air vent selection for one-pipe steam system

trm

I am trying to diagnose and treat some uneven heating issues in my one-pipe steam heated 2500 sq ft house.

I notice that I have quite a mix of different very old air vents on this 30s-era (but upgraded boiler) system. Hoffman 40s, Dole, and Cadwell, to name a few. The Cadwells are "vacuum valves," whereas the other vents allow air to re-enter the system. I have checked all the valves to ensure that they allow air to pass out of the them, but am planning to replace them all around anyway (time for an update after 75 years!).

Question is: Is there a benefit to having vacuum valves all around, and are they even available? Or should I just go with Hoffman adjustable vents (to deal with rads on long reaches)?

Or does anyone have other vent advice to help me balance this system? I need some vents to be faster than others.

Thank you very much!

nicholas bonham-carter

more vent questions

you have an interesting system, and an interesting dillema :"to vacuum or not to vacuum, that is the question".
if i were you, it would be nobler to replace the vacuum parts of the system with good quality gorton or hoffman radiator vents. for the mains venting i would stick to gorton #2. air trapped for too long in the pipes as the steam is trying to rise up from the boiler is the enemy.the main vents do most of that so if funds are limited, replace the main vents first, and the radiator vents as soon as possible.

if you have a copy of dan's steam book [available here] you will see quite abit of information on venting, as well as other tips.--nbc