LWCO not working / Not typical use for boiler / ideas?

steam_in_my_house

Here's what I've got, any suggestions will be greatly appreciated.  



A friend of mine owns a bakery. He is using a steam boiler for 2

purposes, one is to heat a steam kettle, and the other purpose is he

simply opens up a valve to blast the oven with steam when making breads

(does wonders for the crust). He installed the boiler last year ( to

replace a 50 year very very scary boiler), and the bakery is a summer

only operation so at this point the boiler has really only been running

for about 20 weeks in total. Due to size limitations of where the

boiler is installed, and the fact that he doesn't need a large amount

of steam (he has a 62MBH / 158 sq ft/ steam installed), he is running a

residential gas boiler as he could not find a commercial product to fit

his needs.



He is aware that what he is using the boiler for is not what its intended purpose is.



He turns the boiler on, builds pressure up to about 12lbs (where the

pressuretrol high limit kicks the burner off), and then opens the valve

to flood the oven with steam.   Pressure drops, burner kicks back on, makes more steam, stream into oven, repeat)



Since this is an open ended system, no condensate ever returns to the

boiler. So at some point  the probe based LWCO (hyrdolevel cycleguard)

kicks off the boiler, the auto filler triggers, water enters boiler,

LWCO allows burner to fire again - make steam, steam into oven, repeat.)



The issue is at only 20 weeks of operation, the LWCO is not sensing

that the water has lowered pass the probe point and is not cutting off

the burner and triggering the auto fill.  The electronics minus the

probe appear to work fine (if I manually simulate the probe circuit,

the LWCO behaves as expected).  Ocasionaly the LWCO will work, but the

water in the sight glass is dangerously lower than the probe location. 

At this point he has an employee sit next to the boiler when they are

steaming and manually add water to the boiler as needed.



Could a dirty probe somehow fault in a way that would keep the circuit

indicating that there was water at or above the probe level? 



Also how long should a probe last.. when his boiler was working

properly, I spent an evening watching the boiler and counted that it

went through 8 LWCO cycles and the autofill added 16gallons of water. 

At my best guess, in one evening of operation at the bakery the LWCO

circuit and auto filler are running through essentially an entire

heating season worth of cycles.  Meaning in one week he is running 7

years of typical usage cycles, and in one summer season (10 weeks), 70

years worth.   That probe is constantly being exposed from water to

air, and up to 16 gallons of new city water everyday.  And the bakery

is located at a beach town, so the air has that great beach salt to it

that loves to rust and corrode everything.



Any ideas here? Do you think the probe is the issue?  Is there a

different type of probe that could be used that is designed for harsh

situations like this? Should he switch to a float style LWCO?



Thanks!

STEVE PAUL_3

LWCO NOT WORKING

I have 2 answers for the scenario that you pose.

The first problem of the water in the gauge glass being so low is due to the fact that most LWCOs only bring the water up to the minimum safe water level. In this circumstance it appears to be normal.



Secondly, I think the probe is not properly functioning due to a mineral build up because of the constant inflow of fresh city water. The amount of water that you are replacing is far beyond the normal. I would expect a short life span on this boiler due to oxygen corrosion.

Patrick_North

Yikes...

I am not a professional steam boiler installer. I am not a professional baker. But I know enough about both of these fields to know this is not an appropriate application of a residential steam boiler. It sounds downright dangerous.

Does he know that adding makeup water while steaming (and with very low water levels to boot) is at the very least asking for a cracked boiler and possibly endangering the employee who's "topping it up?"

Can a pro jump in here?

Good luck!

Patrick

steam_in_my_house

agreed

he knows it is not the most appropriate use for the boiler, but it is the only one that was small enough (in terms of physical space as well as steam capability0 to replace to 50+ fire death trap that was there.



When they manually fill it, they do kill the burner prior to adding water. When the LWCO/ auto fill were working properly,. the LWCO kills the burner before the auto fill triggers (30 second delay on the auto fill)..; and the auto fill is set to 2 gallons which brings the water level up enough for a 30 minute burn before the next fill cycle.



He know this is not what the boiler was intended for, and knows the boiler will have a shorter life span due to the large amount of city water entering the system.



back to the original question, can excess mineral deposit on the LWCO probe cause the LWCO to not sense that the water level has dropped below the LWCO probe location? Therefore failing to kill the burner and trigger the autofill?

Steamhead

Probably

Pull the probe and clean it. If it looks in bad shape, replace it. 

nicholas bonham-carter

not a typical application

in this case the lwco probe should be cleaned every week, and maybe some sort of water filtration system should be installed. to remove any excessive chlorine/oxygen  from the city make-up water before it rots out the sections--distillation, RO?

is 12 psi really needed for the steam kettle? why not reduce the boiler pressure gradually until just before the steam kettle cannot heat up enough, and leave it at that. i suspect that calcium is more likely to precipitate out of the water at higher pressures.

i agree that the steam does wonders for the crust, but 12 psi is not needed!--nbc

KeithC

lwco

Add a 67

Charlie from wmass

Add a reciever tank

Weil McLain uses 8" steel pipe on the return to add volume on to the system. Also a float type LWCO may last longer. And finally that thing will need serious descaling done. Call Columbia boiler and see if they have a proper boiler to fit his needs. 

Long Beach Ed

Yes...

Scale on the probe will cause this type of clear failure. 



With so much fresh water being added daily, the probe will scale up very quickly. 



As mentioned by others, it should be cleaned at least weekly.



But let's look further at this.  There are water feeders made for this type of service.  The probe is not.  Using it this way is plain dangerous.  People can get killed like this. 



Furthermore, the boiler will rot out in no time from adding all this fresh water. 



This isn't the way to do it.  I'll bet when the thing does blow, your insurance won't cover a dime.   Beware.