Time to change the main vents?

Mark_126

Hi all,

We recently moved into a 1500sq ft house with a single pipe steam system installed, 7 radiators on the first floor and another 5 on the second floor. I bought Dan's book 'We Got Steam Heat' and have systematically followed his recommendations over the last month or so.

- insulated pipes in the basement
- replaced spitting radiator vents
- lowered the pressuretrol as low as it will go with a 1 psi differencial
- evacuate the low-water cut-out sensor regularly
- checked the pitch on all radiators

The near boiler piping looks original with a single riser splitting off to two feeds. Both feeds head out 10 ft then make a 90 degree turn. Feed one continues 20 ft, makes another 90 then has a main vent about 5 ft from the turn. Feed two also continues 20 ft but has the other main vent at the end of the pipe.

The Thermostat is set to 71 when we are in the house and a setback of 66 while we sleep and when we are at work.

My question is what should I do next to address this problem:

- When recovering from setback the boiler pressure will increase to 5psi then cut-out. As soon as the pressure returns to around 0 the boiler will then cut back in and increase again to 5psi. This cycle will continue until the thermostat is satisfied. Once the temperature is reached, the system seems to be working effectively with relatively few heating cycles per hour. As far as I can tell it is not short cycling.

- during this time all the radiator vents on the second floor will hiss loudly (although do not appear to be venting steam)

Should I replace my main vents? One of them looks like a newer Gorton vent, the other looks like a big silver bullet.

Thanks in advance.

nicholas bonham-carter

replacing main vents

check your main vents with the "open pipe" method: put ball valves on in place of the main vents, open the valves, fire the boiler. when steam appears, close the valve and make a note of the time-this is the fastest venting you could have. replace the vents [maybe right on top of the ball valves, and refire, to compare the difference. i would guess the difference should be no more than 10 minutes, and both returns should be hot at the same time. don't make the mistake of using bigger radiator vents to compensate for slow main vents-it won't work!

what definitely seems to need replacing is your pressuretrol, with a vaporstat. your pressure should be no more than 1.5 psi, and under 12 ounces is even better. vents cannot do their job at pressures higher than 2 psi, and may become permanently dammaged.--nbc