Wiring in NuTone 9420CN Twin Bulb Bathroom Heater

[George7941]

Similar to this one https://www.broan-nutone.com/en-us/product/ventilationfans/9422p
House was built in 1987, so that makes it 37 years old.

The pic shows the wirng diagram label on the inside of the heater housing. The heater specifies two 250W IR BR40 lamps. There is a small fan inside the housing blowing warm air downwards on to the user. There is no ventilation fan or light. The wirng diagram does not show the small fan, which is odd.

I am not sure if I am deciphering the wirng diagram correctly. The two rectangles in the bottom third of the diagram are the two (Decora) switches? The middle third is the house wiring inside the walls. The top third is inside the fan?

That would make for two switches controlling the lamps. The right one turns on one bulb and then the left one turns on the second bulb for additional heat.

 

[mk378]

Energizing the black wire would turn on one of the bulbs and the fan. Energizing the red wire turns on the other bulb. The switches are wired that way so that it is not possible to turn on the second bulb by itself without the fan.

The diagram does not show anything that happens inside the box. But the fan would simply be wired in parallel with the first bulb, as a circuit between the black wire and the white wire.

 

[Rogueman2016s]

That’s the wiring diagram, for which you’re looking to wire… what are you trying to achieve? Sounds like the fan blows anytime one lamp is powered and when more heat is desired you turn the 2nd switch on. Should be a power feed either a 12 or 14/2 cable in the switch box with a 12 or 14/3 cable as switch legs going up to the unit. Can’t say how it’s wired up in your house.

 

[George7941]

I was just making sure I was reading the diagram correctly.
There is only one switch controlling this heater as it is wired in the house, it turns on both lamps and the fan.

 

[Rogueman2016s]

yes the initial installer did not run a 2nd switch leg up to the heater.

 

[mk378]

Yes that is a legitimate way to install. It is simply going to run all or nothing then.

 

[George7941]

When I first read the diagram after taking the grill off the unit, I went Whaat? I took the two rectangles in the diagram as depicting the two bulbs in the heater and the second bulb was going to be in series with the first. And why did I interpret it that way? Because diagrams inside a unit, be it a furnace or a dishwasher, typically show the wiring inside the unit. External wiring instructions are usually in an accompanying instruction manual.

 

[Donald]

Do you stand under the unit when drying off after a shower? Would you install one of it did not come with the house?

 

[George7941]

The bulb heater is not mine, I just repaired it for a customer. The circulating fan bearings had worn out and was making a racket. I replaced the skeleton motor.

That said, I expect they are useful. I have a baseboard heater that I linger by after I step out of the shower. The flow of warm air dries me up quickly.