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two residential hot water heaters instead of one commercial

HoyteKingHoyteKing Posts: 83Member
Hello,
I am on the board of a 9 unit condo building with about 30 residents on three stories (and three tiers connected). Our 100 gallon A.O. Smith is leaking after 9 years and needs to be replaced. A building maintenance guy told me years ago that it is possible for a building my size to buy two or three residential heaters for less money instead of another commercial heater. Has anyone done this? If so, how much repiping is involved?

Advantages as I understand it:
- if one heater goes, then the other one is still working while the bad one is fixed
- much cheaper
- the warranty looks to be better

If we were to install a residential, what would anyone recommend?

Thanks
Hoyte King

Comments

  • HoyteKingHoyteKing Posts: 83Member
    One concern a board member just brought up: "... we recirculate the water so every unit has hot water when they want it - no waiting. If we went to household ones they might not be able to stand up to constant use the way a commercial one would."
  • HVACNUTHVACNUT Posts: 2,559Member
    Most commercial gas fired water heaters are power vented. If yours is the case then non commercial water heaters might need a different source of chimney venting. The combination of the water heaters btu ratings must not exceed the rating of the existing chimney. The recirc wont be a problem. Modifications to the gas piping will be needed of course.
    But aside from all that, getting 9 years out of a commercial water heater isn't to shabby.
  • ratioratio Posts: 2,105Member
    From what I've seen using a residential water heater in a commercial setting will void the warranty. But redundancy is good to have. It'll take some careful piping to make them work together, but that can be done on paper prior to starting. Assuming, as @HVACNUT mentioned, there's no impediment to their use (venting, physical space, service access, etc.).
  • pecmsgpecmsg Posts: 907Member
    Check with your Insurance Carrier...…………...Probably NOT allowed!
  • Larry WeingartenLarry Weingarten Posts: 1,588Member
    Hi, I think I’d call the heater manufacturer and ask them if this installation would affect warranty. Having some redundancy built in is certainly a good thing. I might take the opportunity to look at lower flow showerheads which could allow you to install smaller heaters. Also at a minimum, both time and temperature controls can be used to limit recirculation run times, or have a look at gothotwater.com.

    Yours, Larry
  • Intplm.Intplm. Posts: 944Member
    You did not mention weather you use Electric, Gas or Oil fired water heaters. All three of these would have different piping issues.
    What I would do is check and see what your zoning is. How are you zoned in your town / county ?
    Some condos are zoned or categorized commercially, some are labeled as residential.
    To have extra water heaters installed when one fails is a great idea.
    Yes it has been and can be done.
    Dare I say that you have electric water heaters? Many condos that I have worked in do.
    How about yours ?

    And also all the advice above....^^^^^^^....
  • HoyteKingHoyteKing Posts: 83Member
    We use piped in gas here in Chicago. It looks like we need to go with a commercial unit. The recommendation is Bock. Anyone use them? They are rare in the Chicago area.
  • pecmsgpecmsg Posts: 907Member
    Concentrate more on the installing contractor then the name on the box's
  • HVACNUTHVACNUT Posts: 2,559Member
    Bock oil fired water heaters are one of the best IMO. Dont know about gas fired though. Rheem gas commercial water heaters hold up well by me.
  • JohnNYJohnNY Posts: 2,364Member
    I service several multi-family buildings in New York that use a bank of residential water heaters piped in parallel or reverse return instead of a single unit. One building in Brooklyn has three and actually turns one off (rotating) in the summer since the incoming water is warmer and recovery is naturally quicker. I'm not sure it saves them a dime but they think it does and what do I care. Any water heater used in a commercial setting has a 3-year warranty as far as I know but technically this is a residential building so...
    For installations, troubleshooting, and private consulting services, find John "JohnNY" Cataneo here at :
    "72°F Mechanical, LLC"
    Or email John at [email protected]
    John is the Boilers and Hydronic Heating Systems Course Instructor at NYC's Mechanics Institute, a professional Master Plumber, licensed by The Department of Buildings of The City of New York, and works extensively in NYC while consulting for clients in and out of state.
    John also oversees mechanical installations and maintenance for metro-area clients with his family's company, Gateway Plumbing and Heating along with his brother/business partner.
  • ZmanZman Posts: 5,262Member
    If you could provide more details on your existing setup, model number and/or pictures of installation it would help. The BTU rating is probably more important that the gallon capacity.
    It should noted that uninsulated DHW and recirc lines waste a ton of energy. If it is possible to insulate the lines it would be money well spent.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • bob eckbob eck Posts: 892Member
    Residential water heaters are for one house job commercial water heaters are for commercial jobs. Your job is a commercial one.
    You got 9 years out of a commercial water heater that is great considering the commercial water heater has a 3 year warranty.
    You could install 2 smaller commercial water heaters this way if one goes down you still have the other one running.
    If you are using gas you can look at using tankless gas water heaters 2 or 3 TGWH and one storage tank. If one tankless goes down you still have one until you get the units that is down gets repaired.
    I would go with two smaller commercial water heaters that are 75% each of what you now have in. Get the company that is installing the two water heaters to set up a service contract where they come out twice a year to flush out the tank, check venting make sure the water heater is running right. Once a year or every 1 1/2 years replace the anode rod in the tank type water heater. Make user you have a working thermal expansion tank on the water heater.
  • pecmsgpecmsg Posts: 907Member
    bob eck said:

    Residential water heaters are for one house job commercial water heaters are for commercial jobs. Your job is a commercial one.
    You got 9 years out of a commercial water heater that is great considering the commercial water heater has a 3 year warranty.
    You could install 2 smaller commercial water heaters this way if one goes down you still have the other one running.
    If you are using gas you can look at using tankless gas water heaters 2 or 3 TGWH and one storage tank. If one tankless goes down you still have one until you get the units that is down gets repaired.
    I would go with two smaller commercial water heaters that are 75% each of what you now have in. Get the company that is installing the two water heaters to set up a service contract where they come out twice a year to flush out the tank, check venting make sure the water heater is running right. Once a year or every 1 1/2 years replace the anode rod in the tank type water heater. Make user you have a working thermal expansion tank on the water heater.

    That's the only way these units will ever get serviced except when down.
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