has anyone had to put dual lwco on residential steam

walt_2

Inspector wants dual hi pressure and LWCO's on residential steam boilers for Mi code. Whats the best way to accomplish this on a Dunkirk boiler. Has probe type standard connected to a feeder, so I can put another one on the sight glass like a MM 67m with a manual reset but how will they work so its not tripping off the manual reset one in the middle of the night. Is there a better way to accomplish this and does anyone else have to use dual LWCO's on smaller steam boilers. There is not much water level to work with, like on a biger commercial boiler.

John T_2

Burner control

Hi Walt, From Michigan also. Is the inspector asking for a manual reset? All I think would be required is that the secondary controls be in series with the primary controls so that any of them will break the burner circuit. Only one of the controls would control the feeder or the burner cut-in.

Manual reset seems like it would be problematic.

tim smith_2

redundant lwco

yes, here in Seattle it is required. auto and manual reset lwco and pressure controls. Both comm & resid.

Unknown

We have to use both

on commercial boilers only . Heres a pic of a Peerless we recently installed . I assumed that it wouldn't be checked weekly by the tenants , so we used 2 probe LWCOs , the lower one is a manual reset . We also used 2 pressuretrols with one a manual reset . I like to come out of the boiler on at least a 3/4 inch tapping for the pressuretrols so they do not get clogged with gunk in the future .

We also use a combo 67 and a manual reset probe LWCO , just make sure the probe is low enough to not be tripped before the 67 can shut the boiler down . And when we use this combo , we let the 67 control the auto feeder . I am not familiar with the newer Dunkirk model , but most modern steam boilers have appropriate tappings for this scenerio . Good luck Walt .

Mad Dog

Yeah I think he wants, 2 pressuretrols

an operating one and a high limit with reset (usually only required commercially). Irrespective, I like 2 lwco's as well...a probe and a manual - doubly-safe. My own boiler has it and when my customers want the best they get that and a fire sprinkler head. Mad Dog

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David Efflandt

home boiler has 2 LWCO

Bryant boiler that came with my home (IL) has regular McDonnell PS-802 (which also works boiler makeup), and a McDonnell GuardDog RB-120 mounted lower on horizontal L pipe attached behind sight glass.

It appears that the RB-120 supplies main power to the transformer and would knock everything out if it got that low. There is no manual reset, other than having to add water if it remained low.

I am not aware of any secondary pressure switch.