1 Pipe System & Water Hammer

steam2pipe

First question: The condo plumber told us that in a 1 pipe system any radiator can be turned off completely by shutting the valve (not the vent) and it would not affect the rest of the heating system to all other units (3 floors, 12 units). Is this true?

Second question: I read this article on water hammer: https://heatinghelp.com/systems-help-center/what-causes-water-hammer/ and it was really helpful. How often do you recommend skimming a boiler that serves 12 units, 3 stories, old building? The water gets dirty and we were told that not skimming it will cause water hammer. I also wonder if all that sludge will cause issues for the proper regulation of the boiler.

gfrbrookline

Is there a reason why you are asking about turning off a radiator? Are you overheating?

#1 shutting off any radiator will reduce the connected load of the system. Assuming it was calculated correctly when installed the boiler is sized to make enough steam to fill all of the radiators on the coldest day of the year. Most boilers are over sized so if you shut radiators off it will add to the over sizing and make the boiler short cycle and will likely cause temperature swings in other areas of your building. That being said most systems do not have adequate main venting so the heat distribution is not optimal to begin with. Please send pictures of your steam mains and vents, if you have them, and tell us the diameter and length of the steam mains in the basement. These are the large pipes that exit the boiler and usually run around the perimeter or the building with vertical pipes feeding off them going up to the radiators.

#2 you should only need to skim a boiler when it is installed or when you have pipes replaced. The sludge should be addressed by blowing down the boiler through the LWCO weekly while the boiler is at pressure. Blow it down until the water is not sludge, stop when it turns semi clear. You do not want to add more fresh water than necessary.

If you have a water hammering you most likely have a horizontal pipe or radiator that is pitched wrong.

JohnNY

gfrbrookline said:

I
#2 you should only need to skim a boiler when it is installed or when you have pipes replaced. The sludge should be addressed by blowing down the boiler through the LWCO weekly while the boiler is at pressure. Blow it down until the water is not sludge, stop when it turns semi clear.

This is true of a float-type LWCO only.

steam2pipe

Thanks for your comments. The thermostat is not in a good location and when these hallway radiators turn on, it turns off the thermostat so the rest of the condo units never get heat especially the third floor. Meanwhile, the basement overheats all the time.
As far as water hammer, thanks for your thoughts on this.

gfrbrookline

@JohnNY agreed with your LWCO comment. I am used to floats.

@steam2pipe I would suggest replacing your thermostat with a Honeywell visionpro 8500. It will let you put multiple wireless sensors in your units and will average the sensor readings to run the boiler. It is a bit of a pain to do but you can also manipulate it to tell you the actual temp in each unit that has a sensor to debunk too hot/too cold claims.

You will likely need to adjust your radiator vents to balance the heat in the building once you install this thermostat.