New Water Heater Schematic

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SteveMcqueen

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Hi all,

I had to pull my water heater to do some drywall repairs and have decided to install a new one while I'm at it. My home has a dedicated hot water return line and with the old plumbing (the HW return joined the cold water supply just downstream of the shut-off valve, no check valve or expansion tank in the old plumbing) I often felt like hot/warm water was backing up in to the cold side, aka I could never get real cold water when I wanted it. When installing the new heater I plan on adding an expansion tank, new Grunfos recirc. pump (UP 10-16 temp.) and a check valve just downstream of the cold water inlet shut-off valve. The new grundfos pump also has a built-in check valve and will be routed back in to the tank at the drain valve (using a tee obviously)

Does this sound reasonable to you experts?

NewSchematic.jpg


Here's a link to an article that describes what I was experiencing, and proposes the solution.

https://www.pmmag.com/articles/98049-installing-check-valves-in-a-recirculation-system

And the relevant bits...

"If the recirculation system connects to the cold water supply to the water heater, the water can reverse course and go into the cold water supply. If a faucet or fixture is opened to only flow the cold water, the hot recirculating water will flow into the cold water. Hence, hot water will come out of the cold water faucet. This phenomenon doesn’t last long. As soon as the pressures equalize, the cold water again begins to flow out of the faucet.

But who wants hot water out of a faucet before they get the cold water?

In that same situation, if the recirculation pump is off and someone opens the hot water faucet near the intersection, cold water will come out and probably continue to come out of the faucet. That is because the pressure differentials allow the cold water to flow to the fixture rather than the hot water. In this example, hot water may not come out of the faucet until the recirculation pump turns back on.

What was just described is an installation where two check valves are necessary: one on the cold water supply to the water heater before the connection of the recirculating piping, and the other on the recirculating piping after the last connection of a hot water fixture. Without two check valves, the system will not work properly."

Also, is the shut-off valve that's downstream of the expansion tank absolutely necessary? What is the purpose/benefit of this valve?
 
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breplum

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The benefit of valve isolation valve at exp. tank is to make changing it a simple event. Often we use a tee, then valve, then hose bibb, then the exp tank. In that case, the other shut-off on cold side is just to shut down the WH supply.
The hose bibb tee branch to relieve pressure when change-out is required.
Expansion tanks tend to not last so the easier to change the better.
Additionally, isolation valves and unions at the recirc pump and a tee with hose bibb on it to help bleed air out upon startup.
 

SteveMcqueen

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The benefit of valve isolation valve at exp. tank is to make changing it a simple event. Often we use a tee, then valve, then hose bibb, then the exp tank. In that case, the other shut-off on cold side is just to shut down the WH supply.
The hose bibb tee branch to relieve pressure when change-out is required.
Expansion tanks tend to not last so the easier to change the better.
Additionally, isolation valves and unions at the recirc pump and a tee with hose bibb on it to help bleed air out upon startup.

Thanks for the reply. I'm having some difficulty picturing what you're describing. So, after the check valve, where I would normally add a tee for the expansion tank connection (I'm using a flex hose from the wall-mounted tank) I would simply add a hose bib there and connect the flex hose to that?
 

Sylvan

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The 6" heat trap" is wrong it should be at least 27"

I do not like to use a check valve other then on the return line

with the 27" loop on the CW supply there is no stratification of Hot water entering the CW line and no mechanical devices are needed

upload_2021-11-28_11-20-4.jpeg
 

SteveMcqueen

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I wasn't planning to add the heat trap loops. They weren't there in the old system and I was under the impression that they were built in to the WH. The nipple variety anyway.

The WH is in a small alcove with limited space for excess pipes etc. Also, I live in So. Cal. and I'm not too concerned with heat loss. (Should I be?)

Thanks for the diagram but it's unreadable. (too small)

I'll give the linked article a read. Thanks.
 
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SteveMcqueen

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Here's what I ended up with. (I did install the check valve just downstream of the main CW inlet valve.)
20211130_102214.jpg

It's all fired up and hot water pours forth from the faucets etc. Anyone see any glaring problems or code violations?

I'll probably redo the TPR discharge pipe as I reused the one from the old WH so I could get it up and running. I also still need to add insulation to the pipes.

Thanks for all the advice.
 

jadnashua

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Where I live, it's code to have a tempering valve on the hot water supply. That can complicate some installs when you throw recirculation into it since you're not drawing water when recirculating, there's no cold water to temper the outlet...so, some tempering valves have an inlet for the recirculation water rather than going into the drain line. Then, it's mixing the cooler, return water into the hot outlet to retain the set temperature on the tempering valve instead of the cold supply. When you push it into the drain, the tempering valve is fighting to put cool water into the stream, and there's none coming in.

I like the concept of the WAGS valve...it's a totally non-powered automatic water shutoff when it detects a leak by some buildup of water in the drain pan. WAGS - Water & Gas Safety Shut-Off Valve, Lowest Price - Right Here! (wagsvalve.com)
 

Clog

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@Sylvan
Your posts and pictures never cease to amaze. Thanks for all that you contribute to better plumbing practices.

@SteveMcqueen
I went to the same boarding school as Steve, and saw him later at charity events for that boarding school.

You asked for input on your installation photo, and toward that end, I have a few questions...

1. The flexible flue pipe... is that aluminum? Does your AHJ allow mixed metal materials beyond the draft hood?

2. What are the two new horizontal 2x4's bolted to the wall behind the water heater for? Are they bolted to studs? The earthquake straps are bolted a couple of inches away from the bolts to the horizontal 2x4's. Are the earthquake straps also bolted to studs? It is odd that the studs are so close together.

3. How does the flexible gas connector supply go from horizontal to verticle at the shut off valve. Is there a yellow elbow, or is the horizontal to vertical transistion accomplished by an abrupt bend in the CSST line?

4. Are there two ball valves in the Cold Water supply? One shutting off at the wall, and the other shutting off at the T prior to the braided hose leading to the expansion tank?

5. What is the short leg at the bottom of the T?

6. What air pressure is in the expansion tank?


@jadnashua

I considered the WAG few years ago, I mean really thought it through, and ruled it out after considered study, but I forgot the specific reasons why.

I ended up using a Watt's Auto Water shut off, with a UPS, and a relay trigger to shut off the power to the flue dampener, that automatically shuts off the gas valve. Every element is reusable, instead of one time use only. But I think there was some other reason why I ruled the WAGS out, but can't remember why.
 

SteveMcqueen

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@Sylvan
Your posts and pictures never cease to amaze. Thanks for all that you contribute to better plumbing practices.

@SteveMcqueen
I went to the same boarding school as Steve, and saw him later at charity events for that boarding school.

You asked for input on your installation photo, and toward that end, I have a few questions...

1. The flexible flue pipe... is that aluminum? Does your AHJ allow mixed metal materials beyond the draft hood?

I'm not sure of the material. I reused the pipe that was on the old WH, and I'm assuming, is original to the home. (the date on the pipe would confirm)
20211120_140908.jpg


2. What are the two new horizontal 2x4's bolted to the wall behind the water heater for? Are they bolted to studs? The earthquake straps are bolted a couple of inches away from the bolts to the horizontal 2x4's. Are the earthquake straps also bolted to studs? It is odd that the studs are so close together.

I'm not sure I nailed the code requirements, but I found more than one document that recommended bracing behind the WH, in addition to the strapping, to prevent movement during an earthquake etc. They are bolted to the studs on the right side and to some backing firring strips that were inserted to repair the drywall on the left side. These were not present with the old WH installation and it stood off from the wall 2.5-3".

Yes, the straps are bolted to the studs on both sides using 1/4" x 4" lag bolts.

20211124_093744.jpg

3. How does the flexible gas connector supply go from horizontal to verticle at the shut off valve. Is there a yellow elbow, or is the horizontal to vertical transistion accomplished by an abrupt bend in the CSST line?

It is/was a fairly abrupt bend. I'll research it. I wanted to put in a new line as I wrapped up the job but couldn't (quickly) find a new one of appropriate length at the home store that night. I did go reduce the abrupt bend a bit.

4. Are there two ball valves in the Cold Water supply? One shutting off at the wall, and the other shutting off at the T prior to the braided hose leading to the expansion tank?

Yes

5. What is the short leg at the bottom of the T?

A WH drain valve exactly the same as the one on the WH itself, to drain the expansion tank line when I need to change it out. It was recommended by one of the prior posters on this thread. Perhaps I misunderstood what he was recommending.

6. What air pressure is in the expansion tank?

68PSI, same as the PRV/house pressure.

@jadnashua

I considered the WAG few years ago, I mean really thought it through, and ruled it out after considered study, but I forgot the specific reasons why.

I ended up using a Watt's Auto Water shut off, with a UPS, and a relay trigger to shut off the power to the flue dampener, that automatically shuts off the gas valve. Every element is reusable, instead of one time use only. But I think there was some other reason why I ruled the WAGS out, but can't remember why.

Yes, I've owned a couple of Bullitt Mustangs (2008, and currently a 2019) and have been to the Boys Republic school for a car show and charity event. I love the '19 Bullitt, it's fantastic.

See answers above. Thanks for the interest and advice. Let me know if there's something I should change por favor. The new WH setup has been working great.
 
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Clog

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I'm not qualified to approve or condemn any part of your installation, but must say that your work is better than much of the work performed by many of the plumbing services I've encountered in the homes of my friends and neighbors. So any questions I had or comments I make about your installation are solely in the interest of responding to your request and supporting your readily apparent pursuit of best practices.

The close up image you provided of the Ameri-Vent label only applies to the 3" to 4" transition piece, not the flex pipe vent.

IOW, the label only applies to this piece:

095029417755.jpg


The important thing about the label that you presented is that indicated a brand of flue vent piping.

There are about four or five different brands of B vent piping, and not all of them interchange very well.

For whatever reason (whether it be patented designs, or a consipiracy to force folks to buy more pieces of the same brand) the various slots and keyways differ from brand to brand on the connector pieces of flue vent piping.

So, in your case, that is a good thing, because if you believed that the label you took a photo of applied to the flex hose, then that means that the connection you observed between the 3x4 increaser and the flex pipe appeared factory in your eyes, rather than hoky doke.

If the connection appeared factory, then the flex pipe is likely made by Ameri Vent, and thus it is a flex pipe designed for use in flue vent applications, as opposed to say, a flexible aluminum dryer vent pipe. Even if there is no actual difference in materials, the flex vent pipe you are using is likely LISTED for the application, which resolves the liability concern that I had when looking at the original photo, which I could not enlarge.

As for the yellow CSST gas line... the best practice is to replace this line each time the appliance is replaced. Repeated bending of the flex line to accommodate the installation of a new water heater leads to work hardening and metal fatigue... including your recent rebend to remove the hard kink out of the line at the supply end.

If you choose to replace the line, then consider reorienting the supply end of the hard piped gas supply such that the new CSST line need but make a simple upside down U shape, where the axis of the inlet and the outlet of the flex line remains on the same plane, rather than axis of one end oriented 90 degrees from the other.

Looking at the photo below, you may notice that our gas lines are routed similarly, in an upside down U shape having a very large and gentle radius bend that does not constrict the flow of gas, nor does it contain a "P" trap that would hold contamination (unlikely to happen with current gas supplies, but something of concern many decades ago).

The only difference between our yellow CSST gas flex connector arrangements is the difference in plane at the inlet and outlet, where your flex connector is forced to change planes in 90 degrees, whereas I try to get the inlet and outlet planes aligned in hard pipe first, and then run the CSST flex connector with only one simple, gentle, gradual bend from supply to appliance.

80-cimg_1278_a318501b2fbe574ddc168f6fbaf9f8e60d50e732.jpg


,
 
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