Boiler Low-Water Cutoff

Originally Posted By: roconnor
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I am used to seeing a low-water cutoff for boilers, and it’s required by 2000 IRC M2002.2


I was recently helping a friend, who is an HVAC contractor, install a gas-fired hydronic boiler. He asked me if a low-water cutoff was still required. One did not come with the unit, and the installation instructions stated it was only required if the radiators were below the unit (not even shown on the installation piping diagrams). The boiler did have a built in high-temp shutoff.

Does anyone know if the thinking/requirements on boiler low-water cutoffs are changing?


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: jsavino
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Rob


A L.W.C.O. is still required on all steam systems, replacement or original install. Just the types of L W C O have changed. They are wire into the boiler circuit before the burner relay, but after the auto feeder if equipped.



John Savino


HomeWorks Inspection Services, LLC


St. James, NY


631.379.4241

Originally Posted By: jsavino
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Also the control is not included in the boiler package when purchased.



John Savino


HomeWorks Inspection Services, LLC


St. James, NY


631.379.4241

Originally Posted By: roconnor
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This was Burnham water/hydronic boiler. I am curious now if it has an internal LWCO.


I am used to seeing the external LWCO's, and thats what the instructions indicated needed to be installed if the unit was above the radiators. Strange that an external LWCO would need to be installed in that situation, if the unit has a built-in LWCO. Possibly an additional "recommended" safety shutoff, since low water might be more likely with the unit above the radiators?

Or did ya mean all new steam boilers must have an external LWCO?


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: jsavino
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Sorry Rob,


I misread the question. On a hydronic it is not required on residential boilers. I wouldn’t be surprised that they will be required in the near future. When I installed either steam (required) or hydronic I always installed along with a manual reset aquastat set at 220 degress as an extra safety. I’ve seen too many hydronic boilers crack due to the feed valve not feeding the boiler and the boiler gauge was stuck on 20 #. I would recommend one every time.


Mcdonnell/miller manufactures both external for steam and electronic for water boilers.
No boiler has a internal LWCO

As far as being installed if the boiler is above the radiators?
If you had a leak in the piping, the boiler could drain down from the return lines, because they would be lower than the level of the water and the boiler will dry fire.


--
John Savino
HomeWorks Inspection Services, LLC
St. James, NY
631.379.4241

Originally Posted By: roconnor
This post was automatically imported from our archived forum.



2000 IRC ... wrote:
M2002.2 Boiler low-water cutoff
All steam and hot water boilers shall be protected with a low-water cutoff control

I just found it curious that the manufacturer's instructions only required the low-water cutoff where the unit was above the radiators. Makes sense, but I am surprised the instructions were not consistent with the model codes.

My HVAC contractor friend indicated the instructions used to always call for one to be installed, and now reads a little differently.


--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: jsavino
This post was automatically imported from our archived forum.



Rob,


You got me curious, so I just checked the installation manual on my boiler. I installed my boiler 10 years ago. (Peerless WBV04)


The manual shows the installation of a LOWC in the wiring diagram. They call it "Additional Safety Switch (when required)" But it does not mention a LOWC to be installed on a hydronic boiler. On steam, it gives you two location, either for a probe style or float type LOWC.

It would seem to me, that manufactures have to meet a standard, not a code.

Don't forget, there are more tapings in a cast iron boiler then a steel boiler. Making it more versatile.


--
John Savino
HomeWorks Inspection Services, LLC
St. James, NY
631.379.4241