water heater TPR question

[ctgo4it]

Hi all,

I've never seen anything like this. The TPR outlet has a plug in it, and the TPR valve is installed on the water line. I know there's no extension on it, I just want to know about the placement. Has anyone seen this, and is it ok?

Sorry the pics aren't that clear, I took them with my phone

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[homnspector]

It depends on the length of the probe on the T&P valve. I think its supposed to extend 4 inches into the tank. It will say on the tag the length of the probe. I would bet it doesn't.

[Scottpat]

It is wrong.

Think about this. If it does blow, hot water and steam will head up that water line to who knows where.

[hausdok]

No it won't, it'll just spray all over the place because there's no discharge line on it. That is, if it vents.

It's wrong because the probe isn't in the tank. It's wrong because they don't have a discharge pipe on it. If those are galvanized components - can't tell, the color's displays a little weird on my monitor - it's wrong because those nipples should have been dielectric types.

Plumbers around here used to install lots of them on the discharge line, especially in homes with basements. I think some knew that they were wrong, because they'd install a properly spec'd TPR on the side or top of the water heater with a short discharge pipe that would vent into the home if it blew, and then they'll install a second TPR valve that's designed to pop off at 125° on the hot water line up between the floor joists with a pipe that vents to the outside. I guess their reasoning was that the one on the line will blow and vent to the outside before the tank goes critical and they've got the one on the tank as insurance in case it doesn't.

It's just wrong. Write it.

OT - OF!!!

M.

[Les]

It is wrong. Even if the probe is "long" enough, the probe is designed to operate on a single temp area; water in the tank.

Everyone above is correct, plus it is just plain silly commonsense wise!

You will never forget the event, if you ever are present when one discharges!

[John Dirks Jr]

He said the TPR outlet has a plug in it. In that case there is no protection at all no matter how it is installed. Pressure could build until the tank blows.

[homnspector]

"It's wrong because the probe isn't in the tank."

How do you know that?

The only issue about the placement is the length of the probe. At least that's what my wife tells me.

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[Scottpat]

We don't know for sure that the probe is not in the tank. Most of the probes I have seen are around 6"-8" in length. The probe needs to extend into the top 6" of the tank. Since that tank has a side port, it needs to be installed at that point or at the top port that would be for the anode rod.

[Richard Moore]

He said the TPR outlet has a plug in it. In that case there is no protection at all no matter how it is installed. Pressure could build until the tank blows.

No...it would still release pressure. There's no check valves on the nipples. Pressure isn't really the issue here.

The IRC wording is "installed so that the temperature sensing element monitors the water within the top 6" of the tank."

I bought these two TPR valves as visual aids a few years back. One's a Watts (I think the other is a Wilkens).

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Anyway, they are "typical" valves and as you can see the sensor only extends about 3¼" below the threads. I don't think that would make it into the tank in the original photo. So...what others have said. It's just wrong. Judging from the photos they probably need a new water heater anyway!

On the bright side, at least they installed it on the hot side (are all water heaters oriented that way?) and not effectively in the dip tube on the cold side.

[homnspector]

"Since that tank has a side port, it needs to be installed at that point "

Thats true, Watts does say that if there is a spot for a T&P it should be installed there, but if not you can install as per the diagram, so it should function just fine as long as the probe is in the tank. They make them with probes as long as 8 inches.

[hausdok]

Originally posted by Scottpat

Since that tank has a side port, it needs to be installed at that point or at the top port that would be for the anode rod.

Hi Scott,

Not sure that's accurate. I've looked at a lot of these, just as you have, and what I see is a lot of brands that have both a top port and a side port, in addition to an anode rod.

OT - OF!!!

M.

[Jim Katen]

Originally posted by AHI

He said the TPR outlet has a plug in it. In that case there is no protection at all no matter how it is installed. Pressure could build until the tank blows.

He means that the tapping in the tank has a plug in it, not the tapping in the TPR valve.

- Jim Katen, Oregon

[Richard Moore]

Originally posted by homnspector

They make them with probes as long as 8 inches.

I didn't know that! Do now. I checked the Watts site and, sure enough, some models have a version that has an 8" "extension thermostat". Here's the wording from the attached tag of the one I have...(my bold)

"Combination temperatue and pressure relief valves with extension thermostats must be installed so that the temperature-sensing element is immersed in the water in the top 6" (152mm) of the water storage tank. They must be installed either in the the hot outlet service line or directly in a tank tapping. Combination temperatue and pressure relief valves that do not have extension elements must be mounted directly in a tank tapping located within the top 6" (152mm) of the water storage tank. ..."

So...the one in the original photo may actually be just fine after all (ignoring all else that's wrong). I don't know if you could tell if it's an "extended" model. Watts model number on the top disc of the one I have is SL100XL. The extended model supposedly would be SL100XL-8 but I don't know if that would actually be on the label. I'll check next time I pass a plumbing store. And...I also don't know about other manufacturers.

In conclusion...I've learnt something today, which is always a good thing!

[hausdok]

Me too, Richard,

Thanks.

OT - OF!!!

M.

[John Dirks Jr]

Originally posted by Jim Katen

Originally posted by AHI

He said the TPR outlet has a plug in it. In that case there is no protection at all no matter how it is installed. Pressure could build until the tank blows.

He means that the tapping in the tank has a plug in it, not the tapping in the TPR valve.

- Jim Katen, Oregon

Ok I got it now....thanks.

[Les]

and then there is the effect of hot water swirling around the probe in a restricted area (t fitting) and the plastic coating on that probe. not even regarding restriction and turbulance.

[homnspector]

"The extended model supposedly would be SL100XL-8 but I don't know if that would actually be on the label."

It will have either a 4,6, or 8 on the little hangy-down metal tag depending on the length. If the tag is gone I think it is also stamped on the disk.