Takagi T-KIS Error Code - 4 Flashes - Help needed

Discussion in 'Tankless Water Heater Forum' started by yak-55, Feb 20, 2011.

  1. yak-55

    yak-55 New Member

    Feb 20, 2011
    I have a Takagi T-K1S that was installed in 2005 when our house was built. When it works reliably (less and less lately) we have been very happy with it. I haven't had much luck making it fail consistently, but it will now frequently stop heating and throw the blinking LED code of 4 flashes. According to the manual this indicates a FAN or PRESSURE SWITCH problem. (I don't have the remote control which I understand gives more specific error information).

    After several discussions with the Takagi they convinced me the problem was a dirty burner/heat exchanger. They provided a detailed cleaning procedure -- which is quite involved, but I was able to complete. There was VERY little evidence of dirt/fouling on either the HX or burner upon dis-assembly. Unfortunately the cleaning procedure doesn't seem to have helped the hot water drop out problem. I got a 4 flash code again today during a shower. I will talk to Takagi again next week ... but was wondering if anyone here had other ideas.

    Other facts that could be relevant. 1). The problem seems to be more frequent in colder months (colder air temps and incoming water temps) -- but it really doesn't get too cold in Florida. 2). The problem seems to be somewhat better with the outlet temp set to 122F vs 140F (although this makes the available shower temperature in the back of the house marginal due to piping temp losses). 3). I have not seen any other failure codes 4). The unit is installed in the garage, a clean environment and vented thru the side wall (total vent length ~15 inches) 5). NG supply seems correct (3/4"piping and a short run to the meter directly outside the garage wall) 6). I have a functioning water softener upstream of the heater 7). Cleaning the incoming water screen (filter) doesn't help 8). No evidence of any flame sensor or ignition difficulties

    Any thoughts or suggestions appreciated.

  2. yak-55

    yak-55 New Member

    Feb 20, 2011
    Still having the same faults ... generally when high demand (high fan speed) is needed. Also, I have observed that
    the problem goes away (or is at least infrequent enough that I haven't yet seen a failure) if I set DIP switch #6 to
    "ON" indicating an "Outside" installation location. Does anyone know how this setting changes the control/safety
    functions of the unit ? While I appreciate the improved operation, I am a little concerned about the safety implications
    (the unit is installed in my garage -- presumably "Inside" ... but doesn't have a direct vent -- combustion air is pulled from
    inside the garage itself).

    Again, any ideas suggestions or information appreciated.

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  4. Tom Sawyer

    Tom Sawyer In the Trades

    Nov 29, 2010
    Even though the unit is in your garage it is pulling cold air in for combustion just like it would if it was outside. cold air is more dense than warm air and effects the exhaust/inlet fan speed and it's sensor. The dip switch compensates for that. You did the right thing.
  5. yak-55

    yak-55 New Member

    Feb 20, 2011
    Thanks. I appreciate your input. I did call in professional help today (a factory authorized rep) and they agreed the Outside setting was OK to keep for this installation.
    They also replaced a flex pipe connection on the gas inlet (upsizing from 1/2" to 3/4" --- all the hard piping is 3/4" already). Finally the HX was "descaled" (circulating
    a vinegar water solution thru the unit) as a matter or routine maintenance. Hopefully this combination will solve our issues. Otherwise the unit and installation seems
    to be fine according to the rep.

  6. al1701

    al1701 New Member

    Mar 14, 2011
    Brandon, MS
    One little switch changes everything and you get a unit that works, correctly!!

    WOW, I am so glad I found this forum dealing with 4 flashes for the error code. We have a Takagi TK-1s we bought when we built our custom home in 2005 and installed it in our walk-in attic. We tried to put in all the latest things for energy conservation and innovations into our home, one being the tankless water heater. We gave our builder's plumber all the specs on the heater for installation and he said he had installed several of these for other people. Well, when we first tried to use it prior to moving in it would not come on like it was supposed to so we had Takagi send out there Rep to figure out what was wrong and they eventually realized the plumber had hooked up the water supply backwards, go figure after spending the kind of money we did on plumbing the house, JUST STUPID and this was only one of many to surface after we moved in. Well it worked, but we would have trouble just like the other poster did with it shutting off for no reason, couldn't use it with more than one thing on or it just wouldn't turn on for more than 1 minute then shut off, more so in the colder months although in Mississippi it is not really cold all the time.
    For 5 YEARS we have dealt with this and finally last night was the final straw and I decided if I could not fix it I would replace it. After reading the comment and reply about the outside/inside dip switch I checked our board, and low and behold it is set to "inside" even though the unit is in our attic exposed to temperature changes, so I changed it to "outside" and it did not shut off even with 2 showers, wash machine and dishwasher running. So why didn't the Takagi Rep see that and why didn't he see that my STUPID plumber decided to cheap out and reduce the 3/4 inch main gas line he installed from the meter to the heater, down to 1/2 Inch flex (like you use on gas dryers) from the shutoff to the unit instead of getting the correct size flex which is 3/4 or 7/8 inch. 1/2 inch is an inadequate size for the demands of this unit.
    So today I went and got the right size flex, parts, etc. and will install it myself to fix the gas starving tankless heater which is working with the 1/2 inch, but I know it will perform better with the correct size supply line. Why can't people do their jobs when you pay them good money and for Takagi's Rep not to see the problem with the gas supply line or the dip switch setting, just unacceptable that for 5 years we have been frustrated with the performance of this unit which we were excited about putting in our house. But, hopefully after the flex changout we we have happy endless days of hot water.
    Thanks for this forum.
    Al Benton
    Last edited by a moderator: Mar 14, 2011
  7. cbytes

    cbytes New Member

    Dec 1, 2013
    my problem is very similar, except I have a t-kjr and have done all the things listed above.
    I have a 4 flash code after the water runs and stops, I have to hit reset button to get hot water again and it will stay running as long as I don't shut the hot water off but as soon as I do I get a 4 code after the fan purges.
    Steps I've taken:
    1. replaced pressure switch.
    2. cleaned burner and flu according to Takagi tech support. (done it twice)
    3. changed switch #6 to on even though it's inside.

    Relevant info:
    its a 2 year old LP heater and was working great until i decided to take out the pressure switch to put in to an identical unit for my floor heat, that is when i started to get the 4 code, even after swapping back the pressure switch and putting a new one in, I still get the 4 code. Any help would be great.

    after many days of waiting I finally got an email from a service tech and the suggestion he gave solved it. Make sure the tube for the pressure switch is in the L for low pressure and not the H for high pressure. Bam !!! it's been working fantastic for months.
    Last edited: Feb 9, 2014
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