Determining steam capacity of an unknown boiler

Tony Conner

...any harm in just trying it? If it doesn't work properly, can you not close the valves to the newly installed rads, and run as you are now?

Pete_18

Want to add some radiation to system

I want to add 45-70 sq ft EDR to my 1-pipe steam system since the former owners of the house decided it would somehow be smart to remove radiators from half of the downstairs and replace it with this disgusting gas wall mount heater during a 1980 remodel.

I am going to ask my heating guy to reattach about 45-55 EDR to the 1 1/4 in. pipe already drilled in the main and 24 EDR to the 1 in. pipe so that we can hook up the additional radiators.

Unfortunately the company that makes my boiler is long out of business and it's impossible to know what model it is since the tag that had the model on it is gone and nobody left a manual.

From Dan's reference material, I saw one boiler unit that claimed 441 sq ft steam and another that claimed 556 sq ft steam (I don't have any data to know if these are EDR or Net IBR numbers, which unfortunately also makes a difference because I don't know if they take in to account the piping/pickup allowance of 1.333).

I currently have 428 sq ft EDR hooked up to the system and with the 2 additional radiator would have max 507. Lets say worst case scenario my boiler's steam rating is now under what I have connected, other than of course the whole house no longer heating right, how will I know?

I assume without any information supplied by the manufacturer, there's no way to know what the boiler steam output is, right?

Worst case scenario I guess I'll just keep the new radiator valves shut off until we can afford a new boiler that is absolutely sized to include the additional load.

Pete_18

no harm that I see other than $$

that's what I figured. Since I do want a new boiler one day, I figure I can always just shut the valves off like you said and leave them off until I get a new boiler if it becomes necessary.

Bob W._3

Does your boiler pre-date the 1980 remodel? If so, chances are it was sized to the existing radiation, which would have included the missing rads. Just a thought.

Also, the sq. ft. ratings on the boilers would have included a pickup factor. Prior to the mid 1950's that factor would have been even larger than 1.333.

David Efflandt_2

Pressure might be clue

Pressure or whether it pressure cycles after it runs awhile may be a clue if it has reserve capacity. I am no expert, just a HO with an oversize boiler.

Christian Egli_2

Clock the meter

Time the boiler and read what goes through the gas meter per unit time.

For gas, each 100 cubic feet is equivalent to 100,000 BTU.

A little math will give you the boiler input in BTU/h and all the other units you want. Assume 80% efficiency.

This will be approximate but, at least, a very good ballpark figure of what you have.