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Rightway Plumbing
Rightway Plumbing, Plumber
Category: Plumbing
Satisfied Customers: 228
Experience:  Journeyman Plumber, Owner Right Way Plumbing LLC. 7+ years exp.
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How do I hook up 2 hot water tanks where there is only one

Customer Question

How do I hook up 2 hot water tanks where there is only one and add a recirc system as well? I am a General contractor doing this in my own house. The current unit is under the house and cant be moved, the crawl space is too low to install a bigger single unit. The house is 4100 sq ft with 3 bathrooms, 2 of which are upstairs and it takes forever for the hotwater to reach the upper bathrooms.
Submitted: 7 years ago.
Category: Plumbing
Expert:  Mario replied 7 years ago.

you have a few options one is like you are saying add a second tank of equal size this would require piping in the hot and cold the same excat same way so that each nipple and 90 are the same length up to the tees where the wate renters the system and leaves the system


the other way ( the way i recomend ) is put in a rheem tank less unit the ones that make on demand hot water

Customer: replied 7 years ago.
I cant use a tankless unit because the water main comming into the house is a constant 47 degrees. They do not make a unit that will work with that cold of water. I was told by my plumber that I would have to install a manifold. I get how to install the 2 tanks as far as the initial plumbing goes, I need to know how to plumb both tanks into a recirculating system.
Expert:  Mario replied 7 years ago.

remove one of the drain valves at the bottom of the water heaters and install a nipple then a tee

on the top of the tee set a brass circulator and off the run of the tee put in a drain again


after the circ install a va;ve and a drain cock just like a boiler

Customer: replied 7 years ago.
Relist: Incomplete answer.
Neither of the answers that I received were helpful, he took a couple of hours to answer each time and the answers were very short and very general.
Expert:  Rightway Plumbing replied 7 years ago. Here is a great drawing and description of water heaters installed in parallel. This is what I would recommend to increase water volume. Here is a website that offers information on recirculating systems.


You are in the right direction and when you install the return line and extra heater your hot water problems will be solved. I know it's a lot of information to read but between those two sites you have all the information you will need to install your system.


If my answer helps please click accept, If not I would be happy to continue to work with you and try to get the information you need.

Rightway Plumbing, Plumber
Category: Plumbing
Satisfied Customers: 228
Experience: Journeyman Plumber, Owner Right Way Plumbing LLC. 7+ years exp.
Rightway Plumbing and other Plumbing Specialists are ready to help you
Customer: replied 7 years ago.
Thanks for the info. I didn't find much on doing the return, any help or suggestions would be great.
Expert:  Rightway Plumbing replied 7 years ago.


You basically continue the hot water from the farthest fixture away from the water heater. You bring this pipe all the way back to the water heater and connect it to the drain plug at the bottom of the heater.$File/Uprec-gd.pdf Here is a site with a bunch of different hot water return installations. It isn't that complex in practice. You basically make a big loop with the hot water line, and use a pump to cycle the water through the line and back into the water heater. You have to insulate the entire hot water loop to minimize energy usage. Also make sure you install a check valve where the return loop connects to the water heater. You don't want cold water coming back through the hot loop.


Get a small sized pump and perhaps even put it on a timer. A small grundfos or lange pump should be more than sufficient to move water in the lines. If you move the water with too big of a pump for your application, you will subject your water lines to premature wear.