Chimney condensation

[Allen257]

Originally Posted by Terroreyes

Thanks for the input. To clarify, I have a relatively old furnace (15 years). It's definitely not a high efficiency. The chimney isn't lined with metal, but does have a clay liner. Also, one other thing I did was to install a new water heater that vents into the same area. Jim, I don't know why the recess is there. I have a natural gas furnace, but the house was built in 1929, so who know the history of how it was heated along the way. It does have a coal chute.

As soon as the snow melts this weekend, I'm going to pull that cap off and see what happens.

what happened when you removed the cap? I have the same issue. I replaced my water heater with an energy star and a new cap on the chimney and in the winter now I get condensation water coming out the clean out door in the basement. My chimney is not lined either. Not sure if I should use a cap that is more or less restrictive or get a liner. My furnace is old and inefficient too. Let me know.

[yarcraft91]

Originally Posted by KHedquist

I believe here in MN the bldg codes say you cant vent a natural or propane furnace into chimney that doesn't have a metal liner

In Michigan, I believe a clay liner meets code for a non-condensing furnace venting application- at least, that passed inspection on a house I built in 1979.

Terroreyes- I'm sure you know whether your furnace is high-efficiency or not, but at 15 years it's definitely not too old to be one. I had a 93% furnace installed in 1989.

[Justfishing]

What all is being vented into the chimney. With an ash clean out is there a fireplace?

The problem you have is the brick is cold enough to condense the vapor. Old homes were so inefficient that that chimneys would stay warm all the time because the furnace or boiler ran so much. As these same homes have been insulated and more efficient furnaces installed the chimney now cools off between runs and you can get condensation.

My guess in this case is the water heater vents a much lower volume that it cant warm the chimney and you get condensation. You also have a great risk of carbon monoxide in the house. Since the brick is getting wet it is now colder and harder for the furnace to warn the chimney Now furnace exhaust is also condensing.

I don't think the cap is the main culprit as many homes have a cap and don't have condensation problems.

What is needed is liners for the wh and furnace.

[Juls]

Quote:
Originally Posted by Terroreyes https://www.walleyecentral.com/forums...s/viewpost.gif
Thanks for the input. To clarify, I have a relatively old furnace (15 years). It's definitely not a high efficiency. The chimney isn't lined with metal, but does have a clay liner. Also, one other thing I did was to install a new water heater that vents into the same area. Jim, I don't know why the recess is there. I have a natural gas furnace, but the house was built in 1929, so who know the history of how it was heated along the way. It does have a coal chute.

As soon as the snow melts this weekend, I'm going to pull that cap off and see what happens.

Originally Posted by Allen257

what happened when you removed the cap? I have the same issue. I replaced my water heater with an energy star and a new cap on the chimney and in the winter now I get condensation water coming out the clean out door in the basement. My chimney is not lined either. Not sure if I should use a cap that is more or less restrictive or get a liner. My furnace is old and inefficient too. Let me know.

Unfortunately, Terroreyes is a banned user and will not be able to respond to your post here. Sorry.

Juls

[rbsangler]

Install a metal flue pipe inside the chimney and connect all your gas appliances to it....done.

[eye4aneye]

Originally Posted by Old Bricker

If you are running a newer, more efficient furnace into an old unlined masonry chimney it will be a problem sooner or later. Usually this shows up sooner than eight years.The stack temp is too low to evaporate the moisture inside. If removing the cap don't help you should have a metal liner installed or eventually the whole outside of the masonry will turn to snot. That is why water heaters vented in an old masonry chimney is not recomended. It will do this even in a clay lined chimney but it takes a few more years. I've relined many with stainless steel liners and it has worked every time. Cheap to do but expensive and messy if you wait till the chimney is too far gone because the plaster or drywall or anything touching the masonry on the floors above will soak this snot up and will stink forever. Smells like coal smoke.

Good advice here.