Removing debris that clogged a water heater outlet and plumbing faucets (C) D Friedman R Arlyck How to fix a hot water heater: diagnostic & repair procedures

  • WATER HEATER PROBLEM DIAGNOSIS - CONTENTS: Hot Water Troubleshooting Diagnostic Guide - Basic Questions. Start troubleshooting a hot water heating system here.
  • POST a QUESTION or READ FAQs about how the proper starting point when we need to identify & diagnose problems with building hot water tanks, heaters, piping, pressure, flow, quantity, temperature, safety, noises, or other hot water troubles.

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How to fix a water heater that is not working at all or is not working adequately. This article series describes the starting point for fixing problems with a building hot water supply.

We pose a few easy questions to make sure you are taking the quickest and most economical approach to understanding, diagnosing, and fixing hot water system complaints like loss of all hot water, poor hot water flow or pressure, hot water that is not hot enough, running out of hot water, or hot water heater operating cost, noises, leaks, or maintenance.

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Hot Water Troubleshooting Diagnostic Guide - Basic Questions

Leaks at a double water heater installation (C) D FriedmanNot enough hot water, depending on whom you speak with, might be that you run out of hot water too soon, or that the flow rate at the shower is too weak, or that the hot water is really not hot enough.

To really improve domestic hot water supply it's worth taking a minute to accurately describe exactly what the problem is. You won't be spending time and money on the right repair if you fix the wrong problem. Below we clear up some confusing ways people use terms.

Before we detail steps to improve building hot water supply volume, flow rate, temperature, or to fix "not enough hot water" complaints, to look at the hotwater supply troubleshooting articles below. Keep in mind that at your building you may have more than one of these conditions.

  1. No hot water: If you have no hot water at all, but cold water comes out of the hot water faucets, make sure that your water heater has fuel (oil or gas) or power (electric, solar).

    Also check for a defective high temperature limit switch (there is a reset switch on the thermostat) or for a defective upper thermostat (you'll have tepid hot water but no HOT water).
    See NO HEAT - NO HOT WATER: HEATER DIAGNOSIS for details about troubleshooting when you have no hot water at all.
  2. Hot water pressure or flow: if your problem is gradual or long-standing poor hot water pressure, or flow, that is, water comes out of the faucet or shower weakly or too slowly, start your diagnosis here
    at HOT WATER IMPROVEMENTS (the article below)

    Poor hot water flow, or bad hot water pressure, which is usually a piping or clogging problem, mineral clogging at a water tank or tankless coil, or an overall building water pressure problem. In the article below we describe how to improve hot water pressure and flow.

    If your hot water pressure has suddenly been lost but you still have some, poor hot water flow,
  3. Hot water quantity: if your problem is gradual or long-standing poor hot water quantity, that is your water is hot enough, but you run out of hot water too soon.

    If you do not have not enough hot water quantity, you are 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.

    Diagnosis and repair for hot water quantity are

    Poor hot water quantity can also be caused by mineral deposits and clogging in a hot water tank. Mineral clogging can clog pipes (slower flow) or insulate the heat transfer (water not hot enough, slow recovery, noisy water tank).
  4. Hot water delivery time: if you want to speed the delivery of hot water to plumbing fixtures or if the recovery rate of your water heater is too slow, if the water heater is electric check for a defective upper or lower heating element.

    See HOT WATER DELIVERY SPEED UP for details.
  5. Hot water heating costs: If your hot water heating costs are too high check for:
    • The hot water thermostat is set unnecessarily high - see the thermostat on the control or aquastat for your oil or gas fired water heater or tankless coil boiler; or
      see Electric Water Heater Thermostats
    • The hot water heater tank has a sediment or scale problem -
    • Check for long hot water piping runs, especially if the hot water piping is also not insulated and/or runs through cold areas, or if hot water supply piping was routed through exterior building walls (exposed to low temperatures). Running a hot water pipe right alongside the cold water supply pipe to the plumbing fixtures can also sap hot water temperature and increase water heating costs.
    • Check for building occupants who waste hot water - long showers, baths, leaving the kitchen sink hot water running continuously; also check for leaky hot water faucets in the building or for wrong piping connections (we found a running toilet that had been connected to hot water instead of cold water piping)
    • Check for a water heater that is too small for the building it serves - causing it to run continuously
    • Check for a water heater thermostatic control that is out of calibration - keeping water hotter than its setting
    • Consider making your hot water using a different, more economical method. The characteristics of various water heaters such as life expectancy, cost, safety, and capacity are discussed
    • Use your hot water more efficiently.
  6. Hot water recovery rate: if you have good hot water, and plenty of it at a good flow rate, but when you run out it takes too long for your water heater to recover, that is usually an innate property of the water heater type and model.

    The higher the BTUh input rate of your water heater the faster it will "recover". In order of recovery speed, from fastest to slowest, are tankless water heaters, oil fired water heaters, gas fired water heaters, electric water heaters. Solar water heater recovery rates vary depending on sun availability and the type of back-up hot water source provided.


    Poor hot water recovery rate can also be caused by mineral deposits and clogging in a hot water tank. Mineral clogging can clog pipes (slower flow) or insulate the heat transfer (water not hot enough, slow recovery, noisy water tank).

  7. 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 at all or won't get hot enough.
  8. All water pressure is bad, at both hot and cold: If your concern with total water pressure and flow, both hot and cold,

    see WATER PRESSURE LOSS DIAGNOSIS & REPAIR, and if you simply run out of water, both hot and cold,

  9. Water heater itself is acting up or leaking: noises, smoke, odors, leaks, not working at all: you need to jump to our home page for the type of water heater you have. At each of those pages we describe the heater, its properties, and its maintenance or repair.
    • To drain your water heater tank, for example to replace a part or for cleaning,
    • To flush accumulated crud or debris from a water heater (yearly maintenance)
    • To de-scale or de-lime your hot water heater, causes of less hot water, lower water temperature, or noisy water heaters,
    • To diagnose and repair a bad water heater dip tube or anode, causes of water heater odors, debris in the hot water supply, or corrosion problems,
    • To diagnose particulate debris in the building water supply, faucet strainers, etc. that comes from the hot water tank, and how to fix that problem,



Continue reading at HOT WATER QUANTITY IMPROVEMENT or select a topic from the More Reading links shown below.


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WATER HEATER PROBLEM DIAGNOSIS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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