sizing indirect DHW tank

scott200

I'm looking to match a DHW indirect tank to a Buderus GB142/30. Based on a manual J, I'm rather confident in the boiler sizing, but am not sure of the tank size I will need. I have 2 adults and 3 kids in the house- though the kids will be adults before too long. The house has 3.5 baths plus all the usual appliances. No whirlpool tubs. No unusual/multiple shower heads. I imagine I will use a Buderus tank, though I'm open to suggestions. Thanks

Jean-David Beyer

Weil McLain have this worksheet to calculate indirect size

While this is for their boilers and indirects, it is pretty obvious how to adapt their chart to other boiles and indirects. I use cold water in my clothes washer, so I do not include the hot water consumption when filling out their worksheet.



http://www.weil-mclain.com/en/multimedia-library/pdf/weil-mclain-pdf/products/water-heaters/indirect-fired-water-heater/indirec_fired_water_heater_series_3_lus_indirect_fired_water_heater_lit.pdf

SpeyFitter

Girls, or Boys?

You didn't say what kind of kids. Are they girls, or boys? IF they're Girls (and teenage ones at that), take the tank you think you'll need and go up one size right away! (LOL).  Also, the fact they're adults soon shouldn't play into your calculation as who knows how long they might still be living at home.

Based on your description I'd go for a 75-80 gallon tank, set at 135-140 degrees and mixed down to a lower temperature with a thermostatic tempuring valve to prevent potential scalding incidents for anyone who may inhabit there.