Natural Draft HWH Boiler...situation....

[daytona]

I was asked a personal question by a person at a facility where we were doing some repairs to the RTU's. he wanted to know if it was good or bad for a chimney to sweat water (moisture). I mentioned that is not good and what is the situation. Well, in June of 09 the area had major rains and flooding. And in the mishap his basement was flooded, so the Insurance company paid to have the antiqued boiler replace. Thus the problem started. A 105,000 BTU boiler with a 36,000 HT into a masonry chimney (1 side to the ambient) and about 12 ft expose above the roof line. Went and looked at it. TODAY was a 25 degree day and snowing like crazy. The chimney was sweating severely at the top and 3 large wet spots on the side of the house. The boiler has a motorized vent damper and 5" single wall flue pipe in the the same chase with the HWT with the HWT with a 3" single wall flue pipe. Both are going in separate holes in the same chase.
Now before I give my experienced comment I want to see if any of the others have any input before.
Thanks
JB
PS...this is located in SW PA

[BaldLoonie]

With the damper not allowing house air to keep the chimney warm during the off cycle, the cold tile is causing the condensation.

OR

Could be a blockage at the top too. Had that happen a couple times.

[bigtime]

The chimney is so cold that it is lowering the temp of the flue gas to the dew point and its condensing. The old boiler was less efficient and had hotter flue temps. This is something that needs to be corrected. Over time it will destroy the chimney.

[beenthere]

Too big of a chimney. They should have lined it with the correct size liner for that total BTU.

[daytona]

Correct!!
From experience I found this out years ago. So, that is what I told the gentleman that requested me to look at it. The company that installed the boiler insists that it is installed properly and stands by it.
What I did do for him in the mean time is set the vent damper to stay open all the time to assist more heated air into the chimney. I KNOW AND REALIZE that a liner is necessary here. But I told the gentleman to insist on the installer to install one and at the price that would have been priced at the time of the installation

[tim fox]

A lot of municipallities here require a liner every time you replace equipment vented into a masonary chimney.

[Chris_Worthington]

Not an option here, gots to be the right size "if" that means liner, then that whats the inspector wants to see,,,, residential or commercial.

[daytona]

UPDATE....I just got an email from the customer (not mine) that the company owner called and emailed them. (don't have the guts to go in person) And told them that he drove by and took pictures. And he feels that it is the flashing and the area around the chimney is leaking. So, the customer had a reputable chimney/masonry company come and look at it. They said it need a direct vent kit on the boiler and that a liner will rot away in 3 - 5 years.
I emailed back that the chimney company should have suggested a stainless liner or at least an aluminum liner. And the direct vent is fine and they work great, but he still would need a liner for the hot water tank. And that he (the customer) should pull his head out of his butt, take pictures and sue the SOB from the low life HVAC company. But in the mean time get the damn thing fixed and stop the chimney from deteriorating.
This has me pissed more than the customer...........

[steveholt]

This is potentially a life threatening situation. Not only is condensate collecting in the chimney but it’s also likely collecting in the vent connector and boiler itself. The condensate is acidic and over time it will oxidize metal. Vent connectors will fall apart and boiler combustion passes will become blocked. This can cause combustion issues in the boilers resulting in the production of carbon monoxide. This will be compounded by a deteriorating chimney.

A chimney liner is a must and I would suggest a by-pass on the boiler loop to increase the boiler water temperature. This will stop the non condensing boiler from condensing. This will help protect the boiler, vent connector and the chimney liner.

Good luck.

[mikeplumbs]

The G.M. on the job I'm at is certain that the sidewall condensing boiler flue gas is causing an ice damn 30 feet above on a vented eve. 8 feet across from the termination is a 20 foot wall and to the right is another wall 30 feet high. The rest of area open to fresh air. I would think any moisture would be gone within a 10 foot radius. There are also windows above that don't have any condensation on them. Any pro opinions PLEASE?