Heating Helper

CHAPTER 4 - DOMESTIC HOT WATERdomestic hot water sizing requirementsA. RESIDENTIAL: Sizing residential water heaters varies with .manufacturers. HUD and FHA have stablished minimum .permissible water heater sizes as shown in the floowing table...HUD, FHA Minimum Water Heater Capacitiesfor One and Two-Family Living UnitsNumber of Baths 1 to 1.5 2 to 2.5 3 to 3.5Number of Bedrooms 1 2 3 2 3 4 5 3 4 5 6GAS (a)Storage, gal. 20 30 30 30 40 40 50 40 50 50 501000 Btu/h input 27 36 36 36 36 38 47 38 38 47 501-h draw, gal. 43 60 60 60 70 72 90 72 82 90 92Recovery, gph 23 30 30 30 30 32 40 32 32 40 42TANK TYPEINDIRECT (b,c)I-W-H rated draw,gal. in 3-h, 100°F riseManufacturer-rateddraw, gal. in 3-h,100°F (55.6°C) rise40 40 66 66 66 66 66 66 6649 49 75 75d 75 75 75 75 75Tank capacity, gal. 66 66 66 66d 82 66 82 82 82TANKLESS TYPEINDIRECT (c,e)I-W-H rated,gpm 100°F rise2.75 2.75 3.25 3.25d 3.75d 3.25 3.75 3.75 3.75A. Storage capacity, input, and recovery requirements indicated in the table are...typical and may vary with each individual manufacturer. Any combination of.. .these requirements to produce the stated 1-h draw will be satisfactory.B. Boiler-connected water heater capacities [180°F boiler water, internal orexternal connection].C. Heater capacities and inputs are minimum allowable. A.G.A. recovery ratings. . for gas heaters, and IBR ratings for steam and hot water heaters.D. Also for 1 to 1.5 baths and 4 B.R. for indirect water heaters.E. Boiler-connected heater capacities [200°F boiler water, internal or externalconnection].Reference: ASHRAE/Systems Handbook (Service Water Heating)63