Hot water heaters – sizing – brands
tpmcnichol
| Posted in Energy, Heating & Insulation on
Hi,
Need recommendation on hot water heater for 2 applications.
Scenerio #1 Separate new construction guest house w/ new full bath. Would like to find some kind of wall mount H20 heater using propane. I see reference to “on demand” systems. What size would you all recommend….guest house…not a daily use scenario…max load would be 2 showers back to back. No major physical size restrictions.
Scenerio #2: Need an electric H2O heater for a stack washer and dryer. Understand from the washer specs it’s a 20 gallon wash cycle and a 20 gallon rinse….25% is HOT. So that’s 5 gallon per cycle. Can one of the these 6 or 10 gallon pony tanks reheat quickly? No size restrictions per say…but would like to make as small as possible.
Ted
Replies
1) An on-demand heater can do back-to-back showers endlessly. The smaller ones can not handle multiple fixtures in use at the same time, but that should be fine in a guest house. They cost more than a tanked HWH, but you save 4 to 6 sq ft of space, so that's, what? $500 or more saved in building costs. That would easily pay the differential. Note that a larger flue is needed, but that is easy in new construction.
2) No, those small, point-of-use electric HWH do NOT recover quickly. Typically, they have 1500-1800 watt, 120-volt elements. To heat another 10 gallons from 60 to 120 F would take 58 minutes at 1500 watts. Note, however, that a warm instead of hot (or cool instead of warm0 washer load is not the end of the world. Modern detergents are quite good at cooler temps and you would probably rarely notice any difference those times when you did back-to-back loads and the HWH hadn't fully recovered.
Being the shower and running out of hot water? That is to be avoided. But laundry? Find one that is not too expensive (they often cost almost as much as 40-gallon tanks), and the right size. Extra points for higher wattage.