Thanks for Tank and Tankless Heaters

Last weekend, Jim and I finished making the final connections for our tankless water heater. I was admittedly nervous since this is a used Takagi TK2 tankless water heater we had gotten off of Craigslist. So rather than just cutting out the old tank model, we installed a shut-off isolation valve on our old water heater and left it in place for now. That way, just in case we run into problems with the tankless and need to revert back, it's a simple switch.

So, once the new equipment was in place and water lines were soldered together and leak free, we flipped the switch on the tankless water heater. Water flowed in and no leaks! I turned on a hot water tap, and water began to flow through the tankless. Once the flow was high enough (more than 0.5 gallons per minute), the electronic igniter lit the flames, which we could see through a tiny window (Jim is pointing to it the photo). Then the exhaust fan kicked on to push the fumes out the special stainless steel venting. Shortly, there was hot water flowing through the tap! Yay!

In a tankless water heater system, the hot water takes a bit longer to reach the taps than a regular water heater would. This happens because there is no constant heat source heating water all the time, and no standby heat is transferred to the water pipes. This is a trade-off with a tankless water heater. Less fuel is needed to heat, but more water is used and wasted down the drain as you wait for the hot water. Fortunately almost all of our plumbing runs are relatively short, so we haven't noticed this isn't a big deal. It takes maybe an extra 20 seconds at our furthest plumbing fixture.

Anyway, we've now been living with the new tankless for a week. Sunday night, Jen was very happy to finally be able fill the bath tub with hot water instead of running out halfway through! But we noticed when taking a shower that the hot water fluctuated off for about two minutes (completely, so it was cold!) and then came back on.

I read the TK2 manual, did a bit of research, and found a great discussion on problems with Takagi TK2 water heaters. This gave me some good ideas such as cleaning water inlet filter, cleaning the igniter and flame sensor (next to the tiny burner window) as well as checking the temperature sensors in the water intake and outtake lines for any clogs. So I did all this. At first, looking at this thing with the cover off is quite intimidating, but if you try to look past all the electronic wires, it's relatively straightforward.

However, after all these maintenance tweaks, it seems we still have occasional problems with the shower. We still get hot water there (and everywhere else for that matter), and there is no problem if the shower is set to full-hot (not mixing with cold water). I wonder if this is mixing valve issue so we'll have to do a bit more investigation on the temperature fluctuations (and maybe even call Takagi) to get this figured out.

Anyhow, despite these initial problems, I'm quite pleased with the fact that the system works, and I'm really looking forward to cutting out the old tank-style water heater and getting some extra space in the small utility room / shop area in our basement. But we'll hold off on that until these issues are resolved, knowing that if needed, we can fire up the old beastly water heater at any time.