Williamson-Thermoflo gas boilers are available to buy online at eBay and eComfort.com, as of March 2015. Williamson-Thermoflo does not distribute any of its products through its website.
The eBay listings are for new gas boilers, which use natural gas or propane as fuel. The most powerful boiler on sale is a 200,000-British-thermal-unit model, and the weakest is a 70,000-Btu model.
The selection at eComfort.com, which is larger than eBay's, includes several oil-fueled models. The gas boilers range from 300,000 Btu down to 47,000 Btu, and the models have varying exhaust methods, with some models equipped to vent through a 2,000-foot chimney.