Low water cut off not working properly

dagc

Long story short I got a fairly new Weil Mclain WGO-3 from a house that converted to gas. It's installed and working properly, however the Guard Dog low water cut off model ps-851-120 from McDonnell & Miller is not working properly.
The red led blinks about 4/5 times then stays on for a second and then goes off and at the same time a relay clicks. After that this process will repeat intermittently. I also tried to run without water in the system, in this case the red led will stay on steady.
I cleaned the probe and I think it looks fine.
Nothing happens pressing or holding the test button and the green led light never came on, not even when I switched the main switch on/off that controls all the boiler electric part.
Like a said, the boiler is working fine even when I tried run for a almost a minute without water in the system and the cut off didn't do anything

EdTheHeaterMan

STOP! DON'T OPERATE BURNER WITH NO WATER IN THE BOILER!
More to come after I research instruction sheet on the LWCO

EdTheHeaterMan

Ok do you have Green LED and Red LED on your control? Do You have Amber test LED on your control? Seem there are different configurations
Here is the instruction sheet!
https://www.alpinehomeair.com/related/McDonnell & Miller 153875 PS-801-120 Installation Instructions.pdf
The burner should not operate for more than 10 seconds after the red light comes on. There is a delay on break of 10 seconds to reduct short cycling and nuisance off cycles. There is also a delay on (of up to 15 seconds) after the red light goes off, for the same reason
Have not found any blink codes yet. I think it is a bad electric connection. Is it properly wired? (diagrams in the instruction sheet attached)

EdTheHeaterMan

Here is the trouble shooting section:
If control fails to operate as required, perform the following diagnostic checks:
1. Check to be sure that the water level in the boiler is at or above the level of the probe.
2. Re-check all wiring to ensure proper connections as specified in boiler manufacturer’s wiring diagrams
or these instructions.
3. Check to ensure that Teflon® tape has not been used on the threaded connection of the electrode
to the boiler.
4. Re-check the electrical ground connection for the remote sensor and control unit.
5. Check the quality of the boiler water to ensure adequate conductance.

HVACNUT

@dagc, this and your other post are under the heading of OIL HEAT. I saw your question on the other post about jumping TT on the burner. As @STEVEusaPA wrote, that is typically correct with oil, however, not always with a gas conversion burner. What burner is installed?
Are there BV terminals on the burner primary and is there a spill switch attached to the draft regulator on the smoke pipe?
Can you post some pics?

If no wiring was altered, its possible the probe is faulty or the control took a dump. Can you show the wiring or draw a diagram?
The RB-122-120 is a good replacement LWCO.

dagc

> @HVACNUT said:
> @dagc, this and your other post are under the heading of OIL HEAT. I saw your question on the other post about jumping TT on the burner. As @STEVEusaPA wrote, that is typically correct with oil, however, not always with a gas conversion burner. What burner is installed?
> Are there BV terminals on the burner primary and is there a spill switch attached to the draft regulator on the smoke pipe?
> Can you post some pics?
>
> If no wiring was altered, its possible the probe is faulty or the control took a dump. Can you show the wiring or draw a diagram?
> The RB-122-120 is a good replacement LWCO.

It's a oil fired boiler which I got from a house that now has gas, so they didn't want to use oil anymore.
No wiring was altered except I add a new 6 zone switching relay.
I can post pictures later or a diagram

KC_Jones

In my honest opinion, with used equipment like that, I would just replace all the safeties. It's a small investment for piece of mind. Even if you get it working it's still suspect in my opinion.

Fred

Is the LWCO wired and plumbed to an auto water feeder? If not, the LWCO will call for water and keep the boiler shut down until the water level reaches a safe level. Otherwise, you have to manually feed water into the boiler to bring it back online.

HVACNUT

@Fred . It's a hydronic, not steam.

@dagc . Yes, post pics please. You might be missing a very important safety.

If yours is an exterior chimney, does it have a stainless steel chimney liner?

dagc

> @HVACNUT said:
> @Fred . It's a hydronic, not steam.
>
> @dagc . Yes, post pics please. You might be missing a very important safety.
>
> If yours is an exterior chimney, does it have a stainless steel chimney liner?

Here's mine diagram and some pictures

@HVACNUT interior chimney

About the lights for the LWCO I discovered that the green light light is dead with a multimeter. So actually it is on all the time, but the red light still acting like before, will flash for 4 times then stays on for a couple seconds and goes off with a noise of a relay clicking at the same time.

Also I have 2 more weird symptoms. Sometimes the burner is running fine and suddenly will stop for a second and restart right back. And the other thing is instead stop just for a second it will go off on off on multiple times. For about 20 maybe 30 seconds and will stay on normally after that

STEVEusaPA

Ok just to be clear, you have an oil fired boiler that you GOT from someone who converted to gas.
It appears to be wired correctly-ish...
I'd make sure you have a good path to ground, check all connections, then remove the stranded wire from T-T on the aquastat, jump it out and see if you're still getting the chatter. If you are I'd do a little advanced troubleshooting, and take the LWCO out of the circuit. If it stops chattering and the on/off, I'd replace the LWCO. If it continues, I'd replace the aquastat.

dagc

> @STEVEusaPA said:
> Ok just to be clear, you have an oil fired boiler that you GOT from someone who converted to gas.
> It appears to be wired correctly-ish...
> I'd make sure you have a good path to ground, check all connections, then remove the stranded wire from T-T on the aquastat, jump it out and see if you're still getting the chatter. If you are I'd do a little advanced troubleshooting, and take the LWCO out of the circuit. If it stops chattering and the on/off, I'd replace the LWCO. If it continues, I'd replace the aquastat.

I removed the wire and jumped the T-T on the aquastat just like you recommended and it's been fine for the last hour. The LWCO no longer flash either.
I will keep an eye for the next 24 hours and update here

EdTheHeaterMan

> @STEVEusaPA said:
> Ok just to be clear, you have an oil fired boiler that you GOT from someone who converted to gas.
> It appears to be wired correctly-ish...
> I'd make sure you have a good path to ground, check all connections, then remove the stranded wire from T-T on the aquastat, jump it out and see if you're still getting the chatter.
Now the problem has resolved? The SR506 "X-X terminals" to the L8148 T-T control is the issue . If you leave T-T jumped, you will maintain temperature at the high limit setting. Do you have any 18 gauge solid thermostat wire. Make a better connection to the terminals. If the problem returns, the SR506 has a problem or one of the zone thermostats ...or the X-X terminals have something else connected. Do you have a pic of the SR506 wire connections?

EdTheHeaterMan

ALSO... once you have the trouble corrected, we all assume that you will properly wire the control to National Electric Code thru the knock outs, proper connectors and grommets to prevent wire chafing... proper grounding... and it does not hurt to make it look nice!

dagc

> @EdTheHeaterMan said:
> > @STEVEusaPA said:
> > Ok just to be clear, you have an oil fired boiler that you GOT from someone who converted to gas.
> > It appears to be wired correctly-ish...
> > I'd make sure you have a good path to ground, check all connections, then remove the stranded wire from T-T on the aquastat, jump it out and see if you're still getting the chatter.
> Now the problem has resolved? The SR506 "X-X terminals" to the L8148 T-T control is the issue . If you leave T-T jumped, you will maintain temperature at the high limit setting. Do you have any 18 gauge solid thermostat wire. Make a better connection to the terminals. If the problem returns, the SR506 has a problem or one of the zone thermostats ...or the X-X terminals have something else connected. Do you have a pic of the SR506 wire connections?

So I still have the problem but think I found the culprit. Last night I heard the on/off thing again and when I was getting near the boiler it shut down and wouldn't start again. Every time turn the service switch off then back on I could hear the aquastat relay clicking but not the relay on the burner igniter so I checked the igniter and found a burnt solder which I solder it back. The boiler started right up but with the same on/off symptoms.
I have attached a picture where I patched and you can see the cover burnt a little bit too. Also I included the SR506 connections.

dagc

So I found the culprit. It was the relay inside the boiler igniter box. As you can see the picture attached the relay had a bad contact. For some reason one of the probes was wide open not making a good contact so it burnt the solder on the circuit which I soldered it back. Looks good now but I will definitely buy a new one to be on the safe side.

@EdTheHeaterMan I will definitely take care of the connections/wiring when everything is running smoothly. Although I have a wood stove to heat the house I needed the boiler working to have hot water so I did all I could just to have it running as it took 3 days to replace the boiler and hook up new circulator/zones/baseboards to the system