Posted by Harold Kestenholz - Hydronic Network on June 18, 2001 at 14:48:28:
In Reply to: Stop! Don't listen to Harold this one time posted by Tarzan on June 18, 2001 at 10:06:08:
This is an ongoing debate. The most interesting part of the debate is the worry about using the low water cutoff. The same person in talking about a steam system and recommending to blow the steam LWCO down to make sure it works - will be shy about using a LWCO in a water system. Water systems above the boiler tell you long before the boiler runs out of water by bubbling noises. A water system below the boiler should have two low water cutoffs - not rely on the pressure reducing valve to make up for leaks that can damage the house on a sudden break or freeze-thaw. Thus the PRV manufacturer tells customers to follow their advice.
True, the LWCO is not an operating control - it has never been advocated as such, but neither is a pressure reducing valve. The operator is the limit and thermostat. Do add safety devices.