Boiler condensation

rgtoler7 · January 18

Hey everyone, hope this is not a repeat question, but I have a natural gas high efficiency boiler in my old house (over 100 years old) that was installed I believe around 2008. Anytime it gets below freezing there is a lot of condensation that is produced. The condensate lines are clean and the condensate pump works fine. But the condensate still drips into the floor. You can see how much has accumulated in the plastic tote over the last 3 weeks. I know nothing about hvac/boilers/mechanical engineering so it may be very simple. I’m just not sure. It supplies radiators and domestic hot water. Any input would be helpful. Thanks.

kcopp · January 18

Thats a good sign that the exhaust is being sucked back into the boiler from outside. Either a gasket inside has failed or the vent intake and exhaust are too close to each other….

Whats it look like outside?

Furthermore, they also had issues on that unit w/ the exhaust flapper breaking. That wouldn't help matters.

Jamie Hall · January 19

Or it may simply mean that the boiler is working hard, but generating a lot of condensate — they will, after all.

In any event, the condensate should go through a neutralizer and into a building drain with an air gap. A plastic tote is a maintenance nightmare.

EBEBRATT-Ed · January 19

Is this a Navien boiler??

clammy · January 19

A real simple question when was the last time a lic contractor has done a full service on your boiler . Possibly unknown to you but these type of boiler require yearly or bi yearly maintenance which would include combustion testing and checking of both air inlet and exhaust piping,cleaning the heat exchanger .condensate trap check flame sensor and spark ignitor among a slew of other parts which should be checked ,cleaned and re installed .Failure in doing this leads to a shorten of the life span of your equipment and usually a replacement boiler being at some point its cheaper to just replace a non maintained wall hung then changing gas and blower units and control boards . You really need the installer or a reputable contractor familiar w your equipment to check your boiler out and rectify the moisture issue before you have a bigger issue .Just wondering has anyone ever done a combustion test on your unit usually most 1/2 decent tech will leave a print out if not find one who performs combustion testing and has the test equipment if not find a better contractor who does .Final note make sure that your vent and inlet air terminations are within the manufactures recommendation as for distance and location ,improperly installed inlet and out let piping will caus recirculation of the fuel gas which will cause endless issue and shorten the life span of the blower and gas valve aside from possibly electronics which may be exposed to the mildly acidic gases.

peace and good luck clammy

hot_rod · January 19

You certainly don't want moisture getting into the electronics or connections.

rgtoler7 · January 20

https://forum.heatinghelp.com/discussion/comment/1836112#Comment_1836112

HTP

rgtoler7 · January 20

https://forum.heatinghelp.com/discussion/comment/1836055#Comment_1836055

here are the photos of intake and exhaust. They run approximately 5’ from the unit to outside, then approx. another 30’ from outside to the edge of the deck.

rgtoler7 · January 20

https://forum.heatinghelp.com/discussion/comment/1836151#Comment_1836151

Thanks for the very detailed response. As far as a full service, I’m not sure. The previous owner is the one who installed the boiler. He’s a licensed hvac/plumbing contractor. He explained a lot to me when I purchased the home and has come out for a few other things. I’ll ask him when the last time was he serviced it and get him to service it again.

I also sent him the same photos and he mentioned it looked like the intake manifold to the combustion fan is the source and asked about additional humidity in the basement compared to normal. I trust his opinion, but on something like this always want to get more opinions. He’ll be coming to check it out this week.

We did check the spark igniter and change the flame sensor about a year ago.

The biggest thing with the condensate is it’s only when it’s extremely cold. I’ve had different contractors come look, but by the time they get there, the condensation is gone and there’s nothing really for them to see or analyze.

hot_rod · January 20

cut the intake pipe under the deck, put in a 45 to extend it farther away from the exhaust

Download the installation manual for venting clearances. The exhaust may be too close to the building or windows ?

pecmsg · January 20

https://forum.heatinghelp.com/discussion/comment/1836477#Comment_1836477

Theres no reason to run the intake that far. Id cut it at the foundation.

rgtoler7 · January 20

https://forum.heatinghelp.com/discussion/comment/1836477#Comment_1836477

when you say too close, do you mean in length extended from the boiler itself? It’s pretty far away, I don’t know how to extend it any further.

pecmsg · January 20

https://forum.heatinghelp.com/discussion/comment/1836591#Comment_1836591

to close together!

yellowdog · January 21

What modcon allows for 30' of an exterior exhaust run?

PeteA · January 21

The old porcelain insulators are pretty cool. Was the last owner a plumber or an electrician?

PeteA · January 21

since it looks like all of that moisture is directly under the intake and your run is sooo long under the deck, I wonder if there is a slight belly in the pipe and its accumulating water that occasionally gets to be enough that it starts to flow back towards the boiler and drip/leak all over it. Like someone else said, it may be possible to just cut the intake portion much shorter under the deck closer towards the foundation wall.

kcopp · January 22

https://forum.heatinghelp.com/discussion/comment/1836472#Comment_1836472

As I thought… the intake is sucking in exhaust.

Separate the terminals. You could try to shorten the intake but I would still think that the exhaust could drift under the deck. Safest thing is to periscope up the exhaust 12" AND shorten the intake...

GroundUp · January 22

It's recirculating flue gas to the intake which is causing a good portion of this condensation you're seeing. I'd cut the intake (the one with the elbow on it) back as far as you can comfortably reach and reinstall the elbow pointing down. Those UFT boilers often benefit from having a small hole drilled in the bottom of the rubber intake boot inside the boiler, for any accumulated condensate to drain out.

Boiler condensation

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