Condensate drain questions

[mm08822]

Interesting thanks.

Nothing here surprises me outside of the company pushing a installing condensate neutralizer systems for high efficiency gas furnaces very hard -- just to put the condensate in the wastewater system. I am a little skeptical that is necessary for homeowners to (Ph?) treat condensate to release into the into a wastewater/sewer system to make it less acidic. I maybe can see the point a little more if you have a septic tank and a very big air conditioner system draining into it. But it is news to me (I am just a DIY guy though, but also a scientist) if hardly any high efficiency gas furnaces come with a condensate neutralization systems. I very much doubt that little acidic water mixed into the large waste stream will not do any significant harm. I also doubt any modest treatment system is going to remove trace heavy elements (the real problem which will also depend on your system, the gas supply etc) also. This company may be targeting people wanting to be responsible citizens for profit. The money that their customers spend on a such condensate neutralization systems might be better spent on things that potentially matter more and be more doable: Like putting a microplastic filter in a washing machine drain to better keep micro-plastic shards from synthetic clothing out of the waste stream.

Actually, It wasn't in reference to ac condensate, but rather the furnace condensate as they usually combine into one location. The pH could be a concern for components but a small pump and hose isn't too big of a deal to replace if ever needed. Septic systems, maybe, but still not sure of the daily quantity that may go into the septic tank and then it is diluted by all the existing tank water and fresh grey water coming in on top of it.

My point really was, DON"T DRINK IT (as mentioned in above post). Not even sure I would want it on my garden veggies. Flowers ok, but you may find they croaked one day too! A hole in the basement floor has worked well for me for 31 years.

 

[Fav Onefour]

Interesting thanks.

Nothing here surprises me outside of the company pushing a installing condensate neutralizer systems for high efficiency gas furnaces very hard -- just to put the condensate in the wastewater system. I am a little skeptical that is necessary for homeowners to (Ph?) treat condensate to release into the into a wastewater/sewer system to make it less acidic. I maybe can see the point a little more if you have a septic tank and a very big air conditioner system draining into it. But it is news to me (I am just a DIY guy though, but also a scientist) if hardly any high efficiency gas furnaces come with a condensate neutralization systems. I very much doubt that little acidic water mixed into the large waste stream will not do any significant harm. I also doubt any modest treatment system is going to remove trace heavy elements (the real problem which will also depend on your system, the gas supply etc) also. This company may be targeting people wanting to be responsible citizens for profit. The money that their customers spend on a such condensate neutralization systems might be better spent on things that potentially matter more and be more doable: Like putting a microplastic filter in a washing machine drain to better keep micro-plastic shards from synthetic clothing out of the waste stream.

How old is your main drain plumbing?
The acidic condensate is hard on older cast plumbing. If you still have some of that pipe they may be trying to save you hassle later?

 

[rlitman]

...hardly any high efficiency gas furnaces come with a condensate neutralization systems...

Funny, I've never seen one without. It's just a plastic pipe filled with limestone chips. Nothing special, though many are ungodly overpriced for what they are.

 

[lund]

How old is your main drain plumbing?
The acidic condensate is hard on older cast plumbing. If you still have some of that pipe they may be trying to save you hassle later?

The house is 50 years old and has PVC (Schedule 40) drain pipes. The gas furnace has no clear neutralization system. I think the Lennox high-efficiency furnace was installed by the prior owner about 20 ish years ago.

I also have a Cali home that I installed a Rheem/Rudd furnace myself. I am pretty sure that one has no neutralization system for the condensate. That one is also a smaller furnace (small house) with a short PVC exhaust pipe and it seems to blow the water drops out the exhaust pipe (which is fine in the relatively warm Cali climate) so no collected condensate flows back to the furnace to collect into the drain.

 

[lund]

Funny, I've never seen one without. It's just a plastic pipe filled with limestone chips. Nothing special, though many are ungodly overpriced for what they are.

I have two homes with ~20 year old high efficiency gas furnaces (Lennox and Rudd) with no neutralization system in either.

A plastic pipe with limestone chips would have to be replaced a lot (consistent with condensate flow and surface area) to work. That sounds like a pain and a potential maintenance problem with crud blockage (which might also inhibit such a design from working).

Maybe there are local regulations in some areas (where you are?) that require some sort of system? Systems would require regular servicing ... analogous to a water softening system.

 

[rlitman]

...A plastic pipe with limestone chips would have to be replaced a lot (consistent with condensate flow and surface area) to work. That sounds like a pain and a potential maintenance problem with crud blockage (which might also inhibit such a design from working)...

I have a 1 million BTU mod-con boiler at my office. The pipe is a horizontal foot long section of 3" PVC tubing (we've since replaced with a clear tube so you can see when it need servicing) with an inlet tube at the bottom and an outlet tube at the top. We refill it with a couple of pounds of chips every 3 years or so. We can easily go between several boiler servicing cycles without needing to top it off. If your condensate gets blocked with crud, your heat exchanger is going to get crudded up too, so again, not really an issue.

 

[lund]

I have a 1 million BTU mod-con boiler at my office. The pipe is a horizontal foot long section of 3" PVC tubing (we've since replaced with a clear tube so you can see when it need servicing) with an inlet tube at the bottom and an outlet tube at the top. We refill it with a couple of pounds of chips every 3 years or so. We can easily go between several boiler servicing cycles without needing to top it off. If your condensate gets blocked with crud, your heat exchanger is going to get crudded up too, so again, not really an issue.

I am curious: do you have PH verification that this neutralizes the condensate after operating a significant time? That sounds like a very large air conditioner. You might estimate the volume of acidic water this would produce in a year, and then from the PH, calculate the amount of a base that would be necessary to neutralize it. I suspect that would be way more than a "few pounds of chips" every 3 years or so even if you are not in a humid place (which Long Island is if that is your location). If so, the neutralizer (few pounds of limestone chips) could not be doing much or all the material would have been used up many times over in the neutralization process.

I could be off here. But a significant number of products are sold maintaining they do something they cannot based on just simple balances. It is possible you are using something here that might not work as advertised. In reality, the chips might get surface coated and then the rate of use could go down so they might survive. But this would also make them less effective. A powder with mixing in the right amount or a system with enough surface area might be needed.

 

[rlitman]

I am curious: do you have PH verification that this neutralizes the condensate after operating a significant time? That sounds like a very large air conditioner. You might estimate the volume of acidic water this would produce in a year, and then from the PH, calculate the amount of a base that would be necessary to neutralize it. I suspect that would be way more than a "few pounds of chips" every 3 years or so even if you are not in a humid place (which Long Island is if that is your location). If so, the neutralizer (few pounds of limestone chips) could not be doing much or all the material would have been used up many times over in the neutralization process.

I could be off here. But a significant number of products are sold maintaining they do something they cannot based on just simple balances. It is possible you are using something here that might not work as advertised. In reality, the chips might get surface coated and then the rate of use could go down so they might survive. But this would also make them less effective. A powder with mixing in the right amount or a system with enough surface area might be needed.

I was talking about a boiler, not an air conditioner, and yes, you're way off.

We've got well over 100 tons of air conditioning equipment (yes, on Long Island, and yes, we have two seasons, moist and dank), and nothing to neutralize any of that condensate, because air conditioner condensate is not particularly acidic (any standing water is slightly acidic due absorbtion of CO2 in the atmosphere), and since it is no more corrosive than rain water (which itself is atmospheric condensate), it requires no neutralization (you don't neutralize rain water, do you?).

BOILER condensate is an entirely different matter, since the source of the water is from combustion:
CH4 + 2O2 -> CO2 + 2H2O + heat.

That's the basic combustion reaction, where the water is released in the form of steam in the exhaust along with lots of carbon dioxide, but the exhaust gases also include nitrogen oxides (and to a much lesser extent sulfur oxides) that acidify the water when they dissolve in the condensate.

The simplicity of a neutralizer system is that the lower the pH of the condensate, the faster the limestone will get dissolved, and the water that exits the system will no longer be acidic. If there's at least half of the limestone left, it's still working. Easy peazy. It works, because above a pH of 7.4, the limestone stops dissolving, so the water can sit in there indefinitely and not keep wasting limestone.

But hey, you want to calculate it the hard way? Ok, I'm game for feeding this one to AI. Here's what it told me:
For a 100 kBTU/h appliance burning for 2000 hours in a season, expect to generate 7600 L of condensate water in that heating season. Assuming a baseline condensate pH of 4.0, at the stoichiometric ratio for calcium carbonate, you could expect to consume 38 g of chips in a season.

Multiply that by 10 for my million BTU boiler, and that's 378.9 g of chips, which is 0.835 lbs / year. Hummm....

 

[lund]

I was talking about a boiler, not an air conditioner, and yes, you're way off.

We've got well over 100 tons of air conditioning equipment (yes, on Long Island, and yes, we have two seasons, moist and dank), and nothing to neutralize any of that condensate, because air conditioner condensate is not particularly acidic (any standing water is slightly acidic due absorbtion of CO2 in the atmosphere), and since it is no more corrosive than rain water (which itself is atmospheric condensate), it requires no neutralization (you don't neutralize rain water, do you?).

BOILER condensate is an entirely different matter, since the source of the water is from combustion:
CH4 + 2O2 -> CO2 + 2H2O + heat.

That's the basic combustion reaction, where the water is released in the form of steam in the exhaust along with lots of carbon dioxide, but the exhaust gases also include nitrogen oxides (and to a much lesser extent sulfur oxides) that acidify the water when they dissolve in the condensate.

The simplicity of a neutralizer system is that the lower the pH of the condensate, the faster the limestone will get dissolved, and the water that exits the system will no longer be acidic. If there's at least half of the limestone left, it's still working. Easy peazy. It works, because above a pH of 7.4, the limestone stops dissolving, so the water can sit in there indefinitely and not keep wasting limestone.

But hey, you want to calculate it the hard way? Ok, I'm game for feeding this one to AI. Here's what it told me:
For a 100 kBTU/h appliance burning for 2000 hours in a season, expect to generate 7600 L of condensate water in that heating season. Assuming a baseline condensate pH of 4.0, at the stoichiometric ratio for calcium carbonate, you could expect to consume 38 g of chips in a season.

Multiply that by 10 for my million BTU boiler, and that's 378.9 g of chips, which is 0.835 lbs / year. Hummm....

Sorry, I can be a spaz. I was mixing discussed topics with gas furnace and AC thinking you were discussing AC condensate -- which should not be acidic anyway. I think the main issue with AC condensate is metal, mold, and bacterial contamination. The humidity should not matter much for furnaces ... just the temp of the exhaust and what amount of water vapor does not make it out the exhaust to dictate how much water remains to drain. High efficiency means lower exhaust temp and more water condensing.

That is not a high acidic water volume of furnace condensate if the numbers you quote are correct. A PH of 4 is not terribly acidic to send 7600L/2000hours = 3.8 L/hr into a drain: about two grocery store soda bottles an hour with something maybe as acidic as tomato juice if your PH number is right. I thought you were talking about much higher volumes. Is that amount *really* such a problem in a large municipal sewer system? I am skeptical. Maybe if you drained into a small septic tank or directly used it for plant watering. But then I would worry about the other contaminants for furnace condensate since the burning is not pure and the gas has various contaminants that might accumulate. A limestone neutralizer will not take those out regardless ... and I wonder if even a filter would do so. Is your neutralizer supposed to save cast iron pipes from enhanced corrosion? Most drain pipes since have long been PVC or ABS. But there is certainly a lot of older construction around.