New system design w/old pex

[sdrobertson]

I'm inquiring about the use of pex tubing that is not the O2 barrier type. I installed my pex years ago for use with a OWB and I'm now switching to a closed system. I have approximately 160 feet(80 feet times 2 lines) of 3/4 inch pex installed in the ground and into my basement that is not losing any heat so I really don't want to replace it. My question is with 2000 gallons of pressurized storage - how much O2 will the lines gain. I see two ways to deal with the problem. The first would be a plate hx and use another circulator. The second would be to monitor the water and use more chemicals. Is the amount of O2 that will enter the system through the pex line be controllable with chemicals?

 

[Nofossil]

I'm inquiring about the use of pex tubing that is not the O2 barrier type. I installed my pex years ago for use with a OWB and I'm now switching to a closed system. I have approximately 160 feet(80 feet times 2 lines) of 3/4 inch pex installed in the ground and into my basement that is not losing any heat so I really don't want to replace it. My question is with 2000 gallons of pressurized storage - how much O2 will the lines gain. I see two ways to deal with the problem. The first would be a plate hx and use another circulator. The second would be to monitor the water and use more chemicals. Is the amount of O2 that will enter the system through the pex line be controllable with chemicals?

I have no idea about this one. I know that my brother bought a used wood boiler and ran it as an open system. He got ten years out of it before it rusted through. I really don't know how much oxygen gets through non-barrier PEX, especially if it's buried. I don't think you can control the incoming oxygen, but I think you can reduce the resultant corrosion with chemicals. A dissolved oxygen test would be handy - I wonder if such a thing is readily available?

 

[steam man]

I'm inquiring about the use of pex tubing that is not the O2 barrier type. I installed my pex years ago for use with a OWB and I'm now switching to a closed system. I have approximately 160 feet(80 feet times 2 lines) of 3/4 inch pex installed in the ground and into my basement that is not losing any heat so I really don't want to replace it. My question is with 2000 gallons of pressurized storage - how much O2 will the lines gain. I see two ways to deal with the problem. The first would be a plate hx and use another circulator. The second would be to monitor the water and use more chemicals. Is the amount of O2 that will enter the system through the pex line be controllable with chemicals?

I have no idea about this one. I know that my brother bought a used wood boiler and ran it as an open system. He got ten years out of it before it rusted through. I really don't know how much oxygen gets through non-barrier PEX, especially if it's buried. I don't think you can control the incoming oxygen, but I think you can reduce the resultant corrosion with chemicals. A dissolved oxygen test would be handy - I wonder if such a thing is readily available?

I am not really sure how much O2 will get in your system. I've done boiler test for just about everything. Though dissolved O2 can be measured the more typical way is by a chemical test to measure the amount of O2 scavenging chemical residual in the boiler water. That infers a lack of O2. I am not sure of the cost of the chemical-one caveat: the chemical is probably nasty to handle. I am not sure what is available for residential use.