More than twenty years of experience as an electrical contractor in the bathroom remodeling business gives me the confidence to talk on the subject of bathroom fans w/heaters, something that I was regularly involved with.
The most important factor that you need to decide while selecting a bathroom fan w/heater is its capacity, measured in terms of Cubic Feet per Minute (CFM). It denotes the volume of air that the exhaust can throw out of the bathroom in a given time. So, the greater this value, the more effective is the exhaust created by a bathroom fan w/heater.
My recommendations?
I would suggest going in for the maximum CFM, keeping away the ones with a CFM lower than 50. Such fans are designed to meet the needs of many cities that have remodeled bathrooms needing to include an exhaust fan. They have more of decorative purpose that functional, as they aren’t able to move much air to be effective.
Remember that the bathroom fans w/ heater should throw air outside the house. That may be thru the roof, in case it’s right above the bathroom under renovation otherwise thru the wall of the bathroom. If the vent is insufficient, the performance of bathroom fans w/ heater is severely affected.
Next comes the size of the heater of bathroom fans w/ heater. You need to ensure that the heater is designed to work at 120 volts. If the bathroom fan w/ heater works on 240 volts, you’ll have to call in an electrician to install additional wiring and make it operational.
You also get a combined light and fan unit that is easier than a combination of bathroom fan w/heater. Having a light and fan unit with a separate wall mounted heater will prove to be better than a bathroom fan w/heater.
There are many suppliers of bathroom fans w/heater. It will a nice idea to contact your local supplier of electrical goods for further help in getting a good bathroom fan w/ heater that answers all your requirements.