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AGE of WATER HEATERS
AIRBOUND HEAT SYSTEM REPAIR by WATER FEED VALVE
ALTERNATIVE HOT WATER SOURCES
ANODES & DIP TUBES on WATER HEATERS
ANTIFREEZE for BOILERS
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
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
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
GAS PIPING, VALVES, CONTROLS
HEAT TAPES, Heat, Insulation prevent Freeze-Up
HEATING COST FUEL & BTU Cost Table
HEATING COST SAVINGS METHODS
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
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
PIPING IN buildings, Clogs Leaks Types
PLASTIC HEATER VENT
PLUMBING FIXTURES, KITCHEN, BATH
PLUMBING VENT DEFECTS & NOISES
PUMPS, HEAT PUMPS
PUMPS, OIL BURNER
PUMPS, PONY PUMPS
PUMPS, SEPTIC PUMPS
PUMPS, SEWAGE EJECTOR / GRINDER PUMPS
PUMPS, SUMP PUMPS
PUMPS, WATER PUMPS
PUMPS, WATER REPAIR
RELIEF VALVE LEAKS
RELIEF VALVES - TP Valves on Boilers
RELIEF VALVES - STEAM TP VALVES
RELIEF VALVES - Water Heaters
RELIEF VALVES - Water Tanks
SAFETY, HEATING INSPECTION
SCALE REMOVAL, WATER HEATERS
SEWER GAS ODORS
SOLAR HOT WATER HEATERS
SOOT on OIL FIRED HEATING EQUIPMENT
SPILL SWITCHES - Flue Gas Detection
TANKLESS WATER HEATERS
THERMOSTATS, HEATING / COOLING
THERMOSTATS, WATER HEATER
TIMERS for ELECTRIC WATER HEATERS
WATER CONTAMINANT LEVELS
WATER HAMMER NOISE DIAGNOSE & CURE
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
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 GAUGE ACCURACY
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER PRESSURE REDUCER / REGULATOR
WATER PRESSURE PUMP REPAIR GUIDE
WATER PUMPS, TANKS, TESTS, WELLS, REPAIRS
WATER PUMP REPAIR GUIDE
WATER QUALITY TESTS, CONTAMINANTS, TREATMENT
WATER QUANTITY IMPROVEMENT
WATER SOFTENERS & CONDITIONERS
WINTERIZE A BUILDING
Tankless Water Heater Installation Requirements & Costs: this article explains the special installation requirements, purchase & installation costs, & operating costs of of tankless water heaters, also called instant water heaters or "on demand" water heaters. Readers should also see ALTERNATIVE HOT WATER SOURCES to distinguish among these types of hot water producing systems. Portions of this article were provided courtesy of Carson Dunlop - that text has been edited and may not entirely reflect CD's views. Page top sketch of a point of use tankless water heater courtesy of Carson Dunlop Associates.
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As we discussed at Problems & Defects, conventional water heaters are relatively inexpensive due to their simplicity while tankless water heaters are more expensive to purchase and install.
In 2009 in Toronto, Ontario a high capacity instantaneous water heater installation could cost $4000. CDN. Their complexity also means that maintenance and repairs can be more expensive.
Dedicated isolating valves help simplify draining and other regular maintenance.
Below we discuss some of the special requirements for installation of tankless water heaters, followed by a discussion of the operating cost of tankless water heating systems.
Sketch of a point of use tankless water heater shown above/left was provided courtesy of Carson Dunlop Associates.
According to the U.S. Department of Energy,
Note that this advice from DOE addresses hot water heating operating cost and does not include nor provide a payback period analysis that considers the purchase and installation cost for tankless or demand water heaters, though the DOE does observe that assuming a 20-year life for the tankless water heater,
Note that this analysis does not include maintenance and repair costs that tend to be higher for tankless or demand water heaters, nor does it address hidden costs such as extra maintenance cost to address scale formation in areas of hard water, or the possible additional cost of a water softener or water conditioner that may be needed to protect the equipment. When we compared two alternative solar water heater designss in 2011 we found that one company, Bosch, can provide a water heater designed to resist clogging and damage from scale formation in areas of water with high mineral content. We also observed that the cost of this installation was two to three times as much as other water heater models.
Watch out: if money or return on investment is the principal reason you are considering converting to a demand type water heater, you should perform an accurate total cost analysis that reflects all of the costs to install, operate, & maintain both types of water heaters: a tank type water heater and a tankless or demand water heater - for purpose of comparison. At Possible Costs (including hidden costs) Involved in Converting to a Tankless or Demand Water Heater we list all of the costs likely to be involved in different approaches to producing hot water for washing & bathing in a building.
For example, and using the DOE data above, if we assume
Of course there may be other significant reasons to install a demand type water heater besides pure economic operating cost payback.
Impact of higher fuel usage rates & pilot lights on tankless water heaters
The burners are triggered by sensors that detect the flow of water. If the flow of water is too low, typically less than ½ gallon per minute, the burners will not turn on and no hot water will be delivered.
Water-saving shower heads, for example, may not allow enough flow to turn the water heater on, especially when the water heater has a high minimum flow rate. Rheem, for example, requires a .66 GPM flow rate to ignite the burner. (This is probably to avoid overheating in the heat exchanger.)
Some tankless water heaters may not operate properly at high elevation installations. Some manufacturers address this specifically. For example, all Rheem tankless water heaters can be programmed to operate at elevations up to 9,840 feet.
The temperature/pressure relief valve lets water escape if the temperature or pressure is too high. This valve should be connected to a tube that discharges no more than six inches above floor level so hot water won't scald anyone nearby.
Some codes require that the tube discharge outside the building. The tube should be as large as the tank fitting and the tube end should never be threaded, capped or plugged.
The tube should be able to withstand 250°F temperatures, should have no shut-off valve, and should be as short and as straight as possible.
Inspecting several rental properties owned by the same landlord we found that the plumber she used to install tankless water heaters at multiple apartments didn't realize that each gas fired unit needed combustion air.
Each tankless water heater had been installed on an exterior wall and to avoid tenants fooling with the heater, the plumber enclosed each unit in a steel box with a lock.
The tenants complained of gas odors and of constant loss of hot water. Because the units were installed outdoors the dangerous carbon monoxide that was being produced had not resulted in a catastrophe.
Be careful. At least some demand water heaters (such as those made by Rheem) are sold in models designed for a specific fuel such as Natural gas OR LP Gas. These units cannot be converted from LP to Natural Gas or vice versa. So be sure you are specifying the proper model and fuel type when buying a tankless water heater.
Tankless water heaters are considerably more expensive than conventional tank-type heaters, and although tankless units are more energy efficient, it may take a long time to recoup the extra investment.
As we mentioned above, people pay up to $4000 for these units installed (February 2009).
Consumer Reports points out that a tankless water heater may be efficient but not necessarily economical to operate.
The organization reported that tankless water heaters cost $800 to $1,150, compared with $300 to $480 for a conventional tank type electric water heater.
We pose that this gap may also need adjustment for differences in installation cost and equipment life. (Tankless units may need higher maintenance.)
One of the issues is that the large burners require larger gas piping. In some cases the gas piping into the house is not large enough to accommodate the other appliances plus the tankless water heaters. The requirement to install new gas piping adds considerably to the installation cost.
There are also often challenges about where venting can be placed. Exhaust cannot terminate close to building openings, close to air intakes, at inside building corners, too close to grade, etc.
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