We have a 630hp 140lb Blr, when performing low water cutout test, after it cuts out and when refilling the boiler restarts up at idle. I think it is required to be reset but our chief disagrees. 

Your boiler is required to have 2 low water cutouts.  One may be included with your pump control and the other must be installed in another water column and be set at a lower level than the first one.

If you are talking about the 2nd low water cutout, then it must have a manual reset, so it shouldn't start back up by itself at all.

CSD-1 (ASME “Controls and Safety Devices” ), section CW-140; Requirements for Water Level Controls for High-Pressure Steam Boilers, part “b” states:

“Functioning of the lower of the two controls shall cause safety shutdown and lockout“

Although I'm not aware of code that specifically covers the issue, if you are testing the higher of the two cutouts (typically included in the operating float), then I believe the boiler can start back up automatically and having it start at low fire would make sense.  I will ask Joel to check this post over to see if he agrees with this.

If you need to buy a low-water cutout that includes a manual reset, let me know and I will get you a quote.  We are a McDonnell & Miller distributor.  We just don't have many of those entered into our web store yet.  We are typically the least expensive distributor by a pretty comfortable margin.

Reed

Excellent response Reed.  I couldn't have explained it better myself. 

The first LWCO may reset automatically, but the second must cause a shutdown and lock out.

Thanks,

Joel T. Amato

Chief Boiler Inspector

One of the low water cutouts must be of the manual reset type.  This means that if both low water cutouts have tripped/activated then your boiler must be manually reset before it can start.  If the low-water cutout without the manual reset capability trips but the other control does not it is OK for your boiler to start back up on it's own.

Basically:

*Your boiler can not restart itself if the low water cutout with the manual reset is tripped regardless of whether the other one trips or not.

*Your boiler must have at least one low water cutout with a manual reset.

*If "the lower also becomes involved" means the lower cutout trips, then no, you can not have your boiler reset itself in this case.

Does this answer the question, or am I not quite understanding your question?

-Reed