# Water heaters in series. . .



## UALocal1Plumber (May 13, 2009)

Hi everyone, just wanted to stop in an ask your advice about something. I got a call from a local restaurant yesterday, letting me know that they were running out of hot water pretty early in the day. The owner doesn't know much about his building - they rent from a landlord - so we took a look downstairs to see what the situation was. Turns out that the landlord installed a Promax 40 gallon water heater in place of an old out of service boiler. 

Long story short, the DHW capacity for their needs is way too low. The restaurant owner is willing to engage me directly, and fight with the landlord himself over the bill, but he's also trying to get the most affordable job done for himself because he's working on an austerity budget. Well, he's the customer and I'll respect his wants, while still doing a job that's to code and adequate for his needs.

I sized the gas line out, and we have room to add up to 200,000 btuh in the boiler room with no issues. If I take out the existing water heater, that'll turn into 250,000. I recommended taking out the existing mess and installing two ganged Cyclone Xi's. . . customer doesn't have a budget anywhere NEAR that.

He asked me to figure something out, the best I could come up with - that is, an affordable job that will increase his supply - is to add a BT-80 in series with the existing 40. I'll install the 80 as a main heater, bringing the temp to 120 degrees, and use the 40 as a booster of sorts, driving the temperature up to the max without injury to the larger, more expensive unit. 

I have no guidance in the code for this, and just wanted to throw it out to you to see if this sounds like a reasonable solution. The recovery rate provided by the extra heater should satisfy the demand of their fixtures. 

Thanks
Keith


----------



## plbgbiz (Aug 27, 2010)

I would start at the BTR series as a minimum and eliminate the baby tank. Restaurants use a ton of hot water. Also, verify the temps being used. Be sure to temper the water to as many hand washing fixtures as possible to cut down on usage.


----------



## 1703 (Jul 21, 2009)

Here is AO Smith's online sizing. Might give you a starting point in figuring out what they need.

http://www.hotwatersizing.com/

Keep in mind- they are in the business of selling water heaters, if ya know what I mean. :whistling2::whistling2:

I personally don't like your idea. I think that small of a heater is gonna be a problem regardless of where you put it in series (before or after the bt80).

One man's opinion.....


----------



## UALocal1Plumber (May 13, 2009)

I haven't used that calculator before. Thanks for pointing it out to me. 

Keith


----------



## accobra88 (Nov 8, 2010)

You could also remove some of the load and USE the baby tank for lets say the bar area, the hand sinks and possibly just the bathrooms ...thereby taking some of the load off the main heater.


----------



## plumber666 (Sep 19, 2010)

accobra88 said:


> You could also remove some of the load and USE the baby tank for lets say the bar area, the hand sinks and possibly just the bathrooms ...thereby taking some of the load off the main heater.


I agree. Piping water heaters in series is always a bad idea IMHO.


----------



## ReelPlumber (Jan 14, 2011)

Lets start of by asking what is the delivery pressure of the gas being served at the water heater? 
Is this the only appliance that the gas meter is serving?

My thinking was to increase the gas pressure to 2psi from the gas company, then installing a regulator at the water heater which will increase your btu's and then you can install a 120 gallon +or- with w 299,999 btu rating commercial water heater.


----------



## sikxsevn (Jun 23, 2009)

In Texas, at least, any single water heater over 200,000 btu is considered a boiler. Personally I'd lean more towards something tankless, or a condensing commercial unit from
Rheem or A.O Smith. If you do have to use two, pipe them in parallel. Now, some people seem to dislike parallel heater installs, generally only because they lack the skills to install a truly parallel piping system for the heaters


----------



## plumber666 (Sep 19, 2010)

sikxsevn said:


> In Texas, at least, any single water heater over 200,000 btu is considered a boiler. Personally I'd lean more towards something tankless, or a condensing commercial unit from
> Rheem or A.O Smith. If you do have to use two, pipe them in parallel. Now, some people seem to dislike parallel heater installs, generally only because they lack the skills to install a truly parallel piping system for the heaters


True dat!! I can't tell you how many pooched tanks I've seen from poor attempts at parallel piping. Owner always says, "This first tank has lasted 20 years, how come the other one gets replaced every 2 years?"


----------



## Plumbworker (Oct 23, 2008)

whats wrong with the boiler go back with two storage tanks


----------

