We recently had a blower door test performed as part of an insulation upgrade and the found that the water heater was not venting properly. Given that the unit was over 15 years old it wasn't worth correcting the issue both because of its age and because of the amount of corrosion visible on the outside. I didn't think if we opened any valves for draining we would be able to close them again and I certain wasn't going to be able to even remove the anode rod for replacement. We opted to get a super high efficiency tankless unit to both reduce energy costs and to free up some floor space in the basement.
The first step to installation was to mount a strong backing on the basement wall. I fixed a 3/4" plywood board to the block wall near the washer and dryer since that would be the most direct route for the venting requirements. It is also near the utility sink which is necessary for the condensation drain.
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| Plywood backer. |
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| New water heater is heavy. |
The water heater comes with a bracket that gets mounted to the wall or in my case the plywood. This hanging holds it in place nicely while you fasten it permanently with some screws both at the top and the bottom. I mounted it slightly to the right of the backer so I had room to add a larger outlet box to supply the washer, dryer, and now the water heater. Conduit bending is an art I haven't mastered but I managed well enough to do the box offset and go around the hydronic piping you can see at the ceiling.
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| Mounted. |
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| Upgraded outlet. |
With the outlet updated I moved on to the venting. One of the nice features of most tankless heaters, including this one, is that you can use typical PVC piping for both the exhaust and intake venting. With a simple cover for the outside of the house, this was very straightforward to do. I also installed the condensate line using some PEX I had leftover from a previous project, but a plumber informed me I should replace this at some point with regular PVC since the condensate can be acidic and corrode the PEX fittings pretty quickly. Sounds like a Future Nate problem.
Next was getting the water lines connected up. Since the lines supplying the utility sink are 3/4" copper I figured I could just attach on to those. I removed some elbows and replaced them with T fittings and ran new lines to the water heater. The heater came with shutoff valves and the hot supply side included a pressure relief valve as well. I soldered all the piping and fittings into place and water tested them successfully. The last step was to get gas connected.
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| Condensate line and water lines. |
Since I didn't want to deal with cutting and threading a bunch of new black pipe I hired a plumber to come and install the gas supply line. They used a CSST pipe that fed off the old water heater supply and looped around to the new water heater. Once that was connected I was able to turn on the water heater, configure it, and start using it.
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| Gas line installed. |
After the new heater was up and running, I worked on removing the old tank model. I cut and capped the water lines and then removed the venting. The plumbers disconnected the gas line when they installed the new one so everything was disconnected at this point. I tried to drain the tank but the spigot at the bottom of the tank was so clogged with mineral buildup that no water was making its way out. After removing the entire spigot and clearing the hole with a screwdriver all 50 gallons started to spray out over the basement floor. Thankfully I was able to tip the tank toward the floor drain and contain most of the water, but a lot still sprayed out and covered the floor with the mineral buildup that had been sitting at the bottom of the tank for who knows how long. Even the hot supply fitting was nearly closed up due to the corrosion and minerals.
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| Old hot supply corrosion. |
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| Mineral deposits from the tank. |
The old tank heater was dropped off at the Brookfield recycling center and a lot of the copper and brass plumbing components were saved for future smelting in our foundry.
