Would anyone write up a tpr valve with 5 elbows going downwards before exiting the house.
5 elbows???
You’ve got to post that pic. I need a laugh.
Yes.
I regularly find 5 elbows. ART tells me that our record here is 11 elbows over the course of about 33 feet for the drain pipe.
As long as it’s flowing downhill, I don’t think the water would care. There is no requirement that limits the amount of elbows that I am aware of.
There is in many installation guides. For example, Rheem/Ruud/Richmond ca. 2001 limit the number of elbows to four. Too many elbows restrict the flow of water.
Florida Plumbing Code (IPC/IRC) does not limit the number of elbows on a T&P relief valve.
As long as it flows unobstructed downhill, there is no problem.
Alabama limits TPR drain lines to a total of 360 degrees
I’m not convinced, unless one of them points uphill.
It’s simple physics. An elbow is a 90° angle. So as water comes rushing along, it runs into a wall and has to make a 90° turn. Too many of those, and you definitely get the water flow being restricted. How much restriction can be measured if you have the right instruments. But just for fun, imagine that each 90° angle results in a mere 1/10 second delay. Ten of those would result in a one-second delay. That’s very simplistic, but when it comes to water heater explosions, seconds count.
Reminds me of the bumper sticker I saw yesterday on my way home from my
20 WALK inspections:
Yes:shock:
4 elbows max here in Colorado also. I believe that is part of the ICBO national plumbing codes also. I will look it up to make sure.
Doesn’t say about elbows, but a great short general reference chart.
Here’s one of yesterday’s inspections with 10 elbows. This is from one of San Diego’s most respected builders/developers. However, they apparently have a special arrangement with the AHJs since 25% of their houses are perfect, while the other 75% have problems such as this. By the way, the water heater installation guide was with the water heater, and it stated a “maximum of four 90° elbows.”
If in doubt I ALWAYS go by the SAFE and to the more Stringent application / installation guide, MFG says 4, then to me 4 max. And I know of NO MFG. that permit more than 4.
I don’t think I would wish to bet my life on that.
Here is a link to Tech Bulletins for Rheem and Ruud Water heaters.
http://waterheating.ruud.com/dealers/resourceLibrary.asp?displayNode=61
Go look at tech bulletin 1220, T & P Relief Valves, now who do you think knows which is a SAFE way to install that equipment. I would think the MFG. and would hold to their standards.
Since the MFG has the deep pockets you know they are CYAing themselves. MFG it is :-;;
Playing devil’s advocate here:
The document says water heaters “are pressure tested to 300 pounds per square inch (PSI) and have a working pressure of 150 PSI.” Sounds like a 100% safety factor to me. So it’s hard to imagine 4 elbows being OK but 5 makes the installation potentially deadly. Using RR’s calculations as an example, the extra elbow may add a delay 1/10 of a second to the flow rate. 4/10 delay is OK. 5/10 is unacceptable?
The manufacturer’s calls the information about not exceeding 4 elbows a “tip”. Hardly a warning. Maufacturer CYA is right.
I agree you can play it safe and call out elbows > 4, but I still haven’t seen any evidence that quantifies the hazard. I would have a hard time telling someone that 1/10 of a second makes all the difference between life and death when the whole system has a 100% safety factor for pressure.
The whole system has a 100% safety factor for pressure when there are no more than four elbows.
Just continuing to play the devil’s advocate: Do you require hazard quantification for all other situations where the manufacturer provides installation instructions and “tips”?
I just let the manufacturer speak for himself. He has better attorneys than I do.
Yep. I don’t argue with them.
Manufacturer’s recommendations ALWAYS trump code.
If you want to call a “tip” a recommendation, so be it.