You should have risers coming out of both sides of the boiler feeding the header (which should probably be larger) and the equalizer should be downstream of what should be two system risers.
Needs a Header, as was said, best if both risers out of the boiler are used an the two mains, tied together with that Bull headed Tee (that the one riser is tied to) should each feed individually off of the header.
Wet steam, possibly water hammer, spitting vents, increased fuel costs. Balancing could be an issue with the mains and returns tied together they way they are. There are any number of possible issues every system is a little different. Also if that is the only main vent on the system, you definitely don't have enough main venting.
No Header means that water droplets can't fall out of the steam before it enters the Main so you will have wet steam. Bull headed Tee causes the steam to hit the back of that Tee, slowing it down. Depending on how you have those mains vented steam may take the path of least resistence and fill ne side before the other. (May be one reason why you ca't balance the system well). Returns tied together above the water line will cause water hammer as steam can enter those return pipes.
Is this a one-pipe or two-pipe system? That is, do the radiators have two pipes connected to them, or just one? Post some radiator pics if you can. This will tell us more about the way the system (not the boiler) is piped.
All Steamed Up, Inc. "Reducing our country's energy consumption, one system at a time" Steam, Vapor & Hot-Water Heating Specialists Oil & Gas Burner Service Baltimore, MD (USA) and consulting anywhere. https://heatinghelp.com/find-a-contractor/detail/all-steamed-up-inc
No water hammer or spitting vents. Not sure about fuel cost as I have nothing to compare. Do need to insulate and have mains vented. Is it advisable to wait until the end of the heating season to re-pipe and add main vents? System has been keeping us warm for about 10 years.
You can add Main vents anytime if you have a place at the end of the mains to add them easily. You need to add them at the ends of both mains or you will have additional balancing problems. If you have to modify the piping to add the vents, wait till the weather is warmer. I wouldn't do any repiping of the near boiler piping at least until Spring.
Comments
You should have risers coming out of both sides of the boiler feeding the header (which should probably be larger) and the equalizer should be downstream of what should be two system risers.
EcoSteam ES-20 Advanced Boiler Control
Boiler pictures updated 2/21/15
https://www.facebook.com/media/set/?set=a.10202744301871904.1073741828.1330391881&type=1&l=c34ad6ee78
EcoSteam ES-20 Advanced Boiler Control
Boiler pictures updated 2/21/15
https://www.facebook.com/media/set/?set=a.10202744301871904.1073741828.1330391881&type=1&l=c34ad6ee78
Returns tied together above the water line will cause water hammer as steam can enter those return pipes.
http://forum.heatinghelp.com/discussion/151513/lets-start-the-new-wall-off-properly
Is this a one-pipe or two-pipe system? That is, do the radiators have two pipes connected to them, or just one? Post some radiator pics if you can. This will tell us more about the way the system (not the boiler) is piped.
"Reducing our country's energy consumption, one system at a time"
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Baltimore, MD (USA) and consulting anywhere.
https://heatinghelp.com/find-a-contractor/detail/all-steamed-up-inc
I wouldn't do any repiping of the near boiler piping at least until Spring.