Trane Vacuum - plus newly added Vacuum Pump

kmh5147

Just as the title reads, I've recently been restoring my Trane Vac system back to its glory days and have made some major modifications. To start I've replaced all radiator valves to tighten up the system, which so far seems to have been a successful investment. Next, I've removed all of my Gordon vents and replaced them with 3x the original Trane vacuum quick vents and vacuum float vents (To serve as a backup to the vacuum pump). Lastly, I've piped into the dry return an Anver 4.3 hp dry rotary piston vacuum pump with a drier and a pair of differential vacuum controllers.

With all of this said, I just fired it up tonight and have been able to achieve 20 in hg after about 20 minutes of the pump running. Once the pump shuts down, I see a loss of about 2 in hg every 8 minutes or so, which I may be able to improve upon. I have a heatpump to serve my off peak loads so I have not fired the boiler yet, but the time is approaching.

These are my questions to those who might know more about vacuum systems:

What do you think is the max / best vacuum level based on my description would be for this system?

If I maintain the vacuum with the pump, and the system steams creating a natural vacuum as the steam condenses, do you think I will significantly add to the existing vacuum created by the mechanical pump?

Thanks in advance!

Kevin

nicholas bonham-carter

If there is any advantage to having a vacuum pump on your system, it would be the evacuation of air from the dry returns.
When the system is firing, without the pump, the steam will only push the air out of the radiators into the dry returns, before the trap closes. When the trap opens to let out the condensate, I wonder if the air in the returns, rushing into the lower pressure vacuum in the radiator will interfere.
One solution for this problem might be having the traps as far down the line as possible, just before the return piping might join up with other dry returns. That would reduce the amount of air in the dry returns. Alternatively, some sort of check valve could keep the air from rushing back into the radiator.--NBC

Charlie from wmass

If the system is properly installed and maintained there should be equal pressure, approximately, throughout. opening traps will only work if the mass of the water is a tipping point in the equation. The more vacuum the lower the heat output of the radiators as the boiling point of the water is reduced. As the weather gets colder the vacuum needs to be reduced to match the load to the point you begin to make pressure in your system in the very cold weather.