Air Vent on Same Side as Supply Value

Jeff_H

I have a one pipe steam heat system. There are two radiators in my house where the air vent is on the same side as the supply valve (I notice that one of the radiators has a plug on the side that the vent should be; the other one is not so clear).

In understand that this should not be the case (from Dan's book), but am wondering what the practical implications are as far as heating the radiators. These two radiators do take longer to heat (and do not always heat all the way across the radiator), but I believe that they are at the "end of the line" due to an addition that was put on my house prior to my purchasing it.

Could there be any rationale for doing it this way (i.e., should I hesitate to have the vents switched to the other side of the radiator)?

Thanks in advance for any help.

vaporvac

Could you post a pic?

KC_Jones

I have seen this done on purpose to help vent the pipe running to the radiator first, but in these situations there is also a vent on the other side that vents the rad once the steam arrives and closes the first vent. In your situation I can't imagine any reason this would be as the vent would close basically as soon as the steam arrived and you would get almost no heat out of the radiator. I agree with vaporvac some pics would help clarify, perhaps there is something else going on here?!

Jeff_H

Attached are some pictures (I included a close up of the bottom of the larger radiator so you can see that the supply is on the same side as the air vent). There is a plug on the right side of the larger radiator (where I assume a vent was once located), but nothing on the smaller radiator.

KC_Jones

Hmmm. Is it possible this was originally a 2 pipe system? I can't tell for sure in the pics, but it looks like there is an old capped off connection on that small rad (opposite current connection). Also that piping definitely looks newer especially on the larger one in copper which certainly isn't original. It appears as though the vent on the small one was added recently judging by the paint being sanded off. Has the house had extensive remodeling done? Is there any evidence in the basement of abandoned pipes or anything? It's obvious the pipes have been messed with so hard to say what was original. In my opinion from what I can see those vents should absolutely be moved to the other side. It's never really going to work properly the way it is. If they messed with the piping as much as it appears there could be other factors with respect to those rads heating.

Dave in QCA

I have seen this situation several times before. In one case, this was done to slow a radiator down. It originally was too large for the space and was overheating. With the vent moved, the radiator ran cooler but the space was comfortable.

In all other examples I've encountered, it was an error by someone who was doing work on an existing system such as re-piping, replacing a radiator, etc., and the person doing the work did not realize that it was in error and would cause the radiator to heat slow and partially heat at best.

An additional question.... Do you have those HeatTimer Varivalve vents on all of your radiators or were those used hear to try to get more heat? They generally are WAY TOO FAST to be a good radiator vent and will cause an otherwise good system to be out of balance.

Jeff_H

Thank you all for your helpful responses. I believe that the system was always one pipe, there are no abandoned pipes and that these radiators were added to the house as part of an addition (at which time some copper pipes were used). I'll see if I can find out the history/logic of the vent placement from the prior owners to see if there was a reason or just a mistake (I also noticed a radiator where the vent is on the correct side but much higher than recommended).

As to the HeatTimer Varivalve vents, the HVAC person I first used put these on all my radiators. Within one year, half of them "failed" (mostly spitting out water) and I moved to lower venting vents. I'm planning to swap the remaining out even thought for now the heat in my house is somewhat balanced and I am reluctant to throw things off (unfortunately, I think some encased radiators are not pitched correctly and the vents on them have been prone to making noise; I found Hoffman vents to be unbearably loud).

KC_Jones

The spitting vents may not be due entirely to the vent. What pressure is the boiler running at? How is the rest of the piping including the near boiler piping? Sometimes if the pressure is too high and you are getting wet steam the vents can spit (those fast vents certainly don't help the situation). Do you also have adequate main venting? Talking about main venting around here is like a broken record, but it is critical to achieving balance and speed in the steam heating system. I agree with you on the Hoffman's, I prefer Gorton vents they are essentially silent. One of the best improvements I made to my system. Some people like the clicking of the Hoffman, it's all a matter of personal preference.

Fred

Are there conventional radiadors behind those covers? Is it possible there is some type of looped pipe that goes back and forth horizontally behind that cover and ends with a capped end that happens to be on the same side as the steam supply? If that's the case, having the vent at the end of the loop is correct. It's impossible to tell with those covers on.

Dave in QCA

That is not a cover. It is a cast iron recessed radiator, similar to the Gov-ray. http://www.governaleindustries.com/products/gov-ray/

dopey27177

Vent valves are always installed on the opposite side of the steam entry point. To correct any problem with the limited heat Place the vent valve on the correct side of this great heating element. If the unit over heats the space you can replace it with a Gorton # 4 vent valve. tHE # 4 VENT VALVE AT 1 psi STEAM PRESSURE WILL VENT .1485 CUBIC FEET OF AIR PER MINITE or 247 cubic inches of per minute. Another Vent valve is the Hoffman # 40 vent valve where the discharge rate at .5 steam pressure is 150 cuic inches of steam per miute. As the pressure increases the capacity of the vent valve increases. At 2 PSI steam pressure the vent valve will vent up to 600 CIPM.

Your one pipe steam system should not exceed 2 PSIG unless you have other problems.

Not worry about the high end of the steam pressure as the vent valves close when the element is heated. At that juncture steam stops flowing until the vent valve opens and starts it venting cycle again.

If you need more info I can be reached at Dopey27177@aol.com

Hap_Hazzard

The varivalve is a floatless vent. It isn't designed to close on water, so it's a poor choice for a radiator that tends to collect water. It's not so much that they failed; they were wrong for the application. The guy who installed them failed.

Are the spitting radiators by any chance the ones with the vents on the wrong side? Because whoever reversed the piping, for whatever reason, might not have adjusted the pitch of the radiator. One-pipe radiators always need to drain through the supply, so they need to be on a slight incline away from the supply. Any radiator that's pitched the wrong way will collect water in the bottom.

Aside from spitting, this will also cause water hammer at the beginning of each heating cycle. When a steam cloud encounters a puddle of cold water, it collapses as the steam turns into water. The drop in pressure causes more steam to rush in, condense, and further decrease the pressure. The result is an incredibly rapid chain reaction, causing a loud bang or a series of bangs that can make it sound like your pipes are trying to break through the wall.