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Model RA-28 Four-Chamber Tankless Electric Water Heater The Model RA-28 four-chamber tankless electric water heater is designed for potable whole house, residential, applications and commercial applications, such as specialty restaurants, convenience stores, hotels and pet grooming shops. The Model RA-28 is ideal as a back-up to solar and/or geothermal passive heat recovery systems. A minimum of 200 AMP whole house electrical service is recommended. Model RA-28 Features • • • • • • • • • • • • Exterior An endless supply of hot water Heats water only when you need it Very small & compact Lightweight Microprocessor controlled Power sharing technology Continuous venting No moving parts No restriction to flow Self-diagnostics Redundant safety devices Heating chamber made of performance polymer nylon material Specifications Interior A tankless electric water heater shall be installed where indicated on the plans. The water heater shall provide an endless supply of hot water on an as need basis. The water heater shall be compact, lightweight, microprocessor controlled and contain power sharing technology. A minimum of 200 AMP whole house electrical service shall be provided. The tankless electric water heater shall be a Watts Regulator Company Model RA-28. Approvals UL, CSA, BOCA, SBCCI "RA" designed models are for potable water heating applications only and are not warrantied for use in space heating applications. Watts product specifications in U.S. customary units and metric are approximate and are provided for reference only. For precise measurements, please contact Watts Technical Service. Watts reserves the right to change or modify product design, construction, specifications, or materials without prior notice and without incurring any obligation to make such changes and modifications on Watts products previously or subsequently sold. Dimensions - Weight Installation Water Fittings Inlet: 3/4" (20mm) HOT* Outlet: 3/4" (20mm) Shut-Off COLD Mounting Holes 240 volt (AC) BREAKERS 4 pairs of #10 cu AWG w/ ground A – 141/4" (362mm) B – 161/8" (410mm) or 30 A WATTS RA-28 A e on stit not o p e e s 9 W-RA ES-WH 240 volt (AC) BREAKERS 60 A 30 A 60 A 30 A 2 pairs of #10 cu AWG w/ground 30 A *T&P Relief Valve Not Required B *Maximum system flow will depend on design & model selection FLOW RATES, TEMPERATURE RISE & HEAT RATINGS Model Heat Output Rating (BTU) Max. GPM for Temp. Rise 42° –120° Max. GPM for for Temp. Rise 50° –120° Max. GPM for for Temp. Rise 55° –120° Max. GPM for for Temp. Rise 60° –120° Max. GPM for for Temp. Rise 65° –120° RA-28 95,560 2.5* 2.8 3.0 3.2 3.4 GPM = Gallons per minute (Flow Rate) Note: Increasing the temp. output from 120°F will reduce the max. GPM at the higher temp. but will not change the total GPM of tempered water (hot & cold mix) *Note: This represents the maximum flow rate (gpm) to obtain 120°F water when the incoming water temperature is 42°F. ( a max "delta rise" at 2.5 gpm of 78°F) MODEL SPECIFICATIONS Model Weight RA-28 lbs kg 23 10.4 Height inches mm Width inches mm Depth inches mm 153/4 153/4 61/4 159 400 400 Plumbing Fittings inches mm 3 4 / 20 Heating Elements (Watts X No.) Energy Factor 7000 x 4 0.99+ ELECTRICAL RATINGS ** Model Maximum Power Rating (kw) Voltage Rating (VAC) Maximum Current Rating (AMPS) Number of Circuits Required (two wire) Number of Circuit Breakers Required (Double Pole) Circuit Breaker Size (AMPS) RA-28 28 240 116 4* 4* 30 **Optional wiring: Two, 2-wire, double-pol, 6 amp circuits (jumpers must be installed on control board for this option - check with manufacturer.) Capacity WATTS 240 VAC RATED, 240 VAC SERVICE WATTS 240 VAC RATED, 208 VAC SERVICE KW vs GPM For Various Inlet Temperatures To Deliver 120°F 3.5 3 Flow Rate (GPM) Flow Rate (GPM) KW vs GPM For Various Inlet Temperatures To Deliver 120°F 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 2.5 2 1.5 1 0.5 9 11 14 18 Power (KW) 22 28 0 6.75 8.25 10.5 13.5 Power (KW) 16.5 21 Key 44 F INLET 56 F INLET 72 F INLET WATTS 208 VAC RATED, 208 VAC SERVICE Flow Rate (GPM) 4 3.5 KW vs GPM For Various Inlet Temperatures To Deliver 120°F 3 2.5 2 1.5 1 0.5 0 5 7 10 14 Power (KW) 18 24 USA: 815 Chestnut St., No. Andover, MA 01845-6098; www.wattsreg.com Canada: 5435 North Service Rd., Burlington, ONT. L7L 5H7; www.wattscda.com ES-WHW-RA-28 0330 © Watts Regulator Company, 2003 Printed in U.S.A.