Aquastat Settings

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Old 01-08-07, 01:37 PM
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Aquastat Settings

I'm having problems with my DHW. I am unable to maintain a hot shower for any length of time. On a call for heat from the tap, the boiler comes on. But, the circulator cuts on also. Having the unintended consequence of heating the whole house. I know the problem has something to do with the temperature controls on the aquastat(s). What should they be?

I have a Peerless Oil Fired boiler with a tankless coil. I have 2 aquastats. One, the L8124A triple aquastat is installed on the rear of the boiler. The other is a L4006A which is installed on the front of the boiler.

The current settings for the L8124 are High-200, Low-180, Differential-10. This seems to work as intended. The L4006a where I'm confused. Its currently set at 140 with the differential set to 5. When the boiler temp falls below 140 the burner kicks on as intended. But the circulator comes on also, making it harder to generate DHW . I thought DHW was supposed to have priority.
 
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Old 01-08-07, 03:43 PM
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If you've got the triple A'stat, then there should be no need for the second low limit control ... I'm confused about that.

One thought though is that the second stat is set up as a secondary high limit protection ? Although, if that were the case, you wouldn't be running at all, cuz if it's set to 140* the burner would be locked out.

Is there a full model number on the 4006 ? Maybe printed on the back in black ink ? (*you may need a mirror to read it !*)

Did you (or a service guy) change any settings that you know of ?

Can you trace the wiring on the 4006 and tell where it goes, how exactly it's wired to the 8124 ? BE CAREFUL! 120VAC present ! PROBABLY BEST TO SHUT OFF POWER BEFORE REMOVING ANY COVERS ! IF YOU DON'T FEEL COMFORTABLE DOING THIS, THEN DON'T !

What temperature does the boiler maintain normally ?
 

Last edited by NJT; 01-08-07 at 04:01 PM.
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Old 01-08-07, 04:18 PM
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Right now, the R7184 has the T-T terminals jumped. R7184 feeds(black and white wire) directly into L8124A. The Black is connected to B1, the white connected to B2. It does not go into a junction box first.

The L4006A feeds(white and red wire) into a junction box(with emerency shutoff switch), where the pair is joined with the house thermostat(also white and red) and then continues into the L8124A, where it connects into the T T connections.
 
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Old 01-08-07, 04:28 PM
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What temp does the boiler normally maintain ?

I don't understand the 4006 wired with the thermostat ...

Just one zone ? or do you have valves / or / circs ? (circle one)

still thinking...

The only thing I can think is that the low limit circuit on the 8124 somehow got fried or otherwise didn't work, and someone added the 4006 in an attempt to keep a low limit on the boiler for your tankless.

If this be the case, then the behaviour you are seeing is what I would expect it to do. The 4006 is just acting as the room t'stat, and calling for heat, in which case, yes, the circ would run.

If the low limit on the 8124 _were_ working, the boiler would maintain 180* per the setting you say it's at. The way that control is set, your burner would fire when the boiler temp dropped to 170* (setpoint-diff) WITHOUT the circ, and off again at 180* . Only on a call for heat should the circ run. No, I'd say you have a defective 8124 and someone tried to band-aid it on the cheap.

Does that 4006 look "factory" ? I have to admit I don't know if Peerless did this or not. Any Peerless experts out there ? C'mon, you know who you are !

Is this a "new to you" system ? i.e. just move in ?

Know any of the systems history ?

I would have the 8124 replaced (after testing to be certain), and cut the wires off the 4006. Set the high limit at 180* the low limit at 140* and leave the diff at minimum. Unless for some reason, this is a peerless idea... then, I don't know what I'd do! This is only what _I_ would do, YOUR MILEAGE MAY VARY!

-
 

Last edited by NJT; 01-08-07 at 04:52 PM. Reason: stream of un-conciousness
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Old 01-08-07, 04:39 PM
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Yeah, new to me. Someone once advised that I should rewire the L4006A in parallel to the burner circuit eliminating the T-T connections on the L8124A. How do i do this?
 
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Old 01-08-07, 04:52 PM
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Wiring

Originally Posted by Icharlie View Post
Right now, the R7184 has the T-T terminals jumped. R7184 feeds(black and white wire) directly into L8124A. The Black is connected to B1, the white connected to B2. It does not go into a junction box first.]]]

That looks to be entirely proper wiring.



[[[The L4006A feeds(white and red wire) into a junction box(with emerency shutoff switch), where the pair is joined with the house thermostat(also white and red) and then continues into the L8124A, where it connects into the T T connections.
This part makes no sense at all! The thermostat should directly control the TT terminals on the L8124 to generate the heat call. The L8124 should control the burner, starting if the boiler falls below a certain temperature, and maintaining that temperature within whatever the low limit differential is set for. On a heat call, the L8124 will try and run the burner to the temp set by the high level limit control... Is the L4006A wired in parallel or in series with the thermostat wires? I'm almost betting that the low limit on the L8124 failed, and someone did a hack using the L4006 and the TT contacts to maintain the low limit. Might be time to have a pro check the controls for proper operation to see why that L4006 is there? I'm not a pro, but it don't seem right to me. Just a guess on my part, for what it's worth. If it is a hack, there are insurance issues if something ever goes wrong...


Pete

A L4006 in series with the burner would provide additional protection on the high limit, that would make sense. What was done still baffles me.
 

Last edited by radioconnection; 01-08-07 at 05:10 PM.
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Old 01-08-07, 05:23 PM
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"Is the L4006A wired in parallel or in series with the thermostat wires?"

I'm not sure how to tell whether it in parallel or in series.
 
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Old 01-08-07, 05:43 PM
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Thumbs down L4006

I fear you are starting to thread on dangerous ground at this point, especially if you attempt to rewire any of the controls without a good understanding of how they work and how they should be wired. I'm sorry, but it might be time to call in a good burner tech to see what's going on.
 
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Old 01-08-07, 06:24 PM
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The L4006a need only make and break the burner circuit. It need not emulate a call for heat and fully energize the triple aquastat, which is what it's doing. I just dont know why.
 
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Old 01-08-07, 07:25 PM
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Tenant?

The question is why the L4006A is there in the first place. There is a triple aquatat on the boiler. If this is a rental, why isn't the landlord addressing the issue? A pro should be addressing this; hard to second guess what was done by a previous "Tenant".
 
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Old 01-08-07, 08:10 PM
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Originally Posted by Icharlie View Post
Yeah, new to me. Someone once advised that I should rewire the L4006A in parallel to the burner circuit eliminating the T-T connections on the L8124A. How do i do this?
No, absolutely not.

The technician that comes in may end up using the T=T terminals, but
you probably should not.
 

Last edited by NJT; 01-08-07 at 08:30 PM.
  #12  
Old 01-08-07, 08:19 PM
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Originally Posted by Icharlie View Post
The L4006a need only make and break the burner circuit. It need not emulate a call for heat and fully energize the triple aquastat, which is what it's doing. I just dont know why.
You are correct, but that's the job of the low limit setting on your 8124 TRIPLE aquastat. The 8124 _INCLUDES_ a 4006 control built right in to it. The low limit setting built in to the control _IS_ a 4006.

It CAN'T work the way you want or expect it to work wired the way it is.

Your 8124 is DEFECTIVE or DAMAGED.

Have a service guy come out, replace the 8124, and cut the 4006 out, you don't need (or want) it.

If anything, ask the technician if that control can be wired as a secondary hi limit, and set it above the hi limit in the NEW 8124 .

We told ya why... cuz somebody tried to use a cheaper control in order to not spend the bucks on a new aquastat.
 
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Old 01-08-07, 08:25 PM
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Originally Posted by Icharlie View Post
"Is the L4006A wired in parallel or in series with the thermostat wires?"

I'm not sure how to tell whether it in parallel or in series.
If you've got THREE wires joined together TWICE, it's in parallel.
(Two groups of three)

If you've got TWO wires joined together THREE TIMES, it's in series.
(three groups of two)

From the way you say it's controlling your system, I can tell you that it's wired in PARALLEL.

Do you own this home ? or do you rent ?

If you rent, DON'T TOUCH IT! It's NOT YOURS to play with.
If you own the home, CALL A TECHNICIAN!
I'm don't mean to be mean, but truth is that if you don't know the difference between a series or parallel circuit, that you aren't qualified to be re-wiring control circuits.
 
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Old 01-08-07, 08:34 PM
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answer the questions!

OK, one more try:

WHAT TEMP DOES THE BOILER MAINTAIN ?
 
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Old 01-08-07, 08:55 PM
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I own the home. The boiler maintains 170 degrees when DHW is not in use. When DHW is called and temp reaches 140, the burner and circulator kick on until 180ish is reached.
 
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