Yep, It's an ARco vapor system

Steamhead (in transit)

using the standard pickup factors if all the steam pipes are insulated.

Make sure you find that air vent. It might be a "float trap/air eliminator" like the ones you see in chapter 15 of Lost Art. Follow the dry (overhead) return for its entire length and you should see it.

Make sure the mains are properly vented too.

Keep the Vaporstat for the new boiler. You might want to see if the customer is interested in a boiler that can burn either oil or gas, depending on whatever is cheapest per BTU.

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kev

Arco vapor system

Went to look at a steam boiler replacement today and was not real sure what it was. Two pipes with top feed recessed rads. Did notice slightly different looking supply valves and no traps on dry returns, although one main was wet returning to boiler. Simple check valve below water line on dry returns to hartford loop. The boiler is maybe 20 years old and customer is looking to switch to from oil to gas. There is a vapor stat on boiler now, set very low. I did not see any type of venting on mains.So I scratched my head and went upstairs to measure rads. When I went to the LOST ART BIBLE there it was, ARCO VAPOR SYSTEM.Now I now know there must be a vent somewhere in that basement, but its not near the boiler. To size this boiler should I use a larger pick up factor because its vapor? 355 EDR and an indirect hot water maker. The existing boiler has 179,000 BTU input. The customer says the boiler heats the house just fine, so I need to get it right of course. This is my first vapor system so I am not as confident as I should be. Thanks for all replys.

kev

pick up factors

Would be built in to the net IBR sq.ft. EDR chart when I select the boiler? Also, there are no main main vents. The air vent may be covered by a soffet outside the boiler room, or I should say it has to be. If it's not there how could this system work? The rads are ARCO also. Do you know of another chart that would list EDR for these. I did find them in the LIBRARY section ,but chart is hard to read.

Steamhead (in transit)

The dry return vent

HAS to be there, especially since the system heats properly with a Vaporstat.

You are correct, the 33% pickup is built into the Net and Square Feet boiler ratings.

Any small-tube radiator chart should be fine, such as the Burnham Slenderized chart on pages 190-192 of "E.D.R.".

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