Welcome, my name is XXXXX XXXXX I will do my best to help you with your issue.
You should be able to replace the heater module in virtually any Nutone unit. It would help to know the model number but this site has pictures of the different models so you can probably identify your fan from the pictures
Click on "Ceiling Heaters"
The heating assembly is modular in Nutone fan units
It seems there are listings for all parts. Is there a complete assembly and what to do if the heating modular isn't the primary cause My Nutone model is QTXN110HL. Is there a step by step instruction sheet.
You would need a multi-meter to test the voltage to the heating module to confirm that it's getting voltage. If it is getting voltage when you switch on the heat then the heating assembly is the likely culprit. These module typically come with basic instructions.
It's a pretty simple process. Each module (heat, light or fan) is attached with a few screws and has a cord that plugs into a socket inside the unit.
Here is the parts list with a blow up of how the parts go into the unithttp://parts.broan-nutone.com/nutone/Shop?DSP=30115&PCR=1:22000&IID=QTXN110HL
can you give me the exact # XXXXX the heater assembly and is there a instruction sheet on how to install
S97016565 is the part number for the heating element. You will have to ask when you order the part if there are instructions available.