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.

Hot Water Troubleshooting Diagnostic Guide

This page gives a list of diagnostic procedures that can fix just about any water heater problem.

Not 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, a clog at a hot water valve, 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 been lost but you still have some, poor hot water flow at all, some or just one fixture,
   
   see HOT WATER PRESSURE LOSS
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
   
   at HOT WATER QUANTITY IMPROVEMENT. 
   
   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).
   
   See WATER HEATER SCALE DE-LIMING PROCEDURE
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 CIRCULATOR PUMP SPEEDS DELIVERY 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 or makes noises as it heats up-
     
     see SCALE REMOVAL, WATER HEATERS
   • 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
     
     at WATER HEATER COMPARISONS, PROPERTIES
   • Use your hot water more efficiently.
     
     See EFFICIENCY IMPROVEMENT, HOT WATER
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.
   
   See ALTERNATIVE HOT WATER SOURCES.
   
   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).
   
   See WATER HEATER SCALE DE-LIMING PROCEDURE
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 WATER HEATER TEMPERATURE TOO COLD or TOO HOT 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,
   
   see WATER QUANTITY IMPROVEMENT.
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.
   • ALTERNATIVE HOT WATER SOURCES, start here if your water is heated by an electric shower heaer, a high efficiency water heater, a range boiler, a side arm coil water heater, or a solar water heater
   • ELECTRIC WATER HEATERS, your hot water is heated in a tank powered by electricity
   • INDIRECT FIRED WATER HEATERS, your hot water is heated in a separate water tank connected to your heating boiler
   • OIL FIRED WATER HEATERS, your hot water is made by an oil-fired water heater and tank.
     Also
     see OIL BURNER NOISE SMOKE ODORS
   • TANKLESS COILS, your hot water is made by a coil on your heating boiler, you don't have a hot water tank
   • TANKLESS WATER HEATERS or demand or point of use heaters or "instant" water heaters
   • GAS FIRED WATER HEATERS, , your hot water is made by an oil-fired water heater and tank
     
     Also
     see GAS BURNER FLAME & NOISE DEFECTS
• To drain your water heater tank, for example to replace a part or for cleaning,
  
  see WATER HEATER DRAIN PROCEDURE
• To flush accumulated crud or debris from a water heater (yearly maintenance)
  
  see WATER HEATER FLUSH PROCEDURE 
• To de-scale or de-lime your hot water heater, causes of less hot water, lower water temperature, or noisy water heaters,
  
  see WATER HEATER SCALE DE-LIMING PROCEDURE
• 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,
  
  see WATER HEATER ANODES, DIP TUBES
• 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,
  
  see WATER HEATER DEBRIS FLUSH

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2020-07-09 by (mod) - look for an anti-scald device or pressure or flow regulator for your water heater

Jenn

The water heater's thermostat is not likely to be the problem here. On an electric water heater - which I surmise you've got - the thermostat simply changes the water temperature, not flow rate.

But some buildings use a separate mixing valve or anti-scald device outside the water heater. That device mixes cold water in with outgoing hot so as to avoid scalding. If such a device is installed and is malfunctioning both water temperature and flow rate might be affected. Examples are at ANTI SCALD VALVES & TEMPERATURE CONTROL / MIXING VALVES

You'd help me out by also posting a photo of the whole water heater, including showing plumbing connections to it and near to it.

I'd also like to be able to see the water heater brand or logo markings: looks like a Sears heater.

Where is (country and city) and how old is the building where this water heater is installed?

On 2020-07-09 by Jenn

There is a thermostat. I’ve never touched it. [Photo above] [Click to enlarge any image]

There is a dial on the front of the ware heater to control temperature but I’ve never touched it.

On 2020-07-09 (mod) - troubleshooting varyiations in hot water flow rate or "pressure" when cold water is unaffected

Ok that's helpful;

So is there a hot water device that controls temperature - such as an anti-scald valve (or less-likely a flow control valve that limits flow) ? because that's a possible culprit.

On 2020-07-09 00:11:09.401880 by Jenn

I’m on city water and the cold water has consistent higher pressure

On 2020-07-08 (mod)

Are we sure it's only hot water pressure that varies? Is your water supplied by pump and well?

On 2020-07-08 by Jenn

I’ve noticed that my hot water pressure has begun to fluctuate. I have an electric hot water heater that is 22 yrs old. I’m am in the process of remodeling my bathroom so we have only been using the kitchen sink for a week now.

On 2019-11-06 (mod) - diagnose almost zero water pressure everywhere in the house

Travis what has happened in your search for the water pressure problem? If you still have no water pressure you would want to start with the Diagnostics given

at WELL WATER PRESSURE DIAGNOSIS

On 2019-11-05 by Travis

Hey all, I woke up to having almost zero water pressure everywhere in the house. I turned on faucet downstairs and it goes full blast for 1 second then nothing. Water heater made a hissing noise I'm assuming near shut off valve. Could this be the reason it do you thinks its sediment build up

On 2019-01-04 (mod) - odors from oil fueled water heatr

Fredi

It sounds as if your oil burner is not running properly - that can be unsafe, not just smelly. I suggest calling your heating company to ask for a cleaning and tune-up of the water heater and its oil burner.

See OIL BURNER NOISE SMOKE ODORS - home

On 2019-01-03 by Fredi

Oil fueled water heater starts fuming foul odor, and then shots off. The water it self is not foul smelling or tasting. When I restart it will shot off after less than a minute.

On 2018-10-07 (mod) - pilot light won't stay on at water heater

I wouldn't start by assuming the problem requires a water heater replacement. It could be a problem of lack of fuel or a bad thermocouple.

See THERMOCOUPLE REPAIR / REPLACEMENT

On 2018-10-07 by Eddie Q

My water heater, was working fine, but it just went off, pilot lights but don't stay on, it's the hole water heater or just the thermocouple?

...

Continue reading  at HOT WATER QUANTITY IMPROVEMENT or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see WATER HEATER PROBLEM DIAGNOSIS FAQs - recent Q&A about calorifier, geyser, hot water cylinder, water heater troubleshooting - posted originally on this page.

Or see these

Recommended Articles

• WATER HEATER AGE & MANUALS - installation & troubleshooting water heaters by brand, model, manual

Suggested citation for this web page

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

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to WATER HEATERS

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