House Radiator sucking air, low pressure on boiler

[diywannabedc]

Hi DIYers, I am having a problem with my house radiator system that I can't find an answer to - hope you can help. Boiler is in the basement. Main floor is heating fine. Upstairs only bottoms of radiators are hot. I am trying to bleed my radiators, and they improved it a bit. But now, it doesn't seem to have enough pressure - I get some air, but then it peters out before I get water. Now, some of the radiators are actually sucking air. I found the refill valve and added some water, but have no idea how much water to add. The pressure valve reads about 4 psi when off. How long should I open the fill valve? Should I bleed when hot or cold? How do I up the pressure - 12-15% is recommended, right? Thanks

 

[doitall]

Not sure what your talking about. makes me thing you're not in the UK.

What is the make/model of the boiler.

Normally a UK boiler pressure should be between 1-1.3bar.

 

[diywannabedc]

Hi Bath - No, I'm not in the UK, I'm in Washington, DC. But I think we have similar radiator systems - this is a Hydrotherm. Its pretty old and house is about 60 years old. I don't see an expansion tank on it. BTW, I added some water by the valve and 2 of my radiators had air, then water. I'm adding more to see what happens.

 

[spraggo]

Hi Bath - No, I'm not in the UK, I'm in Washington, DC. But I think we have similar radiator systems - this is a Hydrotherm. Its pretty old and house is about 60 years old. I don't see an expansion tank on it. BTW, I added some water by the valve and 2 of my radiators had air, then water. I'm adding more to see what happens.

Your system is probably fed by a water tank in the loft, if so check to see if it is about 1/3 full of water.

 

[doitall]

I think any advice we give is likely to be wrong, dangerous or a good guess.

Just keep topping it up till all the rads are full and leave it at that until you can get someone local.

 

[DP]

Merry Christmas John

 

[diywannabedc]

I see a tank (about 10 Gallons I think? ) right above the boiler but there is no way to tell how full it is. I added more water... hope thats the right thing to do. getting a little more air from the radiators upstairs, so seems to be working. Still worried about overfilling the system though.

 

[diywannabedc]

Alright. Thanks very much for the help though. Happy Holidays!

 

[spraggo]

I see a tank (about 10 Gallons I think? ) right above the boiler but there is no way to tell how full it is. I added more water... hope thats the right thing to do. getting a little more air from the radiators upstairs, so seems to be working. Still worried about overfilling the system though.

I`m suprised that the tank is not fed by its own water supply with a float valve, anyway keep adding water until all air is gone from the rads. Is it possible to drop a piece of string or tape into the tank to see what heigth the water level is?.

 

[diywannabedc]

No, its a sealed tank fed by one pipe. I'm adding more water. With heat on, pressure is now at about 12-14 psi. Seems to be working.

 

[doitall]

Merry Christmas John

Happy Christmas and a prosperous new year Dan.

 

[electronicsuk]

I`m suprised that the tank is not fed by its own water supply with a float valve, anyway keep adding water until all air is gone from the rads. Is it possible to drop a piece of string or tape into the tank to see what heigth the water level is?.

It's hardly likely to be an F+E tank if it's in the basement along with the boiler Probably just an expansion vessel.

 

[spraggo]

It's hardly likely to be an F+E tank if it's in the basement along with the boiler Probably just an expansion vessel.

Damn, I thought the law of physic`s had changed over there