Installing T&P valve inverted position
- Thread starter Leegrif
- Start date
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Code states it needs a downhill slope. No backgrading
camaroderrick73 said:
There are some jurisdictions where they will let you run them uphill so long as they dump outside of the building.
Do not, under any circumstances, run a T&P drain inverted. It shall discharge vertically down and can drain horizontally after the vertical, but should never offset back up or have back fall on it. Never ever.
Nukedaddy
Well-Known Member
Reverse grade is bad for all RVs as it allows the discharge to collect on the "wrong" side of the valve seat, corroding the spring holding the stem/washer in place. Also, most RVs do not have a stem packing, so the water or condensate will leak out along the stem.
There are, however some RVs that provide for such issues, and have a "seat drain" orifice on the side of the RV, often protected by a very small diaphragm check. The discharge from the orifice is far smaller than that of the RV proper, and might be drained to a visible container as a "tell-tale" that the RV has discharged.
Whether such an equipped RV is approved for use in your code jurisdiction would be up to the local inspector. He can, by the way, allow a code variance for situations where the code must be bent to fit the needs of safety and sanitation.
There are, however some RVs that provide for such issues, and have a "seat drain" orifice on the side of the RV, often protected by a very small diaphragm check. The discharge from the orifice is far smaller than that of the RV proper, and might be drained to a visible container as a "tell-tale" that the RV has discharged.
Whether such an equipped RV is approved for use in your code jurisdiction would be up to the local inspector. He can, by the way, allow a code variance for situations where the code must be bent to fit the needs of safety and sanitation.
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His reference to the T&P valve as an "RV" simply means "relief valve".
The relief valve doesn't discharge at full pressure of the system and sometimes just drips a little bit, too. So if you have back fall or trapped water in the pipe, it may sit there and cause problems with the valve or the piping so that it may not operate properly or even fail.
Just try to find a way to pipe it down, with no turns up and with no back fall.
Nukedaddy
Well-Known Member
Caduceus is right. And I should have better sense than to use an acronyms without spelling it out at least once. After I re-read your original post I realized that lowering the discharge may be easier than it looks. Does the discharge go into the wall behind or to the side of the water heater? Is the main reason you have a mismatch due to changing out an electric heater with a gas heater? (Electrics almost always have the T&P relief valve located dead-center top, while gas units are always near the top but on the side of the heater. If the original discharge line goes into the adjacent wall, get out your drywall saw and open the wall to find out where it goes. (straight down through the floor into the crawlspace?) If so, shortening the line to a point where you can pipe to the T&PRV with continuous fall must be done. If the line must pass in front of the heater, consider one or more unions in the line for future removal.
If the original drain does something really strange, or if you are dead set against having to repair and repaint drywall, consider a new discharge line through the floor. Some codes even allow plastic discharges, and you would only have to drill a 1" hole through the floor. (Be aware that some codes forbid discharges into unheated crawlspaces or other space where the end of the discharge might fill with ice and defeat the T&PRV.
If the original drain does something really strange, or if you are dead set against having to repair and repaint drywall, consider a new discharge line through the floor. Some codes even allow plastic discharges, and you would only have to drill a 1" hole through the floor. (Be aware that some codes forbid discharges into unheated crawlspaces or other space where the end of the discharge might fill with ice and defeat the T&PRV.
chukar said:
Now that u say it, you correct I totally forgot about it.. In Cali they want you to install a small tubing into a coffee can the run it uphill.
That's for the refresher, have done that on a loooong time
