Thread: Good or Not Good

Came across this fireplace today. I don't see how this was allowed. Maybe I am wrong but doesn't this flue seem inadequate for a gas fireplace? Seems like a carbon monoxide hazard. Your comments, please.

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I guess the "installer" expected the combustion gases and heat to magically gravitate right toward that tiny little flue pipe opening at the top of the firebox which appears completely flat in the pic.

Not good.

Pretty common with older homes. Most of the ones I have seen had a gas space heater in them or ventless type logs.

I just tell my clients that they should not use them or have a fireplace specialist install listed ventelss gas logs, or put a nice plant in the fireplace.

Originally Posted by Scott Patterson

I just tell my clients that they should not use them or have a fireplace specialist install listed ventelss gas logs, or put a nice plant in the fireplace.

Scott, here in MN, our building code specifically prohibits ventless gas heaters, logs, fireplaces, etc. So when you say ventless, you're really talking about an appliance that actually vents into household air, correct? Thanks

Exactly my thinking, thanks for the fast response.

Originally Posted by Fred Comb

Scott, here in MN, our building code specifically prohibits ventless gas heaters, logs, fireplaces, etc. So when you say ventless, you're really talking about an appliance that actually vents into household air, correct? Thanks

Yep, they have been around for years. Old fashioned gas space heaters. Building codes are only for that new construction and don't cover Aunt Molly's 1945 home with little space heaters in it....

I think the newer units are called infrared heaters.

The ventless logs are very common in many parts of the country, glad to see your state does not allow them.

Originally Posted by Fred Comb

Scott, here in MN, our building code specifically prohibits ventless gas heaters, logs, fireplaces, etc.

"our building code specifically prohibits ventless gas"

Are you sure? Or does your code prohibit 'unvented' gas heaters.

There is a difference.

The old 'unvented' gas heaters caused many to die, however, the new "ventless" gas heaters have a metal tag warning you to open a window or door while operating the ventless gas heater ... are you will die - and the new ones also have oxygen depletion sensors to warn you when you are about to die, thus the new "ventless" gas heaters are allowed.

Actually, in the hearth industry, the terms ventfree, ventless, unvented and lung vented are used interchangeably. They all refer to a gas appliance listed to ANSI Z21.11.2, which is an "unvented room heater".

FYI, the ODS pilot is simply a finely tuned safety pilot that drops out when the ambient room air drops to about 18.5% by volume. The flame speed slows down to the point the flame is off the thermocouple causing dropout. There is no electronic sensor, alarm or gizmo to alert the occupants. There is no CO sensor interlocked either. You can have 20.9% room air and still make tons of CO.

This Fp is a train wreck. Fill with flowers and seal up the hole. Might consider electric logset. Could seal front with Plexiglas, fill with water and stock with fish. FYI, fireplaces must be sized per the code as open hearth Fps even if you burn gas logs.

The old freestanding VF gas room heaters with the ceramic grid that glowed are not listed to Z21.11.2 and do not have ODS pilots so they should be removed.

Originally Posted by Bob Harper

... the ODS pilot is simply a finely tuned safety pilot that drops out when the ambient room air drops to about 18.5% by volume.

If the room air drops to 18.5% by volume, is that a partial vacuum?

Hey, it was late: correction- room oxygen level. For me and you, it would be the FiO2 or fraction of inspired oxygen.

Here is the Minnesota rule on ventfree gas heaters:

MINNESOTARULES, CHAPTER 1346
MINNESOTAMECHANICAL AND FUEL GAS CODES

Chapters 2 to 15 of the 2006 edition of the
International Mechanical Code, promulgated
by the International Code Council, Inc., 500
New Jersey Avenue NW, 6th Floor,
Washington, DC 20001-2070, are
incorporated by reference as part of the
Minnesota Mechanical Code as amended in
this chapter.

1346.0901 SECTION 901 GENERAL.
IMC Section 901 is amended by adding a
section to read as follows:
901.5
Unvented room heaters, unvented infrared
heaters, and unvented decorative appliances
shall not be installed in any dwelling or
occupancy.
Exception: Unvented infrared heaters
may be installed when mechanical
ventilation is provided to exhaust at
least 4 cubic feet per minute (cfm)
(0.0203 m3/s) per 1000 Btu/hr (0.292
kW) input and it is electrically
interlocked with the heater. Makeup
air shall be provided to the space to be
heated.

Also interesting is a map and text from the VentFree gas heaters trade assoc. at this link.

http://www.ventless-gas-fireplaces.com/ventless_products_code_information.html

Their statements about town size and the applicability of the rule have not been verified. I have always been taught that these devices are not legal to install in MN. (See ventilation exception for infrared heaters in the rule).

Originally Posted by Roger Hankey

Also interesting is a map and text from the VentFree gas heaters trade assoc. at this link.

http://www.ventless-gas-fireplaces.com/ventless_products_code_information.html

Not sure about all the others (but they are now suspect), but ... the code reference for Florida is both out-of-date AND incorrect (even back for its date).

The pics below are of the water heater flue going up thru the chimnehy. The picture of a vent pipe going from the left to the right upwards is actually the vent for the range hood angling down to the chimney actually above where the water heater flue comes into the chimney. I also love the chimney cap arrangement.