Remodeling Tips and Reviews

Venting a Gas Tankless Hot Water Heater

Venting  a Gas Tankless Hot Water Heater

Jan 10, 2012

Unlike conventional hot water heaters, gas tankless units generate a significant amount of exhaust and heat to instantly heat up your hot water. To do this safely the units require stainless steel piping which is single walled and either 4″ or 5″. This is in contrast to the conventional units which use a 3″ double walled galvanized pipe. The stainless piping is quite a bit more expensive, usually costing around $250 for a typical installation.¬†¬† But, this can go much higher depending on how far you have to vent the tankless water heater unit. I prefer to use Z-flex, it seems to fit better and install easier. There a a few key components these units require and if you forget to order them then you will slow your installation down.

The appliance adapter: the first piece put on over the unit to properly adapt it to the pipe, this part must be compatible with the type of tankless unit being purchased.

4″ piping in stainless steel: make sure the diameter is correct for your unit, you will need these to move in a straight line out through the roof.

90 degree elbow: Used to turn the vent stack to a side wall. Also available at 45 degrees.

Condensation collector: this piece collects condensation in the vent pipe and reduces corrosion of the unit, these must be installed inline or the venting must turn 90 degrees into the condensation catch and then vent vertically through the roof

Roof System : this system contains 3 important peices: the roof flashing, roof cap, and rain collar. The flashing  is available for steep, standard or flat roofs. You will also need an section of pipe to attach all of this to.

While the venting a tankless hot water heater is not hard, you need to make sure that the pipe is plumb up and down and there is at least a 1″ space around the vent pipe where it pierces the roof and ceiling. No wood or other materials should come into contact with the vent piping because of the extremely high temperatures.

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