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High limiter switch on a boiler


jaindesi's Avatar
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05-11-17, 01:26 PM   #1 (permalink)  
High limiter switch on a boiler

Hello Everyone, I have an old Weil Mclain boiler for heating my house. Model: P-CG-5 Series 1. Aquastat/High Limit switch has gone bad. I am not able to find the replacement part for it. I found an old forum here that explains the issue. Based on that I bought the aquastat made by Honeywell. New aqustat's sensing bulb is too big for the existing well. I have the exact same aquastat model in he below post. Do i need to get another aquastat or something called Universal Strap on aquastat? I am not sure how the strap on part works and where it would go.

This is the old post I found here:
http://www.doityourself.com/forum/bo...ment-pn.html#b

 
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05-11-17, 02:02 PM   #2 (permalink)  
According to the instructions and if I'm reading correctly... the sensor bulb can be slid in or out depending on well depth. The small connecting tubing can be bent slightly but don't kink it.

instruction manual/L8148A,E,J.pdf


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05-11-17, 02:56 PM   #3 (permalink)  
Thanks @PJmax. Thing is i can't even push the front of the bulb in to well. It's too big. I am trying to figure out if I should try to remove the old well and get a replacement. I heard it's not a good idea since it can crack the boiler inside.

 
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05-11-17, 04:17 PM   #4 (permalink)  
If the bulb won't fit into the well.... that is a problem. Since I'm not the boiler pro here I'm not even sure what to recommend.

I'd be hesitant to change the well on an old boiler too.

The other guys should be by soon.


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05-12-17, 08:25 AM   #5 (permalink)  
Would this adapter C308 help? Seems like it might.

http://orders.sidharvey.com/IMAGES/c...d/20104-10.pdf

 
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05-12-17, 12:20 PM   #6 (permalink)  
If the well diameter is too small to begin with to accept the bulb there is no way that I know of to enlarge it except to change the well.

If you look at your existing bulb and compare it to your new one you can see what you will need. What manufacturer is installed now. To my knowledge Weil McLain only used Honeywell and they should be compatible. They are usually 3/8" bulb size.

As far as changing the well, it's a brass fitting that doesn't have to be overly tightened and they're usually fairly easy to remove with the right size wrench. I've never had a problem removing them or heard of a boiler cracking. That's not to say it's never happened just it's never happened to anyone I know in the trades.

If you need a new well you can check the options on this site. On the sight click on heat and then from the menu click on aquastat wells for your options.

Honeywell wells are generally 3/8" bulb size but there are larger.

SupplyHouse.com - Plumbing, Heating & HVAC Supplies You can also call them with any questions.

Hope this helps a little.

 
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05-13-17, 09:18 AM   #7 (permalink)  
Something doesn’t seem right. I have an old 8124A lying around and I just measured the bulb diameter, and it is indeed 3/8 as spott says – and I think the 8148 and 8124 are very similar, the 8124 just being a Triple Aquastat instead of a High Limit only.

So then why wont a 3/8 bulb go into the old well? That would mean the well would have to be less than 3/8 – but I thought wells were only 1/2 or 3/4. Is the well on the P-CG-5 Series 1 really less than 3/8? I guess it could be – or has the opening to the well been properly exposed, that is, is there something else in front of the opening preventing the bulb from going in, like some kind of clamp which may look like it's part of the well.

Just a thought.

 
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05-13-17, 12:10 PM   #8 (permalink)  
Rather than replacing 50 old technology defective Honeywell L8184A take the opportunity to upgrade the system. Out-Door-Resets are aquastats with small probes offering more accurate temp control, plus many other features that provide quick payback thru fuel cost reduction.

Most modern boilers come with ODR's because they are key to improved efficiency. They have a menus of settings to optimize the system operation. At $156 for Tekmar 256 pay back is year or two.

Tekmar 256 - Tekmar 256 Boiler Control - One Stage Boiler - Tekmar - SupplyHouse.com

Read the Tekmar 256 ODR manual on the link to see the many features and benefits it provides.

Side note: Am always find it odd on many DYI threads about people spending a lot of time and money to replace inferior dated products when newer, better featured and often cheaper products are available.


Last edited by doughess; 05-13-17 at 01:13 PM.
 
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05-13-17, 12:31 PM   #9 (permalink)  
Z,
The 1/2 and 3/4 are the spud (threaded) sizes which is different from the tube size. The 3/8 is pretty common but they do make other sizes also. My guess is that the original isn't a Honeywell. It may be a White Rogers or other brand. The tubes also come in different lengths just for informational purposes.

 
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05-13-17, 12:48 PM   #10 (permalink)  
d,
I may be missing something here but what good is an ODR if the boiler doesn't work.

 
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05-13-17, 01:05 PM   #11 (permalink)  
First sentence of thread states aquastat is bad which means burner will not run. So replacing it with either working aquastat or ODR will enable it to run when boiler temp drops below setting.

The Tekmar 256 ODR has a small 5/16" diameter probe that fit most old boiler wells eliminating that isssue.


.


Last edited by doughess; 05-13-17 at 01:24 PM.
 
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05-13-17, 01:18 PM   #12 (permalink)  
Correct. Aquastat is bad. Aquastat controls the burner and the pump on a call for heat. If the aquastat is bad which is telling me the burner or pump or both are not working on a call for heat why would he need an ODR. Isn't it kind of a moot point what the temp is outside.

 
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05-13-17, 05:06 PM   #13 (permalink)  
Wikipedia: "An aquastat is a device used in hydronic heating systems for controlling water temperature." i.e. boiler heat source.

While in some systems the "aquastats" may have other functions and also start pumps and fans. It can be confusing to automatically link the word to those things.

Especially in multi zone systems thermostats are the "call for heat" based activator of control dampers, pumps and zone vales, not aquastats.

 
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05-15-17, 12:14 PM   #14 (permalink)  
My current aquastat is from White Rodgers. I know about the different size wells. I am just not sure if the cracking the boiler while removing is true or not. I do see the thread and able to remove the current well.

Also how do you even install the tekmar 256? Do I need Tekmar 256 and an aquastat?

 
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05-15-17, 12:57 PM   #15 (permalink)  
j,
I can only relate my personal experience of 40 yrs. in the field and removing and installing many of these wells. I have never had a boiler crack or have heard of a boiler cracking due to the removal of a well.

That be said that's not to say that it hasn't happened to someone else. PJ maybe knew of someone or had a different experience. I doubt if he would have just randomly mentioned it.

As I said, you have a good solid fitting to grab onto and with the proper wrench it should come right out. That well is most likely inserted into a plate where your tankless coil would go or in a blank plate connected to the boiler with bolts. If by chance anything cracks it would be the plate which is replaceable and not the boiler.

Without pics I can only guess that's what you have.

As far as the ODR goes it has nothing to do with your aqustat. An ODR is a luxury not a necessity and is not necessary to get your boiler running.

Hope this helps a little.

 
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05-16-17, 08:58 PM   #16 (permalink)  
Spott: As far as the ODR goes it has nothing to do with your aqustat. An ODR is a luxury not a necessity and is not necessary to get your boiler running.

ODR is an aquastat and replaces the existing one. It has many features to save on fuel costs, optimize system performance and move effective control boiler water temp

If sticking with forty year old technology avoids a "luxury" to Spott that is his choice.

I prefer the newer better cheaper. I have a lot more experience than Spott and have no desire to go back to the coal fired boilers used when I was a kid.

Someone should start a thread for whopper falsehoods on DYI. Spott's would get my vote. DYI has many users with minimal experience. I hate see posts that miss lead them. May be the moderator should step in some times.

 
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05-17-17, 12:18 PM   #17 (permalink)  
d,
I'm not going to reply to your mindless personal attack comments other than to say "consider the source."

That being said, after taking an extremely detailed look at the Tekmar 256 in case I had missed something and calling Tekmar directly, they confirmed what I already knew and someone with all of your supposed knowledge should know.

The Tekmar 256 DOES NOT take the place of an AQUASTAT.

It used in addition to your normal boiler controls (AQUSTAT). It merely adjusts the water temp to match outdoor temps when full capacity is not needed and that is all it does. Hence the word LUXURY.

I would not have even responded to your worthless post as I have chosen to do in the past except for the fact I wouldn't want J or anybody interested getting all your WRONG information and wasting their money for nothing.

I will say there is nothing wrong with ODR's under the right circumstances and I had one in my house probably before you knew what the letters ODR stood for. I think they are well worth the money in commercial and apartment buildings where you would see savings and the payback would be recognized before you collect social security.

You are right about one thing though and that is getting misled, just as you are doing with your post to this person. It's good to offer suggestions if you know what you're talking about but sometimes "silence is golden".

Here is the Tekmar number if interested.******* Maybe you can teach them something also. They had a good laugh just as I did. I'm sure they would love to hear your thoughts.

Experience doesn't mean much without common sense.

I hope this helps a little.


Last edited by lawrosa; 05-17-17 at 03:30 PM. Reason: Removed part of #
 
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05-17-17, 03:36 PM   #18 (permalink)  
OK before this gets out of hand I will step in.

We all have opinions but to offer ODR, which you seem to always push D, is not the right way to go here at the moment..

Your offering ODR advice and we dont even know the heat emitters and boiler set up, etc etc

Your ODR can get him spending a lot of money to lower his boiler temps 40F for nothing...

40 year old technology works. The OP came here for a no heat issue. We need to work on restoring that first.

Once his repair is made the fuel saving options can be discussed then.

Its my opinion ODR is best left to mod con boilers period.Not cast iron flame on/flame off's..

Lets stick to the issue at hand please.

Im in a good mood and would hate to give out infractions for bickering..


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05-18-17, 08:11 AM   #19 (permalink)  
Hello guys, I am going to change the aquastat. I ordered two different size wells
These are the two wells I got. 121371A - Honeywell 121371A - 1/2" Aquastat Well

121371B - Honeywell 121371B - 3/4" Aquastat Well

Here is the link to a youtube video of my setup. https://youtu.be/pCzYjBOiZNo

I asked this one guy if he can find the old White Rodgers Limiter switch but he found that the Honeywell replacment should work. He is charging me $600.

 
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05-18-17, 08:29 AM   #20 (permalink)  
Its a 1/2" well you have on that boiler FYI..

This the WR part # for control WR 11B81-3 limit control.

Let me look around a bit see what I find..

Did you test the A stat for 24v? Maybe just a bad transformer.


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05-18-17, 08:32 AM   #21 (permalink)  
Oh just a note that air vent is leaking and should be changed asap...

And on the lid of the a stat should be a part #. It should correspond to what I posted?


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05-18-17, 09:09 AM   #22 (permalink)  
Be sure to note that the replacement aquastat will work with EITHER a 24VAC gas valve, or a MILLIVOLT gas valve. Make sure that you use the correct terminals when you wire the burner to it.
Yeah whatl they have as a replacement

L8148J1009 - Honeywell L8148J1009 - Aquastat Relay, 8°F differential

But I wonder if you can use any multi control a stat from honeywell with a better diff.. That one has a fixed 8F diff. Other models are 15f or adjustable..


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05-18-17, 11:56 AM   #23 (permalink)  
I am not to technical with this part. I am assuming it would work.
@lawrosa, How did you find out if the 1/2" well is the one I need to use?

 
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05-18-17, 01:17 PM   #24 (permalink)  
WM old documents..




http://www.weil-mclain.com/sites/def...1-manual_1.pdf


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05-18-17, 03:07 PM   #25 (permalink)  
jain –

In case you missed it, it’s on page 17 item 8 : ….“Limit Control w ˝” well”.

Did you measure the old bulb diameter/length when you took the old Aquastat off the well?

he found that the Honeywell replacment should work. He is charging me $600.
Maybe I misunderstand … but $600?? If you have already once removed the old Aquastat then you know how to do it. So why don’t you install the new one yourself? OK, just thought of something, that price might include installing the new well also – but $600 seems really high. You already have the parts.

L8148A1017 - Honeywell L8148A1017 - High Limit Horizontal Mount Aquastat Relay, 8°F differential

 
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05-19-17, 09:38 AM   #26 (permalink)  
Thanks. I found the part information in the manual.

I hired someone else to help me remove/replace. He left me hanging so I found someone else who is charging me $600. Now the original guy suppose to be back this weekend to install the new A stat. Hopefully it will workout. Really appreciate all the help I am getting here. I'll update once I get it installed and working.

 
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06-30-17, 11:23 AM   #27 (permalink)  
Finally got everything to work. I am out $1100. New Aquastat, gas valve and rewiring of the zone valves with thermostats. Labor cost me $600. Gas valve $325 and Aquastat $156

 
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06-30-17, 12:58 PM   #28 (permalink)  
j,
Thanks for the update. Glad to hear your all set.

 
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07-01-17, 07:53 AM   #29 (permalink)  
jaindesi paid $156 for an aquastat when for $156 an Out-Door-Reset would reduce his annual fuel costs 5% to 20%. http://www.supplyhouse.com/Tekmar-25...iler-4150000-p

ODR's have many other benefits for the home owner. They have many set up options that can optimize the water temperature for different types of home systems. Check out the manual to see the many features: http://s3.supplyhouse.com/product_files/256-install.pdf

Most new boilers come with ODR's because their benefits are widely accepted.using an old bulb type aquastat for home heating boiler is like buying a new car today that does not have an engine computer. Duh!


Last edited by doughess; 07-01-17 at 10:11 AM.
 
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07-03-17, 11:21 AM   #30 (permalink)  
How hard is it it to clean out the burners? Do I need to remove it or can i just use the wire brush and vacum while it's still inside?

 
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