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
Tankless Water Heaters at Just Tankless.com
Tankless Water Heaters at Just Tankless.com
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Jan. 24, 2010 - PRLog -- Tankless Water Heaters don’t work like the storage tank heaters. There isn’t much that can be done wrong installing “regular” water heaters. However in tankless water heater installation there are many things than can be done wrong that will invalidate the warranty. Most manufacture require that their units be installed by professionals that have gone through their training to validate the warranty. Some of the installation issues are not obvious and become a problem much later.
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” as it flows through their heat exchanger and that requires a lot of gas. So there has to be enough gas pressure and volume, remember pressure and volume are two different things. The tankless water heater modulates its burners according to the set temperature and amount of water (volume) needed. It therefore can work perfectly fine on low demand situation and not work at all when you are running the shower and the kitchen sink at the same time.  Its computer will see that there is not enough gas supply to satisfy the demand and it will shut down and give some audible error indication sometimes.

•   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’ water storage tank or for other reasons. High water pressure puts unnecessary stress on all plumbing components not just the tankless water heater. This can cause premature failure of plumbing valves and connections inside and outside the tankless water heater. The water volume is not so much dependent on water pressure. A lot of times water pressure is confused with water volume. An acceptable water pressure is about 60-70 psi. This can be achieved with a water pressure regulator.

•   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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Industry:Energy saving
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Page Updated Last on: Apr 20, 2011
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