I have just bled out the radiators to my hot water boiler. When I got to the last radiator upstairs, nothing came out. A lot of air, then nothing. I checked the pressure on the boiler and it read about zero. I turned on the system and the pressure went up to about 18 psi, that's about where it always is. After the system turned off the pressure returned to zero. Now, I am pretty sure the system always had pressure to it before when the system was not running. What happened when I bled out the radiators and how do I correct the pressure. I have a Burnham 2A series I believe. This is a gas fired boiler. My radiators upstairs never seemed to get real hot that is why I tried bleeding them. I did bled all in the house too.Thanks for your time and any help. :)

This is a little unusual, but my guess is this. Your pressure reducing valve is not functioning you should have 12 psi cold with the pump off. When you turn on the pump, my guess is this is in the basement of a 2 story house, the pump pushes a water column up to the second floor. The static pressure of this water column is what the gauge is showing you.

Yes, the boiler is in the basement. And if I remember correctly, the psi when off, was around 12. So, what happened and how do I correct it? And how quickly should I get this fixed? It is supposed to be upper 20s tonight. Thanks for you time.

You have to get the pressure up to 12 psi and the upstairs radiator bled or you will have no heat up there. I hate messing with pressure reducing valves. Most popular one used is a Bell and Gosset #67 pressure reducing valve. It has a filter screen that may be plugged. The reason I hate them is when you get them to let in water half the time they won't close all the way and it will overfill the boiler and the next thing you know the pop-off is letting lose. Good luck.

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Originally Posted by zoso43512

I have just bled out the radiators to my hot water boiler. When I got to the last radiator upstairs, nothing came out. Alot of air, then nothing. I checked the pressure on the boiler and it read about zero. I turned on the system and the pressure went up to about 18 psi, thats about where it always is. After the system turned off the pressure returned to zero. Now, i am pretty sure the system always had pressure to it before when the system was not running. What happened when I bled out the radiators and how do I correct the pressure. I have a Burnham 2A series I believe. This is a gas fired boiler. My radiators upstairs never seemed to get real hot that is why I tried bleeding them. I did bled all in the house too.Thanks for your time and any help. :)

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I have a fully pumped system with an open expansion tank.
My pump sounds like it is sucking air into the system when on medium and high speed and I have lots of air in the rads, which I have purged.
But when on the lowest speed it does not let air into the system though the rads take a lot longer to heat up and the bottom of some of the rads stay cold.
Is this a faulty pump?
Warm Front

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Originally Posted by warm front

I have a fully pumped system with an open expansion tank.
My pump sounds like it is sucking air into the system when on medium and high speed and I have lots of air in the rads, which I have purged.
But when on the lowest speed it does not let air into the system though the rads take a lot longer to heat up and the bottom of some of the rads stay cold.
Is this a faulty pump?
Warm Front

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No, the pump sounds like it is working fine. You have air in the system.