Too Much Oil

joe amadio

Recently converted the first floor of an old house from steam to  hot water. Added a hot water boiler and converted all rads on the first floor. Left the second floor steam. Moved the thermostat to the second floor. Its a big old house and there is probably still 1500 sq feet of second floor running on steam. The original system I think is a vacuum system. It has an aerolex alternator with its own site glass on the system. There is never any water in the site glass. All the rads are trapped and seem to be working. There are 4 or 5 supply mains running at ceiling height around basement. On the end of the mains there is a tee with a steam trap on the bull of the tee. Off the back of the tee the line reduces and turns down to the floor and back to the boiler. The outlet side of the traps on the end of the mains then connect to this low return. All the returns from the rads run into return mains that run high almost parallel to the supply mains and pitch back towards the boiler.. These high returns actually connect to the top of the aerator. About 10 feet before the mains get to the aerator they have a tee with a trap that connects to the low return. The low returns and the piping off the bottom of the aerator runs into the bottom of the boiler. I also noticed that the pressure-troll is set at 6 psi. When we converted the first floor we removed all the radiator branch piping and plugged the tees on the mains. The boiler now seems to run for 40 mins at a time and the  pressure gauge never leaves zero. The owner has used 700 gal of oil in a month for just the second floor. I suspect the vacuum doesn't work anymore and the boiler has to run and run to push the steam up to the second floor. Does the aerator need to be replaced or what else should I be looking for?

nicholas bonham-carter

thirsty system

some pictures and a diagram of piping would help diagnose this problem.

remember that steam moves long distances with almost no effort, after the air in the pipes/rads has been allowed to escape.

some old systems contain air removal features [vents] which cannot function at pressures greater than a few ounces. did you say what the pressure was?

tell us more about the "aerolex", and show us a picture.--nbc

Jamie Hall

If...

you really are running that poor boiler at 6 psi, as you say, any vents you may have had on the system are toast.  Second, the lack of motion of the pressure gauge suggests one of two possibilities: you have a steam leak somewhere (you are recording your makeup water usage, are you not?) or the gauge isn't registering -- clogged pigtail or bad gauge.  That needs to be investigated.  The pressuretrol should be set to about 0.6 psi cutin -- basically as low as it will go -- and 1.0 differential; it is possible that if this was a vapour system a vapourstat may be in order.  You don't push steam with pressure.



I suspect that the traps on the drips to the wet return were a later addition, and probably don't belong there.



If this was a vapour/vacuum system, which seems possible, before it got knuckleheaded, you need a set of big main vents at or very near the "aerator".  These will get the air out of the system so the steam can get in, provided that the radiator and crossover traps are in good working order (are there crossover traps from the steam mains to the dry returns?  If not, you need main vents at the ends of each of the steam mains, too).



Are all the steam mains insulated?



And -- do the radiators get hot?  All the way across?  They certainly all should, in a 40 minute run.