Temperature & Pressure Relief Valve - Home Inspection Question

13 years ago

After Home Inspection What would you do:

Below is the home inspection report and issue shows.

{{!gwi}}

Basically the Temperature/Pressure relief valve where it enters the wall is higher than the valve start (creates uphill run)

I know this would be a major problem with a regular tank water heater - but in this case it is a tank-less.

Would it be necessary to open up the sheet rock wall to move the connection lower on the wall? I am the seller...

(located in California)

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Comments (4)

User
13 years ago
I defer to the professional plumbers for the final word but in my research preparing to R&R my WH I read the code and the Home Inspector is on point and correct.

My WH has the T&P on top and all the new generation FVIV WHers I've seen have the T&P on the side and lower than the drain line going into the wall. The code is specific that the line from the T&P is a gravity line and must only go down. Any water sitting in the line at the valve can rust the valve and render it inoperable.

I will either redo the T&P drain line or order an FVIV WHer that has the T&P on top.

Whether tank WH or tankless WH the T&P valve and line must meet code... it is a safety concern.
montel (CA US 10b/Sunset 16)
Original Author
13 years ago
After getting more information - the Takagi Tankless only has a pressure relief valve - that apparently doesn't need to be exclusively a gravity line - can anyone confirm that.

Certainly a Tank system would need it.
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First of all, thank you for your response and good idea! as they say, great minds think alike, using the y connector with an open ended hose is how i relieve the pressure now(i failed to mention that in the post) and it does serve to save me a trip back to the other end of the hose. the problem is that the water pressure at my house is so strong that i have had hoses burst during lunch breaks, and a couple of times when i'm just catching my breath or doing something else for a little while. it seems like a spring loaded pressure release valve is what im looking for, that way i dont have to worry about it. just something that gets to a certain psi and lets go of some water untill the psi comes down. i worry about hoses breaking all the time and still, every summer, i break a hose or two. im always in the yard and eventually, without fail...i forget and boom! i just want something that works without my being there, so its worry free...and i can buy cheap hoses. my yard is 325 feet deep and i have one spigot. can u think of anything else? thanks again.
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The following was posted by Lazypup on a similar question: Both the ASTM (American Society of Testing & Materials) standards and the plumbing codes require that the sensing probe must be in the upper 6" of the water heater pressure vessel. Typically they are side mounted on gas water heaters while they are commonly top mounted on electric water heaters. Either position is fine providing the T&P valve sensing probe is extending into the upper 6" of the internal pressure vessel. Years ago water heaters did not have Temperature & Pressure Relief Valves. Instead they had "Pressure Blowout Plugs" which look like the freeze plugs in an automobile engine block. When T&P valves first became available water heaters only had two threaded ports, hot & Cold, so they would install a close nipple and Tee on the Hot water discharge line and place the T&P on the top of the TEE with a long probe that extended through the TEE and nipple and into the upper part of the tank. If your old water heater has a third threaded tap on the pressure vessl where the probe is extended directly into the water in the tank you may use a standard T&P valve. If the T&P is on top of a tee you must use an extended probe type valve. If you need an extended reach type look for a Watts 100XL. The XL on the model number identifies it as an extended length probe.
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While these are Âpressure relief valves,Â the acronym for that is PRV, which is reserved for Pressure Regulator Valve. So, the popular term for the one you mention is, T&P. That means Temperature and Pressure, and that is really not just more descriptive, but more about your question: "Are (these) valves likely to cause problems?" They are there to solve problems, but interestingly enough, they are a bit of a nuisance. The two conditions are both capable of opening the valve. But the valve is kept closed by a spring. It so happens, that Â especially with older installations Â once a valve is opened and allowed to close naturally, it is more likely to leak. The reason for that, is that the valve is installed in the new condition, with all forces at rest. But if the Temperature and/or the Pressure increase to the danger point, the valve is expected to open. This suggests that moderate over-heat or moderate over-pressure will partially change the spring position or its stored energy. Then, a small influence can open it. This is usually apparent in the appearance of a minor leak. It is the nature of a seat-type valve to have a ÂhomeÂ position. That is, once built, the rubber washer settles on the metal seat, forming a fit natural to the variety of parts and their tolerances. Disturbing this fit changes the nature of the valve, which tends to stay changed as long as the heater is under heat and line pressure. Conversely, if you were to shut OFF the water, remove, clean, chill and reinstall the valve, it should be in Âas newÂ condition and then operate that way. Of course, it could do that without all this. But when they become leakers after opening, it is for a good reason. The ordinary and reliable solution Â especially for professional service people Â is to replace the valve with new. This avoids call-backs and is less labor-intensive ($$.) Your other concern, "My wife is convinced it'll rust out in no time and we'll need a new one." Baloney. Women are just fickle that way. For instance, if she uses a Lawyers-page from the local telephone directory to bookmark her romance novels, you can be sure sheÂs like that. DonÂt worry, once it dries up sheÂll be very comfortable with it Â the water heater, that is. Pinoke
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QUOTE "I learned that as communities grow, instead of upgrading the infrastructure ($$$), cities will often resort to the easy fix which is to crank up the pressure." I find that statement extremely hard to believe because cities do not use pumps to generate the pressure. Municipal water pressure results from static head pressure developed by water towers or locating storage tanks on high elevations within the community. The municipal supplier uses pumps merely to keep the storage tank full. In fact, quite the opposite is true. In many instances the municipal line pressure increases as a result of the city replacing old lines with new lines that are larger in diameter which then results in less friction head from the source to the point of demand, ergo the pressure at the demand is higher. The municipal supplier is not required to provide PRV's. When ever a new installation is set in place the municipal supplier is required to make a tap into the municipal line and run a short section of line from the tap to the "Curb Stop" valve. The property owner is then responsible to install a code approved "Supply Line" from the curb stop to the structure, and all "Distribution Piping" within the structure. In instances where the volume will be measured by means of a meter the municipal supplier will inform the builder where the meter will ultimately be located and they five you a "Fitting allowance" measurement. You are then required to cut out a section of the supply line equal to the fitting allowance length, and in some jurisdictions the homeowner is required to install 1/2 of a meter union on each open end of the line. After the line is inspected the municipal suppliers personnel will supply and install a meter in that opening. Under both the IRC & UPC in instances where the static head pressure exceeds 80psi the homeowner is required to install a PRV (pressure reducing valve). (IRC-2903.3.1 & UPC 608.2) Under both the IRC & UPC either the valve must have an integral bypass for thermal expansion or you must install an expansion tank. (IRC 2903.4 & UPC 608.3).
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User
13 years ago
Regardless of the logic that a tankless T&P may not need to be gravity drained the prevailing policy of the local plumbing inspectors is what matters and will get you a red or green tag. If the tankless doesn't need to be gravity drained it may take many years to filter into the codes.

I think I read somewhere that Watts, the manufacturer of the majority of T&P valves, that in order for the T&P valve to meet spec has to be gravity drained and they don't mention tank or tankless as a distinction.

Look at the last paragraph on page 2 of the following link... http://media.wattswater.com/ES-10L-100XL.pdf

You can call the inspectors and ask, but I'd want something in writing that the current install is OK.

Was this tankless install permitted and inspected?

Since this concern is documented in the home inspection and you are bound by disclosure to offer that info you are right to want to get the answer and do what is necessary.

Let us know what you find out.
User
13 years ago
As a further thought... that your tankless has ONLY a pressure release valve is confusing you.

The pressure being relieved will be in the water channel in the heater so the valve will release at least SOME water along with pressure if it activates and that water will stand against the valve because it can not drain over the high point in the drain line. That water standing against the valve is what can render it inoperable and the reason the drain line must go DOWN from the valve.

Temperature & Pressure Relief Valve - Home Inspection Question

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montel (CA US 10b/Sunset 16)
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Temperature & Pressure Relief Valve - Home Inspection Question

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montel (CA US 10b/Sunset 16)Original Author

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montel (CA US 10b/Sunset 16)
Original Author