Steam Boiler Calculator

I've been working on a steam boiler excel sheet to help size boiler systems and predict performance. It's not done and I have other features I plan on adding. I thought I would upload it here if anyone is interested in using/giving feedback on the calculator. I'll be using the sheet this winter on a few boilers that are already installed that I have access to see how accurate it is.

How it works: Inputs are in orange, outputs are in blue.

The Main sheet takes the GROSS BTU/HR, the water in the boiler when filled to the water line(gal), operating pressure(psig), the weight of the boiler(lbs). The pipe size and count of the risers(the ID is accounted for each pipe size), the size and length of the main line(feet). The main vent that is installed and the number of vents.

The Radiators sheet has a heat load(%) calculation so that after you input the radiator information for the building you can change the heatload on the system. You have the option of radiator type: Column, tube, cast iron radiator/convetor and copper cabinets. Each of these radiator types references EDR tables using the height, number of tubes, and number of sections. You can also input the length of the upfeed pipe from the main, the size of pipe will automatically calculated. Finally the vent/trap can be selected. It takes data from vent tables from the venting capacity chart(at 3oz).

The volume of each radiator type is accounted for, the volume of the main, and the upfeed to the radiator is also accounted for. The radiation off the main and off the upfeed is calculated, right now it assumes no insulation, I may change that later. However, when I put in the data for an actual radiator system I have access to I did get a pickup factor of 1.6, which is a reasonable answer.

Finally the pressure drop is calculated using the appropriate steam charts. This should predict the necessary system pressure to read the farthest radiator. It isn't perfect because the way it is calculated right now all of the radiators come off the very end of the main line and are fed individually.

More to be added:

The heat of enthalpy is dependent on pressure. This is calculated for the boiler, but it will be different in each radiator. But the math is more difficult and right now it is set to 970btu/lb.

Insulation options for the mains and upfeeds.

A selectable list of boilers with all of the applicable performance information.

With the data available for the vents it should be possible to extrapolate and model the vents and traps as orifices for more pressure variation. But may be dependent on low reynolds number effects and may not be accurate.

It should be possible to calculate how long the boiler needs to run to get to pressure and how long it will be off before it turns back on. But that will take a lot of work.

Right now the calculator does NOT work for single pipe steam. I figure they are so small that it's not worth the effort.