Gas range with ductless ventilation

[MOB]

I recently came across a Kitchen with a gas range that had a ductless ventilation system. This cannot be correct? Is there any documentation stating this is wrong so I can have something to back myself up? Or am I incorrect and it is OK to have a ventless system over a gas combustible range?

[charlieb]

Is there an operable window in the room?

[Garet]

M1503.1 General.

Range hoods shall discharge to the outdoors through a single-wall duct. The duct serving the hood shall have a smooth interior surface, shall be air tight and shall be equipped with a backdraft damper. Ducts serving range hoods shall not terminate in an attic or crawl space or areas inside the building.

Exception: Where installed in accordance with the manufacturer’s installation instructions, and where mechanical or natural ventilation is otherwise provided, listed and labeled ductless range hoods shall not be required to discharge to the outdoors.

[MOB]

Is there an operable window in the room?

Yes, there was an operable window in the room. But I guess I don't understand? If all gas appliances must be vented then why would a gas range be exempt? Does not a gas range put off the same exhaust as a furnace or gas hot water tank?

[hausdok]

I grew up in a home with a gas stove. There was a pilot light on that sucker 24/7/365 and in the winter that house was shut up tight as a gnat's ass with 8 people, 2 dogs and several cats. Nobody ever got sick or even got a headache from that gas stove.

There's a reason that they don't want you to heat a home with a gas stove or oven if the furnace breaks down - If it's cold enough outside that you need to use a stove or oven to keep warm, you'll close all of the windows and doors; and, when you're sleeping, all of the CO2 that those sleeping bodies gives off in a closed and unvented house will change the O2-to-fuel ratio and the stove will produce carbon monoxide. The stove pilot light was too small to do that back then and now they have electronic igniters.

A gas appliance that's operating properly doesn't give off CO, it gives off CO2. When you use a gas stove or oven for what it's designed for - cooking - you aren't likely to poison anyone because during those times when the family is awake and moving around they do things that will ventilate the home and the air stays free of CO. A stove exhaust hood is nice; but, even without it you're not likely to see anyone become ill.

ONE TEAM - ONE FIGHT!!!

Mike

[Jim Katen]

Is there an operable window in the room?

Yes, there was an operable window in the room. But I guess I don't understand? If all gas appliances must be vented

What makes you think that all gas appliances must be vented?

then why would a gas range be exempt?

They're not exempt, venting just isn't required for them.

Does not a gas range put off the same exhaust as a furnace or gas hot water tank?

I don't know. I suspect that it's capable of doing so. But the risk of CO poisoning from a gas range is very low. They're almost always supervised when in use and they're rarely on for more than a few hours each day, if that. A furnace and a water heater come on automatically throughout the day and, if a problem develops with them, it might go unnoticed for weeks or months.

If you got to write the code, how would you require gas ranges to be vented? Would you rely on the user to always turn on the fan? Or would you require the fan to come on automatically whenever the range was lit? If so, how would you justify the expense, given that there seems to be no probem with the millions of unvented ranges out there so far?

Another consideration: why aren't self-cleaning electric ranges required to be vented? They can spew vast quantities of CO -- in the thousands of ppm in some cases -- certainly enough to kill pet birds.

- Jim Katen, Oregon