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Indirect boiler size

jurassicjet | Posted in Energy, Heating & Insulation on May 31, 2008 06:36am

Hello:

I have a Buderus GB142 boiler rated at around 85,000 btu’s. I am looking at a Crown Mega-Store 40 gallon indirect water heater. I called Crown corporation directly to ask them a couple of questions about their boiler. While talking to the factory rep he asked me if I had a whirlpool and if I did I should get the 51 gallon model.
My question is this…..the boiler has 40 gallons of hot water in it already. According to the literature it is capable of delivering around 140 gallons per hour of hot water (wow….. thats a lot to me!). So.. I dump all 40 gallons of hot water into the whirlpool (92gal max, 53 min) and continue to fill it with tempered hot/cold mix. Why would a 40 gallon water heater not be enough? If the DHW heater is capable of delivering 140 gph that is 2.3 gallons per minute of hot water. Seems like it would be ok to me.
BTW… I do not plan on filling that whirlpool every day, maybe once or twice a week at the most.

Any thoughts?

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Replies

  1. JeffinPA | May 31, 2008 11:55pm | #1

    The 40 G might be enough based on your calcs for the soaking tub (whirlpool, whatever) but what if you finish dinner, wash the pots and pans, throw a load of laundry in (whites), run over, turn on the dishwasher and then think, Sh** I am exausted, I would really like to take a bath.

    Run up and turn on the water, and about 10 minutes later wonder what the H/F*** is going on with that brand new indirect you just spend an arm and leg on.

     

    does that answer your question?

  2. Clewless1 | Jun 01, 2008 03:57am | #2

    remember ... 40 gal of hot water in your whirlpool is not 40 gal of hot water out of your water heater ... assuming you take a bath at say 97-102 roughly, part of the 40 gal will be cold water.

    The other guy is right, though ... for one use, it may be plenty, but if you have the teenage daughters from hell ... that love to take e.g. 20 min showers (I'm not joking here), then you better have mondo capacity in your system! If simultaneous use/loads are uncommon, maybe not an issue. With quick recovery, it may very well not be a big issue to wait 25-20 min. for your next task.

    1. jurassicjet | Jun 01, 2008 06:10am | #3

      Well, I am starting to lean towards the 51 gallon then. Yes, I have the 3 teenage daughters that you are referring to, not necessarily from hell, but they do take the long showers (I couldn't get one out of the shower once, ticked me off so bad after about 35 minutes that I went downstairs and turned the hot water valve off.. that fixed her).Thanks for the responses so far. I am learning quick here.

      1. Clewless1 | Jun 01, 2008 07:14pm | #4

        ... if they dress like angels and take long showers ... they are only the devil in disguise!! I've done the same to my daughters ... even threatened to install a timer valve. Personally, I think 5 minutes is plenty of time for a shower. I can take one in less than 2 easily ... (no hair). 10 minutes is way generous. Take away their allowance. Let them pay one utility bill ... it will only happen once. Once you are clean, you don't get any cleaner by being in longer.

      2. Clewless1 | Jun 01, 2008 07:15pm | #5

        Better get the1.5 gpm shower head ... we are going to install them at a Navy base. Tested and approved by ... women! I'm not kidding.

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