TPRV function

[Chad Fabry]

Has anyone disassembled a typical TPRV?

I'm curious to know if the release valve floats on the shaft that extends through the valve body to the test handle or if it's fixed on the shaft.

I haven't been able to find a clear enough cross-section online.

If it floats on the shaft, the valve could still release due to over pressure or over temp even if the shaft movement was restricted by corrosion or a ham-fisted installer butting the valve against something.

If the valve doesn't float, then those scenarios would really bad.

[John Kogel]

Chad, you've got to learn to be more specific. []

If you mean a Watts TPRV, Pretty sure the plug floats on the shaft, safety feature. But a rusty shaft might prevent movement, no?

[Marc]

I don't know if this is representative of most TPRV valves.

Click to Enlarge

49.45 KB

Marc

[Chad Fabry]

On that valve the shaft is enclosed inside the casting. Around here, almost all the shafts are exposed.

I'll watch for water heaters at the side of the road and I'll take some valves I procure apart. scrap is way down, I actually have chance at success.

[Tom Raymond]

Why wait for one to appear on the side of the road?

On your next municipal inspection declare the water heater at safety hazard and commandeer the valve.

Or go buy one at Lowes. A new valve will be way easier to get apart.

[kurt]

I'm interested in the support part. What's the gig?

[Jim Baird]

From OP,

"...movement was restricted by corrosion or a ham-fisted installer butting the valve against something...."

I just checked both my fists and they are still, even at my age, pretty meaty.

[Tom Breslawski]

Around here, almost all the shafts are exposed.

[John Kogel]

I've got one in my junk box. Can't say when I'll have time to saw it in half, tho. []

[John Kogel]

Yes, this shaft is exposed, too. []

[mlparham]

Has anyone disassembled a typical TPRV?

I'm curious to know if the release valve floats on the shaft that extends through the valve body to the test handle or if it's fixed on the shaft.

I haven't been able to find a clear enough cross-section online.

If it floats on the shaft, the valve could still release due to over pressure or over temp even if the shaft movement was restricted by corrosion or a ham-fisted installer butting the valve against something.

If the valve doesn't float, then those scenarios would really bad.

You are the governing authority, just call Watts technical support and speak to an engineer. Question answered.

[Chad Fabry]

First, you're all hilarious.

It's a litigation support case where the judge must have a family member in the trades because he keeps asking " what bad things will happen because the contractor didn't follow the instructions?"

I need to know how bad it could be if 5, 270Kbtu btu water heaters connected to the same header, each has its TPRV pinned against the wall.

I want to paint a bleak picture but I want to be sure it's right.

Has anyone disassembled a typical TPRV?

I'm curious to know if the release valve floats on the shaft that extends through the valve body to the test handle or if it's fixed on the shaft.

I haven't been able to find a clear enough cross-section online.

If it floats on the shaft, the valve could still release due to over pressure or over temp even if the shaft movement was restricted by corrosion or a ham-fisted installer butting the valve against something.

If the valve doesn't float, then those scenarios would really bad.

You are the governing authority, just call Watts technical support and speak to an engineer. Question answered.

[kurt]

Run the video of the Mythbusters blowing up a water heater lacking a TPRV. It's dramatic.

When you're all done, you should put a new TPRV on a railroad track and see what it looks like after a train runs over it.

[Tom Breslawski]

Kurt beat me to it. The episode of Mythbusters says it all. The tank blew sky high. Not sure if Mythbusters is admissible in court.

First, you're all hilarious.

It's a litigation support case where the judge must have a family member in the trades because he keeps asking " what bad things will happen because the contractor didn't follow the instructions?"

I need to know how bad it could be if 5, 270Kbtu btu water heaters connected to the same header, each has its TPRV pinned against the wall.

I want to paint a bleak picture but I want to be sure it's right.

Has anyone disassembled a typical TPRV?

I'm curious to know if the release valve floats on the shaft that extends through the valve body to the test handle or if it's fixed on the shaft.

I haven't been able to find a clear enough cross-section online.

If it floats on the shaft, the valve could still release due to over pressure or over temp even if the shaft movement was restricted by corrosion or a ham-fisted installer butting the valve against something.

If the valve doesn't float, then those scenarios would really bad.

You are the governing authority, just call Watts technical support and speak to an engineer. Question answered.

[kurt]

Not sure if Mythbusters is admissible in court.

It should be. It's almost unbelievable.

[John Kogel]

Not sure if Mythbusters is admissible in court.

It should be. It's almost unbelievable.

Yeah the tank can blow a big hole in your roof but, is the TPRV is actually blocked by having the handle up against the wall? I have come to believe it is not. Correction - I just tried the one I've got, and the valve can't be pried open when the handle is clamped down.

Even so, the purpose of the handle is to operate the TPRV manually from time to time to make sure it works and is not seizing up. So it is still negligent for a plumber to shove it against the wall. So I call it interfering with a safety device.

[mjr6550]

Watts or Bradford While also has a video online showing a water heater explosion. they are pretty impressive. I have read several account of water heaters launching through the roof and ending up a 100 feet or more from the house-also shifted the house on the foundation and blew out all the windows. I have read a few accounts of boiler explosions also. Worse than a bomb blast.

[Jim Katen]

Since no one ever actually answered the original question . . .

I had time to mess with a Cash Acme TPR valve today. The valve seat does, indeed, float on the shaft and will open in response to *pressure* without regard to whether or not the top of the shaft is pinned against a wall.

However, a pinned shaft will prevent the *temperature* response function from working properly. The temperature sensor pin pushes up directly against the bottom of the shaft, not the valve seat. So if the top of the shaft is pinned against a wall, it might delay the reaction or prevent it entirely.

[kurt]

Get rid of walls. Problem solved.

[plummen]

We blew one up back when I was still teaching many years ago,Cleared the trees in the field straight up around 25' or so.

[Chad Fabry]

Thanks for reminding me, Jim.

The case I was working on involved Watts valves. I opened a used one that was about 4 years old and I opened a new one off the shelf. They were essentially identical. They worked just as Jim Katen described.

The case involved over 40 installation defects most of which were easily established using manufacturers' instructions and the Building Code of NY. My client, the building owner, prevailed for each and every condition

(which is good because we removed a lot of recently finished surfaces)- the contractor lien was removed, the contractor was ordered to refund XX dollars and to pay a third party chosen by the building owner up to XX dollars to make repairs and replacements. I doubt my client will get a dime; the contractor's corp probably already filed for bankruptcy. he was that kind of guy.

[plummen]

I was called out to a job south of omaha many years ago where somebody removed the drip leg from a leaking pop off valve and installed a pipe plug in its place.

It went through a wall pushing a giant stand up type piano through a bed room wall,Pieces of the piano were stuck in the wall above the head board.

Fortunately it happened during the day when nobody was home.

Property management company that had their maintenance guy work on the water heater went belly up a couple years later.

[John Kogel]

I made a correction to my post above. I found a Watts TPRV that spent 9 years in service before the tank sprang a leak. The TPRV is now scrap, especially now that I mickeyed around with it. They cost about $12 and should be replaced every 10 years or so, but nobody does that.

When I clamp the handle shut in the vise, I cannot pry the valve open.

Free up the handle and shaft, and the valve can easily be opened with a screwdriver.

So for this TPRV, and therefore all of them, blocking the handle would be dangerous and inexcusable. Which was my philosophy all along, but is finally verified.

I see people cut holes in drywall, but why not just drain the tank and shove it over 2"? There's usually some flex in the supply pipes to do that.