Bought a TK-RE02 for my aquastar 240fx (takagi tk-1). The installation instructions are for tkjr and others, but not for the TK-1/240fx. Where do the leads go on this model? Note, this is an AquaStar 240FX

When the noise occurs when there is no hot water being used, it's likely there is a vacuum that's siphoning water away from the unit and causing loud noise and vibration. ... Another common problem that can create noise in tankless water heaters is a dirty flow sensor which controls how much gas is sent to the unit.
https://www.youtube.com/watch?v=Fsb8Wx9PRvY

here is the manual... should be 3 digit error code.. check it out
http://www.hotwater.com/lit/training/321923.pdf

Flowmeter.....Gas Pressure.....Ignition?
I'm not psychic.
Tk-Jr is a dependable 140-145,000 BTU 2nd Gen Unit SS Vent , <.82 EF.
Failure is a Tech Service issue and the Tech may need Factory Support from California. This is probably a pre-A.O. Smith/Takagi unit
Does the igniter spark 3 times than shut down and fan purge HE? Can you smell gas tracer (remember NG/LP is odorless w/o mercapthan in it)? Tech will need a digital Manometer for Line and Manifold Pressure Test. And a Multi-Meter Toll Free # on Unit or in Manual

Better off adding more elbows.

In my case, the error code 21 was caused by the failure of the vent fan to run-on after shut off (easily verified by listening to the unit). The problem was not resolved by swapping either the fan or the control unit with another heater. I talked to a local service tech who had a couple of suggestions. One was to move DIP switch #6 to the upper position. After doing thisit will be necessary to re-initialize the controll by cycling power off and on. This fixed the problem. I emailed Takagi tech support to ask if I should consider this as permanent fix, or if there was something else I should do. Since I got no reply, I'll pass on the tech's other suggestion: buy a Rinnai.

Hi,

Here it is..

http://www.lowenergysystems.com/b2c/ecom/ecomEnduser/items/xt_itemDetailNF.aspx?itemNum=EK034&siteId=1&bulkexists=0

The Tagaki TK-1 is the same unit and the parts are interchangeable...

heatman101

remove from the wall.... donate to charity and purchase a quality tankless water heater!!!

Rinnai, Takagi, Noritz are the only brands I will install. I refuse to even work on Bosch "Aquastar", complete garbage!

cold supply may be reduced as long as you give the heater enough flow to work best of luck

Remove your hydronic pump and replace the flexible impeller coupling that couples the impeller blades to the pump motor. make sure you don't do this on a sat or, sunday (i hate house calls then) and, be sure you have a new pump housing gasket before you start the job. Also check the unit for loose pipe brackets

I have the same problem with a T-K3. The Takagi support site recommended cleaning the burner. When the plummer arrived to attempt the cleaning, he was not convinced that it would help. He called the Takagi 800 number and let them hear the problem over the phone. They had him set the fan speed dip switch (#4 on the upper left bank of switches) to the up ("on") position and reset the system. Problem resolved! Why they didn't recommend this when I contacted them, I haven't got a clue. Anyway, the system hasn't vibrated in several days of use.