vacuum systems

Sunbury Supply Co

We just ran into a vacuum steam system by accident. While
trying to figure out why the boiler was always flooding back. This is a church which someone a few years ago decided
to make into a 6 zone system to save energy. Supposedly I'm
told this system operated ok before (I don't think so ) but
it may have up until they decided to set back each zone to 55 degrees.
I never worked on a vacuum system and only found out by
contacting Barnes & Jones that what I thought was a steam trap at each radiator is a trap but only a trap that creates
a water seal for a vacuum system.
The question is - can I correct this zoned pressure system back to a vacuum system ?? Will it work being zoned ?? Were can I get some information on vacuum systms?? My guess is it would be better ( cost wise ) for the church
to go back to a vacuum system, is my thinking correct since I don't know anything about a vacuum system??
Boy do I need help on this one??
Thanks in advance - Jim

Dave Meers

church flooding problem

Jim,

Flooding back problems in a zoned system can be the lack of vacuum breakers on the radiation side of the zone valves. Check to see if vacuum breakers are installed on the outlet (radiation) side of the zone valves. If they are not installed, condensate can get hung up in those zone(s) when the valve closes. The condensing steam creates a natural vaccum on the condensate in that zone. Eventually the vaccum breaks and the condensate comes back to flood the boiler.

I think you are confusing the terms vacuum and vapor, and vacuum/vapor. The device on the end of the radiators sounds like it is from a vapor system. Can you read any manufacturer's name? Does the system have any pump to mechanically produce a vacuum on the return side of the system? Maybe we can clear this up with some more information.

First thing to do is to check for the vacuum breakers. Keep me posted.

Best regards, Pat

Sunbury Supply Co

Ok maybe I have the wording wrong and we should be calling this vapor. According to Bill Nesbitt at Barns & Jones we should be working down in the 2 or 3" range not pressure in pounds. He said what we have at the discharge of each radiator was a water or vapor seal not a steam trap. The brand name on this ( seal ) is Veco, it is also the name on the radiator manual control valve.
The only thing I found to either vent or vacuum was 2 old Hoffman ait vents on 2 high condensate lines (Model 75A) which are really old. Some of the radiators have Hoffman 1A adjustable air vents and some #40 nonadjustable
but their air vents (probably they don't work either).
The location of the vents are not on the high radiators or necessarily at the end of the mains. Out of seventy some radiators their are only about 11 air vents. The only other vent for the system if you want to call it that is off the condensate pump receiver. Not all the condensate comes back thur the condensate pump. The other 3 high condensate return lines come back and tie together were the old 2 75A vents our.

patrick linhardt

church job

OK Jim, Veco is a brand name of a vapor (steam pressure less than one pound) system. The radiator valve metered the flow of steam into the radiator, no more than the radiator can condense. The device on the return side passes the air and the condensate to the dry (high) return. I suspect some of the devices (the radiators with the air vents) have become clogged or plugged with debris through the years. That is why they added the radiator vents. You need to check the vapor devices to make sure they can pass the air over the top of the water seal and that the water can pass through to the return line. The air vents on the radiators can then be removed, then plug the opening.

I need to do a little research on Veco systems to confirm how they vented the air from the system when it was a coal-fired boiler. However, I'll assume it is now on automatic fire, gas or oil. Air needs to get out of the steam mains and the dry returns. You need to follow the steam mains through the basement and verify that the air has a path to get out through a main air vent. With seventy some radiators, you probably have more than one main. Check them all out. Vent the air from the end of the steam mains to establish good steam distibution. Now follow the dry returns through the basement to verify that the air has a path to get out of the dry return. It can be main air vents or the open vent on a condensate or boiler feed unit. It sounds like this might be how it is piped.

Did you check for the vacuum breakers on the radiation side of the zone valves? Flooding can be caused by many different problems in the system. Since the problem started after the installation of the zone valves, let's start with the vacuum breakers.

There is information in the library section of this site on the Veco system. Go to "The Library", then to "steam vapor/vacuum heating". Veco is the first listing. It is very similar to my favorite system, Broomell. Both used a central air venting process back in the boiler room that I suspect is no longer there. Check out to see if the valves and devices match what you have. The hex nut on the top of the device can be removed for cleaning.

Keep me posted.

Best regards, Pat

john_27

Pat...I remember you from a previous Wetstock in Baltimore......I'm pretty sure that the Veco/Broomell dry return went to a condensing radiator....connected to a warm chimney whose constant negative draft kept the air out of the system....When I converted my Broomell, I wound up installing 13 Gorton #2 vents which made a great difference...just keep them out of the boiler room...they close at 110 degrees. Great to see you helping people out...much appreciated!...John

john_27

Pat...I remember you from a previous Wetstock in Baltimore......I'm pretty sure that the Veco/Broomell dry return went to a condensing radiator....connected to a warm chimney whose constant negative draft kept the air out of the system....When I converted my Broomell, I wound up installing 13 Gorton #2 vents which made a great difference...just keep them out of the boiler room...they close at 110 degrees. Great to see you helping people out...much appreciated!...John

Dave Meers

thanks for remembering

Hi John, I think you had the oversized boiler and some venting issues on an estate that at one time had multiple outbuildings? You are right about the Veco system venting technique. Glad to hear that your system is working well.

Best regards, Pat

Steamhead

These guys are right

you have a VECO Vapor system using water seals. Vapor was the Cadillac of heating in the old days, and is still one of the best systems out there today.

First thing is, if any of the main air vents are vacuum type (like the Hoffman #76) you need to change them to standard vents, properly sized. Get rid of the vents on the radiators. Then you need to straighten out those return lines. This is a good time to hook up with a good steam man- try the Find a Professional page of this site to locate one near you. If you're in the Baltimore area, contact me!

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Sunbury Supply Co

Thanks for the info. I think I'm a good steamman but this it the first vapor steam system I ever ran into, guess I'm not old enough. Around here the highest building is 4 stories. Anyway I agree what I've been reading on the Veco &
Broomell systems with vapor I don't know why anyone wanted to change.
I'll get this figured out with you guy's help in the end. First I want get this system working on inches. Then I guess I'll need to address the zone valves that are installed. My thought is I well need a vacuum breaker shortly after the valve so everything flows when the valve closes. Would you agree on that?? I don't think I need anything else as long as the condensate still flows from the natural suction it gets on the return. Agree??

Dave Meers

on the right track

Hi Jim, you are right about everything, so are Steamhead and John. Get the pressure under control because the system was designed for ounces of pressure, not pounds.
Next, make sure the potential un-wanted vacuum is not created at the zone valves, that is where the vacuum breakers need to be. You want the water flowing downhill back to the boiler, not held up in the radiation by a vacuum. That way we can get the water back before the feeder kicks in some more, and avoid a flooded boiler.

Feel free to contact me if this doesn't solve the problem, there are many other ways to flood a boiler. I have a troubleshooting flow chart for "Boiler is flooding" in my book, Linhardt's Field Guide to Steam Heating, available on this site at "Books and More".

Best regards, Pat