Category Archives: Water Heater Maitnenance

Electric Water Heaters Efficiency and Recovery vs Gas – Hard water effects

There is usually a lot of confusion about the differences between Electric and Gas water heaters. Electric water heaters cost less upfront for the unit and install than gas, but depending on your local utility costs, electric water heaters are typically more expensive in the long run. Gas water heaters generally make up for that cost difference in your utility bills, sometimes even within one year.

Gas water heaters use the heat from burning a fuel (usually natural gas) to heat water, while an electric water heater uses electric resistance coils.

water_heaters_parts_diagram1

When comparing gas vs electric water heater operating cost, its said that gas is almost always cheaper than electric. Gas water heaters typically cost about $30 a month to run, while electric water heaters run closer to $42 a month, depending on utility rates, of course. This analysis of gas vs electric water heater water heater operating costs is based partially on the fact that natural gas is typically less expensive than electricity. Assume that you already have access to natural gas in your home. Having to put in a natural gas line would add expense and mean that it would take much longer to realize any potential hot water heater savings.

Thermal Expansion

Thermal expansion is important to know about when you have a closed plumbing system in your house. A closed plumbing system is when you have a check valve installed in line, that restricts the water from back flowing into the cold side of the system. A check valve at the at the water meter or a PRV (Pressure Reducing Valve) that will make your home a “closed system”.

Thermal Expansion of water in a closed plumbing system can create a number of annoying and potentially dangerous problems. These include; the build up of unusually high pressure in a system (even when a pressure reducing valve is installed), pressure surges, and the continuous dripping of your temperature and pressure relief valve (T&P). In Addition, dripping faucets, leaking toilet fill valves are also symptomatic of thermal expansion.

water-system-expansion

More serious problems can also occur due to thermal. When dangerous pressures are built up in a water heater, internal parts may fail such as the internal flues, fittings or water connections. If a flue way collapses it can lead to the potential release of toxic gases, such as carbon monoxide into living spaces. Thermal expansion can also lead to a ruptured or distorted  hot water heating tank and may void the manufacturers warranty.

Plumbing codes require you to address this safety issue. No matter what your thermal expansion problem may be, whether for new construction or for retrofitting or remodeling an existing there are plenty of affordable options to fix these issues.

When water is heated it expands. For example, water heated from 90 degrees F to a thermostat setting of 140 degrees F in a 40 gallon water heater. It will expand by almost one-half gallon. This is because when water is heated, its density decreases and its volume expands. Since water is not compressible the extra volume created by expansion must go someplace. During no-flow period in a system, pressure reducing valves, backflow preventers, and other one way check valves are closed. Thus eliminating a path for the expanded water to flow back to the system supply. Hence, system pressure increase. This is where thermal expansion tanks and valves come into play.

Thermal Expansion Tanks and Valves

When the water is heated in a closed system it expands. Water is not compressible, therefore, the additional water volume has to go someplace. When an expansion tank is installed the excess water enters the pre-pressurized tank (set at normal house pressure). As the temperature and pressure reaches its maximum, the diaphragm flexes against an air cushion (air is compressible) to allow for increased water expansion. When the system is opened again or the water cools, the water leaves the tank and returns to the system.

expansion-tank

As the water temperature increases, the expanded water is received by the tank.

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As the water and pressure reaches its maximum, the diaphragm flexes against the air cushion to allow for increased water expansion.

Thermal Expansion Valves 

Thermal Expansion Relief Valves are used in the same circumstance as expansion tanks, but instead of expanding within expansion tank, the expansion will escape within the valve and go out through a drain port routed to your nearest floor drain. These are commonly used when there is not enough room for an expansion tank, when these fail you will see a steady flow of water going through the drain tube rather than a normal couple drips. If this problem goes unnoticed for long periods of time you will begin to waste a tremendous amount of water. So make sure you have this routed to a visible floor drain!

Anode Rods

Most water heater tanks are steel with a thin glass lining to protect the metal from corrosion. Since the lining eventually cracks due to the minerals, rust and sediment in the water. Water heaters need a second line of defense. A long metal “anode rod” that attracts all the corrosive elements in the water. These anode rods are made from magnesium, aluminum or aluminum/zinc alloy. Anode rods usually are completely corroded after 5 years, but if you have hard water and are aware of that, the rod may last as little as 2 years. This is something that can be replaced periodically and can sometimes double the life of your water heater. This little bit of maintenance can really save you money in the long run. People are often unaware that you are able to replace these rods and extend the life of your water heater!

Sediment and Hard Water

Is sediment buildup harmful? The amount of sediment that builds up in your water heater will depend heavily on where you are located. If your city water supply is filtered and you water is naturally soft with little mineral content, then you may have very little sediment, but that little amount of sediment will separate from your water once heated. Build up in the bottom of the water heater tank. In other areas you may have a large build up of sediment.

A small amount of sediment at the bottom of your water heater is not serious, and can be removed by flushing your water heater annually. This can really extend the life of your water heater because the minerals in the sediment attack the tank and cause leaks over time. A deep layer of sediment displaces water and reduces the amount of hot water available for your use. This sediment can also affect the efficiency of your water heater because the burner is then having to transfer the heat through the sediment and can overheat the bottom of the tank. Overheating can weaken the steel and damage the lining of the tank. With Electric water heaters, if the sediment covers the bottom heating element, the element can overheat and burn out. If it gets into got water circulating systems it can cause problems with the pump, valves and fixtures they are serving.

Sediment can cause noises like popping and other strange sounds as water between the tank bottom and layer of sediment turns to steam bubbles. This is a warning sign that your water heater may be on the verge of going out and you should be maintaining your system in a different way in the future. A simple flush could add years onto your water heater, this removes some of that harmful sediment that causes issues within your water heater.

Hard water will have a similar effect as sediment except picture white calcium build up instead of sediment. This can build up much faster in certain situations and will cause very similar issues. If you know your water is extremely hard then you should consider  filters, or water softeners. These can make a huge difference for all your fixtures, appliances, look of your water, and most of all the taste. These are all extremely important variables to consider that will save you money in the end. If you address these issues correctly you could increase the life span of your water heater by as many as 5 years in serious cases.water-heater-corrosion

Gas Water Heaters

Cost Less To Operate

Lasts Average Of 13 Years

Takes Less Time To Reheat Water

Works During Power Outage

Less Efficient. More Heat Loss.

Electric Water Heaters

Costs More To Operate

Lasts Average Of 12 Years

Takes More Time To Reheat Water

Won’t Work During Power Outage

More Efficient. No Heat Loss.

 

 

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Troubleshooting Power Vent Water Heaters

Venting

When troubleshooting a Power Vent water heater the venting often goes unnoticed even if there is an issue. The venting is so important to inspect on Power Vent Water Heaters because if they are sloped the wrong direction condensation will makes its way to the blower and damage it. Power vents don’t always form condensation, but there are a couple different variables that do cause them to condensate.

-Ambient temperature and humidity of installation location

-Ambient temperature and humidity of venting space

-Vent distance, slope, and correct product usage

-Vent has slope minimum of 1/8″ AWAY from the blower – Horizontal Applications

-Know the proper vent lengths for the model water heater (see table below)

These are the variables you need to pay especially close attention to when inspecting the venting. If you do notice an issue where the Power Vent is condensating a condensate kit is available to install. This is a Fernco exhaust adapter with a drain outlet that you pipe to the drain using vinyl tubing. An inexpensive part that will solve the condensate problem.

Check for vent blockage and determine if the vent could become clogged by surrounding vegetation. If so, consult with the home owner on a solution to make sure the problem does not repeat itself.

Its extremely important to make sure there is adequate air for combustion and ventilation. An insufficient supply of air will cause re-circulation of combustion products resulting in air contamination that may be hazardous to life. In Such conditions you will notice a yellow,luminous burner flame, causing carbon build up or sooting of the combustion chamber, burners and flue tubes with possible damage to the water heater.

Vents are susceptible to freezing and can be very easy to overlook. If the burner wont stay lit you should check to make sure there are no obstructions and investigate the possibility of frozen vent.

Troubleshooting codes and Vent Length Table

The link below includes a table to troubleshoot any issues you may have

The link also includes Maximum vent length including number of allowed elbows

vent-length-table-troubleshooting-codes-and-cause

Proper Combustion Air

Combustion air is very important for a water heater to run correctly. All different variables should be considered. When an exhaust fan is installed in the same room with a water heater, sufficient openings for air must be provided in the walls. Undersized openings will cause air to be drawn into the room through the venting and causing circulation of combustion products. A very common solution to this problem is the installation of a louvered door.

The formula to correctly determine proper openings

All air coming from inside the building: an opening must have a minimum free area of 1 inch² (6.5 cm²) per 1000 BTU (0.29 kw) per hour of the total input rating of all gas utilization equipment in the confined space, but not less than 100 inches² (645 cm²). One opening must be within 12 inches (31 cm) of the top and one with 12 inches (31 cm) of the bottom of the enclosure.

All Air coming from Outdoors: The confined space must be provided with two permanent openings, one commencing within 12 inches (31 cm) of the top and one commencing within 12 inches (31 cm) from the bottom of the enclosure. The openings must communicate directly, or by ducts, with the outdoors or spaces (crawl or attic) that freely communicate with the outdoors.

  1. When directly communicating with the outdoors, each opening must have a minimum free area of 1 inch² (6.5 cm²) per 4000 BTU (1.2 kw) per hour of total input rating of all equipment in the enclosure.
  2. When communicating with the outdoors through vertical ducts, each opening must have a minimum free area of 1 inch² (6.5 cm²) per 4000 BTU (1.2 kw) per hour of total input rating of all equipment in the enclosure.
  3. When communicating with the outdoors through the horizontal ducts , each opening must have a minimum free area of 1 inch² (6.5 cm²)  per 2000 BTU (0.6 kw) per hour of total input rating of all equipment in the enclosure.
  4. When ducts are used, they must be of the same cross-sectional area as the free area of the openings to which the connect. The minimum dimensions of rectangular air ducts must be not less than 3 inches (7.5cm)

Specially Engineered Installations

The requirements noted under the CONFINED SPACES above must not necessarily govern when special engineering, approved by the authority having jurisdiction, provides an adequate supply of air for combustion, ventilation, and dilution of flue gases.

Sequence of Operation

The sequence of operation is important to know so you can properly diagnose the problem.

Control Sequence of Operation

Start up sequence

Upon powering up, the control checks for the presence of the resistive plug, if the resistance is in the expected range the control will begin normal operation after 5 to 8 seconds.

Normal Heating Sequence

  1. The thermostat senses a need for heat.
  2. The control checks the pressure switch condition.
  3. If the pressure switch is open, the control sends power to the blower motor.
  4. The blower starts moving combustion air through the combustion system.
  5. The pressure switches closes.
  6. The control senses the closed pressure switch and starts the ignition process by providing a spark at the pilot electrode and allowing gas to flow to the pilot.
  7. When the pilot is lit the gas control senses the pilot flame and opens the main gas valve.
  8. The main burner is lit.
  9. The main burner and blower continue to operate until the thermostat is satisfied.
  10. When the thermostat is satisfied the main and pilot gas valves close.
  11. The blower operates for a short post purge period before shutting down.
  12. The water heater remains in the stand-by mode until the next call for heat.
  13. Make sure Power Vent is plugged into a grounded outlet.
  14. Make sure you have correct continuinty

Maintenance

  1. Annually check the operation of the thermostat
  2. The flow of combustion and ventilation air MUST NOT be restricted. Clear the combustion air openings of any dirt, dust, or other restrictions. WARNING! The ventilation air system may be HOT.
  3. At all times keep the water heater area clear and free from combustible materials, gasoline and other flammable vapors and liquids.
  4. Bi-annually conduct a visual check of the main and pilot burner flames to determine that they are burning properly. see Burner Flame Check. If sooting or other burner anomalies are evident, shut down the water heater by turning off the gas per the instructions listed in this manual or as listed on the water heater.
  5. Annually remove the inner door and main burner assembly to clean orifices and related parts of any dirt or other foreign material. Inspect the burner ports for obstructions or debris and clean with a wire brush as needed. Wire brush and/or vacuum clean the combustion chamber as needed to remove scale deposits and debris. NOTE: It is imperative for proper operation of the water that the inner door replaced in the original location.
  6. At least once a year, check the combination temperature and pressure relief valve to insure that the valve has not become encrusted with lime. Lift the lever at the top of the valve several times until the valve seats properly without leaking.
  7. Monthly drain off a gallon of water to remove silt and sediment.
  8. If the combination temperature and pressure relief valve on the appliance discharges periodically, this may be due to thermal expansion in a closed water supply system. Contact the Ace Hi Plumbing, Heating and Air to help correct this problem. Do not plug the combination temperature and pressure relief valve outlet.
  9. A combination sacrificial anode rod/hot water outlet nipple has been installed to extend tank life. The anode rod should be inspected annual and replaced when necessary to prolong tank life. Water conditions in your area will influence the time interval for inspection and replacement of the anode rod. The use of a water softener may increase the speed of anode consumption. More frequent inspection of the anode is needed when using softened (or phosphate treated) water.
  10. The blower has sealed motor bearings and does not require adding oil.