Three potential issues:

1. Condensate drain line should end pointing straight down with at least a 2" gap between the bottom of the drain line and any other surface. This is fairly minor and unlikely to be solely responsible for the issues.
2. The unit needs to be level or condensate won't drain properly. Somewhat minor, but still unlikely to be solely responsible.
3. Your gas service line may not be correctly sized to operate this high-demand unit as well as your home heat (assuming home heat is also gas) in the winter. If this is your only gas appliance, the line may just be undersized. Correct size depends upon the length of the pipe from your gas meter and the number of fittings in that line. Insufficient gas flow can absolutely cause surging and the subsequent blasts of condensate.

josh02_2001

Ok, let's back up a moment:

What Sophie Wheeler said is absolutely not correct. Inlet water temps do matter, but that is not how the heater deals with it. The heater will maintain output temps by two methods: 1.) It adjusts the amount of gas (they have a variable gas valve) and 2.) If they still cannot maintain the outlet temp they throttle the amount of water moving through the system - it does not shut down.

I am seeing two different photos of the condensate drain: One with pex and one with PVC. I assume you changed out the line for the neutralizer. Just a minor point, there should be an overflow upstream of the neutralizer. If the condensate backs up in the neutralizer it will exit the overflow. This overflow is shown in the installation manual - It's just a tee that branches off so if it backs up in the neutralizer it will go out of the tee.

I don't have experience with Takagi, but the condensation around that port does not seem right at all. That has to be exhaust gasses causing that. You just shouldn't be seeing anything coming out of that. I'm not clear why there is a hole there - but if the drain is open all the way, all of the water should drain down the pipe and not out that port. You shouldn't see anything spitting out of that port.

You should be getting an error code when the heater shuts down. That code will give us a lot of information on where to look.

Lastly, I think there is something to the fact that this is happening in the winter. Two things happen in the winter: Inlet water temps go down requiring more gas input to reach the same output temps AND other major gas usage at the same time (the furnace). You should have a maximum of 30' of 3/4" gas line to the heater and no 1/2" gas line. Your supply line from the gas meter before it branches to the furnace and water heater should be at least 1".

Report back any error codes you find.

To test the gas supply:
If you want to see if the gas supply is adequate, open the hot tub faucet (not shower) and a hot sink faucet (kitchen sink would be good). Then bump up the thermostat on the furnace so that it is running. This will cause the water heater to run at full gas input as well as the furnace. See if you get an error code on the unit or if it shuts down. That's the best test of the gas supply.

A general note:

Gas tankless water heaters have been around for a while. Takagi is a good brand. This is all pretty reliable stuff. It's unfortunate you are having a problem, but I suspect an installation issue. It will take some troubleshooting to get to the bottom of this, but the choice of the water heater wasn't a bad choice.

You said: "With a faucet on all the way hot the heater seems to sputter in and out where it sounds like it is turning on and off the gas supply. Not sure if this is normal operation or not."

No, this is not normal.

When the hot water is running the heater should operate smoothly and continuously. It should not turn on and off. When you run a small amount of hot water it should turn on low and when you run more hot water it should ramp up. It should not turn off until you shut off the water.

So what size is that valve and flex pipe? I've been wondering since I saw it in the first photo. It looks like you have a 3/4" pipe that's reduced down to 1/2". If that's the case you want to fix that. The entire thing needs to be 3/4". You really are trying to move a lot of gas (200,000 btu).

60' of 1-1/4" line will move 336K BTU maximum. You mentioned a gas fireplace. Mid-sized ~30K BTU. Gas furnace? Up to 100K BTU. Could you be pushing the limits of your main line?

Since this is only a year old, it should be under warranty. Call Takagi customer service and see if they can help - there is always the possibility of a faulty sensor or controller in the unit.

I don't disagree with the warranty call.

If that's a 1/2" line though I'd replace it first. Let's not give them a reason to point fingers elsewhere.

Thanks Josh, I couldn't really tell from the photo what size the pipes were. The only thing I had to go by was the 3/4" coming out of the bottom of the heater.

There is a tag on the flex line. See if you can google a part number from that tag to tell you what it is -- that's the most reliable way I know.

If we rule out the gas supply (and we are heading that direction) then I'd focus back on why you have condensate spitting out of that port and if condensate buildup is causing the burner to shut down.

As long as you know for certain that the condensate drain is free flowing, and have ruled out gas supply, I think you need to press a warranty issue.

Hold on...

So know that 3/4" appliance connectors are not readily available at Lowe's / Home Depot. You can order them.

I've always just installed hard pipe on my tankless installs.

I'm a little concerned about the smell... so I've had that smell outside when my tankless has short cycled-- but never inside. You should never be getting combustion gases inside your house.

I think it's time to insist on a warranty repair.

A shutdown on low-gas pressure issue would trigger an error code in most units I'm familiar with. Shutdown and no code isn't comforting either.

Order your new 3/4 appliance connector but get going on the warranty repair. There are too many things that don't sound right (combustion gas smell inside, spitting condensation, shutting down without error code, no obvious install issue).

My Myson used to do the same exact thing in the winter. Until i throttled down the intake valve in the winter. It's old school, no electronics, pilot light type, and it's 23 years old with zero issues once I made the summer to winter adjustment every fall and spring.

I do not know how the modern electronically controlled units account for the colder incoming water temperature at all. But, that's the report from the old school style.

Yes, you should be concerned about that. This indicates either a venting issue or an internal leak in the unit. Call them back and INSIST they get a qualified tech to look at it. If the leak were in the gas line to the unit, you would smell gas all the time, not just when the unit is running.

You shouldn't have combustion gases in your closet.

I don't want to parse ANSI manuals, you shouldn't have combustion gases in your closet.

You have too many issues that indicate a venting problem, an internal leak, etc.

I am going to give you one more thing to check... but I'd be pretty pissed right now if I was you.

Double check that all DIP switches are correctly set including the ones for 1.)high-altitude, 2.) Single or dual pipe 3.) vent pipe size 4.) vent length 5.) Common Venting

These are in your manual. I'm looking at a manual online - but can't say for sure it's for your unit.

The 400 ppm CO emission requirement is OUT THE STACK, not in your home. That is a burner efficiency rating and has NOTHING WHATSOEVER to do with acceptable CO in your home. If I were you, I would be raising holy hell with them right now and inform them in no uncertain terms that they need to fix their unsafe unit. Again, this is a SAFETY issue, not an efficiency issue.

EDIT: Per the EPA, in-home levels near properly adjusted burners (as in immediately next to the burners) range from 5-15 ppm. Poorly adjusted burners - 30 ppm or higher.

50 ppm is generally considered acceptable over and 8 hour period, but not acceptable 24/7. Anything over 100 ppm is high and/or dangerous.

Symptoms are as follows:

• 50 PPM - None for healthy adults. According to the Occupational Safety & Health Administration (OSHA), this is the maximum allowable concentration for continuous exposure for healthy adults in any eight-hour period.
• 200 PPM - Slight headache, fatigue, dizziness, and nausea after two to three hours.
• 400 PPM - Frontal headaches with one to two hours. Life threatening after three hours.
• 800 PPM - Dizziness, nausea, and convulsions within 45 minutes. Unconsciousness within two hours. Death within two to three hours.
• 1,600 PPM - Headache, dizziness and nausea within 20 minutes. Death within one hour.

Yeah, thanks for those numbers AIW: I was going the same place...

There shouldn't be any combustion products in the closet. Full Stop.

There is a venting problem or a combustion gas leak. The spitting condensate and condensation around the drain line suggests the same thing. Only flue gasses would leave condensation like that and there shouldn't be flue gases there. My guess is that the gasses are leaking to the inside of the cabinet and exiting around that fitting.

So look Josh:

If this were my issue I'd be saying either Takagi is going to fix this or I am. It would suck to drop $1200 on a new unit... but if a solution wasn't forthcoming real soon, that's exactly what I would do.

As someone advising you - I also have a moral obligation to be clear that you have a safety issue. Good to check DIP switches, gas supply, venting, etc... but at this point it's very clear there's a problem with this unit and you need to deal with that -- even if that means pulling the money out of your own pocket.

Can I get a pic of the room with the furnace and the water heater vent?

Is this a sealed room? do you have outside air intake on the furnace?
I take it you have outside air intake for the water heater (correct?).

Do you have a leak in the return air plenum of the furnace?

So, here's a thought... nothing wrong with the water heater. Room is mostly sealed. Combustion air for furnace (and/or water heater) is being drawn from the room OR a leak in return air plenum is reducing the air pressure in the room. Any chance that's a possibility?

Again this is happening in the winter (furnace running).

Here's the test: with the furnace and the water heater running, and the room door closed, open the door to the room slightly while holding a source of smoke (cigarette, incense, candle you just extinguished) near the opening. Does the smoke get sucked into the room when you crack open the door?

Ok, so we have exhausted everything (pardon the pun).

you have outside air intake on both units

the room isn't going into negative pressure

It's time to deal with that heater.

Hey Josh,

So I was just looking around at the service manual. If you don't have it, here it is.

Just a couple of things:

It looks like there is a loop in the condensate drain inside that would form a trap and should prevent exhaust gases from exiting the condensate line (along with spitting, etc).

Potentially improper / late combustion could cause the pressure in the secondary exchanger to be high enough to expel the water in the trap. Improper combustion should be detected by the unit and throw an error code.

You did not mention the actual error code that you got.

Also - Scale is not the issue here. This is not about needing to de-scale it.

Hey Josh,

Error 611 is "abnormal Fan Motor". If you are sure that was the error, you have a problem with the unit. (see page 18 of the service manual linked previously).

The error code is your very best clue as to what the problem is, so if you get a code, write it down.

If you have that error, you should let them do a warranty repair. Once you have your new gas line in, if that doesn't solve the problem, get warranty repair.

Yes, do replace it. You have an odd combustion problem.

If that doesn't do it, then i think it's some issue with the fan causing some funky combustion (which then blows condensate everywhere).

Yeah, I'm pretty unimpressed with their tech help. Error codes are the first thing to go for.

Sorry, hit post to soon and can’t figure out how to edit from the app.

The top one is the one I bought. Is this a fitting that will work on natural gas lines?

Sorry, I'm very confused

Sorry about that. The 3/4" gas line I purchased had one male end and one female. I need two male ends to make it work with the fitting on the gas line and the fitting on the water heater so I needed to buy an adapter.

The existing 1/2" line that was hooked up before also had an adapter which was the longer lighter colored one in the picture above. The male to male fitting I purchased at Lowes is shorter and looks different, it is the top one in the picture above.

I was wondering if I bought the wrong fitting and what I bought is not something you would use for gas lines, but instead water lines. Just worried the fitting I bought will not create a good seal and will cause a gas leak.

Ok...

So the lighter fitting is stainless steel and is a male tapered pipe fitting on one end and a flared fitting for the flexible stainless steel gas line on the other end.

The darker fitting is a brass fitting with male tapered pipe threads on both ends.

The gas flex line you bought must have a stainless steel flared-to-pipe fitting on both ends as shown below. You may use the brass fitting, in addition to the fittings that came with the flex line, to make both ends of the flex line male. You may not substitute the brass fitting that you bought for the stainless steel flared to female pipe thread fitting that came with the flex line.

You will need to use pipe dope or yellow teflon tape with all of your threaded joints.

You will need to use soapy water to test all of your connections that you made for gas leaks.

Be sure that use a wrench on the fitting on the water heater to hold it to avoid putting too much torque on the heater itself. You don't want to damage the heater by tightening the gas line too much without a wrench to hold it steady.

Josh, how did this turn out?

Doesn't appear to have fixed the problem. The closet still stinks and we are not maintaining hot water throughout baths/showers. Time to contact customer service again.

Yes.

A few points:

1. tell them about the error codes up front.

2. tell them it's expelling the water in the condensate trap, and so you are getting carbon monoxide inside the house.

3. tell them you have gone through the installation thoroughly - it's not a fault of installation.

4.Insist on a supervisor if they aren't forthcoming with a solution

For condensate drain port pinholes and spewing water, the Takagi.com tech support said: “These holes are vent holes. Please verify that there aren't any obstructions on the condensation line causing this back pressure. Most of the time this is the case. Don’k know about the error code and gas smell. Sorry.

Dude,

This is unacceptable. They should have records of your calls and know this isn't a basic issue.

It's really time to get this resolved.

You have to insist on the next level of support or just scrap the heater.

Jake: I am not Josh. I am just helping Josh with what I got from Takagi. Rephrase: For condensate drain port pinholes and spewing water, the Takagi.com tech support said: “These holes are vent holes. Please verify that there aren't any obstructions on the condensation line causing this back pressure. Most of the time this is the case. " I don’k know about the error code and gas smell. Sorry. Josh has not posted yet.

A week ago today I wrote out a long message to customer support so I could explain what was going on and not forget on the phone. A week later no response or return call as I requested in the message. So I called today and was told they will overnight me a new computer board and gas valve, although he said it could be something more major. I was told they do not warranty labor so I have to replace them myself, which he said was easy to do. I'm going to make a go at this next weekend.

Here is a quick update. I had a local plumber come out to try and help diagnose the problem. After about 30 minutes of troubleshooting, he said that it was not venting properly and not running right. After some investigating we discovered the pvc that vents to outside had a big belly in it, see pic, which in turn caused the condensation from the hot air to get trapped in the vent line and reduce the venting area enough in the pipe to cause the air to have to be expelled back to the area of least resistance (out the condensate port). I went to the middle of the pipe and shook it and it was full of of water. I raised it by pushing up on it, and a bunch of water drained back thru the condensate port.

I need to eat crow and apologize for saying anything bad about Takagi since this was a plumbing install issue. In nearly 20 feet of pipe the original installer had one support and that was at the end where it 90’s up to the roof. Not the first problem I had with the original plumber, so I can’t say I am surprised. They installed my fireplace wrong, which I spent over a year messing with and another plumber discovered the problem finally.

I am glad the issue is resolved. I am going to add some supports to the pipe this week to keep it from happening again. I am going to delete this thread in a couple days so as not to give Takagi a bad name when it wasn’t an issue with their heater.

Thanks for all your help.

Please don't delete it. All of the hassle you went through to get to the solution could help someone else. Can you just edit your initial post to indicate right away that it ended up not being a problem with the unit?

The ineptitude of the tech support and the lack of coherent information about error codes is still a problem with Takagi. There ought to have been a vent pressure code. Further, it this was installed by a company/installer they have certified, then they have a training/accountability problem as well.

Yes, please don't delete.

I have similar issues as described here with a Takagi water heater: condensate fluid dripping out of pin holes. This has been a helpful thread for things I should investigate.

I have checked that the condensate PVC drain line is not obstructed: water can cleanly flow out to an external sump pump drain. The neutralizer filter is not clogged (we replaced it), and we even replaced the "condensate drain port" part in case that was faulty. Fluid is by no means spitting out of the drain port, and I do not have the gas smell symptom also noted here. Will post an update later if I find out what is going on, but any advice on what to check would be helpful.

Will check the vent pipe first!