steam vents

prw100

I have a steam heat system, and i know it is common for the furthest radiators to take the longest to get hot, but durring the normal cycling of the boiler the furthest radiator never get hot. They will get hot durring the morning warmup time whenthe heat is in recovery from set back. i have install Groton "D"  evnt now and it has helped a litle but not much.  Is there a larger steam vent available for radiator use??

BobC

Venting

A Gorton D can vent 0.33 CFM and that is pretty aggressive. The Heat timer Varivalve can vent 0.516 CFM. Before replacing the vent on that radiator make sure the main venting is adequate. You should be able to get steam to the end of the main within a couple of minutes of the header filling with steam



Are you sure your main vents are big enough, what vent are you using on the mains?



How long is the main and what size pipe is it?



The mains have to fill with steam quickly to allow all the radiators to come up to temperature.



Bob

prw100

main line vents

I have been told that there are no main line vents in the system, but the mains are about 30-40 feet long, and there are 2 of them going in opposite directions in the basement

BobC

Main vents

I assume this is single pipe steam, just one pipe going to each radiator?



If so there should be vents near the ends of the mains. Are there any plugs that could be removed to add vents?



Without main vents the radiator vents have to remove all the air from the header, the mains as well as the radiator. Also if the mains get vented quickly it usually makes it easier to get all the radiators to heat at about the same time.



Bob

HenryT

agressive venting

Sorry, not trying to hijack your thread, but my issue is somewhat similiar.

I have a large radiator, and the thing bangs like no tomorrow when steam is entering. im guessing that the varivalve is venting too much causing the condensate to run into upcoming steam. I tried a gorton D with teh same results.

should i buy a gorton C or 6? i dont want to keep spending $ on vents that will give me the same issue.

my local supply store does not carry hoffman 1as..



thanks

BobC

hammer

It sounds like you have water trapped in the radiator or the piping that leads to it. When the steam encounters the standing water it collapses and can result in a hammer. Your mains venting could also be an issue.



The Heat Timer varivalve is rated at 0.065cfm at minimum and 0.565 at maximum, while the Gorton D is 0.270cfm. Is there any difference with the Ventrite set and low vs high? The Hoffman 1a runs from 0.020cfm to 0.145cfm.



Have you checked the pitch on the radiator with a level? If it is single pipe steam it should slope towards the input valve, and make sure that valve is fully open. If the slope is wrong, or if there might be a sag in the middle of a long radiator, try shimming the vent end of the radiator up a little bit to get positive drainage for the condensate. Also, on single pipe steam the piping should slope back towards the main so the condensate can find it's way back to the boiler.



Are all the other radiators quiet? You could have issues with the near boiler piping. If the above doesn't work out post some pictures of the boiler, the near boiler piping, the problem radiator, and the pipe that feeds that radiator.



Keep in mind that the above information is for single pipe steam, two pipe steam is different and requires another approach.



good luck,



Bob

HenryT

Thanks

Its single pipe steam. the radiator does heat all the way across, its just the banging wakes me up in the morning.  I will try a smaller vent but just needed an opinion before i got shelling out more $$. I already bought 2 vents for this radiator.

all the other rads in the house heat all the way and with the execption of one more, all of them are quiet. the other noisey rad is suspect is from heat expansion noise as the noise is not cmoing from the radiators but the pipes.

Do you happen to know rating on a gorton C and 6?

Thanks

BobC

vent ratings

The Gorton #6 is 0.150cfm and the Gorton C is 0.270cfm. The Heat Timer varivalve is less that either of these at it'd minimum setting - 0.065cfm.



 You said the radiator wakes you up in the morning, is it coming off a setback and if so how deep is that setback?



I bought my Hoffman 1a's from pexsupply.com. Verify the radiator and piping slope before spending more $$ on vents.



Bob

HenryT

Thanks Bob!

Yes, the biggest radiator bangs and usually occurs after a set back as you predicted.  The pitch is good. How else can i solve this problem?

There is something contradicting that i am seeing on this board. Most seems to agree to vent your biggest radiator with the biggest available vent (i.e. Gorton D or varivalve), but as I did that, some are saying that because the radiator is being vented that agressively, it is causing the condensate to hit the steam that is coming up therefore causing hammer in the boiler.

Is there an exact science? To add to my problem, the biggest radiator is in the same room of my thermostat, so would you advise I vent it even slower so that other part of my house heats up prior to the t-stat being satisfied?  If this is the case, this is against the rule that we need to vent radiator based on size....

Appreciate any inputs!

Thanks

BobC

Venting

There was a post a while back with a very similar problem. If I recall correctly they found a small section of pipe that was level or slightly off pitch and when the corrected that it quieted down.Go over the whole pipe that feeds that radiator and make sure their isn't a similar problem in your system.



i would try jacking up the vent end of that radiator with a 1/4" piece of plywood to be sure it's not a drainage issue. You will have to use a 2X4 to lever it up because the damn thing probably weighs a ton. The input valve could be at fauly, sometimes things get loose inside and the valve isn't fully open even though it seems it is.



The rule is that you size vents by the amount of air you have to vent (volume of the radiator plus the whole length of pipe). Many hold tom the rule of venting the mains quickly but vent the radiators slowly; that indicates you can vent radiators too quickly. You have to temper that with an eye to efficiency, especially if your boiler is oversized. Like most things you have to find a balance between the two.



If the varivalve is working correctly it has a minimum vent rate of 0.065 cfm does setting it at the low end quiet things down?



How deep is your setback? Most people on this board favor small setbacks or even no setback, I have a 4 degree setback myself.



Bob

HenryT

Thanks

Setback is 3 degrees. goes from 68 to 65.

As for the radiator, as you can imagine is a beast. the thing is heavy. Is there a chance that jacking up the vent end of the radiator, would it cause too much tension in the middle of the radiator that it will split into two?

or should i jack up the middle section as well? there are 3 sets of legs holding this beast, left right and middle.

So you recommend me going to slower venting on this big radiator that is in the same room of my t-stat? i never really tried to tinker with the varivalve in the lowest setting, i just outright swapped out the vent with a Gorton D. Now i have a C on it and it still bangs... i may just get a 6 or 5 now,.

BobC

Banging

Your setback sounds fine.



It sounds like going to the Gorton C (0.27CFM) from the Gorton D

(0.33CFM) helped things out. If you still have the varivalve around put

it back on and dial it down (0.065CFM min and 0.565CFM at max); I don't

think you need to go all the way down, play around with it to see if you

can find a happy medium. Adjustable vents allow you to play around without going broke.



If the radiator has 3 sets of legs they all have to be supported, if you put 1/4" under the far end then use a 1/8" at the midpoint. It will take a few people to GENTLY lever that beast up and slide in the shims. A radiator that size can easily dig a trench in a hardwood floor over the decades. I would try playing with the venting before moving that beast.



BTW what pressure is the boiler running at? High pressure (above 1.5 or 2PSI) will exaggerate any faults in the system and make it more expensive to run.

HenryT

Thanks BOB

I will slap the varivalve back on to see how it goes.

the boiler is on pressuretrol set to .5psi cut in and 2psi cut out. sometimes it goes over the 2psi before it cuts out.

I have a low pressure guage on it that tells me im over, but i cant do anything to prevent it from going over the 2 max setting. 

my unit is cycling on and off on pressure until the t-stat is satisfied....could be a sign of oversized boiler but i dont know how else to solve the cycling problem other...

BobC

Pressuretrol

Pressuretrols are not that accurate, take off the cover and try moving the white dial down to 1 and see if the pressure drops.



The lower the pressure the happier everything will be.



The short cycling can be caused by slow venting but I don't think that is the case here unless the main vents are too small, what kind of main vents are you using?



Your boiler is probably oversize and there isn't a lot you can do besides trying to cut down the firing rate by about 20% or so. My own boiler is oversized and I have down fired as far as i dare but it still short cycles. It cycles on and off about 10-12 times before satisfying the thermostat. When it dies, I'll install the right size.



Bob