Circulator will not stop running - Aquastat L8148E


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Old 04-20-10, 07:12 AM
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Circulator will not stop running - Aquastat L8148E

Hey guys...

The circulator will not stop running and is being controlled by an Aquastat L8148E. I have 2 zones each regulated by a 3 wire Taco Zone Valve connected per the Taco wiring diagram.

The only other "modification" is that the transformer in the the aquastat does not seem to be working and it seems to be drawing power from an external transformer hooked up to the Taco Zone valves.

I am getting 120v at terminals c1 and c2 whether the heat is on or off. The pump is constantly hot and although very quiet.. it does sound like it is running.

Because the transformer is no good in the aquastat I have ordered a new unit from Patriot Supply. So i am going to replace the entire Aquastat assembly.

My question is... the constant voltage at c1 and c2... possibly a stuck relay? Anyone seen something like this?

The rest of the heating system seems to work properly to the best of my knowledge (burner, damper... etc.)
 
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Old 04-20-10, 03:59 PM
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The relay contacts could be 'welded'.

But if you want to check further, cut the power to the system and temporarily remove the wires from T and TV. Those wires should be coming from the zone valves.

If, when you remove those wires and turn the system back on again, the circulator stops, then the problem is with the zone valves, wiring, or less likely, a thermostat.

If you know how to use the OHMS function on your multimeter, you can measure those two wires. When there is no thermostat calling for heat, they should be OPEN CIRCUIT... infinite ohms. When the thermostats call for heat, and the zone valves open, they should be a SHORT CIRCUIT... zero ohms.
 
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Old 04-21-10, 07:09 AM
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Thanks so much for the reply... what you are saying makes a lot of sense... will check it out tonight...

I would like to know that everything else is OK before wiring up the new Aquastat and possibly wrecking it. (Is there a thread with instructions on replacing an Aquastat?)

I looked at the way the external transformer is connected to the Aquastat. It is connected to the "W" terminal and the "W" to "Z" jumper is in place. When the wire from the external transformer is removed from the "W" terminal the heating system does not respond at all.... that is why my buddy (who is better with electronics then me) is convinced the transformer within the Aquastat is bad. Also why I was planning on replacing it anyway.

With the transformer connected the system seems to work like it is supposed to (besides the circulator)... call for heat... damper opens... boiler fires... call for heat stops... fire stops... damper closes...

I only noticed the circulator recently because the relay started to make a buzz noise even when there was no call for heat...
 
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Old 04-21-10, 04:09 PM
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Good to be cautious and avoid throwing money away!

You have probably already done this, since you've measured the voltage on C1 and C2, but gotta make sure... you've traced the wires from the circulator back to the aquastat to make sure the circulator isn't being powered directly by some other means, right? Some systems power the pump directly and the pump runs constantly by design.

There isn't really a thread with step by step for replacing, but the booklet that comes with will explain pretty much what you need to know. Make sure to read through it...

A few tips might be in order though... if you have a digital camera, TAKE PICTURES before you disconnect the old one! This way you won't lose track of which wires go where. You might want to go so far as to tag each wire with the terminal number when you remove them.

There is a screw clamp that holds the aquastat to the immersion well. After removing the wires, loosen that clamp and slide the part off the well. The sensor bulb should follow.

When you replace the part, be careful not to 'kink' the capillary tube with the temp sensing bulb on it. If you kink it, it's toast. When you install the sensor, make sure it goes to the bottom of the well and stays there. Carefully bend the capillary tube to hold the bulb at the bottom of the well. You may get a tube of heat transfer compound with the new part, squeeze that into the well per the directions.

Your vent damper... does it have the plug that goes directly into the aquastat? If so, make sure you order the correct aquastat, because there are models of the "E" version that do not have that plug. There should be a four digit 'extension' number on the unit somewhere. It may be on the back, one of the side panel, or even stamped on the board. Perhaps on the label inside the cover...

The piggyback transformer... where does the 'other' wire go? If as you say, one wire is on W or Z and the jumper in place, the other wire would be on either TV or B2, correct? If so, it's almost a sure bet that transformer in the a'stat is bad, and your assumption is correct.
 
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Old 04-21-10, 06:21 PM
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c1 and c2 seem to be going directly to the circulator from the Aquastat.

Two issues though....

TV and T ARE constant. So that is probably why the circulator is running consatantly. Like you said something must be wrong with the external wiring...

I removed all wires T - TV - W... turned on the em. switch and nothing happened. Then tried connecting T to TV.... nothing happened... To me that would still mean a bad Aquastat.. correct?

I have a L8148E1182... I ordered a L8148E1299.... am I screwed? Google did not turn much up besides the 1182 is discontinued. There is NO molex connector for the damper currently.

In case you are interested you were correct... the second wire of the transformer is going to "TV".
 
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Old 04-21-10, 07:52 PM
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Not following too clearly...

You said:

I removed all wires T - TV - W
You only want to remove the wires from the zone valves to T and TV ...

The wire on W that you removed, isn't that the transformer wire? If you take that off, naturally, nothing will happen. So connect back the transformer and just leave the two wires from the zone valves to T and TV off... and see what gives.

TV and T ARE constant
OK, with them hanging in the air, and the ohmmeter connected, you have ZERO ohms, short circuit, correct? If so, and no thermostat is calling for heat, it means that most likely one of your zone valves is kaput. You need to isolate them from each other and test each one. One of them is stucked up.

Hang your meter on the wires and remove the wire on terminal 3 of one zone valve. When you remove that wire from the stuck valve, you should see the meter indicate open circuit. OR, remove the #3 wire on both, and use the meter to determine which one is stuck. when you find the stuck valve, you can determine if it's the valve or the thermostat by removing the wire on terminal 1 of the valve. When you remove the wire from terminal 1, if the valve does not close, you know the head is bad. If the valve DOES close when you remove the wire on 1, the thermostat, or the wiring to it, are bad. You can then go back to the thermostat and pull one of the wires there to determine if it's the wiring or the thermostat.

Chances are it's the zone valve, and the powerheads are easily replaceable.

I have a L8148E1182... I ordered a L8148E1299.... am I screwed? Google did not turn much up besides the 1182 is discontinued. There is NO molex connector for the damper currently.
As long as your current a'stat does not have the Molex connector, the 1299 would be the correct replacement. The 1265 is the one with the Molex.
 
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Old 04-23-10, 06:51 AM
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OK...

After playing around some more... with the external transformer connected T and TV are constant. I cannot figure a way around it. I have taken the zone valves out of the equation.

The transformer is connected to the TV and W terminals. I have only one thermostat hooked up now and it is connected to the T and TV terminals. I can't figure out why the circuit is complete.

I guess none of that matters because the Aquastat is being replaced... so on to my next question. But if you have any ideas I would keep trying things out just out of curiosity.

Patriot Supply states that Honeywell cross references the 1265 as the replacement for an 1182. The guy on the phone was friendly but stern that the 1299 would not work with my unit. So... I really did not know what to do?? I ended up sending the 1299 back to them yesterday.

Do you have any input? Maybe I need to wire up a connector to the damper wires?

BTW... I really appreciate all the help and am very thankful this is happening in the spring!!!
 
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Old 04-23-10, 03:51 PM
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Let's back up a bit...

You need to measure the resistance on the two WIRES, not on the T and TV terminals. If you measure across the T and TV terminals, you WILL see a low reading because you will be reading the resistance of the transformer and the relay coil...

With the wires from the zone valves to T and TV disconnected, what happens when you short the T and TV together? What should happen is that the circulator will run, and if the boiler is cool, the burner will fire. When you remove the short, the circulator and burner should both stop.

How is your damper currently wired up? Individual wires going to various terminals in the aquastat, right?

Can you take a picture of it and post it on Image hosting, free photo sharing & video sharing at Photobucket and drop a link to the picture so we can see what yer working on? (photobucket is free...) Please make sure the photo is clear enough that we can see the wiring... and large enough, and in focus... if your camera has a 'macro' setting you might need to use that for close shots.
 
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Old 04-27-10, 06:52 AM
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OK... I feel kinda dumb for not understanding what you were telling me in your previous post but now I get it... thanks for your patience....

I will give you the short version...

The 1265 did come in... and it seemed to be the exact model. There is a Molex Connector but it comes with "jumper plug" installed. My damper did not have a connector... the wires were individually connected.

I wrote down all the wire colors and their terminals. Swapped out the unit and fired it up. Seems to work just great!! The relay is much quieter in the new unit... old one was buzzing away. That made me happy.

The bulb seemed to be a tighter fit then the diagram indicated. I tried my best to "angle" it the way you and the instructions indicated. I also used the thermal grease that came with it... was slightly messy... lol..

After everything was back together I was still getting a complete circuit at the T - TV wires!!!

Long story short it was one of the power heads causing the pump/heat to stay on... I had an extra head (just had to replace a leaking zone valve) and swapped it out... seems to be working right now. I am getting 24v at terminals 1 - 2 at the correct zone valve when the T-stat calls for heat. Then after a minute or so terminals 2 - 3 become complete like they are supposed to.

Seemed terminals 2 - 3 were complete on the bad head when heat was not called for.... causing the heat to stay on.

It was late last night when I finished everything so I shut the heat off for the night and will double check everything tonight... fingers crossed we should be good to go.

Last question is the high heat setting. I am pretty sure the old Aquastat was set at 185. The new one came set at 210. I looked on the boiler and cannot find a temp setting stamped anywhere... only a "Max of 250"... what is a good setting? I put it at 185 for now.
 
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Old 04-27-10, 04:28 PM
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Good job!

Immersion wells can be different diameters, a tighter fit is actually better, but most importantly that the bulb is at the bottom of the well.

"Standard" setting on a high limit is 180, but 185 won't make much difference. That's only a 'max' setting anyhow, chances are that most of the time your heat calls end before the boiler hits the high limit anyway.
 
 

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