Proper Hot Water Heater Re-circulation Line Piping Questions...

[Y2JDMBFAN]

To keep a long story short, my water heater needed to be replaced with a new one for reasons unrelated to this problem. After it was installed we found that we weren't getting hot water in any of the bathrooms. Come to find out there were 4 passive re-circulation lines with home runs from each bathroom back to the hot water heater and no pump and they header off into the cold water inlet of the water heater. Well, when we closed all the ball-valves on each re-circ line, we got hot water. I was a totally newb in regards to re-circ lines. I did my research and we think that the check valves after the ball valve on each line are probably bad. The plumber suggested putting in a pump, and at the time I didn't know what he was talking about, but I did research and now understand it.

So my plan to fix the re-circ lines is the following.

1. Install (4) of the Callefi Balancing valves, 1 on each re-circ line after the ball valve with flow towards the new re-circ pump.

https://www.caleffi.com/usa/en-us/catalogue/thermosettertm-thermal-balancing-valve-116140a

2. Install a new re-circulating pump piped from the (4) re-circ lines into the drain on the new Bradford White 75Gallon POwer Vent. I was looking at this pump.

https://www.supplyhouse.com/Goulds-...Pump-w-Adjustable-Thermostat-and-Plug-1-2-FPT

I will have the plumber who installed the water heater do the work. Does t his sound like the correct solution to you guys? I figure I can set all of the balancing valves to the same temp and then set the re-circ pump to slightly higher.

Am I missing anything? Correct me if I am off-base here.

 

[Phog]

Your plumber didn't recognize that you had a working passive recirculation system, and then destroyed it while replacing your water heater because he had no idea what he was doing. And now the plumber wants you to pay extra to install a recirculation pump? In my opinion he should fix the system to its prior working state. I would also find a different plumber in the future who is competent.

There are 2-3 things the plumber could have done wrong. First, the gravity recirculation cold return line needs to be connected to a low port on the water heater (often the drain valve port at the very bottom). If the cold return line was moved from the bottom port up to the incoming cold water pipe at the top of the heater, this would both destroy the function of the gravity recirculation line & cause cold water to bypass the water heater and make the hot pipes always cold. I'm guessing that this is what happened to you.

Second, new water heaters typically come with integral heat traps in the connection nipples. These will prevent the gravity recirc from working. The heat trap in the hot nipple needs to be removed. (This will not cause permanent cold water at the fixtures like you have though, it merely stop the recirculation flow so you have to wait a few seconds longer for hot water)

Last, some but not all gravity recirculation lines have a check valve. This is not always needed but it's important to use a "swing" type flapper check valve NOT a spring loaded check. I've heard that sometimes people use a "hot side" heat trap nipple too instead of a traditional check. You could have them replaced, as the one legitimate additional thing the plumber can actually charge you for. They may not even be needed for the system to function though if everything was working ok the day before your new water heater went in.

Make the plumber fix your gravity recirculation system to the way it worked before, you don't need a pump.

 

[Sponsor]

 

[Y2JDMBFAN]

Your plumber didn't recognize that you had a working passive recirculation system, and then destroyed it while replacing your water heater because he had no idea what he was doing. And now the plumber wants you to pay extra to install a recirculation pump? In my opinion he should fix the system to its prior working state. I would also find a different plumber in the future who is competent.

There are 2-3 things the plumber could have done wrong. First, the gravity recirculation cold return line needs to be connected to a low port on the water heater (often the drain valve port at the very bottom). If the cold return line was moved from the bottom port up to the incoming cold water pipe at the top of the heater, this would both destroy the function of the gravity recirculation line & cause cold water to bypass the water heater and make the hot pipes always cold. I'm guessing that this is what happened to you.

Second, new water heaters typically come with integral heat traps in the connection nipples. These will prevent the gravity recirc from working. The heat trap in the hot nipple needs to be removed. (This will not cause permanent cold water at the fixtures like you have though, it merely stop the recirculation flow so you have to wait a few seconds longer for hot water)

Last, some but not all gravity recirculation lines have a check valve. This is not always needed but it's important to use a "swing" type flapper check valve NOT a spring loaded check. I've heard that sometimes people use a "hot side" heat trap nipple too instead of a traditional check. You could have them replaced, as the one legitimate additional thing the plumber can actually charge you for. They may not even be needed for the system to function though if everything was working ok the day before your new water heater went in.

Make the plumber fix your gravity recirculation system to the way it worked before, you don't need a pump.

Thanks for the input, it is much appreciated. I should clarify a few things.

1. He didn't move the passive re-circulation lines. They were always connected to the cold water input on the previous water heater. The only thing he did was cut the old heater out right above the cold water input then piped the new heater directly to that.

2. The passive re-circ system never worked properly. I never got consistent hot water in the shower in my master bathroom shower in the 4 years I have lived in this house. The kids tubs never got hot and stayed hot, they would end up with luke warm water in the tubs. The sinks could also never get hot water in the bathrooms. The water might start warm, get hot for 30 seconds and go back to being warm.

3. After the new heater was installed, I could get warmish water in the bathrooms with the re-circ lines open, but it would never go hot. This was my concern and why I called him back out.

4. It appears there are swing type check valves installed and not spring loaded based on the shape of the check valves after the ball valves.

5. He suggested a pump, but never said it was necessary or tried to push me on it. He did spend 2 hours testing after I called them back out.

6. I don't know about the heat trap in the connection nipple. I will have to email or call and ask.

I now can get hot continuous water at each sink and shower in the bathrooms with the re-circ disabled, the problem is it takes a minutes or so to let the water run first, but as far as showers and baths this is much better than before.

 

[Phog]

Ok -- maybe I was too hasty to throw your plumber under the bus. It's hard to say what happened here, a previous plumber may have messed up the original system. It looks like there might have been a gravity return line correctly plumbed to a low return port on the water heater at some point in time, which got disconnected. And then a return "bypass" was added directly from the recirc manifold into the cold supply line, causing your problems.

In the pics below, I circled what might have been the old recirculation return line (pic#1); then circled and x'ed-out the "bypass" that is causing your cold-water problems (pic#2); and then finally showed with an arrow where the gravity recirculation return would typically be plumbed into for proper convective recirculation (pic #3). Either of the 2 ports indicated in pic#3 should work as a gravity return, the lower drain port might work ever-so-slightly better than the hex-return port a little higher up.



This is not a recommendation that you try and re-constitute an old gravity recirculation loop -- it may have been disconnected for a reason, such as that it never worked quite right. If you would like to move to a pump-powered recirculation system you can utilize your current piping without relocating the return to the lower port. But in this case, a move to spring-type check valves would be called for, plus the balancing valves you spoke of above. (Some recirc balancing devices have an integrated check valve, others don't, so you may or may not need a separate check).

 

[Sylvan]

I often wondered if installing a shut off valve on the HW supply would bankrupt the installer?

Also it would be a very nice gesture to install a valve to isolate the expansion tank if it needs to be recharged or removed

Shame they missed the NBBI or ASME class the day that the discharge pipe from a T&P or Safety or Relief valve shall be cut on a 45DEG angle so no one can add a fitting Just common decentcy and shows they know the intent of the various codes

Another nice thing to do is install a 27 " loop (heat sink) on the CW supply and remove the piece of rubber from the dielectric nipple

 

[Bannerman]

we think that the check valves after the ball valve on each line are probably bad.

A swing type check-valve is appropriate for your application as minimal force will cause the CV to open. The check-valves are not bad, they were just not installed correctly.

In a vertical pipeline such as where the CVs are currently installed, because the direction of flow is from the top downward. the flap (aka: valve clack or disk) within each check-valve will always remain swung open due to the force of gravity. For a swing check-valve to work properly in a vertical pipeline application, the direction of flow will need to be from below upward as gravity will then keep the check-valve flap closed and the force of flow will cause it to open.

Because your check-valves are installed in the return line flowing back to the WH below, to operate properly, each will need to be installed in a horizontal pipeline such as between the floor joists prior to the elbows shown above the CVs.

 

[Jadnashua]

When the expansion tank fails (it will, eventually), it will become full of water and quite heavy. I'd want to put some support other than the copper pipe.

Since it didn't work well before, you can't say that the plumber actually broke it!

To work, the check valves must be oriented properly and still be operating. For it to work properly, the slope and orientation of the piping must be right, or there's enough resistance in the line(s) to stop the passive recirculation.

While, once you get the check valve issue resolved, you might still want a recirculation pump.

 

[Y2JDMBFAN]

Everyone, thank you for your replies. I think the consensus is that the current piping of the re-circulation system is not correct.

1. I would like to keep the shutoff ball valves currently installed, I don't see this as an issue. Since they are already there, they wouldn't hurt anything.

2. I would install a thermal balancing valve such as the one I linked in my original post, under the ball valve mounted in a vertical orientation flowing downward back to the heater. I understand this might not be totally necessary and could probably get away with proper check valves if I install a pump.

3. I don't know if I can find 4 balancing valves in stock with integrated check valves. I should have check valves installed under these thermal balancing valves, correct? If so, would any spring type be OK since this is a vertical install?

4. As far as the re-circulation pump, I don't want something that runs 24/7. Would a thermal set re-circ pump be more appropriate in this case? Is there a brand that is better to use? Is the Laing pump I originally selected sufficient for this application? Do I need any addition shut off valves or check valves before or after the pump?

5. Should I have the new pump connected to the drain line or the hex port above it? If I use the drain plug, should I have him install it on a T and put a drain spigot on the tee?

6. Should I have the plumber remove that extra drain leg with the spigot on it that is connected to the current re-circ piping?

Thanks guys! You all have been a huge help to me as far as understand all of this and what is correct and not.

 

[Jadnashua]

Without a pump, it doesn't take much at all to stop a gravity recirculation system. The difference in weight of hot versus cooler water is minimal and keep in mind that there will be almost no pressure to overcome the tension of a spring. The check valve is for when you open a faucet so that it can stop backwards flow from the bottom of the WH into the lines...mixing the cooler (or maybe cold if you use a lot) water from the bottom of the tank with that coming out of the top. In a recirc system, they must normally end up open, and close when pressure is applied on their outlet side that overcomes the spring tension. I guess, it depends on whether the spring is holding it open or closed...I think it's closed.

Many of the recirculation systems only need a very small pump. The one I have only draws like 9W, and it doesn't run all that often, maybe 5-minutes an hour or so. Some run the pump continuously, but use a special thermal valve to shut the flow off once hot is sensed at the outlet. You do not want a huge pump. Some think that will help in the long term to speed up things if it isn't on all of the time, but a huge pump will run the water velocity up in the pipes, and that can lead to premature wear on the lines and literally erode holes in them. Plus, it adds noise, expense, and wastes energy. On mine, it shuts the pump off as the pump is under the sink of the furthest device and everything prior to that is pretty much in series, so has hot water. It cycles on when it drops to about 85-degrees, and stops when it's around 95 or so. Depending on the branches you may have, you may need more than one thermal valve. Using the individual valves for the branches allows you to fine tune the flow when you do not have a sensor so that they become balanced. Otherwise, water will take the path of least resistance.

 

[Bannerman]

The check valve is for when you open a faucet so that it can stop backward flow from the bottom of the WH into the lines...mixing the cooler (or maybe cold if you use a lot) water from the bottom of the tank with that coming out of the top.

In this case, the recir loop return flow and the fresh cold water feed are both plumbed together to enter the cold inlet to the water heater. Because the swing check valves were installed pointing downward, the swing flap in each check valve remains always held open by gravity and so incoming cold water that should be flowing only into the WH, is being permitted to flow backward through each check valve into the return loop so the water arriving at each faucet is only warm at best.

I suspect if the swing checks are relocated to a horizontal plumbing section, the gravity recirculation loops may function as intended.
If the OP plans to install a recirc pump, then spring checks may replace the swing checks in their current locations.

For the same reason, the downward flowing swing check in the main feed line directly beside the expansion tank, will also provide no backflow protection.

 

[Onokai]

If you have to get a pump get the Grundfos smart pump-super efficient and learns your needs. Less than $10 a year to operate

 

[Y2JDMBFAN]

So a bit of an update, I ended up doing the work myself. Plumbers wanted upwards of $400 to fix it + parts. Right now, I cut the re-circulation line that was going into the cold water inlet on the heater and capped it. Then I put a Lanig pump between that red spigot on the wall and the drain line on the heater, I ended up using stainless hose on the spigot end for now, until I determine how fancy I might want to get. I didn't touch the 1/2" swing check valves below the ball valves. At this point, with the pump running, I get scalding hot water within about 10 seconds to the bathroom furthest from the heater first thing in the morning. I consider that a win. My one remaining question is if it is necessary to put a proper check valves on the cold water inlet to the water heater? If so, I can do it with some sharkbite fittings and check valve myself. I don't plan on messing with the improperly installed 1/2" check valves on each of the 4 re-circ line or putting in the thermostatic valves at this time.

 

[Bannerman]

Congrats on getting it working.

Without check valves that will actually close, the return flow from 1, 2 or 3 loop returns could potentially enter the loop return(s) where water is being utilized, thereby flowing in reverse to the open faucet(s). Because the return flow will have lost several degrees before reaching the WH, if return flow proceeds to feed a running faucet instead of returning to the WH, the temperature at the faucet may be cooler than desired, and the temperature may fluctuate depending on flow rate.

To fully correct the recirculation issues, the existing 4 swing checks would need to be relocated to horizontal piping sections as mentioned previously. If you want check valves in a vertical piping configuration such as the current location, then the swing valves would need to be replaced with spring checks.

 

[Y2JDMBFAN]

Congrats on getting it working.

Without check valves that will actually close, the return flow from 1, 2 or 3 loop returns could potentially enter the loop return(s) where water is being utilized, thereby flowing in reverse to the open faucet(s). Because the return flow will have lost several degrees before reaching the WH, if return flow proceeds to feed a running faucet instead of returning to the WH, the temperature at the faucet may be cooler than desired, and the temperature may fluctuate depending on flow rate.

To fully correct the recirculation issues, the existing 4 swing checks would need to be relocated to horizontal piping sections as mentioned previously. If you want check valves in a vertical piping configuration such as the current location, then the swing valves would need to be replaced with spring checks.

Thanks, any idea what the easiest / cheapest solution would be to cut those check valves out? They are flat up against the insulation / concrete.

I was going to pick one of these up Friday, 4 sharkbite slip couplings, 4 sharkbite checkvalves and a couple ft of 1/2" pipe to use in between the check valve and slip coupling.

https://www.homedepot.com/p/RYOBI-1...ulti-Tool-Attachment-Tool-Only-P340/202868525

 

[Bannerman]

Is the insulation compressible or removable temporarily?

A further possible option would be to allow the swing checks to remain where they are as they will be fully open and so will not be causing restriction. New checks (either swing or spring) may then be installed in the horizontal pipes located between the floor joists above, which will likely provide easy access with less interference.

Since 'scalding' hot water is arriving within 10 seconds to the most distant fixture, I anticipate even hotter water is arriving even sooner at fixtures located closer to the WH. It seems the water temperature may be too high as 120F is the usually recommended maximum temperature to prevent scalding injuries.

Perhaps the flow rate may also be too high. Is it a multispeed pump that may be slowed down? If single speed, you may wish to restrict flow at the outlet side of the pump as excessive flow velocity through the recirc loops may result in noise throughout the plumbing system.

You didn't mention if the thermostatic balancing valves indicated in your OP were installed. If the balancing valves are installed, it may be possible that a check-valve is built into each balancing valve as that is offered as an option.

 

[Phog]

In certain pump orientations it's better for pump health to restrict the pump outlet (pressure side) than the inlet (suction side). In your circumstance I think you will be ok -- the suction side will by facing upward and any vacuum pulled will be up higher up (near the balance valves) instead of at the pump inlet. So don't feel like you need to change anything-- just thought it was worth a mention.