#41 vents sticking

Mike R._2

Steamhead - Thanks for the offer to look at my system, unfortunately I am in CT, that would be a long service call. The closest Find-a-Contractor is 4 towns away but I will call them to look at a delayed ignition problem and add an automatic water feeder - (I'm in the process of moving and this house will become a rental) The oil co. has tried to fix the ignition problem twice but it keeps coming back.


On the proper main vent question - The main is 2" diameter and 70 feet long. I knew the #74 was not the right vent from reading the Lost Art.. but it was there when I bought the house.
If this helps - there is a total of 20 linear feet of convectors in the house.

Mike

Mike R._2

New vents not closing

I had some no-brand vents that were leaking and now I have a problem with new Hoffman #41 vents getting stuck open in a very short time.
I bought 3 vents from 1 supply house – one stuck open right out of the box. The second one got stuck after working for 4 weeks and the third stuck open after 6 weeks.
I went to a different supply house and bought 2 more. One stuck open after 4 weeks and the other has been working okay.
I wrote to Hoffman to see if they knew about a bad mfg. run or something to check on my system. But, I got no response unless it was accidentally deleted with the Spam.

Anyone have a similar experience or any advice?
Thanks,
Mike

Steamhead

Hoffman makes good equipment

and while it's possible they had a bad run, it's also very possible you have a problem somewhere else in the system.

First- are there vents at the end of your steam mains? Are they the right size? Are they working? If not, the #41s are being overworked, and dirt may be blown into them. This may keep them from closing. Try boiling the vents in vinegar and see if this helps. Measure the length and diameter of your steam mains and we can tell you what vents are needed.

Second- what pressure are you running? If this is a one-pipe or two-pipe/air-vent system you should not go beyond 2 pounds. If the Pressuretrol is set where it should be but the pressure still rises too high, you probably have a plugged pigtail. Clean or replace it.

On steam systems, the symptoms and the actual problem aren't necessarily in the same place! Maybe it's time you called in a pro. Go to the Find a Contractor page of this site to locate one near you. If you're in the Baltimore area, e-mail me!

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

DanHolohan

I'm also wondering

if he has main vents on this system. If the 41s are handling all the air the velocity is going to be pretty high and that can quickly blow crud into the vents.

Mike R._2

Thanks for both of the replys.

The main is a #74 that's not too old and I believe is working.
This is a 1 pipe system and the pressuretrol is at .5 and 1.

Velocity may be issue as Dan mentioned, because this is a replacement boiler and it is 1 size larger than the old one, just for good measure as Dan says. The 2" supply out of the boiler opens up to 3", I think, at the header which should help slow things down but the size of the boiler may be overpowering it. On initial start up the steam does travel fast and I already had the nozzle reduced from 1.5 to 1.25.

I'll try boiling out the vents and see if that helps.
Thanks.

Steamhead

Hoffman #74? Bet it's too small

The #74 is a unit-heater vent designed for higher pressures than your system uses. Because of this, the opening in the vent is very small. I'm sure this is at least part of your problem.

Start from the header and measure the length and diameter of your mains. With this info, we can tell you what vents you need.

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Steamhead

Main Vent sizing

Each foot of 2-inch pipe contains 0.023 cubic foot of air. 70 feet works out to 1.61 cubic feet of air. We must vent this amount of air in a minute. This will take the load off those Hoffman #41 vents.

A Gorton #1 or Hoffman #75 would be a bit small on your main, as each will vent 1.4 cubic feet per minute at 2 ounces pressure. Using two such vents would appear to be OK, but if I were venting that main I would use a Gorton #2. It will vent 5.5 cubic feet of air per minute at 2 ounces, which will ensure that the steam reaches the end of that long main before entering any of the radiator runouts. There's more total friction in a long pipe than a shorter one, and the bigger vent overcomes that nicely.

If you can't find Gortons in your area, go here:

www.gorton-valves.com

Talk to Ken Kunz and tell him I sent you. If they don't have anyone in your area who handles their equipment, they will sell to you direct.

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"