New Steam Boiler: Draining Low Water Cut-off

Unknown

Speaking on behalf of Burnham Corp. of which New Yorker is a part of, we would advise as follows. If your boiler is equipped with a McDonnell Miller #67 low water cutoff, then weekly blow down is advisable. The purpose of this is to clear the float chamber of any sediment or debris that has accumulated so that the float can drop and activate the switch in the event of a low water condition. The instructions for this procedure should be on a placard on the jacket of the boiler near the low water cutoff control. Manual filling of the boiler will be necessary to ensure that the proper water level is acheived as most auto fill devices will only maintain minimum permissable water levels.

Various geographical marketing areas will request different types of low water cutoff controls. While most steam boilers are equipped with "probe type" low water cutoff controls, some areas still prefer the "float style" #67 control. The probe type controls require little maintainance and do not require the weekly blow down. These help keep makeup water usage to a minimum which will aid in prolonging the life of the cast iron section assembly. Generally our eqipment is shipped with the probe type control unless otherwise specified per your marketing area. Hope this helps.

www.newyorker.com

Glenn Stanton

Burnham Corp.

Dietrich

Draining Low Water Cut-off in New Steam Boiler

My plumber replaced my old conversion boiler(from oil to gas) with a new gas-fired steam boiler(New Yorker).
He instructed me that I must drain the low water cut-off every seven days in order to trigger the boiler to automatically adjust the water level.
When I stated that I never had to do this with my old boiler(it was about 40 years old), my plumber stated that ALL steam boilers required this process.
This means that someone must always be available to perform this process in my absence(vacations, business trips etc).
My questions are as follows:
1) Is it true that all steam boilers require the weekly manual draining of the low water cut-off
2)If there are boilers that can do the process automatically, should the plumber have related this info to me so that I could have made a informed decision about what kind of boiler to have installed?
I will appreciate any wisdom anyone has to offer.

Joe Grosso

OK Dietrich
I am assuming that your plumber installed a 67 low water cutoff on your new steam boiler.If this is correct you should flush it once every 7 to 10 days as your plumber has said.Your second question answer is you could have had a probe type low water cutoff installed that you would not have to flush every 7 days.If it was me I do install dual low water cutoff on all of my installs and give the option to the homeowner as to which type they want. But that is me.Should have had a steam specialist install your system as most NOT ALL plumbers are not heating men.JMHO please do not jump on me guys:)

Bob Bona_4

your

guy is right. Steam systems are a "hands-on" system. Think pot of boiling water on the stove...shouldn't leave unattended. The idea of regularly flushing the LWC is not to reset the water level, it is to flush the LWC chamber, and ensure that the LWC shuts down the burner. Your old boiler should have been done like like that as well. You have been blessed with luck.

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[Deleted User]

who do you think put in all those old

steam systems hummmm.

John@Reliable

LWCO Flushing ! must disagree with all posts

Dietrich, The only reason to flush the lwco is to keep the sediment chamber(dirt pocket) clear in the event the boiler runs out of water,Most systems only need this done monthly during the heating season.Why? Doing this weekly will increase the amount of sediment.Also by adding fresh water this offen is the kiss of death for todays steam boilers.Even when done monthly just take out what is needed for water to run clear and have lwco and feeder serviced yearly and enjoy that boiler for the next 40 years! P.S. if it takes more than 3-4 gallons to make it clear try it every 3 weeks,anyless than this I would have system piping flushed and checked in the spring. Hope this helps

Edward A. Carey

LWCO

John,

If you tell your customers that a LWCO only needs to be flushed once a month, and the manufacturer states that it should be done once per week, you are really sticking your neck in a noose.

We all are required to do service in compliance with "accepted industry standards and practices". If the manufacturer states a protocol that "they want done with a LWCO" , that protocol establishes the "industry standard".

If you do something different, you are on your own, if that boiler "dry fires". Best case if the boiler dry fires, the boiler is destroyed, worst case the home is.

On a different note, no one has told Detrich that a LWCO must be flushed with the boiler operating, and under full steam pressure. To flush it with the boiler on, but not under full pressure will fail to circulate steam and water up into the float chamber, and therefore you will not adequately clean the float & bellows assembly in the LWCO.

The manufafturer of a McDonnell & MIller #67 requires that ALL float chamber type LWCO controls be flushed once per week, with the boiler on and at full operating pressure. The burner (gas or oil), must shut off immediately when the control is flushed. The LWCO must be disassembled and completely cleaned once per year.

Given that the installation manual for all new #67 LWCO state the above, I e-mailed MM to check if the blow down protocol was applicable to all. They responded to me that ALL LWCO controls (regardless of age) must be maintained in compliance with their most recent manual.

Also, I totally agree with Joe about 2 LWCO. I wish it was mandatory to install 2 LWCO controls on all steam boilers.

Regards,

Edward A. (Ed) Carey

[Deleted User]

i agree

i bring in the MM book and show the customer where it says to do the blow down weekly, it also allows me to show them where the manufacturer says to replace the unit every ten years. this way they know i am not blowing smoke up their butt when i tell them its time for a new unit.

Unknown

Anyone into using 2 probe LWCOs ?

We run into jobs where the homeowner is elderly , and the trek down the stairs for them can get dangerous . What about using 2 probes with an auto feeder with the built in delay ? As long as the probes are cleaned every year , and the water level is maintained at the proper height , any downside to it ?

Bob Bona_4

thanks

for clarifying that the burner should be running when flushing/testing the LWC, Ed. I shoulda been more specific.

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Bob Bona_4

I

would say that the water level would still need to be set to that boilers NWL. The auto feeder is just a safety item, to keep a minimum of water above the LWC..we hope,anyway..

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Unknown

Most new steam boilers

come with a tapping right at the water line for a probe to be used as a primary LWCO . What about tying in the feeder to that , and using another probe in a lower tapping as a backup ?

John@Reliable

Ed, I'm just going by what

Burnham has in there Installion,Operating and Service Instructions. I'm sure M/M is covering thier butt. Just like watts with the autofill, fastfill, I mean pressure reducing valve being shut off after filling.But I also know I replace allot of newer steam boilers way before thier time and wonder about oxygen being added at this time of blow down? They state that frequent water addition can SIGNIFICANTLY shorten the life of the boiler. Excessive water they say is only six gallons per month for an V83,so 5 gallons aweek for blow down is way over thier limits,true so what to do? I guess install a probe type lwco to avoid this problem John@Reliable

Edward A. Carey

LWCO Blow down

John & all,

I was a bit blunt about the LWCO blow down issue. I was not trying to criticize John's opinion, I was just setting forth my thoughts. After reading my own post, I percieved it as a bit condesending. I dislike it when others do that, and I did not like the tone of my own post when I did.

I follow this forum on a daily basis, but I rarely post. However, I do see John respond to many posts, and he gives good solid advice. This forum is fortunate to have his input. John, I apologize if my post was offensive. I did not mean it that way.

As far as the boiler failures, I actually see many more steam boilers see the end of their days due to LWCO problems, that from excess make up water. (Excluding issues of failed underground returns or poor steam vents). But others may have a different experience. That is why I was so pointed on the LWCO issues.

John has raised a very good point. If a boiler manufacturer sells a boiler, and they require limited and specific quantities of make up water, that requirement sets a standard for their boiler. However, if they sell the that boiler with a LWCO that requires a blow down protocol, that ultimately requires more than their recomended minimum make up water, we have a paradox.

I think that maybe our friend here, Glenn Stanton, may be able to shed some light on Burnham's opinion on this topic. Also, any other co rep opinions would be appreciated.

Regards to all,

Edward A. (Ed) Carey

Edward A. Carey

Running boiler

Bob,

The boiler must be running, but the steam pressure is the key to a proper blow down. They system must be up to full operating pressure.

If the boiler is running, but has not yet generated steam, a blow down will only flush the very bottom of the chamber, Hopefully the burner shut down, but it will only be tested at that "moment".

If you look at a #67, it has several different angles built into the shape. If you look where the 1/2" pipe enters the side of the control, it is well below the elevation of the float and bellows, in the top of the control.

If the conrol is flushed with the burner off, or with the burner running but no steam pressure, water will enter the control through the pipe, and flow by gravity directly out the bottom of the control, without ever touching the float chamber.

However, if the control is flushed with the boiler at full steam pressure the water under steam presure will enter the control, and flow directly to the opposite side. The angle of the sides of the contol and the slight incline on the top of the control will divirt the flow of the steam and water to circulate throughout the float chamber, and flush the entire chamber. Also, steam pressure will enter the top of the control through the tube entering the top of the control, breaking loose corrosion that may adhere to the top of the float.

One more thing, then I'll get off my LWCO soap box, (Smile). As per the original post starting this thread, a LWCO should be flushed more ofter when a new boiler is installed on an existing steam system. McDonnell & MIller requires that a LWCO on a new boiler be flushed 2 to 3 times per week, for the first week, and then once per week thereafter.

Regards,
Edward A. (Ed) Carey

Unknown

Good post, Ed.

Solid information.

Noel

John@Reliable

Ed, I did not take

your post as offensive.