The inspector from the bank will be coming around to check on progress. Among other things, I’m hoping to get reimbursed for a rather large bit of radiant heating expenses. In order for that to happen, there needs to be visible progress on the radiant. So that was my top priority…until the water heater went on the fritz.

Not having hot water is a rather immediate problem. The issue was that it was short cycling, so while it was getting hot eventually, in the meant time we’d run out of hot water. I bought the silly thing to prevent that exact problem, and since it was rather expensive, I really don’t want to kill the thing with short cycling.

In the extremely likely event you don’t recall, I have an AO Smith GDHE 50 “Vertex” direct vent condensing 50-gallon water heater. It’s a natural gas combustion heater with a blower, and intake and exhaust lines through the roof. The thing has been through a lot. I originally installed it in the basement, I had to replace the flame sensor after the basement tuckpointing clogged it with dust, I moved it up to the first floor when we redid the basement, moved it back to the basement and it was hooked up by the (previous) plumbers, and then Dean and I re-ran the intake and exhaust from the side of the house to the roof.

It’s worked fairly well through all that. Other than the flame sensor, the only issue was when it was venting out the side of the house the intake would frost up because it was right by the exhaust from the boiler. Since running it through the roof, it’s been trouble free until now. I’ve drained and flushed it a couple of times to keep it in good health, but otherwise left it alone.

From above (blower removed)

I took a look and read through the service manual, and ordered another flame sensor. It seemed the most likely, and I wanted the part on hand if I had to take the whole thing apart. Once it arrived, I started working on the thing, and a collection of tools began to grow next to me: Phillips and flat head screwdrivers, adjustable wrench, nut driver, allen wrench, power screwdriver, hex bit, three bit extensions, socket wrench, measuring tape, pipe cutter, other pipe cutter, pipe wrench, rag, plyers, butane torch, solder, flux, needle nose plyers, gorilla tape, and shop vac.

Un-removable burner assembly

Needless to say, this was a long, frustrating process. I won’t bore you with all the details, just the highlights. The plumbers ran the water supply pipe directly over the center of the water heater, which meant I physically couldn’t remove the burner assembly (I admit to pretending it’s a reactor core). I wound up re-plumbing that, with only two trips to Home Depot only to find that my “shortcut” of using Sharkbite fittings was leaking, after which I just soldered everything. At that point I thought it was fixed and went to bed well pleased.

Easier access

I woke the next morning and took a nice hot shower, then discovered a puddle on the floor of the mechanical room and errors on the water heater screen. An existing fitting, one that I didn’t solder but next to one I did, started leaking. Apparently it got too hot when I was working on the adjacent connection and the solder failed. That flooded not just the floor, but the whole burner. This led to the shop vac, where I literally sucked the water out of the thing.

Water where it should not be (down in the exhaust pipe at the bottom)

At this point it was behaving a better than it had when I started, and I had completely worked out the process to remove the blower and burner, but it still struggled to get through a full heating cycle without an odd gurgling in the exhaust drain line followed by a purge and restart. I checked all the things I could think of, made sure the condensate hose had a trap, cleaned the chud out of the cleanout, checked exhaust pipe slope, but eventually, I went to work on the radiant panels.