need advice on BTU’s for a commercial water heater…

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    • #276230

      This is my first time using this site and I am hoping someone will have a suggestion to help me.

      The situation:

      I run a historic hotel in Sonora, CA and we are having hot water troubles. Our current system uses 2 state 100gal 440K BTU water heaters in series into 2 state 200gal storage tanks. We have a circulation pump with a thermostat to keep the storage water up to temp. This system was installed in 1984.

      The problem:

      One of the heaters is now leaking!!!

      The Question:

      How do I figure out how much capacity we really need here? Is there a formula, maybe from the water heater manufacturers, that tells how much water is needed in a hotel situation? We have 31 rooms in this building and we also have a bar and restaurant, but the restaurant is only open for lunch and dinner. Most of the restaurant water usage would be in the afternoon and the guest rooms only really use hot water in the morning.

      I have a quote from a local commercial plumber for installation but no one can tell me how much I really need. I am considering buying 2 Rheem 100 gallon 199K BTU heaters, but I need to be sure if they are big enough.

      Thanks in advance for any help you can give.
      [email protected]

    • #293685

      good lord are’nt any of you talking heads going to answer this guy i want to learn too!

    • #293686
      Robert Stephen Morton

      robertgf, it took me a long time to fathom out wot was missing.
      Any ideas of incoming temp & required temp?
      Is the Restaurant private or public & what is the throughput?
      How efficient is the lagging on the circulation pump?
      Was the old system coping with the demand?
      He tated that the present system was 880000BTU’s but was thinking of installing a 398000BTU system.
      Maybe he is working on the basis that the global warming is to fill the gap.
      Mate you can only get out of the system wot you put in.
      Bob [email][/email]but remember we work in calories

    • #293687

      Best way out of this problem is to simply calculate the number of gallons/litres you require at a maximum hourly drawoff from the system and size one to suit that capacity or allow for a storage medium to hold sufficient volume at the right temperature with a smaller BTU input from a heater unit.
      Personally I would go for a tankless unit or a number of them manifolded together able to cope with the maximum drawoff demand but also capable of supply economically the smallest demand required.
      No storage tanks whatsoever are required for these units and they could be connected to a ring main system which would give instantaneous hot water at any outlet point as needed.
      This is a popular way of providing hot water on demand down here and I don’t see why it will not work for you there either.
      If you decide to proceed this way have the heaters set at a maximum outlet temp of 60 degrees C to ensure longevity of the heat exchangers within them.

      Selgas Services Ltd
      Craftsman Gasfitters, Plumbers, Electrical Service Technicians

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