.

Within a few inches of the floor is the norm, but that is driven by common practice and manufacturer's instructions for installation. Leaving it 3' off the floor could leave potential for water/steam burns in the event of a blowoff.


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