aidan
Structural
- Jul 25, 2002
- 2
I’ve got an old run-around-coil heat-recovery system, which is handling about 12 cu m/sec of air. Heat is extracted from the exhaust air streams with 4-row coils and the water is pumped to 6-row coils to heat the supply air. The system seems to recover about 50% of the available heat, when it runs in winter.
The original system had a ‘summer cooling’ mode that cooled the air with cold water pumped through the supply coils from a cold water storage tank. I abandoned this feature because it is now illegal and was never a good idea.
The problem is that, because the system once handled domestic cold water, all the existing pipework is galvanized. It has always been filled with plain water and the supply coils have frozen several times. I now want to put anti-freeze into the system. I understand that the usual anti-freeze mixtures (ethylene or propylene glycols) will usually have di-potassium phosphate corrosion inhibitor, which will react with the zinc.
Can anyone suggest any different antifreeze solutions which are compatible with the zinc, or will I have to replace all the old pipework? I tried a couple of large chemical suppliers, but they were not helpful. Any other bright ideas would be welcomed.
TIA
The original system had a ‘summer cooling’ mode that cooled the air with cold water pumped through the supply coils from a cold water storage tank. I abandoned this feature because it is now illegal and was never a good idea.
The problem is that, because the system once handled domestic cold water, all the existing pipework is galvanized. It has always been filled with plain water and the supply coils have frozen several times. I now want to put anti-freeze into the system. I understand that the usual anti-freeze mixtures (ethylene or propylene glycols) will usually have di-potassium phosphate corrosion inhibitor, which will react with the zinc.
Can anyone suggest any different antifreeze solutions which are compatible with the zinc, or will I have to replace all the old pipework? I tried a couple of large chemical suppliers, but they were not helpful. Any other bright ideas would be welcomed.
TIA
