low boiling point

Brad White_203

in the 1920's and 30's, there were vacuum-retaining vent valves designed just for that. To hold a vacuum allowed a continuous output and at lower temperatures given the vacuum levels. There was something in the library about that, an article from a trade magazine, if I recall.

Now, Dan H. mentioned a system, (Paul System?), a ad-hoc variant of which involved running garden hose from vent points back to a vacuum pump, with some success.

Oddly enough, I am now researching and writing a report for a project, a 1960's high rise which had (has) a Dunham Vari-Vac system. I say "had" because well-intentioned tampering over time has had unintended consequences one can imagine. The vacuum pumps were recently replaced and how controlled I will have to find out.

My "Plan A" is to "de-improve" the system back to where it originally was supposed to be.

Point being, yes, vacuum steam has legs.

nicholas bonham-carter

speaking of low boiling points

anyone have any opinions on the benefits of converting a medium size 1-pipe system to subatmospheric operation?[even if the boiler burns gas instead of coal]
seems like it would be easy to put check valves before all the main and rad vents.
would that give even quicker venting?
maybe some improvements in the shoulsder season?--nbc

Unknown

Been done,

You would have to have a vacuum line from each rad in order to pull the steam in.
Remember NB-C high pressure always goes to low.

Dave

nicholas bonham-carter

subatmospheric ruminations

i don't think i need a vacuum pump. my system could make a vacuum the old fashioned way--by condensing steam, and then not letting the air back in.check valves would be in board of the vents to keep the air out.
wouldn't this contribute to greater speed of steam arrival during those times when it's very cold, and the boiler is cycling on pressure?
unless there could be unintended consequences it might be an improvement.
the tricky part is to rig up a check valve in front of the 1/8" rad vent connection without mini water-hammer.--nbc

Unknown

nicholas bonham-carter

Nice thought, but how would the steam get there in the first place?
Is that not how it works now?, through the vent.
Are you not thinking of the old vapor/vacuum vent type systems?
Just trying to understand, be patient with me .

Dave

nicholas bonham-carter

speeding up the west wing

here's what lead me to these thoughts:
this is a large old family house converted to 7 2-br apts in 1920. the west wing has always been cold, as it has more exposure. since the advice has been to put the t-stat in the coldest area, that's where it is.
the occupant of that apt had surgery, and wanted a little higher temp than 66 deg; so i increased the venting on the 2 dry returns that serve that area from double-hoffman 75 to biggest gorton +1 hoffman.
now the rest of the house is cooler; as the thermostat is satisfied as soon as she gets the heat more quickly. the other 4 returns only have the 1 big gorton on each.
soooo...i thought "maybe if much of the time i didn't have that residual air inhaled between cycles on the vaporstat to remove, balancing would be easier..."
maybe i just need even more venting.--nbc