How many gas appliances in one chimney?

[barlyhop]

This is extremely rare for me to see. I have an inside masonry block chimney with clay liner. Venting into this one chimney is (1) 2002 high efficiency furnace @50,000 BTU. (2) 2008 gas 40 gal water heater. (3) 1973 gas wall mounted space heater.

The furnace enters the chimney below the others. The space heater and water heater enter very close to the same height as each other but on different planes.

The furnace vents into the chimney because the homeowner built a planter against the exterior wall where the discharge really should have been. (best guess)

The chimney cap was leaking and the top piece of tile liner was deteriorating.

Is there any code forbidding this set-up? I read about the rule of: size of largest vent plus 50% of all others not to exceed flue diameter.

In total we had (3) 4 inch vents going into an 8" square chimney.

I also suggested that they remove the space heater in the basement recroom and check flue liner requirements in their municipality.

Any suggestions on this one??

[Brandon Whitmore]

That's a goofy set up. I don't believe that Cat1 and CatIV systems can vent into the same flue, but don't have a code cite. I'd have to look this up if I ran into it.

[Garet]

Cat IV (high efficiency, plastic vent) operate under positive pressure and Cat I (mid efficiency, metal vent) operate under negative pressure. They're not compatible. If that's what you saw it was installed by a bozo.

[Stephen D. Gazo]

I see Bozo has moved to the left coast.

Cat IV (high efficiency, plastic vent) operate under positive pressure and Cat I (mid efficiency, metal vent) operate under negative pressure. They're not compatible. If that's what you saw it was installed by a bozo.