Condensate just started coming down the exhaust stack

[phil178821]

I have a Weil Mclain WTGO-4 boiler that has a tankless coil for DHW and provides houes heat. Run temps are 160/175 for Lo/High. In 2017, previous owners converted the boiler to natural gas. Since I bought the house in 2018, I had some relays updated but have not had any issues with the system.

This summer, I noticed condensate splash marks on top of the boiler (exhaust vents up the top). It clear that it drips from an elbow in the exaust vent maybe 4 feet up. I have never had this happen before; it just started some time this summer.

Boiler temps and pressures are normal and everything appears fine. Obviously burn times are short since its just maintaining 160F in the summer for DHW, but I dont think thats it since this hasn't happened in the previous two summers.

Only two things I can think of that are different this summer than previous years:

1) I had my roof redone in June. The exhaust stack wasn't changed but they did shingle and seal around it. I don't see how this could do anything but maybe it needs a close look because they somehow impeded air flow?

2) the garbage pales could maybe have been within a couple of inches of the fresh air in vent. The boiler is in a small utility closest (maybe 3x8ft). There is one (maybe two, will have to double check) grate (maybe 4x10") that lets fresh air in. If flow in is impeded, could that cause burn issues and lead to condensation?

My annual PM is next week, so I would appreciate any ideas or things I should discuss with my tech then

[pecmsg]

What size chimney liner is in there?

[phil178821]

Not sure of the diameter of the top of my head. Maybe 6 or 8”? It will be easy since it’s an exposed, solo stack. I can check on Sunday when I get home.

I can also upload a photo once I’m back at my computer. Thanks, P

[phil178821]

The main stack appears to be 7 or 8" in diameter. You can see in the photos the condensation starts where the stack of the boiler connects to the "chimney stack" that breaks through the roof. The whole thing is exposed metal chimney (inside and outside). No brick or stone.

[Juan Madera]

Have tech check the draft and draft damper. Might not be getting enough dilution air, therefore condensation. Also see if the B-vent is intact on the roof. Cool air circulation into the inner liner could be an issue as well.

[Juan Madera]

......and turn off the make up water, then check next day to see if the system pressure drops. If so, possible pinhole leak in the HX that is too small to give you a puddle on the floor but adds enough moisture to the exhaust that it is condensing.

[phil178821]

......and turn off the make up water, then check next day to see if the system pressure drops. If so, possible pinhole leak in the HX that is too small to give you a puddle on the floor but adds enough moisture to the exhaust that it is condensing.

Thanks, a lot Juan. I am curious if the roofers did something to the "B Vent" when I just had my roof redone in June (about the same time this started up).

Someone on another forum mentioned the stack might be too large (it was designed for oil but should be reduced for gas) and that the damper isn't necessary for gas. Would this make sense? I bring this up with my technician as well.

Thanks again.

[Juan Madera]

Damper IS required for gas. If this was a gas appliance from birth, it would have had a draft diverter for dilution air. Damper is superior to draft diverter providing it is operating properly.

[phil178821]

Damper IS required for gas. If this was a gas appliance from birth, it would have had a draft diverter for dilution air. Damper is superior to draft diverter providing it is operating properly.

Would it make sense that the air surrounding the boiler (given its a smallish closet) is too warm, so draft up the chimney is insufficient? Or insufficient make-up air flow into the room through the small vent that goes to the outside?

Maybe I should see if the tech thinks I should install a fan to bring more air into the room during burns?

[Poodle Head Mikey]

New roof, eh?

Does the new leak coincide with a rainstorm or with the boiler's ON cycle?

PHM
--------

I have a Weil Mclain WTGO-4 boiler that has a tankless coil for DHW and provides houes heat. Run temps are 160/175 for Lo/High. In 2017, previous owners converted the boiler to natural gas. Since I bought the house in 2018, I had some relays updated but have not had any issues with the system.

This summer, I noticed condensate splash marks on top of the boiler (exhaust vents up the top). It clear that it drips from an elbow in the exaust vent maybe 4 feet up. I have never had this happen before; it just started some time this summer.

Boiler temps and pressures are normal and everything appears fine. Obviously burn times are short since its just maintaining 160F in the summer for DHW, but I dont think thats it since this hasn't happened in the previous two summers.

Only two things I can think of that are different this summer than previous years:

1) I had my roof redone in June. The exhaust stack wasn't changed but they did shingle and seal around it. I don't see how this could do anything but maybe it needs a close look because they somehow impeded air flow?

2) the garbage pales could maybe have been within a couple of inches of the fresh air in vent. The boiler is in a small utility closest (maybe 3x8ft). There is one (maybe two, will have to double check) grate (maybe 4x10") that lets fresh air in. If flow in is impeded, could that cause burn issues and lead to condensation?

My annual PM is next week, so I would appreciate any ideas or things I should discuss with my tech then

[phil178821]

Is what I mentioned in my last post the "Dilution Air" you mentioned above, Juan?

Also, what are the wires on the damper? They go to the burner controller. I am guessing a sensor/kill switch if draft is off?

Thanks for the all the feedback and info. I will report back after I meet with the tech on Friday.

[phil178821]

New roof, eh?

Does the new leak coincide with a rainstorm or with the boiler's ON cycle?

PHM
--------

hmm. thats really hard to say. Since the roof was done in June, we have had more intense rainstorms (on the CT shoreline) than I ever recall. I have never actually seen it "wet" but i thought it looked like it had spread at one point, making me think it was the boiler (but then again.. we've had so many storms). I guess it would have been smart to clean it up and see if it returns +/- rainy conditions...

[Juan Madera]

Device on damper is most likely a "spill" switch. Kills burner if senses hot gas spilling out.

Is what I mentioned in my last post the "Dilution Air" you mentioned above, Juan?

Also, what are the wires on the damper? They go to the burner controller. I am guessing a sensor/kill switch if draft is off?

Thanks for the all the feedback and info. I will report back after I meet with the tech on Friday.

[phil178821]

The technician came on Friday. He checked draft and smoke. He said the draft was perfect and their was no smoke. He looked at the flame and said it looks good. Also, he felt the inside of the chimney through the damper and said it feels clean.

He said the condensate looks more like a one time event and that the boiler is running well.

Now that was the extent of what he did for my "annual maintenance". I thought he would open the boiler up and inspect and clean if necessary. He said no, there is no need to do that on a gas boiler. I feel a little shorted here; was that really all he was supposed to do?

Thanks.

[pecmsg]

The technician came on Friday. He checked draft and smoke. He said the draft was perfect and their was no smoke. He looked at the flame and said it looks good. Also, he felt the inside of the chimney through the damper and said it feels clean.

He said the condensate looks more like a one time event and that the boiler is running well.

Now that was the extent of what he did for my "annual maintenance". I thought he would open the boiler up and inspect and clean if necessary. He said no, there is no need to do that on a gas boiler. I feel a little shorted here; was that really all he was supposed to do?

Thanks.

Impossible to "Look at the flame and say it Looks Good" A combustion analyses needs to be done! Get a different tech or contractor!

[samgevas]

Impossible to "Look at the flame and say it Looks Good" A combustion analyses needs to be done! Get a different tech or contractor!

This.

There are few things more irritating than a boiler that should have gone another decade, but died for lack of a tiny combustion adjustment. A CA and a tech that really knows how to use it are your best friend.

[phil178821]

Impossible to "Look at the flame and say it Looks Good" A combustion analyses needs to be done! Get a different tech or contractor!

Yeah, that's what I figured. I was never crazy with this company. A couple of years back I starting searching for someone else but a lot of the companies didn't want to work with my boiler since it was converted to gas. Many were oil only.

[pecmsg]

Yeah, that's what I figured. I was never crazy with this company. A couple of years back I starting searching for someone else but a lot of the companies didn't want to work with my boiler since it was converted to gas. Many were oil only.

Converted to gas and no CA performed?

Sad really sad!

[phil178821]

My roofer just stopped by to check out the seal at the base of the chimney. He said everything looked good on their end but he did notice the top section of the chimney felt a little loose. He said it looks like its maybe the joint where two sections of chimney come together. Maybe in one of the intense rain storms, the slightly loose fit at a junction of pieces let some water in? Or is the slightly loose fit intentional/by design? As he described it "they dont just lift apart, but it feels like you could easily work them apart with some effort".

Should it be sealed? Is this something I can easily seal myself? If not, would a normal boiler tech do this or is there a chimney person I need to call?

Thanks

[phil178821]

Converted to gas and no CA performed?

Sad really sad!

The conversion was done in Jan/Feb of 2018. I bought the house in Oct 2018. I assume (probably wrongfully) that CA was done at the install. I did have the gas company do CA and everything looked good in Feb of 2019.