Hot water recirculating caused leak?

[Patrick from IN]

I had a return line and recirculating pump professionally installed almost 3 years ago so that we had (nearly) instant hot water at the far end of the house for our master bedroom. The pump has been running 24/7 since then. A few days ago I had water intrusion from a leak inside my kitchen wall on the copper pipe return a couple of feet from the water heater. It has caused thousands of $$ damage to my home. The plumber who installed the return line came out to find and fix our leak. He says that the recirculating hot water caused the leak (basically, that moving hot water "wore out" the copper pipe at the elbow), and recommends that I stop using the recirculating pump. Has anyone else experienced anything like this? I wonder if using a timer on the pump to only come on for an hour or so at peak usage times (morning, evening) would work better?

 

[Gary Swart]

I have had a reci like what you describe in my home for about 15 years. Runs 24/7. About a year ago, the pump gave out and I had to replace it. Other than them zero problems. I'll have to defer to the plumbing pros about the water wearing the copper out. I question that, but again, I'm not a pro.

 

[Sponsor]

 

[Reach4]

A few days ago I had water intrusion from a leak inside my kitchen wall on the copper pipe return a couple of feet from the water heater. It has caused thousands of $$ damage to my home. The plumber who installed the return line came out to find and fix our leak. He says that the recirculating hot water caused the leak (basically, that moving hot water "wore out" the copper pipe at the elbow), and recommends that I stop using the recirculating pump.

Well water? What is your pH? Softened?

 

[Patrick from IN]

Well water? What is your pH? Softened?

City water, and yes we have a softener. No idea about pH.

 

[Reach4]

I was wondering if you had low pH water. If copper fails, I would suspect pH below 6.5. With city water, I would expect they would not have a pH under 6.5.

He says that the recirculating hot water caused the leak (basically, that moving hot water "wore out" the copper pipe at the elbow)

Does that mean the pipe failed near the elbow, or the elbow failed?

Note that type M copper (red ink) is not allowed for potable water in some places. In other places it is very common.

I don't have an answer for you. That wear-out doesn't seem likely to me. I am not a pro.

 

[Jadnashua]

You may have too large of a pump. One thing that can cause problems is high velocity. A second is an improperly prepped pipe. The common way to cut pipe is with a tubing cutter. This causes the end of the pipe to become bent in. A proper joint has that end reformed so it is again straight when you then solder it into a fitting. If this is not done, especially if the velocity is high (and hot water is worse), it can cause turbulence and that can literally eat through the pipe. It usually happens at intervals after a joint with the worst case closest, and diminishes as it gets further away. A typical recirculation system does not need a very big pump.

 

[Cool Blue Harley]

The corrosive resistance of copper is due to an oxide film that naturally forms on the walls as it comes into contact with flowing water. If the velosity of the water is to great, then impingement, also referred to as erosion corrosion, occurs, stripping the protective oxide coating.

Hot water, especially in a pumped circulation system, is required to maintain lower velocities because of hot water's greater tendency to release oxygen bubbles, which increases with velocity, causing acceleration in corrosion.

 

[Master Plumber Mark]

Your plumber should have offered that to you in the first place... Teel makes a nice
pump and the last one I installed with a timer on it cost about 600

You would be wise to install a pump with a timer on it that will only run at peak hours...
If you dont do this you will probably have other pin holes in the system sooner than later...
Your copper water lines are probably getting paper thin in areas of more friction ...I have seen them
so thin you could almost press on the the pipe and it felt like a beer can bending...
it might be wise to make your return hot line out of pex



Also on a side note, You are basically ruining your hot water lines in the home running hot water constantly through
them 24-7 and you are killing the life span of your water heater making it constantly heat....
I would keep a close eye on the heater too and it might be wise to put a water alarm near it too...

a common heater cost about 250 a year to heat the water,, you are probably doing twice to three times that amount in your home every year and working the heater to death......
To conserve energy its also a wise to insulate the hot lines from the heater throughout that whole loop because you are constantly throwing off heat into the house and basically heating the home in both summer and winter

all this trouble just to have instant hot water to keep the wife happy

I feel for you man....

 

[FullySprinklered]

Came home to a wet basement floor two days running last week. Water squirting out of an elbow multiple places both times. Patched up with leftover pex and a sack full of sharkbites. 40 year old M copper was paper thin in the fittings. Couldn't cut the pipe anywhere near the offending elbows. The cutter just crushed the pipe. I think Jim threw some voodoo on me with all that talk about cu pipes wearing out. My first experience with it. Had to be at my house.

 

[Bgard]

What level of hardness are you keeping with your softener? The water softener removes the minerals from the water, if you are trying to keep the water lower than 7 grains the water becomes aggressive, the water is seeking minerals to replace what was removed by the softener and the copper pipe is the place it gets it from the pipe will have erosions that look like termite borings. Running the pump 24/7 is like adding a hydronic heating loop in your house, you only need a very low amount of flow less than 1 gpm. Sometimes the water will flow simply from convection without a pump. You should use one of the pumps that has a timer and aqua switch built in so it only runs when it is needed and only until the water coming back is at the set point.

 

[hj]

A circulating pump SHOULD have a throttling valve on its outlet, NOT the inlet, so the flow can be reduced to just keep the line warm. Too much velocity erodes the copper at turns.

 

[Jadnashua]

FWIW, the recirculation system I have (RediTemp, and no, I do not work for them or get anything!) typically runs for about 1-minute, maybe every 15-minutes during the time I may typically want hot water. The valve is rated at over 1M cycles, so it should last a very long time and the electronics are solid state. The pump is quite small (something like 1/28th HP, if I remember correctly). Without the system on (say I get up extra early for something), it takes about 2-minutes to get hot water at my shower...with it running, less than 10-seconds. Since I run the tub spout until I get hot water, that means each time I'm saving about 10-12g of water. Some studies have shown that when you combine the costs of the water, sewer, electricity, using a recirculation system on a timer saves energy when done right. It certainly can save water, and that, in some places is worth way more than the cost for the environment. If you have power where you need to install it (and have the room, but it's not huge), it can be installed in less than 15-minutes by most people. I was able to add a receptacle underneath my bathroom vanity so I could add mine...a fairly simple, quick thing since most have power above them...just ran a line off of the load side of the GFCI receptacle to a new one in the cabinet. It's best if you can have a dedicated recirculation line, but that wasn't feasible on this retrofit. I find that flushing the toilet means that purges essentially all of the warm water out of the cold line, so, at least for me, hasn't been an issue. Other faucets further away are not impacted by warm water in the cold line since it doesn't need to run that much water back to the WH.