Gas furnace and water heater flues

[phatdonkey]

I just replaced my gas water heater last week.

When i went to hook the new one to the chimney i needed to adjust the length of the pipe from the wall to the WH. I was able to slide the pipe from the wall out all the way. To my surprise, when the pipe came out of the wall i see it just dead ended into the terra cotta stack, like a smoke dragon setup. I also saw the furnace does the same. Is this a concern? It was really clean in there, no soot to be seen. Just curious if i should run kiners up there or not. Not sure of the size of the square tile flue. Ill get up on the roof this week and see.

Any info on a plan would be great.

The attached photo shows where the 2 exhaust pipes penetrate the wall and into the open terra cotta flue. 4 inch pipe for the furnace and 3 inch for the WH. No issues the last 3 years. Just curious if i should do this "right".

 

[blades]

No you do not need a liner, but if that flue is older and you are switching from standing pilots to on demand, be aware that the lack of that small pilot heat now leaves you with a cold flue so installing a liner is beneficial prior to it deteriorating. what happens in the shoulder seasons and somewhat in the summer months is condensation forms in the flue ( those old standing pilot lights kept this at bay). That mixes with the little bit of combustion byproducts producing an acid that leaches out the terracotta joints- At that point it is line or rebuild and line. This has become a very common problem ( seldom talked about) in the northern climes of the US. Now the latest furnaces and water heater having an exhaust that can be sent down a plastic pipe gives you the option of running the plastic pipe up the flue one for each appliance just need to cap it off seal it where they exit. I see this conversion quite a bit in my area. depending on the set up and other factors these units can also be vented out the sidewall but sometimes that is not a good option. My furnace intake for combustion air and exhaust is out/in the side wall via pvc. My hot water heater is vented out the side wall but it is a conventional burn system below the tank ( No standing pilot). I did have to add a backflow damper the HW exhaust. As it did not come with one and the exhaust pipe is also pvc.

 

[phatdonkey]

Thanks for the reply. The new water heater is like the older one. Standing pilot. There is always a draft. In time I may just line it and add a combiner at the bottom and pipe them both into the same line. Thanks for the quick response.