View Full Version : T&P drain

12-15-2008, 10:57 AM
I need to replace the T&P valve on my water heater and am wondering about how to connect the drain. The valve is currently hard piped into a 3/4 copper drain leading outside. When I replace the valve, would it be OK to connect to the existing drain with a flexible braided supply line, or would that not hold up if the valve released? Thanks--Brad

T&P Valve looking at two sides.

12-15-2008, 11:48 AM
It would hold up, but would not pass codes or inspections because of its construction.

12-15-2008, 12:24 PM
Where I am at code does not allow for a T&P to be piped outside or under the house. Must be piped to at least 6" (IIRC) above the floor, termination visible from the appliance. I'd check your local codes.

12-15-2008, 02:41 PM
the idea is that if the tp valve does blow off excess pressure, the resident will see it and be appropriately alarmed to take action. So it should be inside and visible,

12-16-2008, 07:20 AM
the idea is that if the tp valve does blow off excess pressure, the resident will see it and be appropriately alarmed to take action. So it should be inside and visible,

That makes sense, because I didn't notice the weeping with the current drain only about an inch over grade outside...until it created a swamp.

12-16-2008, 05:51 PM
It also says it must terminate in a location which will not cause damage, and most interior locations would cause damage.

12-16-2008, 08:27 PM
Not seeing t&p's piped to daylight always looks weird to me.

12-16-2008, 09:39 PM
504.6 Requirements for discharge piping. The discharge
piping serving a pressure relief valve, temperature relief valve
or combination thereof shall:
1. Not be directly connected to the drainage system.
2. Discharge through an air gap located in the same room
as the water heater.
3. Not be smaller than the diameter of the outlet of the
valve served and shall discharge full size to the air gap.
4. Serve a single relief device and shall not connect to piping
serving any other relief device or equipment.
5. Discharge to the floor, to an indirect waste receptor or
to the outdoors. Where discharging to the outdoors in
areas subject to freezing, discharge piping shall be first
piped to an indirect waste receptor through an air gap
located in a conditioned area.
6. Discharge in a manner that does not cause personal
injury or structural damage.
7. Discharge to a termination point that is readily observable
by the building occupants.
8. Not be trapped.
9. Be installed so as to flow by gravity.
10. Not terminate more than 6 inches (152 mm) above the
floor or waste receptor.
11. Not have a threaded connection at the end of such piping.
12. Not have valves or tee fittings.
13. Be constructed of those materials listed in Section
605.4 or materials tested, rated and approved for such
use in accordance with ASME A112.4.1.
504.7 Required pan. Wherewater heaters or hotwater storage
tanks are installed in locations where leakage of the tanks or
connections 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.
504.7.1 Pan size and drain. The pan shall be not less than
1.5 inches (38 mm) deep and shall be of sufficient size and
shape to receive all dripping or condensate from the tank or
water heater. The pan shall be drained by an indirect waste
pipe having a minimum diameter of 0.75 inch (19 mm). Piping
for safety pan drains shall be of those materials listed in
Table 605.4.
504.7.2 Pan drain termination. The pan drain shall extend
full-size and terminate over a suitably located indirectwaste
receptor or floor drain or extend to the exterior of the building
and terminate not less than 6 inches (152 mm) and not
more than 24 inches (610 mm) above the adjacent ground

12-20-2008, 01:45 PM
Are you totally positive that it's the T&P valve that's the problem and not your pressure regulator? Usually the T&P valve will leak before the Pressure relief valve since the hot side is under more pressure from the heat.

Just something to check before you go and replace the T&P valve.

You can also just cut the existing drainline well below the MIP going into the T&P valve. Unscrew put it back into the next T&P and reconnect using a Sharkbite coupling to put it back together. Depends on the codes for your state and local as to what you can use. If compression fittings are legal to use, u can get a brass compression coupling (not a g-coupling).