Optimizing Steam through Mains

usndave03

I was having issues with slow venting mains so after insulating the exposed pipes, fixing the near boiler piping and upgraded the venting on 1 side (will do the otherside but I have a ceiling clearance issue to deal with 1st), the steam gets to the end of the mains at about 25-30 min from when the boiler fires up. Is this acceptable or can I do better? The contractor installed a vaporstat but I'm confused on its setting. Looking through the wall forum I havent really found a clear answer on how this thing should be set. Does my setting look ok? I piped in 4 Gorton#2s and 1 Gorton#1 off a 3/4" tapping (i think its maxed out for that size tapping) I want to get the steam to the end of my mains as fast as possible before I start  tackling balancing the 18 radiators above.

Jamie Hall

Depending on the size and firing rate of the boiler -- and the length of the mains -- 25 to 30 minutes sounds no worse than perhaps a little long, particularly if one of the mains is still not insulated. A much more interesting and valuable timing is from the time the boiler starts making steam to when it reaches the ends of the mains.

The vapourstat setting looks quite reasonable for most steam systems, although if this is a vapour system the cutout should be lower -- more like 7 to 8 ounces, instead of 12.

usndave03

Thanks @Jamie Hall
How does one know when the boiler has made steam and released it to the mains? I have been using a laser thermometer and taking readings off the drop header and risers to the mains. I estimate the boiler is making steam at around 10-12 min when the risers to the mains reach a temp close to 200 degrees. So that would mean its taking 15-20 min to reach the ends of the mains.  Both my mains are insulated but only one side has the increased  venting...the otherside only has 1 hoffman 75. I will be installing the increased venting on that side as well but I need to get the contractor to tap into a location that will allow for the height of the Gorton #2s (it may have to be on the return at the end of that main). Both my mains are about 60ft long (2 1/2" pipe) and my boiler is firing at 150-175 KBTUs.

Jamie Hall

200 plus on the risers is one pretty good guide to steam coming up -- many times you can just hear it! That gives you a velocity of the steam front in the mains of about 4 feet per minute, which actually isn't that slow.

JUGHNE

Did you have the gas meter clocked?
The boiler is capable of producing more btu's than the 150-175.
This was mentioned in your previous post.

usndave03

@JUGHNE yes the gas meter was clocked im not sure what the result was. I ordered the Carlin burner full firing diffuser plate kit with the full intention of increasing the fire rate. However, the contractor noticed that he could bump up the w/c on the gas pressure and still be within manufacture specs. So he did that and wanted me to time the steam this week when the temp drops outside and see if it makes any difference. If not, he will increase the fire rate as originally intended.