FROZEN STEAM COILS: HOW DO YOU PREVENT THIS?
Even if you have steam coils or steam distributing (non-freeze) coil, you can still freeze the coil. When freezing occurs, everyone immediately looks to the steam coil as the cause. When in fact, there are numerous reasons that must be looked at well before the coil. Freezing generally happen in older systems, however if your new system is not maintained properly or correctly installed, your steam coil can and will freeze.
In a Standard Steam or Steam Distributing Coil, a freeze-up can occur when condensate freezes within the tubes of the steam coil. The two most common reasons for freezing steam coils are the steam trap and the vacuum breaker. The function of steam trap is to remove the condensate as soon as it forms. Condensate usually collects in the lowest part of the coil. If your steam trap is not sized properly or it isn’t installed properly, condensate will lay in the coil and it will inevitably freeze as soon as it sees outside air. Water expands when frozen leaving the coils subject-able to bursting. The vacuum breaker is also needed to rid condensate, minimizes water hammer, and equalize the coil. Don’t plug it. Install a goose neck and keep it clear from insulation.
Here are some tips that can help prevent your standard steam and steam distributing coils from freezing:
- Standard steam coils should NEVER see any outside air below 40 degrees F. Where OA is present below 40, you must go with a steam distributing coil
- 5/8” OD Steam distributing coils over 72” long are recommended to have a dual supply
- 1” OD Steam distributing coils over 120” long are recommended to have a dual supply
- 5/8” OD tubes should be the minimum for any steam coil application
- Pitch the coil. Some manufacturers pitch the coils core to make it easier to drain
- Always have a vacuum breaker
- Always have an air vent
- Always size the steam trap accordingly
- When in doubt, text Joey
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