steam boiler pressure low?

lina

I have a 2 fl house with a Weil Mc-lain EG 40 gas boiler. The last room on the 2nd fl has a cold radiator. Bleeding the radiator works for a few days then it is cold again. Changed the air vent valve and bleed the rad again, it worked for 5 days then got cold. Bleed the system again and again, it works for a few days then it is cold again. I believed it was due to the pressure( 2 psi) being low. But I was informed at another website that the pressure was not the problem. I was referred to come to this site from steam forum. Can anyone help?

Barbarossa

1) IS THE PRESSURE GAUGE CORRECT.
2) IS THE FALURE TO HEAT THE UNIT RELATED TO LOW OUTDOOR AIR TEMP.
3) ARE THE PIPES INSULATED?
4) ANY NOISE IN THE PIPES (A WATER PLUG).
5) WITH THE VALVE OUT IS STEAM AT THE TAPPING, DONT BURN YOUR SELF.
2PSIG SHOULD BE MORE THEN ENOUGH

Steamhead

If the last radiator is cold

the vent at the end of the steam main probably isn't big enough. It is this vent that gets steam to the end of the main quickly, before it starts to rise to the radiators.

Measure the length and diameter of your steam mains and tell us what vents are on them. If they have old insulation, measure its outside diameter without disturbing it and subtract 2-1/4 inches to get the likely pipe size. With this info we can tell you what you need.

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RonWHC

Ahem.

Is this a steam or hot water heating system? Most folks I know "bleed" hot water radiators? If it is hot water, 2# won't do.

lina

cold last room of the house

lina

cold last room of the house 2

the boiler uses hot water to heat the radiator in the house. When I bleed the radiator hot water comes out and it works for a few days and stops. Changed the air vent valve to a size D. So it is probably steam with hot water. The pressure gauge reads 0-2 psi., but the steam pressure limit control was set low. Had it increased to 5 psi and the heat is working for now for 2 days. Hopefully the room will remain warm.

David Efflandt

So is it water or steam?

If it is hot water, 2 psi would not even get it to second floor, and 5 psi would only lift the water 11.5 feet above the gauge (unless pressure goes up when boiler is on). The boiler would be totally full of water with a temperature control, there would be an expansion tank somewhere on the piping, and there would usually be one or more circulating pumps (unless a gravity system).

If it is hot water and you are using a D air vent (intended for steam radiator) and such low water pressure, that could certainly explain how air gets into the radiator.

If it is a steam system, you should not be getting water from a vent on a radiator and 2 psi would be enough to push steam hundreds of feet. Unless the boiler was overfilled, there would be a water level in the boiler sight glass, a pressure control (Pressuretrol or Vaporstat), and usually no pump.