Hi-efficiency water heater & furnace

[jeff48356]

Are we allowed to wire the outlet for the high-efficiency gas water heater to the same circuit that powers the 120V gas furnace blower motor? If I'm not mistaken, the Code allows only HVAC-related loads on that circuit (condensate pump, humidifier, air cleaner, etc.). I would interpret it as that the water heater is an HVAC appliance (after all, HVAC contractors are licensed to install them), and they are usually placed near the furnace, like in the mechanical room.

 

[ActionDave]

Are we allowed to wire the outlet for the high-efficiency gas water heater to the same circuit that powers the 120V gas furnace blower motor?

No you can't.

If I'm not mistaken, the Code allows only HVAC-related loads on that circuit (condensate pump, humidifier, air cleaner, etc.).

Yes it does. Those are directly related to the function of the furnace.

I would interpret it as that the water heater is an HVAC appliance (after all, HVAC contractors are licensed to install them), and they are usually placed near the furnace, like in the mechanical room.

Big leap in logic there. Gonna need a jet pac and a parachute to get there and make a safe landing.

 

[iwire]

Are we allowed to wire the outlet for the high-efficiency gas water heater to the same circuit that powers the 120V gas furnace blower motor?

Assuming the gas furnace is central heating equipment (And I can't imagine it is not) In my opinion no.

422.12 Central Heating Equipment. Central heating
equipment other than fixed electric space-heating equipment
shall be supplied by an individual branch circuit.

Exception No. 1: Auxiliary equipment, such as a pump,
valve, humidifier, or electrostatic air cleaner directly associated
with the heating equipment, shall be permitted to be
connected to the same branch circuit.

Exception No. 2: Permanently connected air-conditioning
equipment shall be permitted to be connected to the same
branch circuit.

No you can't.

I agree.

Yes it does. Those are directly related to the function of the furnace.

That and a little more.

I would interpret it as that the water heater is an HVAC appliance

Big leap in logic there. Gonna need a jet pac and a parachute to get there and make a safe landing.

I don't see it that way, certainly a water heater is heating equipment. I have not seen anything that leads me to believe that the "H" in "HVAC" is limited to space heating. However even if a water heater is HVAC equipment I don't see 422.12 allowing it to be connected to the central heating equipment.

 

[Dennis Alwon]

I agree with the post above. I also am wondering why a gas water heater needs an outlet. Is this for venting of the gas? I still don't see this as fitting the bill. Is it that hard to get a wire to the water heater. I am sure the load is insignificant

 

[iwire]

I think a lot of the new gas fired hi efficiency units come with a cord so plumbers don't need us when replacing theses units.

I am picturing something like this.

Or this

 

[Dennis Alwon]

I know the first pic units need power but I didn't think that was what the op meant- I would call that an on demand. I have never seen the other style with a cord and plug.

 

[GoldDigger]

I know the first pic units need power but I didn't think that was what the op meant- I would call that an on demand. I have never seen the other style with a cord and plug.

The high efficiency burner and heat exchanger produce such a low flue temperature that a fan is needed for forced draft.
I can see them being hard wired too, but the drain for the fan and controls is pretty low. They do not need a dedicated circuit, but the heater still cannot share.

 

[Allen Smith]

Hi-efficiency water heater & furnace

You can assume a high efficiency gas water heater to the same circuit that powers the 120V gas furnace blower motor only if it will be directly connected to the function of furnace.You can consult with professional HVAC contractor, he can give you detailed information about furnace working.