Tankless Water Heater Problems
Tankless Water Heaters are sophisticated appliance and need to be installed correctly to function and for the manufacture to honor the warranty. Tankless problems are mostly because of wrong installation, sizing and location.
By: Al Johnson at JustTankless.com
Here are some of the common installation problems we have come across with tankless water heaters.
• Gas Supply Issues
Tankless water heaters need a lot of gas when heating water because there is no storage tank. They must heat the water “instantly”
• Exhaust venting issues
Tankless water heaters are computer controlled and monitor many things when heating water. They monitor for example the exhaust temperature for cleaner burning and adjust the combustion. Because of the high density heating process the exhaust can become very hot quickly. That heat needs to be vented out quickly. When the venting is restricted by long runs or too many bends and turns the unit can shut down as it is unable to perform as needed.
• Internal Corrosion
The heat exchanger is the heart of any tankless water heater and expensive to replace. It is made of special copper or stainless steel alloy and is very resistant to corrosion. However improper installation can cause corrosion on there and other parts. Because of its high efficiency tankless water heaters condensate and the condensation water is acidic. The condensation forms along the vent pipes, which are stainless steel and won’t corrode. However that condensation needs to be collected and diverted from the heat exchanger as not to corrode it. The condensation is collected usually via a special vent pipe and drained away from the unit. This issue is not one that will be apparent initially, it will not be covered by warranty.
• Burner Corrosion
The gas burner on tankless water heaters sits usually below the heat exchanger and anything that drips or falls on the heat exchanger can fall on the burner. The burner has many small and larger holes for gas to exit for combustion. If the venting is not properly terminated or condensation is not collected it will over time drop and collect on the burner. This causes the burner holes to be restricted and not supply enough gas. The computer monitors the burning process constantly and will shut down the unit if it cannot achieve desired clean burning or temperature. This is an issue that will come to light over time and will not be covered under warranty.
• Pipe Freeze
Tankless water heaters can and are often installed outdoors. Most units have an internal electric heater to protect the heat exchanger from freezing temperatures to prevent cracking or other damage to them. The electric heater is however not designed and meant to warm the entire plumbing. It is therefore important to keep the length of water pipes going to the thankless water heater as short as possible and protect them against freezing by wrapping them with proper materials. It is therefore important NOT to turn the power to the unit off during freezing temperatures. The unit’s electronic and other components are designed to work in freezing temperatures.
• Scale Buildup
In areas with hard water it is important to either flush the unit periodically as recommended by the manufacture or to install a scale filter. Hard water can cause mineral build up in the heat exchanger and cause improper operation and premature failure that won’t be covered under warranty.
• Water Pressure
Some areas have high water pressure, in excess of 100 PSI. This could be because they live close to the municipalities’
• Improper Sizing
This could be one of the most common mistakes, although not an installation issue but it leads to not having enough hot water when needed. Unlike storage tank water heaters the tankless water heater needs to be sized correctly for expected hot water demand. This is does not involve just by getting a larger unit. Its gas, water supply and location play an important role in correct sizing.
• Improper Location
The tankless water heater does not need to be installed where the old storage tank water heater was. Often that is not the ideal location as the demand and operation is very different.
Electronic, valve or other component failures occur very seldom with good tankless water heater s, it is mostly incorrect installation that leads to premature or operational failures. Some brands are more prone to failures than others but a good, properly sized and installed tankless water heater can last for 20 or more years and operate flawlessly like when it was new.
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Page Updated Last on: Apr 20, 2011