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Vent Valves & Pressuretrol ?

SteamHeat Member Posts: 159
<span style="font-size:12pt">Two of my radiator air vents and my main system air vent at the end of the steam header seem to NOT close when they are hot allowing a lot of dry steam to come whooshing out.</span>

<span style="font-size:12pt"> </span>

<span style="font-size:12pt">What brand of vents would be good as a replacement?</span>

<span style="font-size:12pt"> </span>

<span style="font-size:12pt">Before I replace them, I am wondering if my Pressuretrol is not working properly.</span>

<span style="font-size:12pt"> </span>

<span style="font-size:12pt">After running my oil burner for an hour, I shut it down to avoid breathing in any more steam fumes. It takes about 25 minutes from a cold start to heat the first radiator and about 1 hour to get them all hot. From a warm start it takes about 10 minutes to get the first one hot and about 30 minutes before steam starts whooshing out of the ones with questionable valves.</span>

<span style="font-size:12pt"> </span>

<span style="font-size:12pt">I wonder if the valves failed because the pressure got too high?</span>

<span style="font-size:12pt">How does one do diagnostics on a Pressuretrol?</span>

<span style="font-size:12pt">How long should a properly sized burner run before Pressuretrol shuts it down?</span>

<span style="font-size:12pt">How long after shutdown should it restart? </span>

<span style="font-size:12pt"> </span>

<span style="font-size:12pt">Yes I am going to order the “Steamy Deal” but I am just trying to keep warm right now.</span>

<span style="font-size:12pt"> </span>

<span style="font-size:12pt">Thanks for any help help.</span>


  • Vents

    If steam is coming out of them it sounds like your main vents aren't working. All vents, main and radiator, have to be replaced periodically as they have working parts and wear out. I figure about 3 years is the average life of a vent though some go much longer.  High pressure (3 PSI +) will soon destroy vents. For main vents most of the pros use those manufactured`by Gorton.  Of Gorton's main vents, the Gorton #2 has 3 times the venting capacity of a Gorton #1. Look around the internet.There are several sites that offer good prices on Gortons.

    The whole idea of main vents is to get the air out of the main as quickly as possible as otherwise  air is blocking steam from getting to the radiators. The faster the steam gets to the radiators, the faster the rooms warm up and faster the thermostat setting is satisfied. The faster the thermostat is satisfied the shorter time the time that the burner is running. The shorter time the burner is running the less fuel used.

    Steam at a lower pressure travels faster than at a higher pressure and can travel at 30+ mph so that . All this shows you that it is important to get the air out of the steam's way as quickly as possible.

    For more info on main venting you might want to take a look at Gerry Gill's website as he has a good article on main venting. Gerry and Steve are steam experts.


    I've attached  a drawing of a vent "Menorah" / "Antler" set up.

    This drawing was done by Brad White and the interesting thing to notice

    is the use of the pipe union. With the union you can makeup, add to, or

    service the vents on your work bench and then attach them to the steam

    main using a single connection. Saves a lot of skinned knuckles trying

    to attach the vents and fittings up between the joists!  The idea is that it get the vent away from the end of the elbow like the one you have which helps keep water out of the vents. It might  also help improve you TV reception! :)

    On the Pressuretrol - the high cutoff works when the steam pressure in the system reaches the set pressure. If your system is leaking huge amounts of steam this pressure point won't be reached and boiler will keep on running. The pressuretrol restarts the boiler when the steam pressure drops below the set point (the differential)  You'll need to fix the "leaks" (main vents) first and then you will be able to determine if your pressuretrol is working correctly.

    Your will also probably want to get another pressure gauge as the 0-30 PSI gauge is next to useless on steam systems. You must leave the 0-30 PSI gauge in place as it is required by code/insurance.  Just use a tee and some elbows and tee the new low pressure gauge off the line the other gauge is attached to. Both gauges should be protected from contact with live steam by a "pigtail". Most of the people here get their gauges for the Gauge Store. Here's a link.


    I use the 33020 model 0-3 PSI and it works well.

    I didn't mention radiator vents at this point as you may find a lot of your problems go away once you have the main vents straightened out.

    - Rod
  • SteamHeat
    SteamHeat Member Posts: 159
    Vent Valves & Pressuretrol ?

    Thank you very much for the very educational reply. I was wondering why the 30 PSI meter never deflected at all. I thought it was just dead. :-)

    I will look for a Gorton #2 fast. Breathing steam fumes is not enjoyable. :-)

    I have a feeling I'll still need the radiator vents, since you say life expectancy is around 3 years and I think the current vents are approximately 70 years old. No that's not a typo.

    Thank you for your help.
  • Main vents

    Take a look at this thread . One of the people in the thread called Gorton and they recommend a suppler with good pricing.


    You're right, you'll probably need some radiator vents.  You'll be surprised what a difference it makes when you have adequate main venting.

    - Rod
This discussion has been closed.