Sizing

j a_2

Went on a call to replace existing steam boiler...Asked a couple of questions first, like are you comfortable , in the winter, answer was no its cold in here...Do you know if all the rads heat up, answer, no...Went down to the basement and looked at existing boiler and near piping...It was a oil fired 150k btu boiler...Header and main was 2 inch and it is a single pipe dry return..Oh and there is a wet loop supplying a kicker in the kitchen that heats poorly...My first concern is a 2 inch can only handle 386 sq ft. without producing problems, I think...secondly the wet loop is piped incorrect, I am not a fan of wet loops...Walked thru the house and looked around seems like there have been many additions to the heating system..I had to tell the customer there is no way I could just simply  replace the old boiler and walk out the door....I am looking at returning the load to match the supply main then possibly adding a second hot water boiler to supply forced hot water in the rooms on the 3rd floor and the kitchen...I am looking to see what you guys think....Thanks J A

moneypitfeeder

need more info

Is this a standard 2 pipe vapor system? According to Alt's house heating plans, pg 142 (free google e-read) the capacity of a 2" main not to exceed 200ft is 386 equiv. sq. ft. of steam rad at 240 Btu. What is the connected load you are trying to heat off that 2" main. Were you able to measure the rads? If you are going to replace the boiler, what about adding a new riser to a second main to allow for the some of the "newer added" edr to be split off the current main, and upping the boiler size to match the load? (instead of 2 boilers). Were you able to run the system and check the traps to see if they are functioning? Could be your fine with the connected load other than the hot water loop, and that's why they are cold.