Multiple water heaters with recirculation pump.

[fishdaddy]

I am looking at replacing existing water heaters and have run this by 3 different local plumbers and got 3 different answers. I know this is way more info than you need but each plumber had different reasons for why this and/or other options would not work.

The house has 3 electric tank water heaters (2-50gal. & 1-40gal), with no gas availability. Water heaters are mounted in small separate closets (24"x30") with doors opening to outside of the house. House is single story and shaped like a “U” with 4 bathrooms. The 50-gallon heaters are at each end of the U and are 160 feet apart and the 40 gallon is mounted 45 feet away from the first water heater.

All water lines are run in the attic. House has an open-air tile roof (no plywood or underlayment so exposed to outside temps.), but pipes are wrapped and have a fair amount of cellulose insulation over them. Water is from a deep well with split separate cold-water lines to each heater from the well.

The Kitchen, laundry, and one bathroom are at one end of the U and the master bathroom (with a large 80-gallon Jacuzzi tub) and 2nd laundry room is at the other end of the U. The other 2 bedrooms are near the center of the U.

I am looking at replacing the two 50-gallon heaters with new conventional tank heaters (the old ones are shot) and eliminating the 40-gallon heater by installing a separate recirculation line with a pump between the two 50gal water heaters so that all fixtures can pull hot water from both tanks.

My question is, can a recirculation pump be used to loop water between two tanks that are 160’ apart, and would it be feasible based on the heat loss and electrical expense from that distance and the parameters listed above? Also, would it be better to plumb the loop to the top cold water line or the bottom drain of the tanks?

Alternative options would be appreciated.

 

[Fitter30]

Each heater would need its own recir pump to its own heater. The pump programming would be different times. Three heater could be tied together by piping them reverse return if they were closer together. With a 80/gallon tub 50 gallon heater with 120° water just couldn't fill it at 105° with 65° incoming water.

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[Master Plumber Mark]

Why do you want to do this??
If what you presently have is working good why would you want to go
to all the trouble of running recirc lines and all the other issues just to eliminate a 40 gallon heater??

all the recirulation pumps are gonna do is wear out the heaters and probably wear out the water lines
in your home and cost you more money in the long run

I am just wondering ...thanks

 

[fishdaddy]

I know know this is way more than you are asking for but here are some of the factors that are leaning me towards changing the current heaters/plumbing. I will be living in this house for at least the next 12 years until I can retire. Unfortunately, I live in Ca where energy costs are through the roof and are expected to rise substantially based on current legislation being proposed. I currently have a $650(+) a month electric bill. There is also legislation that will require a water meter on our well and the cost of water will be significant. The previous owner (who supposedly was a contractor) had done two additions to the original house and each time they did an addition they added another water heater. Even with having three water heaters that are fairly close to the bathrooms it still takes a significant amount of time to get hot water to the fixtures due to how they ran the plumbing and how inefficient things are, so needless to say we are wasting a lot of water (which is also straining the septic system.) Most of the pipes in the house are 3/4" old cast iron and with the mineral content from the well the hot water pipes are about a third of the way clogged, the areas that are not cast iron are only 1/2 inch copper, but seem to have minimal sediment in them (so looking at replacing with all 3/4"copper.) Current water heaters need to be replaced anyway (one shorted out, another is rusted through and leaking, and the other is forming rust blisters at the bottom of the tank.) I was looking at on demand units but that would require upgrading the service panel and additional wiring and also would not solve the delay in hot water. I then looked at heat-pump units (as there are rebates for them here), but the water heaters are located in small closets on the outside of the house and would either have to be ducted into the house (which I was told was expensive and would drop the temperature of the vented rooms by 20 degrees, thus increasing heating costs) or would have to be vented to the outside of the house through the doors, where temps in the winter would negate any benefits to having a heat pumps. I have done what research I can and have run this by 3 local plumbers, but each had a different solution to the problem. Based on the fact that I did not have much confidence in the plumbers that I called out and on the cost of the solutions they were offering (one guy wanted almost $15K), I will probably DIY the work (I have done extensive work on other homes in the past with success (including plumbing), so hopefully not getting in over my head. Lol
I am looking for additional advice and/or recommendations as to the best way to proceed.
Thank you again for your time and comments!

 

[fishdaddy]

Why do you want to do this??
If what you presently have is working good why would you want to go
to all the trouble of running recirc lines and all the other issues just to eliminate a 40 gallon heater??

all the recirulation pumps are gonna do is wear out the heaters and probably wear out the water lines
in your home and cost you more money in the long run

I am just wondering ...thanks

I accidentally replied to your question below.

 

[Breplum]

Keep the existing locations, when repiping your old "steel" pipe
(we never had cast iron pipe in CA)
(Cheaper to repipe with PEX btw)
Pipe in a return loop for each stupid WH or one big loop (what most sane people do)
Use a recirculation system with pushbutton or motion sensor or other user activated method like Taco Smart plus, so that water recirculates when wanted. Sure, you have to adjust lifestyle to wait some seconds, but no water wasted waiting and no power wasted running pump when not needed. That is what CA requires now for new construction.
TacoGenie is a poor man's way forward.https://www.tacocomfort.com/product/taco-genie/

 

[John Gayewski]

It very much depends on the piping layout on whether or not you need more than one pump. It's likley you don't need the instant hot water at every fixture but really only some fixtures.

A schematic of the piping and layout is the ONLY thing that can answer your original question.

I would guess you could add some piping and connections and have the water circulate to one heater and be happy and save water.