Thread: Light switch on gas furnace !

Hi everyone,

Is it normal to have a light switch to shut off a natural gas furnace ? Shouldn't there be a breaker instead ?

Is the air intake exhaust ok, it looks like a poor installation to me but I'm not too familiar with gas furnaces. The flue exhaust is on the opposite side of the house and looks ok.

Thank you for your help

Originally Posted by Christian Tag

Hi everyone,

Is it normal to have a light switch to shut off a natural gas furnace ? Shouldn't there be a breaker instead ?

Is the air intake exhaust ok, it looks like a poor installation to me but I'm not too familiar with gas furnaces. The flue exhaust is on the opposite side of the house and looks ok.

Thank you for your help

Having a switch is what I always see, it's fine.
As for the intake/exhaust, I cannot say.

Originally Posted by Christian Tag

Hi everyone,

Is it normal to have a light switch to shut off a natural gas furnace ? Shouldn't there be a breaker instead ?

Is the air intake exhaust ok, it looks like a poor installation to me but I'm not too familiar with gas furnaces. The flue exhaust is on the opposite side of the house and looks ok.

Thank you for your help

The short piece of plastic vent pipe pictured, appears to slope away from the furnace. If it does then that part is wrong. Water should run back to the furnace, not drip from the end of the pipe.

Light switch is fine for shut off. There should be a breaker controlling this circuit.

Ideally the furnace service switch should be on the furnace or higher up on the wall so as not to be mistaken for a light switch or prone to accidentally being shut off by something hitting it. Rocker switches are easily switched. Not much resistance. I like the toggle type switch that use to be the norm before decorator type switches came out.

It ought to have "furnace" written on it and it should have "on" or "off" written on it, but the switch itself is not a defect.

Exhaust normally should slope back to the furnace. Not so for the intake of a high efficiency furnace, AFAIK. I don't see a defect.

No problem with either of them.

Something looks funny in the photos to me.

Are we looking at the exhaust pipe in one photo and the intake in the other? Looks like it is going from 1-1/2 inch pipe to 3 inch, and then to 1-1/2" out the wall. Hard to tell if that is 2-1/4 inch tall brick, if it is that puts the pipe around 1-1/2". Either way they increased the pipe size (due to the run, or # of elbows???) and should not be reducing it again, unless there are two sets of pipes??? But, then, the intake and exhaust are usually the same size pipe.

The switch is fine, but the furnace should be on its own breaker in the panel.

Ontario Electrical Code - Canadian Electrical Code

Loomex supply cable should run in 7/16" flexible conduit for the last few feet near furnace where it is less than 59" (1.5 metre) above the floor or where it is subject to mechanical damage.

Further from the Canadian Electrical Code -
16. Rule 26-806 of the Code is amended
(a) by the revocation of Subrule (5) and the substitution of the
following:
(5) Oil or gas fired heating equipment
(a) that is located in a furnace or boiler room, shall have the
disconnecting means located on the outside wall of the room,
adjacent to the door; and
(b) that is not located in a furnace or boiler room, shall have the
disconnecting means located near the entrance to the area in which
the heating unit is located.

There is not requirement that I know of that the switch has to be labeled "furnace". Its really just a service disconnect.
Most I see are mounted on the side of the unit, or close by on the wall.

Originally Posted by Jack Feldmann

There is not requirement that I know of that the switch has to be labeled "furnace". Its really just a service disconnect.
Most I see are mounted on the side of the unit, or close by on the wall.

OP and Respondent are Canadian.
*could be?

I believe I have seen somewhere in the codes there is a requirement that a furnace cut off switch has to be located such that a person does not have to stand or cross in front of the furnace to turn it off. Is this correct? Makes sense to me.

Stuart you are correct. It does mention that fact in the Cdn code.

Thanks for the reminder.

Originally Posted by Raymond Wand

Stuart you are correct. It does mention that fact in the Cdn code.

Thanks for the reminder.

I'm thinking it is in the IBC set somewhere or the NEC because I don't know anything about Canadian codes.

Originally Posted by Jack Feldmann

There is not requirement that I know of that the switch has to be labeled "furnace". Its really just a service disconnect.
Most I see are mounted on the side of the unit, or close by on the wall.

That's why I said "ought to be", not "required"
Looking at the pic, it might just as easy be a light switch. I don't see a feed to the furnace from that switch.

Originally Posted by Christian Tag

Is the air intake exhaust ok, it looks like a poor installation to me but I'm not too familiar with gas furnaces. The flue exhaust is on the opposite side of the house and looks ok.

I am a little confused. As I understand from what you have said, it is a high-efficiency gas fired furnace with the combustion air intake on one side of the house and the exhaust on the other.

If this is so, it may not be in accordance with the manufacturer's installation instructions. They usually require the intake and exhaust, if exiting the house, to be within three to four feet of each other (with other location stipulations). This is to prevent localized atmospheric conditions affecting combustion.

As for the pipes in the pictures. Many contractors up the size of the pipe so that they don't need to do any calculations regarding the length and number of direction changes, to remain within installation requirements.

As previously pointed out, moisture from the exhaust should return to the furnace, and screens should be installed to prevent things from finding a new home.

My last comment is location. As you are up North, are the pipes above the normal snow drift height+ for the area?