Help on oversized boiler

Ed_4

Ed_4

oversized boiler, need opinions

Hello Wallies, I need your valuable expert opinions. I have a little more interest than most people in heating systems. I have read the Art of Steam Heating and last week I went to IBR school in New Jersey just so I would have a better idea how heating systems work.

My current situation is this. I have a basement, where the boiler is located, a store on the first floor and 3 floors of apartments above that. I have 2 inch thick insulation on all my steam pipes from the boiler, through the store and up to the 2nd floor where the first apartment is located. The store is not currently heated. There are no radiators on the 2nd floor, just 4 bare 2" risers. The Thermostat is on the 3rd floor. Because of extensive rehab work, the system was just repiped a few weeks ago as a one pipe counterflow steam system. My boiler is a Weil McLain EGH 105. It is 3 years old. The net rating on this boiler is for 1,125 square feet EDR of radiators. I went around and measured and counted my connected radiation load today. I have 746 square feet of radiators. Of this 746 total, 204 is disconnected because of rehab work and 66 is shut off because the radiator is way too big and overheats the room. That leaves me with a total of 476 feet of radiation connected. Needless to say, I am short cycling like crazy. Luckily there is no water hammer, because all my near boiler piping is according to directions and I have plenty of pitch back to the boiler. I called the guy who sized the boiler 3 years ago. When I asked him how he sized the boiler, he was evasive. Personally, I think he sized it from the car. He said the boiler was not too big and when I told him that everything I read sounds like we need to replace the boiler, he started getting really annoyed. The he said he had a plan, which he would tell me on Wednesday, when he comes over to look.

My questions are this

1) Was this system doomed from the beginning? Even with all radiators connected, the boiler is over 150% of needed capacity. I can not force the tenant to turn on the 66 foot radiator that is off, which gets me to the 165% level of needed steam. Even in my best case scenario, I can only get 680 feet of radiators total. Even if I replace this radiator, it will only be with one that is 20 or 30 feet in size. The room is not very big and is warm already.

2) What are my options? The 204 feet of radiators represents my apartments radiators. I was not planning to hook them back up. I was planning on putting radiant in my floor and leaving steam to heat the top 2 floors. In 3 years time, when the tenant upstairs leaves, I will put in a separate radiant system for those 2 floors.

john_27

Some Thoughts

Have you checked the pickup factor(mentioned in Dan's Lost Art}...the original system spec had to take into account not only the radiators, but the piping in the basement as well...if you have a lot of piping, this may explain a portion of the questioned "overage"...also, please don't assume that removed radiators means substantially less square feet of radiation...for the same reason,ie., the pickup factor...john

[Deleted User]

check with the boilers

manufacturer to see to what extent you can downfire the burners,,that would help with the short cycling some..i think ive heard about 20%...if memory serves.

Paul Mitchell

Get the air

out quicker.

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"