Gorton Vents venting slowly

Dave in QCA

On the chance of committing steam blasphemy, I am going to question the supreme status of the Gorton #2 air vent.



Dave takes a deep breath,   "Here Goes!"



Observations:  On a cold start-up, or during a steaming cycle which occurs after a LONG off time, the Gorton vent seems to work just great. 



However, with my cycles set for 1/hr, close observations reveal that the Gortons are venting at a rate far below their rated cfm.  My system is controlled by a Tekmar 279. At the start of a cycle, that occurs one hour after steam was established in the previous cycle, my end of main temperatures are around 135-140F.  When the boiler starts to produce steam and I am registering 1-2 oz of pressure at the boiler, I can hear venting on the line that is vented with 2 Hoffman 75 vents.  I hear nothing and can detect nothing on the Gortons.  As the pressure starts to climb to 3-4 oz. ( I should mention this is a 2 pipe system with orifices set to operate at 8-10oz)  I can hear very minor sputtering at the Gortons.  They are hot, but not steam hot.  I would say they are the temperature of the air in the 135-140F main.   As the steam works its way through the steam main, (venting of course is occurring through the radiators) my condensate sensor, which is located on the steam main, just after the last radiator riser takeoff, comes up to temperature quickly when steam arrives at that point.  Pressure continues to rise and as it gets to 8 oz., the sputtering sound on the Gortons gets louder.  If I bump the Gorton, I can hear the inner workings rattle, but can tell that they are not as loose as when cold.  After about 5 more minutes, the sputtering will stop and I can feel that the Gortons are now steam hot.  When bumped, they do not rattle.   It has taken 5 minutes for the last section (30') of 2" pipe to vent under 4-8 oz of pressure.   The Hoffman vents completely vented the line they are one many minutes ago and snapped shut.



This leads me to believe that the Gortons are not venting at the rate they would be expected to, on my system with well insulated mains.  GW Gill has a video that shows the inner workings of the Gorton vent, and his comments indicate that the vent "starts" to close at 110F and may be fully closed at 130F.  <a href="http://www.youtube.com/watch?v=Wl8vQ2MYhMs  ">http://www.youtube.com/watch?v=Wl8vQ2MYhMs   </a>

Do most systems cool down to a temperature around 110F between cycles?   If not, it would appear to me that in real applications the Gorton vent is probably venting far less than it amazing capacity as is stated in the charts.



I am getting very good distribution as a result of the orifices that I installed about a month ago.  But, I am wondering now, what the closing temperature is a Dunham 1E trap.  I am seriously considering removing my vents and installing crossover traps as would have originally been installed on my Dunham system. 

One of the drawings for a Dunham system that I have shows a simple swing check valve on the system vent coming from the air eliminator and return trap.  Since I can control the system pressure at 1 psi or lower, neither the return trap or air eliminator are necessary.  Dunham indicated that its vapor system was appropriate and effective for ON/OFF systems and they even show the setup in conjunction with a gas fired boiler. 

It would seem to me, that if I connected the system the way it was originally, that venting would be as good or better than they way it is functioning with the warm Gortons.  Further, if I can get the system tight enough to hold a vacuum, that venting would be even faster because their is little or no air to expel.



Also,  on of the comments that I have heard from some of the most experienced pros is that vacuum can cause the condensate to get "held up" and slow return.  It appears that Dunham had a provision to correct this phenomenon as they included a line between the steam header and the return piping with a swing check to allow flow in the direction of the return line to the steam line.  Thus, when the boiler shut down and a strongest vacuum is pulled in the cooling steam mains and radiators, this vacuum would open the check valve until the return piping was at an equal vacuum, thus eliminating backward flow in the condensate lines and letting gravity do its work.



I would really like to hear everyone's thoughts and comments.  Tell my why I am wrong.

Rod

Venting Problem

Hi Dave-  I'm wondering if it's the vents or the system. If I remember rightly people were experiencing a bad bunch of Gorton #2 s last winter. Any chance it might be connected to these?  I'm sure you've already considered this, but what about temporarily swapping the Hoffman #75 s for the Gortons as that would show whether it was a vent problem or not.

Happy Thanksgiving to you!

- Rod

Dave in QCA

Tried out a Mepco/Dunham 1E trap

Happy Thanksgiving to you too, Rod.



I just returned from experimenting with a trap installed in place of one of the Gorton #2s.  When the boiler started to make steam, I could feel warm air venting through the trap.  A thermometer indicated that that the air temp was 130F and went up to 140F.  I could feel no venting through the Gorton that was connected off the other side of the tee.  The pair of Hoffmans on another much shorter steam main closed at the same time that steam got to the condensate sensor located about 30 feet back on the main that I had installed the trap on.  Within about 30 seconds, steam arrived at the trap and it closed tightly after emitting a very small billow of steam.



The Gortons open up and vent just fine if they are cool.   It appears that my mains stay too warm for them to work properly.  Although, I would have to say, with the orifices installed, I am still getting even distribution.  So perhaps, in spite of the fact that they are not venting much, the system is still working.

Dave in QCA

Dunham Information

I am going to see if I these Dunham images will post so that they are readable.

gerry gill

you have it all pretty much figured out correctly.

Most systems would not retain that kind of heat between cycles..yours apparently is..testiment to your good insulation i guess..the gortons will be closed at around 130 degrees, so just as you have figured, you get great venting on cold start, but between cycle venting you may need to have a couple hoffmans in the manifold..or as you say, use a cross over trap..or multiple cross over traps for faster venting..or a 3/4 trap for added venting..radiator traps make fantastic air vents by the way when used in that manner..but all your assessments seem to be spot on.

Jamie Hall

I knew there was a reason...

I didn't change those crossover traps to vents!



My Gorton and Hoffmann are at the end of the dry return, just before it turns down to the Hoffmann Differential Loop -- and if the crossover traps are working and if the vapourstat is working they never see even warmish air, never mind steam -- and never close.  Works fine...

Dave in QCA

A Valued Opinion!

Gerry,  your feedback is worth a million!  I appreciate it. 



Regarding traps, I just happen to have 3 brand new Mepco IE straight traps that would work great for this application.  They are rated just about the same as a "COLD" Gorton #2.   I don't know why I bought them except that I picked the up for $10 a piece on ebay.  I keep finding more little projects to tune this baby up.  In a year or two, I hope to save enough to change out the boiler that is twice the size that it needs to be.

MrDvorak

Vacuum?

Would the same problem apply when letting air in? I have a strong suspicion that my two G2s are very slow to let air in at the end of a long cycle when going back from a set back temperature. The rads suck air in like crazy and my poor 3PSI Wiki gauge is deep in the negative territory.

Dave in QCA

I believe so

My observations were that the G2 was slow to open and allow air to go in.  My 2 Hoffmans opened sooner.  But, since my system was designed to operate in vacuum anyway, I figure its a good thing.

Steamhead

Might try

putting the Gortons on a pipe extension- uninsulated of course. Then they would cool down more, and the warmish air reaching them would be cooled down too. 

MrDvorak

Intelligent vents...

This almost begs for the question - instead of relying on arrays of expensive ancient vents that never seem to perform as expected, would not it make sense to build smart fast vents using devices like Tekmar setpoint controls and zone valves?

gerry gill

yes.

that could be correct also.

gerry gill

yes you could

on the dry return only..original two pipe systems didn't even use vents, but a pipe into the chimney or out the roof..problem is when steam gets into the return..but another tekmar setpoint could trip out the boiler also..i may catch flak for this next comment, but i am a steam rebel.. ---''use your imagination'' (you could always take it back off).

MrDvorak

Vacuum relief valve?

Thank you Gerry, I got inspiration in your excellent videos on YouTube!



Would an installation of a vacuum relief valve on a dry return (preferably as close as possible to the boiler) help with the slow opening of main vents and brief vacuum in the system?



I am thinking about a vacuum relief valve like this one, or is there a better one to go with?

http://www.google.com/products/catalog?q=vacuum+relief+valve&um=1&ie=UTF-8&tbm=shop&cid=11791659051538370231&sa=X&ei=orjNTrPDE6nh0QHyu_UO&ved=0CI4BEPMCMAE

gerry gill

absoluetly, but make sure its rated for steam.

I have a hofmann model #62 on my systems main to break vacuum.

MrDvorak

Vacuum relief valve works well.

Thank you Gerry, it works and quite well, too! I installed the vacuum relief valve on one of the legs of a dry return that never sees steam but that is quite close to the header. I was watching the system a few moments ago:



After ~30mins, pressure goes to 8oz -> vaporstat cuts out -> thermostat sets heat off at the same moment -> pressure is dropping like a rock -> slightly below 0PSI, the vacuum relief valve opens for a few seconds and audibly lets lots of air in -> few seconds later, G2s open and let some more air in for a few more seconds. All feels good.

Abracadabra

which vacuum relief valve?

MrDvorak, which vacuum relief valve did you install?

MrDvorak

The cheap one

Hello A9A,



I installed the el-chapo Watts N36-M1 that you can see in the link above because you can buy it literally everywhere and mine never sees steam. A Hoffman 62 would probably be a better choice as it can break shallower vacuum. http://www.pexsupply.com/Hoffman-401446-62-3-4-Straight-Vacuum-Breaker-11748000-p

MrDvorak

G2's are "breathing" when burner is on

I am playing with a temperature controller and stuff these days and I observed a quite interesting thing - the G2s do not stay closed for the whole time while the burner is on. They close when steam reaches them at the beginning of the cycle, then they close and prevent more steam from reaching them so they cool down to about ~120F and open again (while the burner is still on), then they quickly heat up and close again, etc.