2 pipe vapor presure

Tom Bulger

Re: Replacement WM boiler for residential 2 pipe vapor system
Problem: New Boiler is flooding

1. Re: Hydronics Institute - Installation Guide: Residential hydronic heating - Guide 2000, Part 10page 10-38. "..It is critical to operate vapor systems at no higher than 1/2 psig." What is the correct operating pressure for this system? (The Owner has always operated the previous boiler at 5 psig?!)
2. RE: Hydronics Institute - Installation Guide: Residential hydronic heating - Guide 2000, Part 10 page 10-39 shows a distance of 12" below boiler water line to the top of pipe with check valve 6.
- Is there a critical distance from the boiler water line to the top of pipe with check valve 7?
- Is there a critical distance from the top of pipe with check valve 7 to the top of pipe with check valve 6?
- Is there a critical distance from the top of pipe with check valve 7 to any other point in the system?

Steamhead

Most Vapor systems

should not be operated at more than 8 ounces or so. Replacing the Pressuretrol with a Vaporstat will make this possible.

Tell us more about the system- Who made it? Does it have traps? Water seals? Orifices? Post pics if you can- we love this old stuff!

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

ta finnegan

System pressure

You need to give us the connected load in EDR. We also need the size of the mains. The length of the longest run (approximate length, width and height of the building helps too)

From there we can back into whether it was designed for a 1 or 2 oz pressure drop. Usually 2 pipe systems were designed for 2 oz.

Figure out the longest run and double it. Divide by the one or two oz. figure. Then double that. That will be your cut in pressure. Cut out will be no more than 1 psi more.

Sounds complex, it's not.

Give us the details and we'll help you fill in the rest.

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