[Kenswing]

Originally Posted by Rocksnap

Adding a recirculating pump (in a timer) and a cross-over valve on your furthest fixture will accomplish the same thing. I checked into adding this on our build, but the $8200 cost was insane. Tho a dedicated return line buried in the slab was their method. This method should be less than $500 installed.

$8,200?! Wow! I wouldn’t have done it at that price either. When we built in 2021 it was only an $1,800 up charge.

[retiredguy123]

Hot water recirculating is just another thing that I don't need, along with a water softener, water filter, or painted concrete. In these threads, I have never seen an actual calculation of how much money, if any, you can save. I can wait 40 seconds for hot water to reach my shower. If you can't wait, turn on the hot water faucet and the hot water will come faster.

[Kenswing]

Originally Posted by ltcdfancher

I agree. A timer is a feature in the model of tankless heater being installed. I appreciate the analogy of the how water lines effectively becoming the tank.

Only the tank is now at every point of use inside the house instead of in the garage. And your tankless will never run out of hot water.

[retiredguy123]

Originally Posted by Kenswing

Only the tank is now at every point of use inside the house instead of in the garage. And your tankless will never run out of hot water.

If a tankless water heater will never run out of hot water, why do they come in different sizes?

[Gweezda]

Circulation systems make the hot water from the tank available instantly through out house. There is no hot water in a tankless system until the heater turns on when a faucet is opened At that point you still have to wait for heated water to get to the fixture in use What am I missing here?

[Kenswing]

Originally Posted by retiredguy123

If a tankless water heater will never run out of hot water, why do they come in different sizes?

Volume. Obviously a household unit doesn’t produce enough hot water to supply a hotel. Depending on outside temperature our unit can produce about 11 gallons a minute. We will never run out. You get the unit that meets your usage requirements. But I’m pretty sure you already knew that.

[larrycrilley@gmail.com]

I copied and pasted your post directly into Chat GPT. It provides a direct answer instead of providing many links (and ads) to help you search for the answer.

ACCORDING TO ChatGPT -

“Your reasoning about the advantages and disadvantages of the two recirculation methods is spot on. For new construction, a dedicated return line is generally considered the superior option, provided it’s feasible within the budget and construction plan. Here’s why:

Dedicated Return Line
1. Efficiency: This system keeps the cold and hot water supplies completely separate, ensuring you always have actual cold water when needed.
2. Consistency: A dedicated return line provides more consistent recirculation without affecting the temperature of the cold water line.
3. Energy Savings: When paired with a recirculation pump controlled by timers or motion sensors, it minimizes energy and water waste.

Cross-Over Valve
1. Cold Water Warming Issue: As you mentioned, a cross-over valve uses the cold water line as a return, which can temporarily result in lukewarm “cold” water. This is especially noticeable if water sits idle in the pipes for a while.
2. Simplicity: It’s less expensive and easier to retrofit into existing homes since it doesn’t require additional plumbing for a return line.

In New Construction

For a new build like your Well Point home, the dedicated return line is likely what was roughed in, as it’s the most appropriate choice for construction from scratch. It aligns with modern energy-efficient and comfort standards, especially in areas like Florida where water temperature fluctuations are noticeable. You might want to confirm this with the plumber or builder to ensure it matches your preference.

Additionally, ensure the recirculating pump is configured correctly (e.g., timer-based or demand-activated) to balance comfort, energy use, and longevity of your tankless heater.”

[RRGuyNJ]

Not sure how they plumb their version of recirculated hot water but I'm sure it's not the way I would do it. I would use a flow detection switch in the hot water outlet line that would energize the circulator. When the hot water is turned on the circulator will come on and charge the loop with hot water. When hot water returns to the water heater an aquastat will sense the hot water has charged the entire loop and turn the circulator off. The circulator will charge the loop faster than purging all the cold water in a conventional system. The water heater doen't run unless needed saving on gas usage. Water waste is minimal. I don't see the Villlages builders doing it this way due to the price of all the components. I would get in the car and get on site to see what's going on. Good luck with your build.

[retiredguy123]

Originally Posted by Kenswing

Volume. Obviously a household unit doesn’t produce enough hot water to supply a hotel. Depending on outside temperature our unit can produce about 11 gallons a minute. We will never run out. You get the unit that meets your usage requirements. But I’m pretty sure you already knew that.

Sort of. But, a tank water heater works the same way. If you have a large enough tank and heating element for the volume you use, you will never run out of hot water. So, in terms of never running out of hot water, both systems can achieve the same result. If you have a large family and a small tankless water heater, you will run out of hot water.

[Wondering]

Originally Posted by ltcdfancher

Fellow Villagers,

The plumbers roughed-in the plumbing for our new home in Well Point yesterday. We opted for recirculating hot water for our tankless heater. Does anyone have experience with how these things are plumbed for new construction?

From the installation manual, there appears to be two acceptable methods: using a dedicated return loop; and, a cross-over valve. The cross-over valve uses the cold water lines as a return path while the dedicated return loop is, well, dedicated to bringing the water back to the heater.

My question is, “how is the system plumbed for new construction?” Dedicated return or a cross-over valve?

The dedicated return seems better to me for some reason.

The water lines in my current Florida home run through the attic. In the summer, the cold water is very warm and in the winter is damned cold. I’ll have warm cold water year-round with the cross-over valve, I fear. (Albeit for just a short while.)

Your new circulating pump is going to be costly to run, even if you have a timer, for certain times of the day, when you need to shower. I had one and disconnected it.

[maistocars]

Originally Posted by ltcdfancher

I wish I had contact information for any of those people!

Call Mike Scott Plumbing - they do just about all of the new construction plumbing. Very friendly - they'll answer all your questions.

[nn0wheremann]

After 21 years our 40 gallon tank water heater sprung a leak. I looked at tankless as a replacement. I chose another old fashioned tank type water heater. Other than springing a leak, there is little to go wrong. No motherboards, no timers, the only thing electrical is the igniter (gas heater) which we would need for the tankless anyway. At the cost of gas here, with a two person household, the energy savings with a tankless would not likely recover the cost in either my or the water heater’s lifetime. The device is located in the garage, not more than six inches from the master bathroom shower head. Hot water can not be much more instantaneous than that.

[Bill14564]

Originally Posted by retiredguy123

Sort of. But, a tank water heater works the same way. If you have a large enough tank and heating element for the volume you use, you will never run out of hot water. So, in terms of never running out of hot water, both systems can achieve the same result. If you have a large family and a small tankless water heater, you will run out of hot water.

Difference between being sized for maximum expected flow rate and maximum expected volume. The tankless heater is sized for the rate of flow regardless of the volume used. The tank system is sized for the volume used regardless of the rate of flow.

[Bill14564]

Originally Posted by Gweezda

Circulation systems make the hot water from the tank available instantly through out house. There is no hot water in a tankless system until the heater turns on when a faucet is opened At that point you still have to wait for heated water to get to the fixture in use What am I missing here?

A recirculation system ensures that hot water is at the tap when you turn it on. It does this by asking for hot water until the temperature at the fixture reaches the set point. Water isn't wasted by flowing down the drain; instead, it is sent back to the heater (recirculated).

With a hot water tank, the recirculated water goes back into the tank and the heating element runs as necessary to keep the tank at the right temperature.

With a tankless system, the element runs every time the recirculation system calls for more hot water. Normally, the element in the tankless system ONLY runs when you turn on the faucet. With a recirculation system in place, the element will run throughout the day to keep hot water in the line.

The tankless system saves money by running only when you need hot water. Adding a recirculation system will increase the need for hot water and decrease the savings.

[Sweet Caroline]

Originally Posted by circlerman

For those that have installed the recirculating pump with timer and crossover valve, does that cause the water in your cold water lines to always be quite warm?

We have had an after market installation for years and love it, set on a timer. Had the plumber install an electric box in closet in garage. Yes, the cold water line is warm but I don't drink out of that faucet so that is ok. After it runs for a while it becomes cold. Funny thing is that I have a spot in my living room tile floor that stays warm!!