Good Morning,

I have a newer boiler system-1998 in a 2 story house, (but it still has an old style expansion tank).

I have 15lbs pressure reading on the gauge, but I do not have any heat in 2 radiators on the top floor. I have tried to bleed, but little or no air is coming out of the bleeders. Valves are turned on!

In a previous post it was mentioned that you can increase the water pressure to help bleed the system. I am hoping this could help my situation, but I don't know where the "pressure adjustment" is and if it is the right thing to start with.

I also wanted to know if there were any special techniques in bleeding the rads? Can I open more than 1 valve at a time? Does the boiler need to be on-running while I do it?

Thanks,

To bleed air the boiler should be running. You should be able to hear air comming out as you bleed.
Your 15 pound setting should be OK.
Your pump could havre a bad impeller.
Try running the boiler then bleeding and post back.

Thanks.... I turned open the bleeder with the boiler running and had air for a few seconds but then it stopped. I closed and reopened- same result. Still no heat from rad. Should I hear the air until water starts to come out? If so, this is not happening.

Actually the air noise should be present as it vents.
if you cannot get the air out the system pressure might have to be increased.
When was the last time this system was serviced?

I had the system serviced 2 yrs ago... it was cleaned and the expansion tank drained...too full. About the impeller the motor sounds quiet,e g. no weird noises!

I would like to turn up the pressure a little so that I can see if it will cause more air to vent however I am not familiar enough with this specific system to know how to adjust it.

BTW, is it a problem if I try to bleed two rads at the same time?

Thanks again,
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You should only bleed one at a time and you might have to bleed them more than one time. There is a pressure reducing valve in the fill water line. It may have a fast fill lever or a adjustment screw locked by a nut on the top of it. many are red in color. Turn screw down to increase pressure but just a 1/2 turn at a time and then see what the gauge reads in a few minutes.
if it has a lever just raise it for a second to all a bit of water into the boiler. You do not want to go over 20 pounds for testing purposes.

If this fails call for service. BTW you might also isolate the expansion tank and drain. Once drained do not forget to open the isolation valve back up. The isolation valve prevents water from going into the tank while you are draining it. Try draining the tank first then if that does not work do the add pressure thing.