Installing a tankless water heater is more than just a quick stroll into Home Depot or a professional parts supply house and buying a tankless water heater and odd installation parts.  Most tankless water heaters come with a warranty that is voided if the unit is not installed by a contractor.  More to the point the warranty will be voided if it is not installed by a factory trained installer.  There are 5 things wrong with the installation pictured below, it was actually installed by a plumber but he was not trained in installing tankless water heaters.

1. Improper Venting- The vent that was used is Type “B” double wall vent, this and most tankless water heaters require specially sized Category III stainless steel venting with sealed joints.
2. No Condensate Drain- When any tankless water heater has more than 5’ of exhaust vent a condensate collector and drain is required.
3. Improperly Gas Supply- The inlet gas pipe size required for tankless water heaters is ¾” I.D. or inner diameter.  This is because of the high demand (199,000 B.T.U.) of the burner.
4. No Tankless Valve Install Kit- Tankless water heaters are to be installed with tankless valve install kits which allow bypass and unions for service and maintenance of the appliance.
5. Incoming Water is Untreated- Because hard water is extremely aggressive and tankless water heaters “flash heat” the water, it needs to be preconditioned to prevent scaling and leaks inside the heat exchanger.

This water heater is a Takagi and in all my years servicing them Takagi is the only one that will function for quite some time when improperly installed.  The pictured unit had been installed for 4 years before it failed because of improper install.  When a tankless water is installed properly and the incoming water is treated it should last for 20 years or more.

In the above install repair parts, labor to install them and the other corrections was not much more than replacing the entire water heater.  Removing and re-installing the heat exchanger, computer components and a few new sensors would take hours and the parts were only available from the manufacturer and were several days away even with expedited shipping.  All of these combined issues made the decision easy for the client.  Below is a picture of the after install. The new gas line is ¾” I.D., the venting is Z Flex® and goes about 9’ straight through the roof.  The condensate collector is installed with a drain to the exterior.  A Webstone Isolator valve install kit supplies water after the AWF Heater Extender treats it.  It is a win; win for the homeowner and for the professional.

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