Vacuum Breaker for One Pipe Steam

cnjamros

Can anyone provided up to date recommendations for a vacuum breaker on a one-pipe steam system? I had been using a bronze check valve, but it doesn't always close tightly, causing steam to escape. It also tended to drip hot condensate quite often. I've now plugged it for the time being to avoid dripping onto dear family members.

I have several Gorton 2s and a B&J Big Mouth on this particular main, and none of them seem to open quickly enough to prevent steam being sucked back out of the radiators when the boiler shuts off, sucking in air through the rad vents. See the attached images... the graph lines named "Rad" are the radiator temperatures. Note that in the Non-Vacuum-Breaker image, the temperature curve drops sharply upon boiler shutoff... versus WITH a Vacuum Breaker, where the temperature curve has a more gradual decline... keeping more heat in the rad for longer.

I've seen mention of this device (below) in other discussions here on the wall... I'd be interested in any experiences with it, or suggestions of other solutions:

http://www.amazon.com/Barnes-Jones-MPT-Vacuum-Breaker/dp/B0191X6YK6

Thank you!

ethicalpaul

I'll be very interested to see your responses.

I had initially looked in the other direction--how to make my radiator vents hold a vacuum. But nothing is available today seemingly. All the check valves I could find had too high a cracking pressure--I need ounces.

My radiator vents also suck and I don't like it.

acwagner

I don't have any experience with vacuum breakers, but I did have my rads whistle on shutdown when I had small capacity radiator vents. It was usually the first rad on the line that did that.

I deviate from the typical "vent rads slowly" theory and vent everything fast. When I switched to that approach the whistling went away.

If you don't have any success with the vacuum breaker, another option is to look at your venting strategy.

EBEBRATT-Ed

I usually use check valves but if you want a vacuum breaker try Tunstall Associates

cnjamros

@acwagner do your rads heat fully all the way across? I find, on my particular problem rad, once I get above a certain amount of venting I only get heat across the top. It may be the same effective amount of heat as venting slowly and only filling 1/3 of the rad, but I'm just curious

@EBEBRATT-Ed do you get condensate dripping from the check valves, or do they seal fully for you? Is there any ongoing maintenance that you find is necessary on the valves?

Thanks everyone.

acwagner

@cnjamros My rads fill from the top down usually. From what I understand, that's normal since the steam is lighter than air. On most calls for heat they may only heat partially across. My system is balanced and quick to respond, so I adjusted my thermostat so the temperature response window is much narrower. It means the system runs more frequently but for shorter duration.

My radiators are from the 1920's, and I've never had a problem with venting too quickly on them. I have a radiator that is something like 28 EDR and I have a Gorton D on it and it heats evenly and properly. The only rads I had problems with were more modern radiators that I had temporarily installed that had smaller internal spaces. Most of my radiator vents are Gorton sizes 6, C, and D. My mains are correspondingly vented fast as well.

EBEBRATT-Ed

@cnjamros
You will have better luck with a good quality angle pattern check valve. Get one rated for 200 or 300#. Angle pattern has the check valve seat at 45degrees. The cheap ones are ng

rcrit

Do you have any links or pointers where to find them, which ones are decent? Any installation tips? I'm a mere homeowner.

acwagner

I looked closer at your two graphs, and I noticed one is depicting a temperature change from 70 to 72 at the thermostat and the other is a constant 72 at the thermostat.

Vacuum breaker or not, I would expect those two scenarios to have different radiator temperature profiles. One is a recovery from setback and the other is holding a constant temp. The system in general is going to respond differently in those two scenarios. I don't consider that an apples to apples comparison, if that's what you're going for.

cnjamros

@acwagner excellent point. although I have noticed other symptoms system-wide that indicate the lack of vacuum breaker resulting in lower max-heat for the upstairs radiators. However, I will take a second look to make sure I'm doing a proper comparison

cnjamros

I disassembled my check valve this morning and noticed some accumulation of "gunk" around the flapper seal. I disassembled and cleaned and reinstalled, so we'll see if that will perform better than when I previously had it in service.

I currently have the valve on a continuation of the antler that feeds my Big Mouth vent, separated by a double elbow to allow leveling. Should I have more separation between these two... perhaps elbow and up 6" or so to minimize contamination? I've also seen mention on the forum of a pigtail before a check valve. Wondering if anyone has thoughts on these scenarios?

acwagner

I'm curious--how are you collecting the data? Thermocouple on the radiator?

Seems pretty slick. I've been looking for a way to do something similar.

mikeg2015

I use this. Mostly because of noise. I have a long 3” main with a lot of volume.

https://www.supplyhouse.com/Watts-0556031-3-4-LFN36M1-Lead-Free-Water-Service-Vacuum-Relief-Valve

I don’t see how preventing air into the radiators would matter much. The steam cools and is consumed almost immediately. Thats why there is such a large and rapid vacuum. The radiators will fill
With air regardless. They have to. Its not a sealed system.