Hoffman #75

Joe Grosso

I would like to know if hoffman #75 air vents are correct on a vapor system with bucket traps on the returns then returns go into a feed tank before the boiler.Vapor stat is set for 2psi with cut in at 6 oz.This is what I found on this job.Customer told me that if set lower would have problem heating third floor of this 1697 old home.Ran it and played with the settings and it seems that the owner was correct with these setting.He was told this by his old heating man that has passed away.Problem is that on second floor on bedroom not getting any heat out of one radiator .It just makes noise like a bad bucket trap.Any ideas would be appreciated.

Steamhead

Bucket traps don't handle air well

so you want to vent before them if you can. Whether or not the #75 is correct depends on how much air you want to vent.

If that's a Vapor system, 2 PSI is a bit high. Most Vapor systems were designed to run at around 8 ounces. I would try to find out why the steam won't reach the third floor with less than 2 PSI.

Are the bucket traps placed on the dry returns before the feed tank? If so, that's wrong. The traps on the radiators are there to keep steam out of the return. In this case, the feed tank will serve as the dry return vent. The exception is when the return line dips down and then back up to enter the feed tank. In that case you need to vent the dry returns since air won't vent thru that dip.

I have found the Gorton #2 vent is great for Vapor systems. It has 4 times the capacity of a Hoffman #75, and costs about the same.

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Joe Grosso

Steamhead

What I understand about this system is that not long ago there where hoffman #74 air vents on this system and where replaced by the #75.Also no traps on the radiators and bucket traps on wet returns.Is it possible that there is just not enough venting going on in this one area of the home.

DanHolohan

I agree with you, Frank

I think the Gorton would be best for this one, and before the traps. Wonder why they chose buckets for this?

Joe Grosso

Dan and Frank

I will try to get there wed and take some pictures to show you the system so you have a clear picture of this .Thank you again for the info.

Steamhead

No traps on the rads?

Joe, I think you have an old Vapor system with either water seals on the rad return bushings, check balls or flappers in the return ells (you may have to take one apart to verify these) or orifices on the rad inlet valves. There HAS to be some way of keeping steam out of the dry return.

If the system uses orifices, you MUST keep the pressure low. Otherwise steam will enter the dry return, which could pressurize it enough to stop steam flow to the top floor. A Vaporstat is essential on this type of system.

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Steamhead

The Hoffman #74 vent

is a medium-pressure (up to 35 PSI) unit-heater vent. Since it is designed for higher pressures, the vent port is much smaller than the #75.

Changing to the #75 vents was definitely a step in the right direction- but I'm not at all certain that step was big enough.

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