Response to 'Article'

[Darren Miller]

In the 'Articles from Inspection Community', Brian posted "Common venting of gas appliances". I tried to post a reply there, but it wouldn't let me, so I'll do it here.

In the article, it stated the following-
Category III Appliances in residential use are mostly tank-less water heaters that are vented through the wall with stainless steel. These appliances operate with positive vent pressure and, therefore, cannot be adjoined to a gravity-vented water heater.

I believe the word 'mostly' needs to be understood better.
Here in NJ, while not frequently, I do on occasion see Cat III boilers and furnaces. I think it is important that the inspector read the appliance spec plate before reviewing the appliance. Here's photos of what I found in a house I inspected in August.

[neal lewis]

I see those Weil McClain boilers too, and sometimes they're vented with regular single wall rather than the sealed stainless Z vent.

Are there any newer Cat III Furnaces around? I've seen some older models.

[Darren Miller]

As usual, you are correct Neal.

The furnaces I've seen are older types; it seems all the new direct vents furnaces are 90%. However, the boilers are almost all newer; I believe the one in the photo was 2 years old.