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Posted by T Bender on December 08, 2010 at 12:30:04:
In Reply to: Re: M&M LWCO #67 posted by HeatPro on December 08, 2010 at 10:28:19:
: It's a simple float-operated switch that cuts off the burner power when the float falls low, and reestablished the power to the burner when the water rises enough in the body of the 67 control.
: If a feed water solenoid is wired to open when the water falls, it usually overfills the system, as steam cycles often leave steam in the system to return as condensate water at a later time than when the control allows water in.
: Other auto-fill devices that would be attached to the 67 contacts involve a metered amount of water and a delay to prevent overfilling.
: Novices often believe an auto-fill device is a good idea; however, stuck valves or changed timings have the occasional fault of making a one-pipe system into an upstairs sprinkler system when the valve hangs open or keeps adding water on each cycle due to dirt in the radiators, piping, or failing vents.
I was playing with the rocker switch and just noticed that there seems to be a middle ground of the switch where both circuits are energized at the same time. I was always under the impression that its either burner circuit or feedwater circuit thats energized. I would imagine you would have to overlap a little to prevent the boiler from banging off as soon as you produce a little steam and the water level falls a little. It does seem hawever that the right way to do it is to monitor the sightglass and add water manually... as necessary. Thanks for the help.