just installed a new gas boiler for our one pipe steam system. The radiators on the right half of the house heat up very quickly and are very hot (20 minutes). The radiators on the left half of the house take a very long time to get hot (45 minutes or longer). The right half is on one main the left half on another main. I installed all new varivalves on each radiator. All radiator valves on the floor are wide open. All radiators are tilted slightly in the correct direction. I installed new main steam vents. I tried swapping them from right to left, but right gets hot quickly and left side of house does not, so it's not the main vent. Before the gas boiler was installed, all radiators got very hot. What happened to the left side of the house? All pipes in basement are insulated properly. Boiler was skimmed to remove any oils etc. Any suggestions?

close down the varivents on the radiators that heat faster. this is how you balance a system.
hot water heat you turn the radiator valve by the floor but with steam that valve remains fully open or fully shut.

You need adjustable air vents on the radiators so you can slow down the fast heating ones, and speed up the slow ones.

i had just assumed a varivent is as its name implies 'variable'.

I am not sure what a "varivalve" is since it could be some kind of radiator control valve.

Time your mains...You may need to add more venting to the slow main.It's not uncommon to have to add more than one, on a main. You vent the mains fast, and the radiators slow.Each main should have its own riser off the header, not tee off in 2 different directions.No copper near-boiler piping.



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There are several responses and I'll try to reply to them all. I already had the hot ones closed and the cold ones open, but thanks for the suggestion.

Why would I have to add more main vents now? I have done a ton of reading and talked to as many people as I could so I understand the basics of how a steam one pipe system works. The radiators worked great before we put in the new boiler? I had someone else suggest adding a vent to the slow heating side, but I don't understand why it isn't venting as well as it used to. I would hate to spend more money on something that may or may not work. Can you explain why. I am just trying to learn as much as I can. If I close one of the large radiators the other 5 radiators heat up quickly and get really hot. If I close the other large radiator and open the one I closed, same thing happens. The other five heat up and get really hot. At first I thought there might be a blockage in the pipe, but that doesn't seem to be the case. thanks



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see:

[www.fiainc.com]

[www.eisincorp.com]

Quote

The radiator air valve comes in different sizes to allow different amounts of air to escape from at different rates. This is necessary for the system to be balanced. Balancing the system involves adjusting the rate of steam flow provided to the radiators both with the supply valve and venting air valve, so that an individual radiator produces heat appropriate for the room it is heating.

Although not at all intuitive, the names given the different sizes of air valves, from smallest to largest, are as follows: #4, #5, #6, C, D and #1.

Common applications of these different valve sizes include:
•#4: Used on radiators in room with thermostat and on radiators affecting the thermostat;
•#5: Used on radiators near the boiler & in warm rooms;
•#6: Used on radiators further from the boiler & in cold rooms (e.g., 2nd floor);
•C: Used on radiators furthest from the boiler (e.g., 3rd floor);
•D: Used on radiators needing a lot of venting (e.g., long branches or extra large radiators);
•#1: Used at the end of steam piping mains.

In general, larger valves are used at the end of long pipe runs (mains) and in colder rooms. Smaller air valves are used nearer to the steam boiler source and in rooms which have a thermostat

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



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What was the net BTU rating of the boiler that came out? What is the net BTU rating of the new boiler?

m & m, my thought as well. undersized boiler???

I'm using adjustable varivalves. I was told these were the best ones to use

Not sure on the btu. Will check and get back to you. Does it make a difference that we had an oil fired boiler and replaced it with a gas fired boiler?

Steam and air are both gases. The steam has to push the air out of the system in front of it as it flows to the radiators. IF the first ones have "large" vents, then they will heat up faster because the steam will fill them first. You have to slow them down so the steam has time to continue down the pipe to the other ones. The last ones should have the largest opening so the steam can get to them quicker, then fill the intermediate ones. If the vents are adjusted perfectly, which is hard to do, all the radiators will fill with steam at the same rate and the house will heat nicely.The important thing, however, is that if the main cannot evacuate the air in it then it all has to come through the radiator vents, which can take a long time and "mess" up the system's balance, which is why the main line vents are important. IF the new boiler heats faster than the old one the single vent may NOT be able to keep up with it, which is why you may need a better one or an additional one.

You need to know the sq/ft EDR of the radiators to know if the boiler is large enough.

True, Paul, but just knowing the old vs. new BTU ratings would be a start.