Liquid coming out of tankless water heater's condensate drain line?
April 9, 2016 4:29 AM   Subscribe

I recently had a Rinnai tankless gas water heater installed professionally. I am noticing that during use, some liquid drips out of the bottom, from the condensate drain line. Plumber said "just put a bucket underneath to catch it and then pour down the drain." Uh, really? Some minor googling tells me condensate from tankless gas water heaters tends to be VERY acidic. What's the correct way to handle this?

Is the water really safe to just catch in a bucket and pour down a drain or should I be pushing the plumber to install a neutralizer of some sort? Also, it just seems weird to me that this thing is dripping into the open in the first place, whether or not it's acid. Am I wrong in assuming part of the standard install price should have included adding a pipe or something from the condensate drain to the nearest waste/gray water drain (probably where the laundry water goes, as that's nearby)?

I am feeling extra nervous about this being done right because this whole job occurred after my previous heater bit the dust in the middle of the night (yay flooding the whole house). I had to make a very quick decision about what to replace it with and I am still reeling from sticker shock from the cost and hope to not have to deal with another failure again. I want to make sure that 1. everything was done according to code to keep my plumbing system and house safe and 2. I am getting my money's worth.
posted by joan_holloway to Home & Garden (19 answers total) 1 user marked this as a favorite
Your boiler should not be leaking. Full stop.

When this happened to our (newly installed) boiler, it turned out to be because the flue had come loose & it was quite possibly leaking exhaust fumes as well as water into our kitchen.

A newly installed condensing gas boiler should not be leaking anywhere. Get your gas engineer back & insist that they find the source of the leak and fix it.
posted by pharm at 5:00 AM on April 9, 2016

Best answer: Generally, yes, the condensate line should be run to a drain. Is there one nearby that it could be run to? Howver, it is not uncommon, in my experience, for tankless water heaters to be installed with the condensate line running into a bucket. That's a bad solution, obviously, and I'd ask your plumber to come back and install a drain line if at all possible (you may need a lift pump to get it from the heater to the drain).

The condensate is acidic, but certainly not to the degree that you need to worry about neutralizing it before disposal. There isn't very much, anyways.

(Just to be clear, there is no leaking. This is a small amount of water that comes from the exhaust system of the heater - water produced from burning gas, not from the plumbing side. There is a condensate drain line, but it isn't connected to anything.)
posted by ssg at 5:07 AM on April 9, 2016

UK gas safe installation rules must be a bit stricter than US ones then. I don't believe that a bucket would satisfy UK building regulations!
posted by pharm at 5:17 AM on April 9, 2016

Response by poster: To follow up on ssg's reply- I am also concerned about the quantity. Over the last 24 hours my bucket had accumulated about 8 oz of liquid coming entirely from the condensate drain.

Is 8 oz over 24 hours a lot? This is from the heater being used for two 10-minute showers, two hot baths, running the dishwasher once (my dishwasher apparently doesn't generate its own hot water), and running one medium sized load of laundry on warm. In the winter there would also be additional usage of hot water to supply the radiant heating system throughout the house. So I imagine that could be 50 oz or so over the course of a week. It sounds like a lot to me but I have no point of comparison.
posted by joan_holloway at 5:25 AM on April 9, 2016

That sounds like a reasonable amount of condensate. I would not be concerned about the amount, but I'd still be looking to drain it directly.
posted by ssg at 5:39 AM on April 9, 2016 [1 favorite]

Best answer: The amount of condensate would depend on ambient air temp and humidity. But, the amount you're getting sounds reasonable. If there is a nearby drain that you can unobtrusively run a line to, I'd do that.
posted by Thorzdad at 5:42 AM on April 9, 2016

Best answer: I have only seen water heaters (tank and tankless) with condensate lines running to drains; I have never seen one just left to drip on the floor or into a bucket. Even if that is a legal installation, it doesn't seem like a good one, and I would want to get that fixed if at all possible.
posted by Dip Flash at 5:52 AM on April 9, 2016 [1 favorite]

Best answer: We had a tankless heater installed a couple of months ago and the condensate line not only goes into a drain, it first goes through a small box with little granules or pellets in it, which I didn't understand the purpose of until I saw your question - I suspect it mitigates the acidity before the wastewater goes into the drain. The tankless heater it replaced did not have that little box but I also don't remember anything dripping directly on the floor so I would assume it also had condensate routed to the sewer line.
posted by acanthous at 6:07 AM on April 9, 2016

Best answer: Our tankless heater drains directly into our laundry tub via some tubing that runs along the wall - the heater is about 10' away from the tub. There isn't any filtration between tank and tub. Yes, there is a surprising amount of liquid condensate that drains out.
posted by sarajane at 6:39 AM on April 9, 2016

You should find out what the building codes are in your area. I can't believe that a condensate line is not required to go to a drain of some sort. Also, what are the manufacturer's recommendations? Your previous hot water heater had an overflow pan that should have a drain plus the over pressure valve on the old unit should also have been piped to a drain, so there should be a drain in the area. Sounds like a lazy installer to me.
posted by Grumpy old geek at 6:55 AM on April 9, 2016

Response by poster: Thank you for the info so far! It sounds like it is not an emergency I must fix ASAP but something I should bring up with the plumber to ensure the job is complete. Does anybody happen to know what the building codes in the city of Seattle say about this or where I could find out as a not-so-knowledgable person? The plumbing company thus far says a drain is not required as a part of the install so if I want it, I have to pay extra. I'd like to be informed before my next conversation.

And no more threadsitting, I promise.
posted by joan_holloway at 8:05 AM on April 9, 2016

In my region of the US, this installation wouldn't be up to code. The condensate line has to go to a drain. Mine goes to the laundry sink where the washer drains. The basic detergents (and water) neutralize the acidic condensate. You can also get one of those neutralizing boxes described above if you're not draining using the laundry drain.
posted by quince at 9:13 AM on April 9, 2016

I'm not too clear on the construction of a tankless water heater, but condensate is from the exhaust gases which would exit though some sort of flue, which ought to be will insulated. This would keep the exterior parts cool (so as to not set the house on fire, and maybe to prevent burns if someone is puts his hand in the wrong place), but it would also keep the flue hot, discouraging condensation.

If you are getting too much condensate, it may have to do with the flue.
posted by SemiSalt at 9:23 AM on April 9, 2016

Best answer: Does anybody happen to know what the building codes in the city of Seattle say about this or where I could find out as a not-so-knowledgable person?

Someone here will probably know the specific answer to this, but more generally this is the kind of question that can usually be solved with a phone call or visit to your local building permit office. Their core function is to make sure that work is done appropriately and to code, and in my experience they love it when someone says "I want to make sure this is correct, can you please advise?"
posted by Dip Flash at 9:26 AM on April 9, 2016 [2 favorites]

Best answer: The bucket bit is BS. The acidic part is not important, (just think of what gets put down drains,) but the need to remember and empty buckets is just stupid.
The condensate should either drain to the outside, (house,) or into a drain. It is very common to use a condensate pump which is a little pump and basin with a float switch to accomplish this. You can use a neutralizer if you like but most of the time thats like rinse aid in a dishwasher in terms of anybody bothering. For the posters who are freaked out by condensate coming out of a hot water heater be reassured that it is ok for a Condensing Hot Water Heater to produce condensate. The point of condensing is that it is extracting the latent heat in the water vapor that is the product of combustion thereby making a more complete use of the energy released by burning the fuel.
posted by Pembquist at 9:40 AM on April 9, 2016 [2 favorites]

Best answer: SemiSalt: If it’s a condensing gas heater then it’s designed to recover heat from the exhaust by passing it over either the incoming cold water or the return flow of the central heating, depending on what it’s being used to heat. The condensate runs down internally & out the condensate pipe by design.
posted by pharm at 11:43 AM on April 9, 2016

Best answer: If you care about your waste plumbing you really should run it through a condensate neutralizer. I don't know what kind of venting you have, but i would install a pvc p-trap to prevent any flue gases existing through the drain. And then run pex to the neutralizer and then to the drain
posted by ihadapony at 12:41 PM on April 9, 2016

Response by poster: Thank you everybody! It sounds like the consensus is "this is weird and should be fixed but probably isn't dire" so that is a huge relief. I appreciate hearing especially from people who have the exact setup I am looking for so I know it's not an abnormal request.
posted by joan_holloway at 7:40 PM on April 9, 2016

SemiSalt, high-efficiency gas appliances are explicitly designed to minimize exhaust gas temperature and produce condensate in order to obtain higher efficiency.
posted by Good Brain at 5:11 PM on April 10, 2016

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