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WATER HEATERS
ALTERNATIVE HOT WATER SOURCES
  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
ANTI SCALD VALVES
CHIMNEY INSPECTION DIAGNOSIS REPAIR
Clogged Piping & Hot Water Flow
ELECTRIC WATER HEATERS
GAS FIRED WATER HEATERS
  DRAFT HOODS - gas fired
  Gas BTUH & Cubic Feet
  GAS PIPING, VALVES, CONTROLS
  SPILL SWITCHES - Flue Gas Detection
HOT WATER IMPROVEMENTS
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
  Temperature of Hot Water is Too Low
INDIRECT FIRED WATER HEATERS
OIL FIRED WATER HEATERS
ODORS IN WATER
  DRAFT REGULATORS - barometric dampers
  OIL BURNERS
  OIL BURNER NOISE SMOKE ODORS
  OIL PIPING
  OIL TANKS
MIXING VALVES
RANGE BOILERS
RELIEF VALVES - TP Valves
SEWER GAS ODORS
SOLAR HOT WATER HEATERS
TANKLESS COILS
  Clogged Piping / Tankless Coil & Hot Water Flow
  Mixing Valves
  Tankless Coil Leaks
  Tankless Coil Hot Water Increase
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
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How to Safely Increase Hot Water Temperature your Water Heater
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How to improve hot water water temperature without being scalded and burned
How to stop running out of hot water, How to make hot water hot enough

Our site offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. Our contact info is at inspect-ny.com/appointment.htm.

This article explains how to improve the hot water water temperature & water temperature safety in a building. Thanks to Carson Dunlop, a Toronto Home Inspection Firm and Home Inspection Educator, for permission to use sketches shown in this article.

Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use the links at page left to navigate this document or to go to Other Website Topics. Green links at left show where you are in our document & website.

Here we describe various ways to improve hot water quantity, pressure, and flow are discussed beginning at HOT WATER IMPROVEMENTS and continuing at HOT WATER QUANTITY IMPROVEMENT.

At ALTERNATIVE HOT WATER SOURCES we describe various water heating methods. The detailed characteristics of various water heaters themselves, such as life expectancy, cost, safety, and capacity are discussed at ALTERNATIVE WATER HEATER PROPERTIES

How to Correct Hot Water Temperature that is Too Low

If your hot water temperature is just not ever hot enough here are some things to check:

Check the water temperature settings on the water heater control. You can increase the water temperature setting, but beware of scalding. See Mixing Valves for a discussion of the installation and use of anti-scald valves to avoid hot water burns, and for a table of temperatures at which hot water burns occur.

The temperature control on the gas fired water heater shown in our photo at left has been set to "Low" and could be turned "up" to a hotter temperature if building hot water is found to be too cool.

Check for long runs of un-insulated hot water piping, especially if the piping runs through cold walls, basements, crawl spaces, or attics. If the water is leaving your water heater at a high temperature but arriving too cool at the sink, shower, or tub, see Insulate Hot Water Piping for details.

Check for a leaky water heater tank dip tube (sketch courtesy Carson Dunlop) at your water heater tank. If your water is heated by an electric, gas, oil, or even solar-heated water tank, the tank probably uses a dip-tube to direct incoming cold water to the bottom of the hot water tank.

If the dip tube is leaking (metal dip tubes are often intended to corrode) it may be leaking incoming cold water into the top of the water heater tank.

The water tank dip tube, often made of a special metal to combine its function with that of a water heater tank sacrificial anode (to reduce water tank corrosion and leaks) performs these functions:
- incoming cold water is placed at the bottom of the water tank, closest to the heating element or burner
- incoming cold water does not dilute and cool down the outgoing hot water which by natural convection will normally rise and be found at the top of the hot water tank
- construction of a dip tube of an intermediate metal (perhaps zinc) will permit it to function as a sacrificial anode in the water tank to reduce the corrosive effects of hot water on the water tank body itself - this makes the water tank last longer. We discuss the hot water tank sacrificial anode and dip tube in more detail at Check the Sacrificial Anode & Dip Tube of Your Water Heater Tank.

Check for a burned out electric water heater heating element: if your water heater is electric it probably has two heating elements, an upper and a lower unit. It's easy to diagnose a bad electric water heating element, and you can suspect a problem with the heating elements in an electric water heater even before doing any testing: (sketch courtesy Carson Dunlop)

If the hot water coming out of the electric water heater is hot but runs out more quickly than previously, we suspect that the lower heating element has burned out. The upper water heating element is heating up just the water in the top of the water tank. So you have just a small amount of hot water before you run out.
If the hot water coming out of the electric water heater has become tepid when it used to be hot (and no one has changed any other hot water settings), we suspect that the upper heating element has burned out. When only the lower heating element in an electric water heater is working, it will warm the water but it will normally be unable to raise the temperature in the whole water tank to a high enough level. So you have plenty of tepid "hot" water.

Check for an oil fired water heater that needs cleaning: oil fired heating equipment, when properly adjusted, does not burn perfectly clean.

Burning heating oil produces soot which over time sticks to the interior surfaces of the water heater's interior. There the soot acts like an insulator, reducing the transfer of heat from the burning heating oil through the metal of the water heater's heat exchanger, into the hot water itself. You may have plenty of water but its temperature is not as hot as it used to be.

Often service people called to clean and tune an oil fired heating boiler do not clean and adjust the oil-fired water heater unless specifically asked (and paid) to do so.

Just as your oil fired furnace or boiler should be serviced annual (for safety and to lower heating costs), so should your oil-fired water heater be cleaned and tuned annually.

It's likely that this service will be earned back easily in reduced heating oil costs. See How To Cut Heating Costs for details.

Check the temperature settings at the mixing valve installed on your water heating system. See Mixing Valves for a discussion of the installation and use of anti-scald valves to avoid hot water burns, and for a table of temperatures at which hot water burns occur. At the top of this page we show a photo of a mixing valve on a heating boiler.
Check the temperature settings at the aquastat combination control if your hot water is made by a tankless coil on a heating boiler.

The "low limit" control shown in our photograph at left maintains hot water in the heating boiler to assure that the tankless coil can produce domestic hot water.

During the heating season, the "high limit" will control boiler operation and boiler temperatures will normally be hotter than what was set here at the "LO" control. See Mixing Valves for a discussion of the installation and use of anti-scald valves to avoid hot water burns, and for a table of temperatures at which hot water burns occur.

Hot Water Temperature Safety Warning

Setting water temperature above 100 degF may cause serious scalding burns.

A.O. Smith, the manufacturer of this water heater warns about water temperatures over 125 degF.

See Mixing Valves for a discussion of the installation and use of anti-scald valves to avoid hot water burns, and for a table of temperatures at which hot water burns occur.

How do we Improve the Hot Water Volume & Quantity?

As we discussed beginning in the previous section of this article, there are several different hot water problems:

Poor hot water flow, or bad hot water pressure, which is usually a piping or clogging problem or an overall building water pressure problem. See Clogged Piping & Hot Water Flow and see
Poor hot water quantity: not enough hot water, or running out of hot water very quickly. Insufficient hot water quantity may be due to the way hot water is being made (a water heater that is too small, a tankless coil on a new small heating boiler, or an instantaneous water heater that is being asked to supply hot water too rapidly. We describe various ways to improve hot water quantity, pressure, and flow are discussed beginning at HOT WATER IMPROVEMENTS and continuing at HOT WATER QUANTITY IMPROVEMENT.
Hot water temperature that is not hot enough: water temperature is just too cool. Insufficient hot water temperature may be due simply to the setting of a temperature control on a water heater or mixing valve, or it may be due to flowing water too fast through a tankless coil. Hot water that is not hot enough can be caused by quite a list of problems, some of which are easy to correct. See Temperature of Hot Water is Too Low for steps to correct water that just won't get hot.

Articles Describing Steps to Increase Hot Water Quantity

The articles listed below offer more details about steps one can take to increase hot water quantity, pressure, and flow in a building. Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Anti-Scald Valves & Hot Water Quantity - improve safety and meter hot water more slowly - makes it last longer
Clogged Piping & Hot Water Flow - diagnose and correct poor hot water pressure and flow due to pipe clogging
Extra Tanks to Increase Hot Water- pre-heat your hot water absorbing ambient building heat or increase hot water quantity with cascaded, staged, multiple water heaters, possibly using more than one energy source
High Efficiency Water Heaters - if replacing a water heater, consider a model that saves money in operating cost
Insulate Hot Water Piping - worth doing where piping is accessible, especially on piping running through cool areas
Insulate Hot Water Tank? - probably not worth doing except in special cases; important safety warnings
Larger Diameter Water Supply Piping - worth doing if replacing clogged pipes or building new construction
Tankless Coil Hot Water Increase - various tricks can significantly improve the safety and water quantity available
Temperature of Hot Water is Too Low - where to look for problems when the "hot water" is not hot enough

A Comparison of Alternative Hot Water Heaters & Sources

The following articles discuss alternative ways to produce domestic hot water for washing and bathing.

High Efficiency Water Heaters such as direct-vent gas-fired water heaters
Indirect-fired Water Heaters which use a separate heating boiler to produce a larger quantity of hot water
Instantaneous Water Heaters point of use systems that have little or no standby energy losses
Multiple water heaters in parallel to increase total hot water quantity
Multiple water heaters in series to stage hot water heating for varying levels of demand
Range Boiler Water Heaters an older form of indired-fired hot water heating used with separate heating boilers
Side Arm Coil Water Heaters similar to instantaneous and tankless coil water heaters, often used with range boilers
Solar Water Heaters using solar collectors, an indoor water tank, pump and controls, using minimal "on-grid" energy
Tankless Coil Hot Water Increase a heat exchanging coil immersed inside of a heating boiler heats provides (somewhat limited) hot water. various tricks can significantly improve the safety and water quantity available

The characteristics of various water heaters such as life expectancy, cost, safety, and capacity are discussed at WATER HEATER PROPERTIES

Ways to improve total hot water quantity, pressure, temperature and flow are discussed beginning at HOT WATER IMPROVEMENTS and continuing at HOT WATER QUANTITY IMPROVEMENT.

Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

WATER HEATERS
ALTERNATIVE HOT WATER SOURCES
  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
ANTI SCALD VALVES
CHIMNEY INSPECTION DIAGNOSIS REPAIR
Clogged Piping & Hot Water Flow
ELECTRIC WATER HEATERS
GAS FIRED WATER HEATERS
  DRAFT HOODS - gas fired
  Gas BTUH & Cubic Feet
  GAS PIPING, VALVES, CONTROLS
  SPILL SWITCHES - Flue Gas Detection
HOT WATER IMPROVEMENTS
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
  Temperature of Hot Water is Too Low
INDIRECT FIRED WATER HEATERS
ODORS IN WATER
TANKLESS COILS
  Mixing Valves
  Tankless Coil Leaks
Water pipe clog repair guide

Technical Reviewers & References

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.

Daniel Friedman - InspectAPedia.com ^TM Website Author/Editor
Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
Arlene Puentes, an ASHI member and a licensed home inspector in Kingston, NY, and has served on ASHI national committees as well as HVASHI Chapter President. Ms. Puentes can be contacted at ap@octoberhome.com
AO Smith produces AO Smith water heaters in addition to Reliance, State, Maytag and others. www.aosmith.com/prod/wpc.htm. AOS's gas water heater manuals offering advice and safety warnings about adding water heater insulation are available at
www.statewaterheaters.com/lit/im/res-Elec/184671-000.pdf and at
www.hotwater.com/lit/im/res_gas/184123-000.pdf
Rheem who also makes electric water heaters provides a manual for electric water heaters at
waterheating.rheem.com/content/resources/documents/use_care/ResElecProfessional.pdf. Rheem says, as do other water heater producers, that their water heaters meet the "National Appliance Energy Conservation Act standards with respect to insulation and standby loss requirements making an insulation blanket unnecessary"
Rheem also warns consumers that adding an insulation product [or making any other modification to their equipment] is likely to void the product warranty and may be unsafe:

"The manufacturer’s warranty does not cover any damage or defect caused by installation, attachment or use of any type of energy saving or other unapproved devices (other than those authorized by the manufacturer) into, onto or in conjunction with the water heater. The use of unauthorized energy saving devices may shorten the life of the water heater and may endanger life and property. The manufacturer disclaims any responsibility for such loss or injury resulting from the use of such unauthorized devices "
Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

More Information on Inspecting and Repairing Heating Systems

Carbon Dioxide Gas Toxicity
Carbon Monoxide Gas Toxicity, exposure limits, poisoning symptoms, and inspecting buildings for CO hazards
Dust from HVAC? An Investigation of Indoor Dust Debris Blamed on a Heating/Cooling System Reveals Carpet Dust
Goodman Furnace High Temperature Plastic Vent HTPV safety recall US CPSC notice
Home Heating System Should Be Checked [for proper venting and for CO Carbon Monoxide Hazards - DJF]
Inspection Procedures for Oil-Fired Heating Systems Detailed step by step approaches for inspecting complex systems]
Lennox Pulse Furnace Safety Inspection/Warranty Program: Carbon Monoxide Warning
Oil Tanks - The Oil Storage Tank Information Website: Buried or Above Ground Oil Tank Inspection, Testing, Cleanup, Abandonment of Oil Tanks
Oil Tanks Above Ground, UL Standards, guidance for home owners, buyers, and inspectors
Plastic Heating Vent Pipe & Other Heating Safety Recall Notices
Weil McLain Model GV Gas Boiler/gas valve CPSC recall/repair
Domestic and Commercial Oil Burners, Charles H. Burkhardt, McGraw Hill Book Company, New York 3rd Ed 1969.
National Fuel Gas Code (Z223.1) $16.00 and National Fuel Gas Code Handbook (Z223.2) $47.00 American Gas Association (A.G.A.), 1515 Wilson Boulevard, Arlington, VA 22209 also available from National Fire Protection Association, Batterymarch Park, Quincy, MA 02269. Fundamentals of Gas Appliance Venting and Ventilation, 1985, American Gas Association Laboratories, Engineering Services Department. American Gas Association, 1515 Wilson Boulevard, Arlington, VA 22209. Catalog #XHO585. Reprinted 1989.
The Steam Book, 1984, Training and Education Department, Fluid Handling Division, ITT [probably out of print, possibly available from several home inspection supply companies] Fuel Oil and Oil Heat Magazine, October 1990, offers an update,
Principles of Steam Heating, $13.25 includes postage. Fuel oil & Oil Heat Magazine, 389 Passaic Ave., Fairfield, NJ 07004.
The Lost Art of Steam Heating, Dan Holohan, 516-579-3046 FAX
Principles of Steam Heating, Dan Holohan, technical editor of Fuel Oil and Oil Heat magazine, 389 Passaic Ave., Fairfield, NJ 07004 ($12.+1.25 postage/handling).
"Residential Steam Heating Systems", Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
"Residential Hydronic (circulating hot water) Heating Systems", Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
"Warm Air Heating Systems". Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
Heating, Ventilating, and Air Conditioning Volume I, Heating Fundamentals,
Boilers, Boiler Conversions, James E. Brumbaugh, ISBN 0-672-23389-4 (v. 1) Volume II, Oil, Gas, and Coal Burners, Controls, Ducts, Piping, Valves, James E. Brumbaugh, ISBN 0-672-23390-7 (v. 2) Volume III, Radiant Heating, Water Heaters, Ventilation, Air Conditioning, Heat Pumps, Air Cleaners, James E. Brumbaugh, ISBN 0-672-23383-5 (v. 3) or ISBN 0-672-23380-0 (set) Special Sales Director, Macmillan Publishing Co., 866 Third Ave., New York, NY 10022. Macmillan Publishing Co., NY
Installation Guide for Residential Hydronic Heating Systems
Installation Guide #200, The Hydronics Institute, 35 Russo Place, Berkeley Heights, NJ 07922
The ABC's of Retention Head Oil Burners, National Association of Oil Heat Service Managers, TM 115, National Old Timers' Association of the Energy Industry, PO Box 168, Mineola, NY 11501. (Excellent tips on spotting problems on oil-fired heating equipment. Booklet.)

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