Time to Steam?

tom_54

should it take from the time the boiler starts to make steam to the point where it starts to enter the mains? I am just trying to get a rough idea.

Steamhead

Depends on the boiler

Most new ones you buy today generate steam in about 5 minutes, give or take, from a cold start. At this point the steam starts to enter the mains.

Once this happens, the main vents should allow the air to leave the mains in about a minute. Now the steam is available at every radiator take-off. At this point, steam enters the take-offs and travels to the radiators, at a rate determined by the radiator vents.

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tom_54

thanks steamhead

Is it true that if you have a steam boiler older than 20 or 30 years (which I have) that it's efficiency is somewhere around 50% while most newer boilers are up around 82%?

Frank Weigert_2

Venting the mains

Steamhead,
how long would you say is normal for the air to get out of the system in a 2 pipe Vapor System, since here the air has to travel through all the radiators to get back to the one vent at the end of the dry return. I have a Gorton #2, but it still takes at least 3-4 minutes.

mpeterfr

Venting mains

How do you determine if the main has been completely vented in a minute? Should you be able to feel air escaping from the main vents and then stop?

Thanks.

tom_54

I tell by felling

the tee where the main vents originates from. I have not insulated the tee so if I touch it and it burns my hand than I can be reasonably sure that steam has made it to that point.

mpeterfr

How long does that take?

How long does/should it take for the tee to get that hot?

John Shea

steam is at the end of the mains when...

your main vents stop venting. It is the steam that shuts off the vents. This is, of course, assuming that there aren't problems with the "A" dimension or faulty vents, etc.

Fred Harwood

Efficiency

Combustion efficiency in a matched boiler package can be about 83 percent. Older boilers with large passages don't scrub the gases throughly, so even with high combustion efficiency, heat transfer is less and stack temps higher. How much less is key to knowing when to change boilers.

Steamhead

Still a bit slow

but it probably did OK on coal. Oil or gas firing generally requires more venting capacity.

Also, does your system have thermostatic traps connecting the ends of the steam mains to the dry returns? If so, these are your steam main vents, and you can change them to get more capacity.

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Steamhead

And

some old boilers were horribly inefficient- mostly the round ones. But if you're not ready to replace yet, it may be possible to baffle an older boiler to increase its efficiency. Whether or not this will help, and by how much, depends on the boiler.

Tell us about your boiler- make, model, ratings, if oil what type of burner, and post pics if you can.

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Frank Weigert_3

No traps

I was thinking about adding a 1/2 inch venting connection with a trap. Even though is is not the way 2 pipe was designed, would it hurt to add a main vent at the end of the main ? Alternatively I was thinking about adding a top of riser vent right before the last radiator in the third floor, would that be overkill ?

BTW Steamhead,
you helped out my friend Frank Aloise in Philly a couple of weeks ago (I was the one that gave him your phone #), he had nothing but good things to say about you.

tom_54

Weil McLain Boiler

Boiler Size = A-B-)B18
Series: 3
Oil = 1.25 GPH
Baffles = 110
Min Valve Cap Safety = 134 Lb/Hr Relief = 134 MBH
Sq Ft. Steam = 420
MBH Water = 100.5
ASME Max W.P. Water = 30 PSI Steam = 15 PSI
Tankless Water Heater = 5 G.P.M

I also have the EDR for my radiators that I can post if needed. Attached are some pics of my boiler.

Steamhead

AHHH! Now I know

where I heard your name.

It's perfectly fine to add vents to steam mains on Vapor. I've done this many times- but not on Frank's Webster system. That one has crossover traps, and I changed the dry return vent to a Gorton #2 to speed up steam distribution and help the old boiler limp along.

It's easier to add main vents than crossover traps, since you only need one connection. The riser vent would be a good idea if that riser turns out to heat slowly.

If you tell me the length and diameter of each steam main, I can tell you what you need. If they have asbestos on them, measure the outside diameter of the asbestos (without disturbing it) subtract 2-1/4 inches and that's almost certainly the pipe size.

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Frank Weigert_3

Frank Weigert_3

Vents

Steamhead,
the total lenght of my main is approx 95 feet, it is 2 " pipe. The Steam travels from the boiler through a 12 foot long connection across my garage ceiling and then tees into the main from above in a 45 degree angle. The side that runs back to the boiler is approx. 45 feet long and pitched down. At the boiler it drops into the wet return which is only a couple of feet long. The side that runs away from the boiler is 50 feet long and counterflow. I am not sure if the dead man who designed this system was a master of his trade since this part of them main is not dripped and the dry return actullally runs above the main, which means there is no good way to add drip lines either. There is no wet return other than the one back at the boiler. The riser at the end of the counterflow main tends to hammer at startup, I was wondering if venting this part of the main could possibly decrease the amount of startup condensate by speeding up steam distribution.

Steamhead

Put a Gorton #2

on the end of each main. This will vent both at the same rate. Then see if you can localize the hammering- you'll probably find something off-pitch and holding water, or maybe steam getting into the dry return thru a bad trap.

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Frank Weigert_4

Thanks Steamhead

I will give that a try. I suspect a sagging pipe in the second floor is causing the hammer, there are no traps it's and orifice system.

Steamhead

Orifice Vapor systems are great

they have fewer moving parts than any other system I know of. I see a lot of Trane orifice systems around here. What brand is yours?

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Frank Weigert_4

Orifice System

It's and ADSCO. You actually helped me here on the wall to identify it about one and a half years ago.

Steamhead

I remember now

another wonderfully simple system that will probably outlast all of us.

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