I need to get an air compressor to purge the pipes in my house of water before winter so that the water doesn't freeze while I am away. There is not a common low pipe in my house, so I need to use an air compressor. Does anyone know how much psi and cfm I need from a compressor in order to make this work.Thanks,Eric
You could do this job with just 10 or 20 pounds of pressure, if that's all you had. If you drain your waterheater first, the amount of cubic inches of pipe space has to be trivial. I think just about any air compressor you get will work here, as long as it's not one of those little battery operated ones for cars, and that might even work, if you had a good connection and were patient.
The piping in a domestic forced hot water system is designed to operate at around 15 psi. The copper pipes will hold 60 psi with no problem. You need a fairly decent flow of air to blow the water out successfully. The CFM is what you need, in other words volume. that said one of those small air compressors will absolutely not work. A small pancake compressor will work if you allow the tank to fill up and then release the air into the system to to blow the water out. The pump itself takes a while to compress the air and then relase that volume to blow the water out. As you suggest, drain as much water as possible, then use the compressor. If you are going to rent a compressor you will be best served to rent a gas powered compressor as they have a quick recovery high cfm rating. Keep in mind you do not need to blow all the water out but you must get it out of any low lying pipes or elbows. I once blew a house out that had a section of pipe that could not be evacuated. I could blow the section out, but water would gravity feed back to that area. I cut that pipes lowest point and installed a spigot. that may not happen to you, but keep it in mind. When you apply an air source to the system make sure to set teh regulator to 70psi max. if the pressure is allowed to build to 120psi which is teh normal high shutoff, it may blow a line or worse, effect teh boiler or its hardware. After the system is drained it is a good idea to set the pressure in the expansion tank to 12psi while you still have teh compressor in the area.
You could do this job with just 10 or 20 pounds of pressure, if that's all you had. If you drain your waterheater first, the amount of cubic inches of pipe space has to be trivial. I think just about any air compressor you get will work here, as long as it's not one of those little battery operated ones for cars, and that might even work, if you had a good connection and were patient.
The piping in a domestic forced hot water system is designed to operate at around 15 psi. The copper pipes will hold 60 psi with no problem. You need a fairly decent flow of air to blow the water out successfully. The CFM is what you need, in other words volume. that said one of those small air compressors will absolutely not work. A small pancake compressor will work if you allow the tank to fill up and then release the air into the system to to blow the water out. The pump itself takes a while to compress the air and then relase that volume to blow the water out. As you suggest, drain as much water as possible, then use the compressor. If you are going to rent a compressor you will be best served to rent a gas powered compressor as they have a quick recovery high cfm rating. Keep in mind you do not need to blow all the water out but you must get it out of any low lying pipes or elbows. I once blew a house out that had a section of pipe that could not be evacuated. I could blow the section out, but water would gravity feed back to that area. I cut that pipes lowest point and installed a spigot. that may not happen to you, but keep it in mind. When you apply an air source to the system make sure to set teh regulator to 70psi max. if the pressure is allowed to build to 120psi which is teh normal high shutoff, it may blow a line or worse, effect teh boiler or its hardware. After the system is drained it is a good idea to set the pressure in the expansion tank to 12psi while you still have teh compressor in the area.
All the answers are OK. In fact you don't need to get all the water out, you just need to have more air or space so the water in the pipes can expand. This is what causes the pipes to burst. You could also try a wet-dry vacuum and suck all the water out. As said before drain the water heater first and then go outside and shut off the main open all the the valves in the house hot and cold go outside and use the wet vac at the hose connection. This should also work.
All the answers are OK. In fact you don't need to get all the water out, you just need to have more air or space so the water in the pipes can expand. This is what causes the pipes to burst. You could also try a wet-dry vacuum and suck all the water out. As said before drain the water heater first and then go outside and shut off the main open all the the valves in the house hot and cold go outside and use the wet vac at the hose connection. This should also work.
