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 Mobile ViewWATER HEATERS AGE of WATER HEATERS AIRBOUND HEAT SYSTEM REPAIRS ALTERNATIVE HOT WATER SOURCES Electric Shower Heaters High Efficiency Water Heaters Indirect-fired Water Heaters Instantaneous Water Heaters Multiple water heaters in parallel Multiple water heaters in series Range Boiler Water Heaters Side Arm Coil Water Heaters Solar Water Heaters Tankless Coil for Hot Water Tankless Water Heaters ANODES & DIP TUBES on WATER HEATERS ANTI SCALD VALVES APPLIANCE EFFICIENCY RATINGS AQUASTAT CONTROL Functions BACKDRAFTING HEATING EQUIPMENT BACKFLOW PREVENTER VALVE, HEATING SYS BACKFLOW PREVENTER, HEATER WATER FEEDER BACKUP HEAT for HEAT PUMPS BLEVE EXPLOSIONS BOILERS, HEATING CARBON MONOXIDE - CO CHECK VALVES, WATER SUPPLY CHEMICAL CONTAMINANTS in WATER CHIMNEY INSPECTION DIAGNOSIS REPAIR CLOGGED DRAIN DIAGNOSIS & REPAIR CLOGGED SUPPLY PIPING CROSS CONNECTIONS, PLUMBING DEBRIS in WATER SUPPLY, Water Heater DRAIN a WATER HEATER TANK ELECTRIC WATER HEATERS Electric, Gas, Oil Water Heater Efficiency Electric Shower Heaters Electric Water Heater Checklist Electric Water Heater Controls List Electric Water Heater Element Replacement Electric Water Heater Element Tests Electric Water Heater High Temp Cutoff Test Electric Water Heater Repair Guide Electric Water Heater Reset Switch Electric Water Heater Thermostats Electric Water Heater No Hot Water Electric Water Heater Parts Identification Electric Water Heater Reset & Temp Set Hot Water Temperature & Pressure Valve Timers for Electric Water Heaters Water Heater Anode & Dip Tube Check ENERGY SAVINGS in buildings FLOODED HEATING EQUIPMENT REPAIR FLOODED WATER HEATER REPAIR FREEZE-PROOF A BUILDING FROST HEAVES, FOUNDATION, SLAB GALVANIC SCALE & METAL CORROSION GAS BURNER Flame & Noise Defects GAS FIRED WATER HEATERS DRAFT HOODS - gas fired Gas BTUH & Cubic Feet Gas Conversion LP Natural Gas GAS PIPING, VALVES, CONTROLS SOOT on OIL FIRED HEATING EQUIPMENT SPILL SWITCHES - Flue Gas Detection GAS PIPING, VALVES, CONTROLS HEAT TAPES, Heat, Insulation prevent Freeze-Up HEATING COST FUEL & BTU Cost Table HEATING COST SAVINGS METHODS HEATING SYSTEMS HOT WATER SUPPLY HOT WATER IMPROVEMENTS HOT WATER DELIVERY SPEED UP HOT WATER EFFICIENCY IMPROVEMENT HOT WATER PRESSURE EXPANSION RATE HOT WATER PRESSURE LOSS HOT WATER PROBLEM DIAGNOSIS HOT WATER QUANTITY IMPROVEMENT Alternative Hot Water Sources & Methods Anti-Scald Valves & Hot Water Quantity CLOGGED PIPING & Hot Water Flow Extra Tanks to Increase Hot Water Insulate Hot Water Piping Insulate Hot Water Tank? Larger Diameter Water Supply Piping Water pipe clog diagnosis Water pipe clog repair guide HYDROGEN SULFIDE GAS INDIRECT FIRED WATER HEATERS MANUALS & PARTS GUIDES - HVAC MIXING / ANTI-SCALD VALVES NO HEAT - NO HOT WATER: HEATER DIAGNOSIS NOISE / SOUND DIAGNOSIS & CURE NOISE CONTROL for HEATING SYSTEMS NOISE, PLUMBING CHECKLIST NOISE, WATER HEATER ODORS GASES SMELLS, DIAGNOSIS & CURE ODORS IN WATER OIL FIRED WATER HEATERS PIPING IN buildings, Clogs Leaks Types PLASTIC HEATER VENT RADIANT HEAT RANGE BOILERS RELIEF VALVES - TP Valves on Boilers RELIEF VALVES - Water Heaters RELIEF VALVES - Water Tanks SAFETY, HEATING INSPECTION SCALE REMOVAL, WATER HEATERS SEWER GAS ODORS SOLAR ENERGY SYSTEMS SOLAR HOT WATER HEATERS SOOT on OIL FIRED HEATING EQUIPMENT SPILL SWITCHES - Flue Gas Detection TANKLESS COILS AQUASTAT CONTROL Functions Clogged Pipes / Tankless Coil De-Scale MIXING / ANTI-SCALD VALVES Tankless Coil Conversions Tankless Coil Leaks Tankless Coil Hot Water Increase TANKLESS WATER HEATERS Electric Shower Heaters Guide to Tankless Water Heaters Operation & Characteristics Problems & Defects Hot Water Delivery Speedup Installation Requirements & Costs Should I Convert to a Tankless Heater? Calculate Water Heater Requirements Capacities of Tankless Water Heaters Life Expectancy & Applications Temperature Pressure Relief Valves - Water Heaters THERMOSTATS, HEATING / COOLING THERMOSTATS, WATER HEATER AQUASTAT CONTROL Functions Electric Water Heater Thermostats TIMERS for ELECTRIC WATER HEATERS VALVES, PLUMBING WATER CONTAMINANT LEVELS WATER HAMMER NOISE DIAGNOSE & CURE WATER HEATERS WATER HEATER ALTERNATIVES WATER HEATER ANODES, DIP TUBES WATER HEATER AIR INLET WATER HEATER DEBRIS FLUSH WATER HEATER DRAIN PROCEDURE WATER HEATER EFFICIENCY WATER HEATER FLUSH PROCEDURE WATER HEATER NOISES WATER HEATER PROBLEM DIAGNOSIS WATER HEATER PROPERTIES Electric, Gas, Oil Water Heater Efficiency Water Heater Life Expectancy Comparisons Water Heater Operating Cost Comparisons Water Heater Purchase & Maintenance Costs Water Heater Water Quantity Comparisons Water Heater Recovery Speed Comparisons Water Heater Safety Comparisons WATER HEATER EFFICIENCY WATER HEATER SCALE - De-Liming Procedure WATER HEATER SCALE PREVENTION WATER HEATER SAFETY WATER HEATERS for HOME HEATING USE? WATER ODORS, CAUSE CURE WATER PIPES, Clogs Leaks Types WATER PRESSURE & FLOW MEASUREMENT WATER PRESSURE VARIATION CAUSES WATER PRESSURE TOO HIGH: DANGERS Definition of Static Water Pressure Definition of Dynamic Water Pressure Measure Municipal Water Pressure Measure Pump & Well Water Pressure WATER FLOW RATE MEASUREMENT HOT WATER PRESSURE EXPANSION RATE WATER PRESSURE GAUGE ACCURACY WATER PRESSURE LOSS DIAGNOSIS & REPAIR WATER PRESSURE REDUCER / REGULATOR WATER PRESSURE REPAIR GUIDE - WELLS WATER PUMPS, TANKS, TESTS, WELLS, REPAIRS WATER PUMPS & WELLS WATER PURIFIERS WATER QUALITY TESTS, CONTAMINANTS, TREATMENT WATER QUANTITY IMPROVEMENT WATER SOFTENERS & CONDITIONERS WINTERIZE A BUILDING More Information |
Tankless water heater capacity sizing: here we explain how to calculate the size or capacity of tankless water heater you will need in a building. InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers nor with topics or services discussed at this website.© Copyright 2010 InspectAPedia.com and Carson Dunlop Associates, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website. How to Calculate Tankless Water Heater Requirements
T1 = incoming water temperature T2 = desired output hot water temperature at the plumbing fixture (say a shower) GPM = anticipated hot water flow rate or usage rate in gallons per minute. Example: If your incoming water temperature to the building is 40 deg.F. and you want to provide hot water at a bath shower at 100 deg. F., and if your shower fixture runs at 3 gpm, then T1 = 40 deg.F., T2 = 100 deg.F. T2 - T1 = 60 deg.F. - that's the temperature rise you need.
Your tankless water heater will need to be able to provide a 60 deg. temperature rise at 3 GPM. Note 1: our example does not consider temperature losses in the piping between the water heater and the point of use nor the use of temperature limiting or anti-scald valves in the plumbing system, both of which reduce the actual hot water flow rate in gpm While 100° may be a good shower temperature, this means that mixing valves at the shower will be delivering almost 100% hot water. This may make filling a bathtub slow or result in lower water pressure than anticipated. When we blend hot and cold water, we enjoy a higher flow rate and commensurately higher pressure at the shower. Note 2: it's quickly apparent that if the hot water system is going to be asked to provide 100 deg.F. hot water to multiple fixtures simultaneously, the gpm heating rate of your tankless water heater is going to have to be big - and may be beyond the capacity of the equipment. In this case see our Multiple Ganged Tankless Water Heaters article. Gas fired tankless water heaters can usually produce more hot water faster than an electric unit. Electric tankless water heaters are simplest to install and operate, requiring only wiring and water piping, no fuel piping, no venting or chimney. If your building includes three or four bathrooms or even just two baths, and if the occupants are likely to want to run hot showers simultaneously at multiple fixtures, the performance of a single demand water heater or tankless water heater may be marginal unless the unit is quite large. Questions & Answers regarding this articleQuestions & answers about how to determine the size of tankless or demand water heater needed. Ask a Question or Search InspectAPediaHTML Comment Box is loading comments...
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