steam vent valves

tony_19

hello all

i read on the wall that it is ok to use the same size air valve on all radiators if they are the same size thruout a house, like the hoffman 40, this is a 6 unit building an the apts. have the same radiators, it seems the lower floor right above the boiler room and the apts above that heats up much faster, last year i changed the main vents to 2 gorton no. 2   but i still have overheating, or should i put either the hoffman 1a or heattimer variable vent,



thank you

tony

BobC

vents

what kind of air vents do the radiators have on them now? Are the slow to heat radiators all on the same main and do any of the radiators on that main heat correctly? Also the boiler should be operating AT or BELOW 2PSI maximum.



Heatimer Varivents are usually much too aggressive and can cause more problems than they solve unless used only for specific situations. Hoffman 1A's are adjustable from 0.026 to 0.225 CFM. Since you have replaced the main vents with the large Gortons you probably want the vents set to 1 or 2 on the adjustment dial to start out with. If Ventrite #1's are available in your area they are a better vent but remember #1 on these is OFF so I'd start out at setting 2-5 initially. The VentRite's only go up to 0.125 CFM (at setting 8) but that is not usually a problem.



Bob

nicholas bonham-carter

6 unit steam system

you may still need more main venting on your system. i have a large 7 unit building with 18 gorton #2 main vents. if the risers are tall, you could put a faster vent on the top radiators.

as bob correctly states-keep the pressure low, as vents operate badly at high pressure, and are often made into interesting paperweights above 3 psi!.

a good low-pressure gauge [gaugestore.com--0-3 psi] will show you what the pressure is, and will show you the back-pressure during the air venting phase of firing, which in my case is 2 ounces [i have a vaporstat as well, with a 0-15 ounce gauge].--nbc

tony_19

vent valves

thank you Bob...

the radiators have a variety of Gorton vents I sized according to how far from the boiler with putting the small ones on the first floor and working up to the size d on the third floor i also modified the hard to heat apt with changing the angle shutoff valve and putting a stratight valve off a tee and putting a vent on the tee to make it act like a riser prior to the radiator, and this year i moved the sensor to the hard to heat apt i want to see if it will work better, but i would like to solve the overheating of the near boiler apts. do you think putting the same valves thruout the building would ne ok , i remember reading it in the Lost art of steam heating to use the same valves .

thank you

tony

tony_19

6 unit steam

you think i need more venting on the mains ? the one near the boiler does not have any at all it is about 10 ft and the long main is about 80 ft and the riser goes up 3 floor i gues about 30 ft should i put another gorton 2, you said u have a 7 unit with 18 #2 how main mains do you have.



thanks

nicholas bonham-carter

how much is enough?

the radiator air vents will never be able to do the job of allowing the air to escape from the whole system, no matter how much extra you pay the gas company to force the air out of their constipated little openings! they are only responsible for letting the air out of the riser and radiator, once steam has completely filled the main. steam will only get to the radiators quickly with generous main venting. you can never have too much main venting as long as it is evenly distributed through the various dry returns of the system. of course they are expensive, but they are also invaluable. if you hear your radiator vents hissing on every heating cycle, it tells you more main venting is needed. more vents also causes the air velocity through the vent to be lower, and less likely to pick up debris thus clogging the orifice.

my 1,050,000 btu boiler feeds about 100 ft of 5 in. main, which then splits into 6 dry returns coming back to the boiler, each with 3 gorton #2' and the preexisting hoffman 75 vent. my basement supply pipes fill first at 2 ounces, and then the risers fill, maybe at an ounce more. this gets the steam rising in every riser simultaneously.  in the 1 top apartment, i have gorton d's on the rads, to get the steam up to the top floor quicker than the second. all the others are the hoffman 40's. like you i have my visionpro sensor in the apartment which is the most exposed.

i can feel the temperature of the dry returns heating up, and they seem pretty even, which is the desired result. i wish i had an ir camera like the flir, so i could see the steam progress through the pipes, but they are still too expensive, so i have to rely on my 0-15 ounce gauge to show the back-pressure of air escaping.

do you have good insulation on your header and mains? if not that could be the cause of the hot apartment.--nbc

tony_19

venting

thank you...i will try to post some pictures of the header and the two mains, i do have gorton d on the top floor apt radiators but maybe like you said i will vent the main a little more and see what happens, do you think i should put a vent on the short run, even though this is where the hotter apts are, it is 3 units in front and 3 units in back on 3 floors, and the hotter apts are the back ones which is where the boiler is.

nicholas bonham-carter

hotter apartments

our boiler is in the middle of the building, so we don't have that problem.

can you determine whether it is the radiators heating up quicker at the back even with no vent on the main, or is it escaping heat from uninsulated pipes underneath? sometimes with improper supply piping, one main will get more steam than another [see bull-headed tee].

next time you're over there, shut the boiler off for an hour or so to cool off the return piping. then fire the boiler, and feel the returns to see if the hotter one is that much more quick than the other longer front one. keep increasing the venting until you have identical times to heat up on each one. you will still need main venting on the shorter one. this makes sure the mains are full of steam first before the risers start filling.

after we installed our new boiler, and bit-by-bit corrected all the deferred maintenance issues, lowered the pressure to 8 ounces cut-out, installed all the venting, i calculated a 30% fuel saving, corrected for the degree-day difference of the winters before, with greatly increased comfort. keep up the good work, it will pay off.--nbc

tony_19

venting

the apts right above the boiler are much warmer then the ones in the front i dont know if they heat faster or not and the main is insulated so ther isnt much heat escaping from it. like i said i will take some pictures and post them.

thank you again

tony 

BobC

Questions

Tony,



Before changing all the radiator air vents lets try to get a better understanding of how the system is working now. The initial goal is to vent the mains fast and the radiators slowly, you want the steam mains to fill with steam fast and at about the same rate. Some pictures of the boiler, mains and main vents would help. Make a simple sketch of the piping to see if the problem radiators are related to each other in some way. IE: they are at the end of one main



Assuming the boiler is cold or just warm, how long does it take steam to get to the last radiator takeoff on each of your steam mains? Even with insulation you should be able to tell be CAREFULLY feeling the vents. My main vent gets steam hot within a minute or two of the header getting hot but my main is pretty short so yours might be more. How close are the main air vents to the end of the mains and can you see a place to mount a air vent on that short main?  What diameter are the steam mains?



Is the boiler cycling off on pressure before the thermostat is satisfied? If the boiler is correctly sized that could indicate inadequate venting on the mains and it's costing you fuel.





The venting on the hot apartment should probably be lower, was the thermostat in this area before you moved it? The overheated apartment might need TRV's to control the steam better but try to sort out the mains venting first because they don't give them away.



Bob

tony_19

pictures

i took some pictures i hope it helps, the pictures with gorton is the long main aproximnately 80 ft from the boiler and this the one that heats the hard to heat apt., the sensor used to be in the back apt. top floor now i moved it to the front apt on the same floor, i belive the short main is 2"  i am going to tap it next weeek and put a couple of gorton no.1 that used to be where the 2 are now 

tony_19

venting

the apts have different vents i used the gorton chart and went accordingly i put the d on the top floor and smaller ones c or smaller on the other floors.

nicholas bonham-carter

vent location

i am finding it hard to grasp the layout of your piping. are the gortons on a return? if so those returns should not meet above the waterline, but should each drop down to the floor into the wet return. the location of the tapping into the pipe would be better made on the top to avoid water-logging. maybe a layout drawing will help us visualize the layout.

have a look at the shop here and order the steamy deal of books so the principles of steam heat will become second nature, and you will be better able to correct/diagnose any problems.--nbc

Steamhead

You'll probably need more vents on that long main

maybe I missed it, but what pipe size is it?



On another matter- are those Federal Pacific electric panels? If so, you will want to check this out:



http://www.inspectapedia.com/fpe/fpepanel.htm

tony_19

venting

i believe its a 3" main but i will have to double check

tony_19

venting

the gortons are about 10" back from the end of the main i couldnt put them on top because the ceilibg is there the tap is drilled about 1/2 way on the pipe. the reurn is at the end dropping down to the floor and going back to the boiler. i have the books but i figured it would be  nice to ask some questions and see what everyone else has done with siimilar problems.



thanks 

Steamhead

If it is

you'll need four Gorton #2 vents on it.

tony_19

placement of vents

one more question is it ok that the vents are on the main or is it prefered to be on the dry return, if you see my first picture i placed them about 10" back from the end of the main  the dry return is to the right ,there isnt much room and it would be placed lower i guess i can put a long nipple to raise it above the main any suggestions, i looked in my book all steamed up and it showed the vents on the dry return

Steamhead

If you pipe the vents

so the run (as opposed to the branch) of the tee points straight out from the main rather than parallel to it, you will have room for another set of #2 vents piped the same way. 

tony_19

vents

thank you all for your help i did put the #2 the way you said they are peppendicular to the main i have 4 of them and a i also installed 2 no. 1 on the short main now i have to go one day and check to see if i can time how long it takes for the long main to heat up compared to the short one

thanks again 

tony_19

vaporstat

do you think it would be better in the long run to use  a vaporstat then the pressuretrol alot of the plumbers i have asked dont seem to think a vaporstat would make much of a difference have you seen more efficiency with the vaporstat, also at your building the apt vents do you size thjem according to the radiators or placement in the building



thank you



tony