Main Vents

Steamhead (in transit)

when boilers burned coal, the fire burned all day once it was lit. Therefore once the air was out of the system, it stayed out- so what if Junior's bedroom radiator took an hour to get hot?

Nowadays we don't have that kind of time, since the oil flame comes on and goes off. We need to vent the mains quickly each cycle. The system design has to change to accomodate automatic firing.

On systems with no main vents, we usually drill and tap 1/2" pipe thread into the side of the last tee on the main, with a slight pitch toward the tee so water will drain back. We come out with a nipple from the tapping and elbow up to the vent. Unless you have proper tools and experience, it's best to have a pro do this.

These vents must be more-or-less vertical to operate properly. If they're off vertical a bit they will still work, but don't try to install them horizontally.

Gorton #2 vents are the biggest vents made today. But to make sure they're properly sized, if you haven't done so already, measure the length and diameter of each steam main and post the results here. We can tell you for sure.

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Jonathan Walpole

Installing main vents

I have an old one-pipe steam system with a boiler from the 60's but there are no vents on the mains. My service guy otld me it was designed that way and they aren't needed, but everything I have read here says otherwise. So, do I need vents? And if so, can I tap them directly into the main or do I need to cut the line and add in a tee? And most importantly, should I hire someone to do this for me (though probaly not the guy who told me I didn't need them)?
Thanks for your help.

Jonathan Walpole

There are three mains, each 2.5 inches diameter and 30, 34 and 42 feet respectively.
When you say to tap into the last tee on the main, does it matter if that last tee is less than 15 inches from the end of the main? Also, on two of the mains I have limited head space, does it matter if the base of the vents is only just above the top of the main? Also, how much clearence around the vent do I need? Sould I be concerned about heat from the vent? This is a 200 year old house with very dry timbers.
Thanks for your advice.

Steamhead (in transit)

Though it isn't a \"textbook case\"

tapping the side of a tee and installing the main in an elbow screwed onto a horizontal/back-pitched nipple should work fine. I've never had any problems doing it this way, but I do like a little more height if available. The 15 inches back is optimum but again, you shouldn't have trouble if the condensate doesn't back up. There won't be so much condensate to begin with if the steam pipes are insulated.

I doubt if the vents would get hot enough to ignite anything, but leaving an inch or so of clearance can't hurt.

As far as what vents to use: For the two shorter mains, use one Gorton #2 on each. For the longest one, use a Gorton #2 in combination with a Gorton #1 or Hoffman #75.

You will be amazed at how well this works!

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Jonathan Walpole

The pipes are wrapped with a thin (maybe 1/4 inch?) fiberglass roll insulation which I'm guessing is not nearly enough. Do you have a recomendation? State Supply has 1" fiberglass insulation with an aluminum jacket - is that my best bet?

Also, since you have been so helpful, should I consider replacing my boiler - it's got to be at least 40 years old and provides our hot water as well. We seam to be going through about 40 gallons a month in the summer just for hot water, about 800 gallons all year, plus 4 cords of firewood.

I like the steam heat, but I am concerned about efficiency and constantly rising prices. Should I consider consider replacing the system? Maybe radient heat? Do you have any thoughts on bio-diesel?

Steamhead (in transit)

Answers

Yes, that 1" thick fiberglass is very good on steam pipes. But if you're allergic to fiberglass, have a pro install it.

There are much more efficient ways to make hot water than keeping a boiler at temperature all the time. I like indirect tank-type heaters that use hot water from a boiler to heat water in the tank. Not all of these are rated for use with steam boilers, check with the manufacturer to be sure.

What type of boiler do you have?

You'll get the most cost-effective savings by fixing your steam system. Bio-diesel as far as I know has not been approved for general use, though that could change any time.

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Jonathan Walpole

The boiler is an American Standard, Boiler Number A 35 M, Series Number 2B JI (I wasn't sure which is the model number).

In terms of the hot water, there seems to be alot of debate about indirect tanks and tankless systems. We don't have a very high hot water demand, and our piping is old and water presure is low so we don't use more than one hot water demand at a time. We have been considering solar hot water, but that will probably wait till next year. If we were to go with a tankless system, would that let us shut off the water temerature sensor on the boiler so it would only run for heating demand, or do you still need to keep the water at a certain preheated temp.? In the depth of a New Hampshire winter, our cellar stays around 45-50 degrees but that will probably drop as I improve the insulation on the steam pipes.

Leo

I don't have numbers

I don't have numbers to give but I worked for a company that replaced one of these boilers on a hot water system. It was a piece of junk and took a few years to convince them to replace it. The lady saw the owner of the company on the street and began to rave about the fuel savings. She said they were using less and keeping the house warmer. She also said it was a big decision to get a new boiler over a new dining room set (very typical).

Leo

Steamhead (in transit)

Leo, that one must have been in pretty bad shape

I've gotten decent results out of A-3 series boilers if they have 3450-RPM flame-retention burners and proper firing chambers. Otherwise they will soot up and waste fuel, like any cast-iron vertical-flue boiler will if not set up properly. If that A-S you had was a dry-base 3-pass with a similar series number it was probably an Arcoliner, which was less efficient.

Jonathan, especially with low hot-water demand as you have, the first thing I'd do is switch to another method of generating hot faucet water. There's no point in keeping any boiler at 180 degrees or whatever to heat your faucet water. The standby losses are killing you. Maybe one of the new tankless heaters would fit the bill. If it doesn't have to remain at temperature for hot faucet water, the boiler would then be configured to fire only when the thermostat calls for heat in the rooms.

Compare the output rating in square feet of your A35M (588 square feet EDR) to the amount of radiation you have. If the boiler is considerably oversized I'd replace it also, even if it's in good shape.

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