Takagi T-K1S Just Quit, Now What??

[thepipe]

Hello, All:
HELP! After only 9 years of use, my T-K1S began leaking inside today. I tried to figure out where it was coming from, but can only determine its general location: below the copper heat exchanger. In addition to the leak itself, I think the water shorted something out because it won't respond to demands for water. The unit does have power, the 3A fuse is good, and the GFCI is operating properly. My TK-RE02 remote indicates error 74, which is remote error. When I remove the remote from the circuit there is no change to the operation of the unit.

Is this worth fixing? If replacement is better, which brand and model should I consider? I'm not in love with Takagi, but would be open to a similar unit from them (or anybody) which would just "bolt in" to the old location. The T-K1S BTU output, 190k, has been perfect for us. I don't need the added expense of the PVC-venting units and despise the thought of discarding that expensive stainless vent pipe already there. I must decide soon since we have zero hot water.

Any thoughts?

 

[Dana]

Turn the power off, turn off the gas, and really open it up. If it's a leaking gasket or something it could be a cheap & easy fix. The heat exchanger itself should be good for a coupla decades at normal hot water usage levels. Call Takagi - they probably have replacement control boards for the thing for FAR less the cost of a replacement water heater, and they're pretty good about talking through the de-bugging process with homeowners.

But if it's something unrepairable, replacing it with another tankless isn't necessarily the "right" thing to do. If you are heating your house with a hydronic boiler you'll get better value out of spending the money on an indirect fired tank running as a "priority zone" off the boiler. If you have a basement that usually needs a dehumidifier, a heat pump water heater can make a lot of sense.

Or, you can search a compatible replacement. IIRC the TK-2 and KD-20 are pretty much direct drop-ins for the TK-1 - you wouldn't even have to change the plumbing (much) and they use the same remote. But both of those models (like the TK-01) are also a decade out of date, not currently being retailed.

The TK-Jr and TK-3 or newer Takagis would require more extensive re-plumbing but you may be able to use the same wall bracket with some of them. You can find TK-Jrs out there for under $500, and I think it uses the same remote (can't remember for sure.) The TK-Jr. is more than enough burner for most 2-3 person families, but a bit marginal for running two simultaneous showers in different bathrooms.

 

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[thepipe]

Turn the power off, turn off the gas, and really open it up. If it's a leaking gasket or something it could be a cheap & easy fix. The heat exchanger itself should be good for a coupla decades at normal hot water usage levels. Call Takagi - they probably have replacement control boards for the thing for FAR less the cost of a replacement water heater, and they're pretty good about talking through the de-bugging process with homeowners.

But if it's something unrepairable, replacing it with another tankless isn't necessarily the "right" thing to do. If you are heating your house with a hydronic boiler you'll get better value out of spending the money on an indirect fired tank running as a "priority zone" off the boiler. If you have a basement that usually needs a dehumidifier, a heat pump water heater can make a lot of sense.

Or, you can search a compatible replacement. IIRC the TK-2 and KD-20 are pretty much direct drop-ins for the TK-1 - you wouldn't even have to change the plumbing (much) and they use the same remote. But both of those models (like the TK-01) are also a decade out of date, not currently being retailed.

The TK-Jr and TK-3 or newer Takagis would require more extensive re-plumbing but you may be able to use the same wall bracket with some of them. You can find TK-Jrs out there for under $500, and I think it uses the same remote (can't remember for sure.) The TK-Jr. is more than enough burner for most 2-3 person families, but a bit marginal for running two simultaneous showers in different bathrooms.

Dana:
Thanks for your response. I tried opening it up this morning with EXACTLY your thoughts in mind...and promptly stripped one of the three screws holding the manifold plate to the gas valve. Ugh! I may have to replace. We frequently run two showers and the dishwasher or washing machine, so a TK-Jr would be insufficient for us. Forced air propane, so no boiler involved. The basement is heated with a woodstove, so no dehumidification is needed. Actually, I have to have a pot of water on the stove during the harshest months. I don't know too much about hybrid water heaters other than they are around the same price as tankless, but with the same storage tank limitations as tank units.

 

[Dana]

You never need to dehumidify in the winter, but in the summers the average outdoor air dew point is above the deep subsoil temps in NJ, so the air near slab is hovering near saturation, and the basement air gets musty-moldy. If it's leaking so much air that you're force to add humidity in winter, it's almost surely leaking enough air to need dehumidifcation to keep basement are at a human-healthy level in summer.

If you're heating the basement with a wood stove, a HPWH is probably the right solution. An 80 gallon GeoSpring is enough to run multiple showers for 10+ minutes, and is WAY cheaper to run than a propane tankless at recent years' electricity & propane pricing in NJ. A 50 gallon might cut it with low-flow shower heads, but it could be cutting it close if simultaneous long showers is a common occurrence, unless you give it a bit of a boost:

If the main drains downstream of the showers is in the basement, a decent sized drainwater heat exchanger feeding both the cold-side of the showers and the cold feed to the water heater will extend the "apparent capacity" in showering mode, and probably make the 50 gallon unit work. It may not pay off very quickly in energy use with heat pump water heaters, but has pretty good NPV against standard electric water heaters or propane tankless. A ~50% rated efficiency drainwater heat exchanger would make a TK-Jr a viable proposition for dual-showers, too, since it's delivering 70-75F water to the hot water heater instead of 35-40F water at the winter-low temp.

Both length and diameter improve the return efficiency of these things- the largest one that fits is usually the right choice, since the higher return efficiency more than makes up for the marginal component cost. (Looks like they could have gone with an even longer one here, but didn't.)

 

[thepipe]

I love the heat exchanger idea, but the manufacturer says the drain pipe need to be vertical. My drain runs about 50 feet, pitched horizontally. I also Googled GeoSpring and was astonished to find the number of issues with leakage, many of which are being resolved through litigation due to the extent of the damage.

 

[Dana]

The GE GeoSpring is now on it's third generation. The first generation went big on the intial roll out with a less than perfect design, and had it mass produced in Asian with less than perfect vendor control, which is why the internet is papered with complaints about the product. A couple of years ago they moved production to Kentucky and tweaked the design for higher reliability and ease of manufacture, and more recently released the third generation much higher-efficiency line up. The current versions a much better product than internet scuttlebutt would have you believe.

Drainwater heat exchangers don't really work in 1-story slab-on grade houses, but can work with many or most homes will full basements, or reasonably deep crawlspaces foundations. There is one vendor that sells a version that can be installed horizontally but it's reliability is still uncertain and efficiency lower than the vertical gravity-film types with the slinky-wrap.

 

[thepipe]

I didn't realize that they had redesigned it. Frankly, I'm not so concerned with the first two generations' faults as I am the manufacturer's apparent unwillingness to make good on their products' failures and the damage these failures caused.

 

[Toadster]

Hi all, here's a recent update for anyone who landed here.

I had the same problem recently - no hot water in the morning, then it would work later in the day. I read this forum, and sure enough, when I heated up the circuit board with a hair dryer, after half a minute heating the burner would ignite and hot showers ensued.

I bought a new circuit board and changed it out and now, two weeks later, everything works great!!

One suggestion, before you take out the old circuit board, take a picture (or two or three from different angles) to make it easy to match up the new one. Only takes a few minutes to replace (of course, unplug it before anything! )