Williams Furnace Company Replacement Models

Williams Furnace Company has been manufacturing heating products for over 100 years. While their products are engineered to last, you may reach a point where the heater should be replaced. If you have an older Williams heater, you can use the chart below to identify the most current replacement model. Not all models listed are direct replacements as heater technology has evolved over the years. Be sure to verify the measurements, fuel type, and specifications to make sure that the new model meets your needs. 

Old Model Number	Replacement Model Number
1403611	1403821
1403612	1403822
2001611	2001621A
2001612	2001622A
2001612.3	2001622A
2203611	2203821
2203612	2203822
2506912	2509822
2509611	2509821
3003611	3003821
3003621	3003821
3003612	3003822
3003622	3003822
3501511	3501522A (Conversion Kit Available)
3501512	3501522A
3501512.3	3501522A
3501911	3501921A
3501912	3501922A
3502511.4	3502522A (Conversion Kit Available)
3502512.4	3502522A
3502911.4	3502921A
3502912.4	3502922A
3509611	3509821
3509612	3509822
5001511	5001522A (Conversion Kit Available)
5001512	5001522A
5001911	5001921A
5001912	5001922A
5002511.4	5002521A
5002512.3	5002522A
5002512.4	5002522A
5002911.4	5002921A
5002912.4	5002922A
5009611	5009821
5009612	5009822
6502511.4	6502521A
6202512.3	6502522A
6502512.4	6502522A
6502911.4	6502921A
6502912.3	6502922A
6502912.4	6502922A