boiler water level...doesn't seem right

Hipape

Hello,
This strikes me as odd: "Lowest Permissible Water Level" - attached with screws, presumably by manufacturer (Newly installed New Yorker CGS50) is about 3 inches below the LWCO probe feedthrough. Furthermore, I had surging issues which were cleared up by a couple of skims (separate issue: after 1st skim, surging was cured...then a few weeks later it was back..total of 3 skims so far) During the surging days, when the water level went below the sight glass, the LCWO kicked in (amber light on hydrolevel CG400 came on) and stopped the burners. Does the probe make a right-angle inside the boiler and head towards the floor? The LWCO instructions show the probe is horizontal. Thanks!

ethicalpaul

No, it's OK. Doesn't it make sense that the LWCO would stop the boiler before the water level got to a level that would harm the boiler?

Hipape

Yes, it makes sense that the LWCO would stop the boiler! I just don't understand why LWCO doesn't stop the boiler when the water level gets to the probe position. I am happy that the LWCO works, just trying to understand how it senses that the water level is 3 inches below where it is...

Hap_Hazzard

The LWCO should stop the boiler when the water level gets below the probe. It looks like it's just below the normal water line, so it should stop well before it gets to minimum.

ethicalpaul

Your posts are confusing me. If the water level gets below the probe level then yes, it should shut down your boiler.

EBEBRATT-Ed

If the water level is bouncing the probe gets confused. When it is surging a lot the water level in the boiler and the level in the sight glass may not agree at that instant

Corktown

I think what Hipape is addressing is the disparity between the position of the LWCO probe and where the water level of the boiler can lower to and the boiler still operate without being cut off, as one might expect. For Hipape, at some point, the water level drops even further, below the sight glass, and only then does the LWCO kicks in.

I've wondered the same thing about my boiler, a Weil-McLain EG-35 with a Mcdonnell & Miller PS-802-24 LWCO. I know that there is a delay built into the LWCO circuit so that a short-lived dip below the target level, as one might get with a bouncing or surging water level, doesn't short-cycle the boiler, but the boiler seems very happy to continue along clearly below the LWCO probe (but in my case, still above the bottom of the sight glass) without ever turning off. And yes, testing the device and cleaning the probe is on my short list, but if memory, fragile as it is, serves, the circumstances I've described have been the case even after a probe cleaning.

So, to Hipape's (and Marvin Gaye's!) point, "What's Going On?" ....

Corktown

This might not be directly applicable to the thread, but I always appreciate a nice illustration! ....



https://controltrends.org/by-industry/commercial-hvac/burner-and-boiler/01/boiler-low-water-cut-off-mounting/

ethicalpaul

if the water is surging, foaming, or even just boiling, it will splash water on the probe keeping it from cutting out.

That's why the Cyclegard line of LWCO interrupt the heating cycle for 60 seconds to let all that settle down to get a more accurate measure of if the water is below the probe.

Jamie Hall

In my humble opinion (yeah, right)... a probe type low water cutoff should be designed to cut off the boiler when the water level drops below the probe. In an automatic reset type cutoff, if there is any delay in operation it should be on reclose. Water level drops to critical? Off you go. Wait and see if it comes back, and then come back on if it does.

Now if the probe operates an automatic water feeder, then there should also be a delay in the feeder, to prevent overfeeding in the event of a bouncing water level.

EBEBRATT-Ed

You would think the boiler mfg would mount the lwco 2" above the bottom of the glass but they don't