Reference Photos for Mills 4500 A

I threw all my old Smith stuff away. The 350/450/650 are all gone. They all used a rectangular breeching to tie the two back sides together. To connect that header to the flue you can use rectangular or round. It has to be large enough because those boilers all have to be operated with a neg draft in the fire box.

413-562-9631 Call Smith

Yes. Smith only sells 2 boilers now. The model #19 and the #28…..if that. All the Mills boilers are gone …sad. And they made millions of them.

@AJCimino, thanks so much for taking the time to scan these documents and for sharing them with us. They are fantastic. We've posted them in our Heating Museum here:

https://heatinghelp.com/systems-help-center/category/heating-museum/

I helped and instructed many contractors on how to build thousands of the 350/3500, 450/4500, and the 650/6500 H B Smith boilers. They were not the most efficient boiler design but if you wanted longevity these were the boilers that you wanted. You could replace any bad section without having to disassemble the whole boiler. For many years, they were the companies "bread and butter".

@Smith19 asked: "Did these typically come with a power flame burner as standard spec?"

I believe when the first Smith-Mills boilers were originally designed, the factory burner package consisted of a shovel and a fireman.

The fuel was manually introduced into the combustion chamber by placing coal on the grates with the shovel. The firing control was completely mechanical, although it did require a fairly sophisticated human interface.

Modulation was accomplished by adding more or less coal, and combustion testing usually involved looking at the fire and deciding whether it looked about right.

If you ever have trouble finding the original burner assembly, replacement shovels are still readily available at most hardware stores, farm-supply stores, and probably a few general stores.

It was an extremely common firing configuration. The biggest disadvantage was that the burner technician occasionally demanded lunch breaks and a paycheck.

As the years went by, some of those Mills boilers did have PowerFlame burners installed, I remember removing a Mills Boiler from a Church that was fired with a Carlin Oil burner.