air in baseboard

Dave_10

I currently own a house that has steam radiators in the main part of the house & hot water baseboard in a family room. The heat in the main part of the house works fine but the baseboard in the family room has a surging noise (like the circulator motor is looking for its prime) that you can hear in the pipes. The system has two flo valves (one on the feed & the other on the return line) that are turned down tight to prevent any loss of water in the system. I would pressurize the system and remove any trapped air in the line but it would return in a minute or so. It is an open system and has a Taco circulator motor that is new and is water lubricated. Any suggestions would be greatly appreciated. Thanks
Dave

TJ_2

Confused

You have a hot water loop on a steam boiler, right? Is the circulator pump below the water line of the boiler? I don't understand how you can have air trapped in a baseboard loop. It seems like it would be pushed out of the system in the course of normal operation.

Are the flo-valves working properly to prevent any backflow?

[Deleted User]

dave could you draw a schematic

and attach it to this post. it would help us help you. i'm trying to visualize what your system looks like in my mind. could you describe better what you mean by ''it an open system''. is it a loop off the steam boiler? is it fed by its own boiler?

Big Ed_2

a few thoughts

You could have a leak which will suck in air above the boiler wate line. You mentioned that you pressurize the system and removed the air ? Are there bleeders on the radiation or purge valve below the water line? The arrow on the circulator , is it pointing in the direction of the radiation ? Are you sure it air ? Is the circulator on a horozontal position.

P.S. Water "lubricated" circulators have a tough time with gritty condensate.....

Unknown

cavitation

It could be very hot water flashing to steam in the pump impeller. Open the bypass some more to get the temperature down a little. There is almost no pressure there to prevent flashing, so temperature control is the only way to prevent it.

Noel

TJ_2

Pumps for steam boiler hot water loop

So what kind of pump is recommended for a direct hot water loop off of a steam boiler. Currently, I have a B&G 100. I have a Red Fox iron in reserve because the 100 is showing signs of imminent death.

Unknown

Ive used many different pumps

Check with the pump manufacturer for application details. The B&G 100 has been a great pump, for me.

However, no pump will work well unless it is piped to prevent cavitation. To do that you must know what the pressure and temperature are at the inlet of the pump. Under a certain point, different with various pumps, the water will turn to vapor and cavitate. If your boiler is at 1PSI and at 215 degrees, and you feed that straight into the pump inlet, unmixed, the pump will cavitate.

Steam boiler water is gritty. All pumps can be expected to fail earlier than if in a clean, hot water system.

Noel