Hot water circulating line - new build

1,509 Views | 14 Replies | Last: 3 yr ago by ravingfans
bobbunker
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Just learning there have been problems in PEX and Copper both for hot water circulating lines. Is it the hard water wearing out connections? Builder saying a timer will almost surely fix the future potential problems. That small doubt is concerning. We haven't designed the system yet but i'm thinking having a timer, and then run a larger diameter circulating loop (1.5") then branch off of it to every tap. The branches wont be hot but should be close enough to the loop that it wont take long for hot water to hit each tap.

What are your thoughts, recs and experiences?
Martin Q. Blank
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Unless you have 12 bathrooms, a 1.5" line will just take that much longer to heat up and waste energy. What are the problems with PEX or copper?
Sweet Kitten Feet
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S
Not sure why a timer would fix a problem of lines wearing it, it would just delay it. My pump has a timer on it, but I plugged it into a smart plug. It comes on at 6am, and then turns off whenever all of us leave. As soon as someone comes back home it turns back on. Definitely cuts down on run time. Turns off completely at 9pm.
bobbunker
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The problems they say are just due to the hardness/minerals in the water. The timer would delay the wear in the pipe is all he could come up with. Said the starting/stopping was good on the pipe. When I discussed this with some friends they both have had failures in their circulating systems over the years. Pipe just wears out. I put much stock into the builders comments until my friends both said it has happened to them.
GrimesCoAg95
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AG
Why not just put in two tankless water heaters? I have one on each end of my house and do not wait long for hot water.
TMoney2007
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AG
Pipe just wears out like what? Like it gets clogged?
Garrelli 5000
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AG
Love recirculating hot water. Our new home has tankless w/no recirc. Took a while to adjust routines so you aren't "waiting" for the water to warm up.

Never heard of the pipe issues, but definitely put a timer on the pump. Our first two lasted about a year each running 24/7. Once I put a timer on them they started lasting about 6 years. We'd set the timer to run 7am - 10pm on weekends, and during the week from 5:30am - 8:30am, then again from 5:30pm to 10pm.
Take the trash out staff.
chuckd
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AG
bobbunker said:

The problems they say are just due to the hardness/minerals in the water. The timer would delay the wear in the pipe is all he could come up with. Said the starting/stopping was good on the pipe. When I discussed this with some friends they both have had failures in their circulating systems over the years. Pipe just wears out. I put much stock into the builders comments until my friends both said it has happened to them.
I'm not sure what you mean by pipe wearing out. Why would that be a specific problem to the recirculation line?
JSKolache
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AG
The outlier in our floor plan is kitchen sink. Bathroom runs are all central and close to the manifold. So i put a 2 gal electric tank under the kitchen sink for like $150. Yeah it's a workaround, but it was a cheap spend, and we have instant hot where we needed it most.
bobbunker
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chuckd said:

bobbunker said:

The problems they say are just due to the hardness/minerals in the water. The timer would delay the wear in the pipe is all he could come up with. Said the starting/stopping was good on the pipe. When I discussed this with some friends they both have had failures in their circulating systems over the years. Pipe just wears out. I put much stock into the builders comments until my friends both said it has happened to them.
I'm not sure what you mean by pipe wearing out. Why would that be a specific problem to the recirculation line?
I'll have to get some specifics on the pipe failures that builder is saying has occurred. I watched some info on Grundfos site. There are much better pumps on the market now that regulate flow based on straight time, based on daily usage times, and based on temp.

AgLA06
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AG
Garrelli 5000 said:

Love recirculating hot water. Our new home has tankless w/no recirc. Took a while to adjust routines so you aren't "waiting" for the water to warm up.

Never heard of the pipe issues, but definitely put a timer on the pump. Our first two lasted about a year each running 24/7. Once I put a timer on them they started lasting about 6 years. We'd set the timer to run 7am - 10pm on weekends, and during the week from 5:30am - 8:30am, then again from 5:30pm to 10pm.


So you'd have no hot water for a shower during the week on days off, holidays, and during the summer between 8:30am and 5:30pm?
Sweet Kitten Feet
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S
No you'd still hot water. It just takes longer for the hot water to reach that faucet.

In my case I hooked our pump up to a smart outlet. I use the Google Home presence sensing so if we're home between 6am and 9pm it'll be on. But when we're all away from the house it cuts off. ANd then it's always off from 9pm til 6am unless I turn the plug back on.
79TAMU79
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AG
9 year tankless with recirculation pump on timer using PEX and no issues at all. Highly recommend it.
Catag94
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AG
1) Have plumber use Uponor pipe and fittings.
2) be prepared for half life on your water heaters because they work far more often.
3) if/when you decide to go with tankless water heater system, you won't want the loop.
Happy Thanksgiving. Hope this is of some help.
CaptnCarl
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AG
I don't see anything wrong with the hot water return lines. They are becoming more popular, especially with the tankless heater having the circulation pump built in.

My parents house has one, which was built in the 70's. They have had to replace the pump, but no issues with the plumbing itself. If the pipe was installed correctly, no reason it would wear out.

It definitely is nice to turn on a faucet and instantly have hot water, which greatly reduces wasted water.
ravingfans
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AG
I had a Taco Hot-Link System installed when the water heater had to be replaced. It is really awesome. no special plumbing, no separate return line, etc. "Occasionally" the cold line might be a little warmish, but never hot and not for long when it has just recirculated the water.

I discovered after it was installed that our water branches out when it hits the kitchen in two directions. I bought an extra HLV-1 valve to get the hot water recirculating through both branches. works like a charm!

The special return line sounds like a good idea, but really not necessary if you use something like the Taco.

The Rib raves about the instant hot from the Taco, so I win points all the time, years later

Having a Water Heater Tank provides plenty of hot water for our needs, and avoids the pitfalls of tankless which include inconsistent temperature (sudden blast of super hot water!), limited supply of water (depends on the tank inside the tankless water heater), higher initial cost, and running extra gas lines to the tankless units.
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