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Adding second water heater

jwh2ohouse's picture

Adding second water heater (post #197396)

jwh2ohouse on Fri, 01/07/2011 - 11:41
in

I am finishing the basement of a 2 story home.  Currently there is one 50 gallon gas water heater in the second floor right above the main floor master bath.  This heater is also near one of the 2nd floor bathrooms.  All of this is on the upper right of the house when viewing from the front.

The full bath in the basement will be on the opposite side of the house and right below the kitchen and laundry room.  Hot water takes a long time to reach the kitchen (probably the laundry as well but haven't tested).

There is a room under the basement stairs where I was planning to add a low-boy electric water heater next to the lift pump.  Now I am trying to figure out how to connect the heater to the system.  My pea-brain comes up with 3 options:

  1. Completely separate the two heaters.  That is, dedicate the upstairs heater to the 2nd floor baths, master bath, and main floor powder.  Dedicate the basement heater to the kitchen, laundry, and all hot water need in the basement. 
  2. Cold-In and Hot-Out on the basement heater.   I would also re-route all the hot lines so that the kitchen, laundry, basement bath, and all else in the basement was downstream from the basement heater.  Seems like I would need some sort of mixing valve to ensure the basement tank was used first for the downstream demand.
  3. Hot-In and Hot-Out on the basement heater.  I would re-route as in option 2.  This seems that it would ensure quicker hot water but would leave the majority of the load on the second floor heater.

Any other ideas? Thanks in advance..

-A +A

I'd go with #1. (post #197396, reply #1 of 6)

by MarkH in reply to jwh2ohouse [original] on Fri, 01/07/2011 - 13:40

I'd go with #1.

I don't understand 2 and 3.  (post #197396, reply #2 of 6)

by DanH in reply to jwh2ohouse [original] on Fri, 01/07/2011 - 19:13

I don't understand 2 and 3.  Where and why does the "mixing" occur?

From the standpoint of overall load, a 50-gallon heater should be sufficient for the average family home unless there are teenage girls -- the main issue would be the time it takes for hot water to arrive in some locations.

An electric heater, in most parts of the country, will be more expensive to operate than the equivalent gas heater.  This would tend to suggest a hot-in/hot-out arrangement where the electric wouldn't do the bulk of the heating work.


We are like tenant farmers chopping down the fence around our house for fuel when we should be using Nature's inexhaustible sources of energy -- sun, wind and tide. ... I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait until oil and coal run out before we tackle that. --Thomas Edison

I happen to be near (post #197396, reply #3 of 6)

by jwh2ohouse in reply to DanH [original] on Sat, 01/08/2011 - 06:37

I happen to be near Charlotte, NC, where electric rates seem very reasonable compared to gas - maybe because we are less than 15 miles from a nuclear power plant.  I also went with the electric because of the restricted room under the stairs which I don't think works with a gas heater per code.

With Cold-In / Hot-Out, I was thinking the mixing would occur where the new hot line met the old hot line.

I like your idea of Hot-In / Hot-Out.  I decided to draw a schematic for what I'm thinking.

PreviewAttachmentSize
New_Water_Heater_Schematic.pdf38.07 KB

Well, the valving's a little (post #197396, reply #4 of 6)

by DanH in reply to jwh2ohouse [original] on Sat, 01/08/2011 - 06:55

Well, the valving's a little convoluted, but that's the idea.  Technically you could do with fewer valves, I believe, but then you'd have longer wait times when running on one tank.


We are like tenant farmers chopping down the fence around our house for fuel when we should be using Nature's inexhaustible sources of energy -- sun, wind and tide. ... I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait until oil and coal run out before we tackle that. --Thomas Edison

I agree!   Thanks for the (post #197396, reply #5 of 6)

by jwh2ohouse in reply to DanH [original] on Sat, 01/08/2011 - 09:03

I agree!   Thanks for the feedback.  The valves will be a bit spendy but I'm trying to build in flexibility before I cover the basement ceilings with drywall.  Also, the basement will also be a stand-alone apartment.  I have this OCD-like drive to do projects like this perfectly.

I went with the hot in plan (post #197396, reply #6 of 6)

by gfretwell in reply to jwh2ohouse [original] on Sun, 01/09/2011 - 09:23

I went with the hot in plan on my new bathroom renovation, also feeding the kitchen. It is just a little 120v heater that holds a few gallons of hot water. It gives you virtually instant hot water while you are waiting for hot water from the main unit. I putit in the attic, directly above the feed to the kitchen/bath "tree" so it is a short pipe run. I am in the sub tropics and the water heater doesn't really turn on for most of the year since the attic usually cruises at 120-140 degrees. I do have a big drain pan under it, piped out through the soffit.