Plumbing – Installing a tankless water heater next to electric service panel

You should make two phone calls. The first to your local building department, which should be able to answer all your code related questions. They may even have a handout or other documentation, that outlines the requirements of replacing a water heater.

The second call should be to a local Rheem dealer, or directly to Rheem. They will be able to answer any questions you have about the equipment.

Some things to watch out for:

• Make sure you drain the old tank completely, as water can be quite heavy.

• When draining the tank, make sure you open the hot valves at fixtures. This will allow all the water to drain back to the tank.

• When opening valves at fixtures, watch out for mixing valves. These can accidentally backflow cold water through the hot water pipes, which would lead to an undrainable tank.

• If you have to install an expansion tank, make sure you charge it properly.

• Make sure you know where to dispose of the old tank, as some municipal garbage collectors will not take water tanks.

The tankless water heater can be mounted with either concentric venting (preferred) or dual-pipe venting - one for intake and one for exhaust. Because of this, we would not be able to 'common vent' in with the furnace exhaust or even the chimney itself because the concentric would be pulling air down the chimney or suck in the exhaust of the furnace. We could take the exhaust pipe of the dual pipe option and add it to the chimney or furnace, if sized correctly, but regardless we'd still have to direct vent outside for the intake. So, because of this, it makes the most sense to go with the concentric venting and route it outside.

The best location that we're working with is in that old coal storage room. This provides access to 3/4" water lines and the 1" gas line that we can pull off of for the 3/4" line needed for the water heater. The only workaround now is with venting. The gas meter in my picture is actually farther down the exterior wall than is shown (the gas line does a 90 after coming through the wall) and up to where it's shown in the picture. This allows the easiest access to venting outside through this area, although we're required to keep a 3' distance from the gas meter for it's regulator. This shouldn't be a problem because we actually have to run it up the wall about 3' anyway to clear the snow level. If this isn't workable, the other option is to run the vent to the complete other side of the basement and come out of the wall there. This could come close to the maximum allowable vent span, but it's an option currently.