weil mclain cgi4 lockout

craig_E

lately my boiler been cycling to power/purge lockout. had guy here today thought it could be pressure switch. at one point it did turn on, heat to 180° and then turned boiler off and it kicked back on at 160°. thought we needed new pressure switch, on second attempt to see if everything started up okay and then kicked back off/on it didn’t. guy said couldn’t be pressure switch because blower never turned on first. although it kicked on first in last series. so he determined had to be the controller module that was faulty. suggested would be cheaper to just by myself and just unplug and plug wires into new one, seems easy enough. so i did that. now on new controller board when i turn boiler on i’m just getting a solid green power light and LCO blinking. no idea what’s going on. it will circulate if i have thermostats on but boiler is not turning in to heat up otherwise, any thoughts?

Ironman

“LCO” or “LWCO” = low water cut off.
Whats the pressure on the boiler gauge?

How did your “guy” determine that board was bad? Did he follow the diagnostic instructions in the I/O manual?

Ironman

Here’s the manual:
https://www.weil-mclain.com/sites/default/files/field-file/CGi%20Series%204%20Boiler%20Manual%20%20%200520.pdf

craig_E

pressure looks low. did not have manual, he went through series of starting boiler, detached wires for pressure switch to trick the boiler starting up. worked, switched wires back on for pressure switch and it started working normal. on one more round of starting up to max temp and seeing if boiler heats up once temp falls it didn’t kick back on. next going through he said blower should be turning on before the pressure switch even should, and right now it’s not but was working fine before. this lead him to determine had to be the controller

Ironman

The pressure is low. It should be at least 12psi when cold. Your fill valve needs adjustment or replacement.

The board is sensing a low water condition. It’s not gonna start the burner until that’s corrected.

craig_E

okay. how high should be when boiler temp is running higher

neilc

how many floors to the top radiator ?

you need 12 psi in the boiler cold,
if psi climbs over 20 when hot, you need to investigate your expansion tank,
post a big picture, floor to ceiling, showing boiler, pipes, tank, and circ

Ironman

I’d say if it goes over 25psi when the water temp reaches 180*, then there’s a problem. But you don’t correct that by lowering the cold static fill pressure.

 12psi cold is needed to lift the water one story; 15psi for two stories; 18+ for three stories.
 

You need to get enough pressure in the boiler for the control to sense it and let the burner fire.

craig_E

well it was locked out again this morning when i got up, now it’s in the middle of heating up again after lockout ended. it’s hitting 20psi but here’s some pics

EBEBRATT-Ed

@craig_E

Nothing to do with the problem your having but the expansion tank should be supported before it breaks off and floods your basement. There supposed to be in the vertical position with the pipe nipple on top.

You could have a dirty flame sensor.

neilc

you are still under 10 psi

neilc

inside upper scale on the gage

HVACNUT

If it happens again, see if the red light comes on at the actual LWCO. It's the RB-122 with the green light just above the old board in the pic.

The wiring for the LWCO goes into the 1900 box with the switch, and there must be a splice in there to connect to the wires connecting to the board. 

Shut off power at the breaker and check connections at the LWCO, behind the switch, and the molex connector at the board. Also check/ tighten all grounds.

It could also be a dirty sensor on the LWCO probe.