Main Vents

NJSteamhouse

My mains do not have any vents on them and I need help choosing where to install some and what sizes. My system is a one pipe counterflow. The main runs about 8' as a 2" pipe and then reduces and continues another 10' as a 1-1/4" pipe. There is also a long (16') 1-1/4" branch off the beginning of the main that runs in an opposite direction.

I have about 8-12" above the main (including space between the joists) to fit valves. Is this system big enough for a Gorton #2 or would it be fine with smaller valves?

Jamie Hall

You could use a Gorton #2 and the end of the reduces inch and a quarter pipe as a vent on that line, and another one on the other branch. You could probably get away with #1s, but in my humble opinion there's no such thing as too much venting on a main!

DanHolohan

Jamie Hall said:

You could use a Gorton #2 and the end of the reduces inch and a quarter pipe as a vent on that line, and another one on the other branch. You could probably get away with #1s, but in my humble opinion there's no such thing as too much venting on a main!

I agree with what Jamie said. Good advice.

JStar

We find the best rate of venting with using one Gorton #2 for every 20ft of 2" main. I would use at least one #2, maybe even two.

NJSteamhouse

Should I put the vent at the end of the 2", where it reduces to 1-1/4"? Or should I put the vent toward the end of the main (end of the 10' section of 1-1/4")?

Also, how tall is the #2?

Jamie Hall

about a foot in from the end of the inch and a quarter, if there is a convenient place for it, but near (preferably not right at) the end.

A #2 is only about 6 or 8 inches tall -- I'd have to go measure it -- but it's happiest if you can elevate it from the pipe it attaches to on a nipple -- say 4 to 6 inches.

NJSteamhouse

Are adjustable radiator vents a good option with steam systems? I am considering adding either adjustables or TRVs in order to cut down on the heat going to unused rooms.

My house is a 2 story and the upstairs always ends up quite a bit warmer than the 1st floor.

David Nadle

TRVs are easy to add to 1-pipe steam and are a good solution to your 2nd floor problem. I had the same problem with oversized radiators upstairs and a couple of Danfoss TRVs took care of it.

NJSteamhouse

Can you send me a link for the Danfoss TRVs? I can find them on the Danfoss site but I am having trouble finding a place to order the correct ones.

David Nadle

supplyhouse.com carries their stuff. Besides the actuator you need the Danfoss 1-pipe adapter and a separate straight, not angle vent of any brand.

If you have good airflow around the radiator vent, use the direct-mount actuator. Otherwise, the remote sensor and dial combo can be mounted nearby or on the outside of a radiator cover.

KC_Jones

I would add one thing about TRV's. Results may vary. I have 2 of them in my house and now thinking about removing them. Now that I have proper piping and venting on my mains the TRV's are a problem. I can not get enough heat into those rooms and now they are frigid. If you are just trying to cut heat to a totally unused room that is one thing, but to me be careful using them if you plan on working on improving any other parts of the system. One suggestion that is much more affordable would be to balance your venting. If upstairs is too warm put really slow vents in those rooms and in the cooler rooms faster venting. I did this this year in my house and if I didn't do it myself I would have never believed it. My upstairs is actually cooler than downstairs. I ended up slowing the venting down too much in my kids room and now need more heat. Prior to this my upstairs was a sauna I actually had several vents upside down to turn the rads off. It was crazy. That's why I put the TRV's on which worked...until now. As a more specific example my kids room has a rad with 6 sections and I have another rad on the first floor with 12. I currently get the 12 section all the way hot before the 6 section is halfway and that is just with venting. It is in all honesty amazing how much control you can have with just vents. That is just one persons experience and as I started this with results may vary. As for a place to order them from here is a link, great people to deal with. You need to buy 3 pieces, the TRV, operator and a straight vent to get it to work.
http://www.supplyhouse.com/Danfoss-013G0140-Thermostatic-Rad-Valve-w-Vac-Breaker-1-Pipe-Steam-5551000-p
http://www.supplyhouse.com/Danfoss-013G8250-Direct-Mount-Operator-5558000-p

David Nadle

There's no reason you can't balance the system with TRVs and there's no reason TRVs should keep the room colder than their set point. Maybe the vents on your TRV adapters are too slow after your re-balancing. Replace them with faster vents.

The problem with trying to balance an over sized radiator with a slow vent is that on very cold days the boiler will run long and the radiator will fill up despite the slow vent and you'll be roasting in February. Go too slow and you'll also have problems in mild weather when the boiler cuts out before the first section is warm. TRVs let you use a fast enough vent for the mild weather while preventing overshoot in cold weather.

David Nadle

Ideally, all radiators would be sized to cover heat loss for that space, and all vents would be sized to fill all radiators in the same amount of time. But it is very common for radiators to be oversized, especially when they were sized for an uninsulated house and insulation was added later, or when rooms were subdivided.

Changing the vent size is not the best solution to an oversized radiator. You may be able to find a sweet spot that provides comfort on most days, but more likely you will find the scenario bc3510 desribes, with radiators turned off completely because of those days where the oversizing comes into play. TRVs are a better way to reduce the effective size of a radiator because they allow venting at a balanced speed but shut before overheating can occur. TRVs are especially beneficial for a typical residential steam system without zones.

The previous owner of my house kept the upstairs radiators turned off for this reason. I added the TRVs and they have performed so well it's hard for me to understand why they're not more widely used.

KC_Jones

I don't disagree with any of your statements just presenting it doesn't always work the way you say. Right now the problem I am having is the TRV needs heat when the boiler is off. By the time the thermostat is calling for heat it has gotten too cold in the room. The boiler fires to raise the temp in the house by say 1 degree. So I raise the temp by 1 degree in all rooms then the boiler shuts off and the TRV room still isn't up to temp. Basically over the course of the day it gets colder. I have tried big vents small vents anything and the timing just never comes out right. I am not complaining nor looking for a solution, I have the solution and that is to remove it. I only presented my information because as I said results may vary. My TRV's worked great until I replaced the boiler and upgraded my main venting. Now it's terrible. It is a very expensive proposition to add them as BC said and I don't think it appropriate to lead people to believe it's is the end all solution to a problem. People could come on here read about them spend hundreds on them then realize it doesn't do what they want. Again results may vary and I am not trying to argue just present different perspectives.

David Nadle

I stand by what I wrote and I don't think it's inappropriate at all. It's interesting that originally your TRVs "worked great," then you made some other changes and now it can't be anything but the TRVs that are the problem. Perhaps the actuators are damaged and stuck shut. They can be damaged by overpressure. If the TRV in good repair and the room is not warm enough that can only be the venting speed or having the wrong set point.

For one-pipe steam, at about $120 per radiator materials cost and not much more complicated than changing a regular vent, I don't see how it's particularly expensive or difficult. Would I add them blindly to a 24 radiator system without first balancing and outdoor reset? No. But after all that is done, if there's still a comfort issue on the sunny side of the building, or upper floors, or just one particular room, I would look to TRVs for those problem areas.