New Boiler, new balancing problem

Motivated Amateur

I recently had my original 300,000 btu Burnham boiler replaced on a one-pipe steam system (circa 1931). The original near-boiler piping included two separate risers coming out of the boiler- one to the front of the house, on heading toward the rear, and a single wet return with no Hartford Loop and no equalizer. The new boiler is correctly sized, and piped according to the manufacturer's specs, which calls for one riser into the header, which then splits off first to the front main, and about 6 inches further down the header, into the rear main.
The problem is that the front of the house now heats up completely before the rear even begins to vent any air.(Before I replaced the boiler, both main vents had been plugged.) I had put vents at the end of both mains, and heat-timer vari-vents on nearly all of the radiators. Is my solution to plug the vent in the front main, to entice the steam to head toward the rear? Or am I simplifying this too much?

Alan(CaliforniaRadiant)Forbes

Sounds as though

the main vent on the rear main isn't large enough.

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Unknown

Best Answer

is to increase the venting capacity of the main that is not heating with a larger main vent or possibly two main vents. Hope this helps.

Glenn Stanton

Burnham Hydronics

Dale

Pressure diff

Sounds like section not heating is still a larger pressure difference than the one that does, could be on the main side or the return side. I guess I would start by getting next to the air vents on each side on startup and make sure the air is coming out and the steam getting hot to each. If not just unscrew the offending vent temp replace with a ball valve and see how that works, if it works OK then the rad vents are next to check. The steam folks would also like a picture of that new near boiler piping with the main OK and not OK marked.

Steamhead

Main Vent Sizing

Measure the length and diameter of your steam mains, and tell us what vents are on them. With this info, we will know if they're properly sized and what to get if they're not.

With the proper main vents, you can then set your radiator vents to the sizes of your radiators, and everything will heat up evenly.

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