Water Heater Repair

Our water heater has been flaking out for the last few months. You may recall from previous posts that like most Taiwanese houses, we have a tankless water heater, also known as an on-demand water heater. Most American homes have the big water heater tanks. With a tankless heater, it only runs when there is water flowing through the hot taps. With a tank heater it keeps a big ~40-60 gallon tank heated constantly.

Usually when our water heater flakes, it is because the battery is dying. We have a gas heater with electronic pilot light. The ignition is powered by a D size battery. When it runs down then the pilot light may not light all the time. This time the battery was fine. The problem was that the water flow wasn’t triggering the heater to turn on.

The tankless heater uses a water valve on the bottom of the unit. When water is flowing, it is supposed to raise up a plunger with closes the pilot light contact and starts the flow of gas. This plunger is also regulated by a thermocouple which raises and lowers the gas flow as the proper heat level is attained. The problem was that this plunger was barely moving up any more.

I’d been able to put off repairs by adjusting the heat and water pressure settings so that the plunger would rise up just enough to turn things on, but over time it got worse and worse. And if anyone turned on another tap while you were taking a shower, that’d be enough to trip it off again. Over the last few days it got especially painfully flaky.

So yesterday I decided to read up more about how these tankless heaters work. I couldn’t find an English manual for my particular model since it is a local brand, so I looked at some manuals for some Bosch models that were similar. I found out that the water valve innards have an expected service life of 2-5 years.

While I like to do repairs myself whenever possible (at least so I understand how things work if nothing else), this repair was getting a bit too complex, so we called the manufacturer’s service line yesterday and they sent out a service guy this morning. I showed the guy what was going on and he immediately pulled out a rubber diaphragm and said that’s what was broken.

I watched as he pulled out the water valve, disassembled it, and pulled out the old rubber diaphragm which had a nice 2 cm gash in it. He put it all back together with the new one, and reassembled the water heater. Went to turn on the hot water tap and the plunger shot straight up to the top immediately. Voila, it was fixed. After he left, I readjusted the temp and pressure settings so that the shower would run hot water for the entire upper half of the dial.

I was happy that I had mostly figured out the problem myself, happy that I could speak enough Chinese to describe the problem to the repairman, but most of all I was happy to be able to take a shower this morning without twiddling the hot water off and on to get it to turn on, and without it randomly turning off in the middle.

The estimated repair they told us on the phone was TWD1000 (about USD31.00), but it ended up being only TWD400 (about USD12.50). It’s really nice that repairs like this are so cheap here.