Best Location for LWCO on old boiler

D107

We are having a LWCO and spill switch installed on our old WM boiler since we realize it will be a few years before we can replace it. Original install way before we got here. Much as we hate to throw new money on an old appliance, we may be going away for a few weeks this winter and realized that we could use these safety features--actually we should have installed them years ago. A contractor has suggested placing the LWCO at the red arrow location on the boiler. Note that the circs are on the returns--don't know if that bears on LWCO location. I'd like to know what brands or types people recommend--I assume only steam boilers use the probe type LWCO. Looks like the elbow might have to be sawzalled off to get the LWCO in; one concern is that vibration might cause any issues with this old boiler.

STEVEusaPA

Might be easier to just change the aquastat to one that has a LWCO. Can we see a pic of the boiler with the door off showing the aquastat and the immersion well?

D107

Thanks; see attached photo. Not that you need my arrow, but it points to what I assume is the aquastat since that's where I set the water temp max dial.

leonz

Is the wiring diagram for the boiler on the access panel for the burners???????????

Your triple aquastat should look like a rectangular box with a metal cover that slides over the controls.

I your first image it looks like your triple aquastat is mounted on the right side of the boiler as you are looking at the front of the boiler.
The box with the two runs of BX cable coming out of it are most likely where the triple aquastat is.

The tapping where you think your aquastat is is probably an old water sensing contact LWCO that should be replaced with a McDonell & Miller RB122-E which is the type of LWCO I have for my coal stoker.

I had a digital Hydrostat 3250 Plus in my coal stoker boiler and it failed and the replacement unit failed and the first one did not detect the low water condition and the boiler almost boiled out and almost failed.
The second Hydrostat 3250 Plus failed while I was standing next to the boiler while it ran on oil and The LWCO function turned itself off and after that I will not use a digital triple aquastat

Please look on the xylem web site to down load an operation and installation sheet that shows where the LWCO needs to be installed

First and foremost you need to have the LWCO installed as the first electric boiler control that will shut the boiler off in the event of a low water condition at all times.

My thoughts on a rainy cold monday

D107

@Leonz. Thanks. The tapping where you think your aquastat is is probably an old water sensing contact LWCO that should be replaced with a McDonell & Miller RB122-E which is the type of LWCO I have for my coal stoker. That tapping is from one of the three relays mounted on the side of the boiler for the three heating zones. The tapping I pointed to with the red arrow is a high limit for water temp as far as I can tell. It says 'Type 11B81-3'. I have attached some photos, including the wiring diagram. It never occurred to me that there may already be a low-water cutoff. Note this is a WM CGM-7 PI installed 1981. From my first set of photos, the 19 box on the left with the two transformers says R8285D 5001, Honeywell--you'll see closeup photo in the new batch here. There is an apparent Honeywell ignition control--newer looking--on the right in the first batch of photos, pictured close-up here that is up against the same wall as the hi-limit but I don't know if it has a probe. I'd be happy to know a LWCO is already there or if it can be installed in this area instead of up higher in one of the circulating zones.

leonz

AH, OK, apparenty this Weil Mclain boiler only comes with a LWCO when it is set up for steam from the factory.

If you pull the cover off the box on the far left of the photo you will most likely find the triple aquastat there.

The other two boxes are probably for the circulators as they are labeled 1 and 2.

Your boiler needs to have a legend written for it to locate all the wiring and ALSO to have wire numbers attached and properly labeled in the legend fro the boiler.

If you can please contact Weil Mclain before you leave and as them for a paper copy of your boilers instructions so you can have it to put in a 3 ring binder notebook for the boiler so you have all the information at your fingertips. My 3 ring binder is 4 inches thick with all the material I have for my dual fuel coal stoker and its been a godsend for reference and to help others.

You also need to print out all the information for your triple aquaststat and the circulator controls and put them in the 3 ring binder as well and have a separate sheet for the circulators so you can have a basis to identify the brand and the circulator information from their ID plates if still legible.

The other thing to think about doing is to have isolation valves installed on each of the circulators to make it easier to change one of them if a circulator fails on you.

I know its a lot to think about, but your sanity must prevail in this so you can leave and know the boiler will be there to work for you. You can leave the home at a lower temperature while you are away to save money on fuel too.

STEVEusaPA

The notes about a LWCO being installed refer to a steam boiler. The last picture may be the aquastat. That's probably where you can change the control, and the well to an aquastat with LWCO. If you could take a pic with the cover off.
The Hydrostat 3200 (for gas) w/LWCO is a fine control that would work well. You do have to change the well for LWCO.
I've never had a problem with one.
Beckett also makes an aquastat, but I prefer the Hydrostat.
edited:

D107

Thanks Leonz. I have the original paper manual, no problem. Where you think the aquastat is I guess could have an aquastat there but it is primarily the relay for the basement zone. I did the labeling Basement, Zone 1, Zone 2. I wouldn't put more money than I have to into the old boiler. Any new boiler of course we'd want isolation valves. The circs are not that old--we replaced all three with a Taco 007 and two 3-speed Grundfos 15-58.

D107

@Steve. Just to make sure you mean photo #3310 as my last photo. The Honeywell S8610U was installed in 2005. On the bill it said 'ignition module' which I guess would have a well behind it to ignite based on water temp so it was also an aquastat. So I guess you're saying the Hydrolevel 3200: https://www.oswaldsupply.com/hydrolevel-fuel-smart-hydrostat-3200-model-45-3200-universal-temp-limit-lwco-boiler-reset-120-v-24v-out.html?kw=45-3200&c=Shopping&gclid=EAIaIQobChMI55mdiLeq1wIVUbbACh32BQZVEAQYBSABEgK6XfD_BwE would require a new well drilled-installed to be wired to the existing ignition module? Sounds much less expensive than installing elsewhere.

STEVEusaPA

I'm not quite sure, as I would like to look into it. Someone else may have an exact answer. If I could see a picture of that control with the cover removed. I wouldn't try to drill for a new well, if that is even possible.
You have a well somewhere, just need to see where and how it's wired. The pictures come thru so big it's hard to see.
It does look like your aquastat may be the first picture. Let me call and see what I can find out in the meantime.

STEVEusaPA

HydroLevel recommends the 3000, has LWCO. You'll just have see what size well you need to replace.

D107

@STEVEusaPA Much appreciated for looking into this. FYI I'm attaching a wide angle, side view (2nd shot) and closeup of that high-limit control––the one that says 'Type 11B81-3'–– in one post so you can compare. Seems to have a well going right into the waterside--it would have to to measure water temp; and I see one of the yellow wires coming from it goes right into the Honeywell ignition module. I assume that's what you meant by 'first picture---really the first picture after the schematic. The last photo––of the honeywell S8610U I'm not ready to remove that piece's cover yet--a bit afraid to mess with it.

D107

One of the great things about the Wall is that it forces you--in this case an educated homeowner--to do research both before and after you post a question. Now that I've checked out the recommendation of the Hydrostat 3000 and Electro-Well, the existing high limit White-Rodgers 11B81-3 I am left with two questions:
1-Is there a slight safety advantage in putting a LWCO higher in the piping above the boiler--where the LWCO I believe will work on pressure––rather than in a well into the boiler itself––since it may engage at a higher water level?
2-Having a hard time getting a clear response from local contractors––do they want the job––or WM on the correct size of the replacement well-probe:
• I assume my 1981 Weil McLain CGM-7 PI hot water boiler is a ‘Standard’ NOT Millivolt boiler. ?
• standard insertion length of probe/wells is 3.5. ?
•Insulation Length for this boiler: 1” .875”, 2.25”, 2.5" ?
• On WM parts list (see attached jpg)
it says well size is NPT 1/2”; but White-Rodgers 11B81-3 specs at 3/4”. Which is it?

STEVEusaPA

It's the 1/2 inch one. I'm basing that on the part number 11B81-3 on the bottom of your limit control.
If you call HydroLevel, they may be able to tell you what size & length you need for your well.
Unless you need an 'extra short' well, I would guess the 48-221 is the correct one. But confirm with HydroLevel.
I think this low water cutoff/aquastat, will only work in the boiler-unless it works with that very short immersion well.
There are others that you can put in the piping.
Either way your draining down the system, just a question if you want to do some piping.