Most radiators not heating

tylerjgardner

I'm a service technician that's new to steam. I read a couple books by Dan H that helped me so much. I worked at a lady's house and got her steam boiler up and running. Her house is under construction and other contractors messed around with the system. When I got there the pressure was over 5 pounds and I found that the previous contractor filled the whole system entirely with water. I drained the whole system and did the repairs nessesary and fired it up. I walked around the house and only 2 radiators were working. She probably had around 12 total. My theory is that every radiator air vent was compromised by the other contractor when they filled it up with water Including the 1 on the end of the steam main. I removed the air vents on the radiators to see if air was pushed out. It seemed like there was air being pushed, but not as much as I thought. Also the pipe wasn't hot on the supply side. The valve was opened. It was a one pipe system. I even removed the steam main Vent and saw some steam coming out but I'm not sure how much is normal. The wet return line was warm, I'm guessing because the condensate was warm? My suggestion was to change out every air vent including the steam main Vent. Why else wouldn't the radiators get heat?

Paul S_3

Replacement of air vents, I would start there first. You would barely feel air coming out this is normal, especially if its very low pressure. I sometimes wet the back of my finger and put it near the radiator vent/tapping to get a better feel if its moving air. Also keep in mind the system piping if there's back pitched piping or sags in the piping that can hold water. I would make sure your getting a correct water level reading at the gauge glass, they tend to clogg up. Also set the pressure trol to cut out at 1.5- 2psi. Also make sure the pigtail below pressure trol is clear.

Wcurtis

listen to this

https://www.heatinghelp.com/news-and-media/dead-men-tales/the-unseen-damage-of-a-flooded-steam-system/

Wcurtis

if the system was flooded the weight of the water in the pipe likely interrupted the piping pitch

JUGHNE

Did the construction people change any piping……even some hangers??

Long Beach Ed

Heat up the system and then remove an air vent on a cold radiator and see if it heats in a couple of minutes. If it does, the vent is bad.

Remove each vent and blow the water out of them. Make sure the water level is correct and near boiler piping is correct. The vents can have water in them that will obstruct airflow until it drains or is shaken out.

Make sure the system did, at one time work. No sense chasing little problems if the boiler is considerably undersized or if the piping is pathetically incorrect.

STEAM DOCTOR

Check the gas pressure. Unfired boiler can certainly cause this issue

mattmia2

flooding the system could have caused several issues:

destroyed/clogged the vents

moved sediment to a place where it is formed a dam that is holding condensate in a main or runouts so it won't heat until that condensate is evaporated

moved piping through the weight of the water so it is now holding condensate somewhere

contaminated the water in the boiler so that it is now surging or priming. is the water line in the boiler stable when it is steaming?