steam boiler replacement size

Pete_18

We will have approximately 511 EDR hooked up to what we hope will be a new steam boiler (my calculations may be off, so feel free to look at them below). Looking at the WM SGO (as an example), they have the SGO-4 which is rated at 450 NET IBR Steam and the WM SGO-5 which is rated at 542. I don't want to be undersized or grossly oversized since I know both situations will cause problems // endless runtimes or short cycling.

If it helps at all, house has no insulation today and leaky windows. While we do plan on blowing in insulation at some point, we have no plan to either remove radiator/radiator sections or install replacement windows.

If it changes the situation at all, we potentially plan on using a heat exchanger to connect either a radiant floor zone or hot water zone in the future (not immediately). I have read through the information Dan put together on how to do something like this.

Below are my calculations which I may have messed up, so feel free to do your own:

Sec Col/Tubes Height EDR/sec EDR

12 5-tube 35-36 5 60

17 5-tube 20 2.67 45.39

21 5-tube 26 3.5 73.5

9 5-tube 38 6 54

8 2-col 38orn 4 32

7 5-tube 37 5 35

6 3-col 42orn 5.5 33

10 2-col 38 4 40

7 5-tube 36 5 35

3deep 25-wide 17 10

(this is an old style wall hanging one and is a pure
guess -- 3 inch deep, 25 inches wide, 17 inches high)

6 2-col 38 4 24

6 2-col 38 4 24

15 3-col 22 3 45


Which would you use suggest and why?

Also, is there a reason I care about having an automatic water feeder? My water level has always been good in my current boiler and I have to remove the disgusting water from the boiler each week anyways, so adding water at the same time to replace the removed water is not a big deal.