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Apartment building

JStar Member Posts: 2,752
I'm preparing an estimate for a 36 unit apartment building with showers only. Want to verify my numbers. 2.5 gpm shower heads. No other appliances. Approximately 2 people per unit. 72 people total.

What should the first hour, recovery, and boiler output be? I've gotten several different answers from different sources.


  • bob eck
    bob eck Member Posts: 930
    Gallons of hot water

    Go to www.hotwater.com look for sizing.

    If using 2.5 GPM 36 units with 2 people with a 100* F temp rise you need 314 gallons for a medium peak demand.

    Look at using Delta 1.5 GPM shower heads and you only need 188 gallons for a medium peak demand.

    I have the 1.5 GPM shower heads in my house and they work fine.

    If using the 1.5 GPM shower heads you will be using a smaller water heater plus the building will use less water and their water and sewer bill will be less. If on a well pump system and septic system these systems will last longer using less water.

    What about using tankless gas water heaters for this type of job. Only uses energy when hot water is needed.

    Take a look at using the A O Smith high efficiency condensing tankless gas water heaters. The ATI540H vents with PVC pipe and you can link 4 units together without a special controller or with a controller you can install up to 20 units.

    Soon you will be able to common vent multiple units for commercial jobs.

    Their heat exchanger warranty now is 5 years and soon going to 10 years for commercial jobs.

    If using the 1.5 GPM shower heads you would need 8 units.

    If using the 2.5 GPM shower heads you would need 13 or 14 units.

    Big savings using lower flow shower heads.

    A O Smith does have a 910 model 380,000 BTU and you would need 5 units for 1.5 GPM SH and 8 units for 2.5 shower heads this model vents with stainless steel venting

    Depending where you are I can quote you on this job send me a email.
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