Trying to figure out what's happening here!!

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Old 01-13-09, 08:06 AM
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Trying to figure out what's happening here!!

Hello all,

I'm new here so pardon my ignorance!

I have a basic six zone hydronic system consisting of a Burhnam propane boiler, Aquastat L8148E Relay, Taco 008-F3 Circulator and Synchron 35335L ZV motors. I'm trying to understand its behavior so please bear with me as I detail out this system and explain what I "think" is the operating procedure.

When the Tstat is NOT calling for heat, the voltage across the two wire is approx 27 VAC. When a room temp exceeds Setpoint (SP) the voltage across the same two wires goes to 0.00 vac.

When this occurs, the circ pump suppose to start up and the Zone Valve (ZV) is suppose to open up (confirmed). The Synchron motor starts spinning and the ZV opens up therefore sending water to that zone (baseboard).

The Synchron motor stays energized even though the motor can't spin any longer after the ZV is fully open. The limit switch in the "head" of the ZV is suppose to turn on the circ pump and tells the boiler to go to "high fire" (confirmed).

According to the literature on this Aquastat relay on Honeywell's site "A call for heat by the
thermostat starts both the burner and the circulator.


What I'm experiencing is this: as soon as there is power to the Aquastat relay, the circulator starts running. As soon as there is call for heat, the ZV opens up and the boiler goes into high fire.

My question is this: should the circulator keep running continuously 24/7? If the answer is no, I need to take the Aquastat apart to find the culprit. Due to the orientation of the Aquastat, I've been using a telescopic mirror to troubleshoot. Is it possible to move the Aquastat from its current position or is it affixed to the well head in such a way to make this not possible?

Things I've done to troubleshoot:

Disconnect wire going to Tv term - circ stops
Lift all Tstat wires on the circuit board (CB) - no change, circ keeps running

The Boiler is cycling as needed based on water temp.

Picture of the overall hydronic system:



Aquastat Relay



Aquastat Relay location/orientation


Thanks for any feedback.

 
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Old 01-13-09, 07:27 PM
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Wow, 27 views and no ideas?
 
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Old 01-13-09, 08:45 PM
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Just thought I would let you know I am trying to figure this out, but am quite tired and may need to finish this in the AM.
 
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Old 01-13-09, 08:52 PM
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Impatient? Try to remember that we're all volunteers... nobody is getting paid to answer any questions... and you aren't paying to have them answered. So, you get what you get... sorry if it's not fast enough for you.

If your circulator is wired to C1 and C2, then NO, it should not run 24/7.

If lifting either the T or TV wire stops the circulator, the problem is NOT in the aquastat.

Try this: Disconnect BOTH the T and TV wires. The circ is OFF, the burner is OFF. Correct?

JUMPER the T and TV together, the circ should run, and if the boiler water is below the high limit setting, the burner should also fire. (I'm not sure what you mean by 'high fire', does your boiler have a 2 stage gas valve?)

REMOVE the jumper again, and both circ and burner should shut down.

This will prove that your problem is NOT in the aquastat.

Do you know how to use the OHMS scale on your multimeter to check for continuity?

Push all the thermostats all the way down. All the zone valves should be CLOSED. Check for continuity across the two wires that were connected to the T and TV (with them still disconnected). If you have continuity with all the zone valves closed, then the problem is one of the following:

1. All the valves are not closed. One may be physically 'stuck' open.

2. One (or more) of the ENDSWITCHES are defective and 'stuck' calling for heat.

3. Defective/damaged wiring of the ENDSWITCHES to the boiler. (the RED wires on your valves)

You can check for 1. by operating the manual open levers on each valve. If the manual lever is 'swinging in the breeze' with no load on it, the valve is stuck open. If the valve is truly closed, when you operate the manual lever you will feel resistance and hear the gears turning as you manually open the valve.

2. If this is the problem, you will have to disconnect one red wire from each valve and test for continuity between the two red wires from each valve. You need to disconnect the wires because all the ENDSWITCHES are wired in parallel. You can't find the bad one unless you electrically isolate them.

3. Pretty much a visual check here... examine the wiring and make sure that there are no loose strands of wire touching each other.

So, get to work... and make it snappy... I ain't got all night ya know!
 
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Old 01-13-09, 08:55 PM
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Is the circulator in fact wired to the C1 and C2 terminals on the aquastat?
 
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Old 01-13-09, 09:00 PM
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Thanks Trooper for bailing me out on this one. I was just doing the research to make sure I am giving the correct info and I find you already did all the typing for me

Mark
 
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Old 01-14-09, 07:17 AM
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Thanks for the info, much appreciated. Let me go check the wiring and do as you suggested and will report back.

BTW, my definition of "high fire" only means that the boiler is coming on to heat the water. Sorry for the confusion.

Oh, before I go, let me clarify a few things:


If your circulator is wired to C1 and C2, then NO, it should not run 24/7.


Yes, it's wired exactly as in the nameplate picture shown above.

Push all the thermostats all the way down. All the zone valves should be CLOSED. Check for continuity across the two wires that were connected to the T and TV (with them still disconnected). If you have continuity with all the zone valves closed, then the problem is one of the following:

1. All the valves are not closed. One may be physically 'stuck' open.

2. One (or more) of the ENDSWITCHES are defective and 'stuck' calling for heat.

3. Defective/damaged wiring of the ENDSWITCHES to the boiler. (the RED wires on your valves)


All Tstat wires have been disconnected from the termination board (see the first picture, on the right). So that leaves the endswitches (limit switches) feeding the Aquastat.

1. All the valves are closed and this is confirmed by checking the temp of all downstream pipes. They're all cold after the ZV.

2. ENDSWITCHES - I'll check all the limit switch contact closure and report back.


thanks again!
 

Last edited by alia176; 01-14-09 at 07:48 AM.
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Old 01-14-09, 08:11 AM
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Ok, tested the wires.

Looks like one of the limit switches is showing a NC (continuity) when it should be NO contact. I went straight to the termination board on the wall and identified all limit switch wires then started to lift one at a time until the circulator stopped running.

I'll take off the motor assembly and inspect the limit switch to see if it's repairable.

Thanks very much once again. Beer 4U2
 

Last edited by alia176; 01-14-09 at 10:01 AM.
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Old 01-14-09, 08:09 PM
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Update: the limit switch was stuck in the closed position. A little bit of contact cleaner unstuck it so hopefully this will last another 10 years or so!

Cheers.
 
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Old 01-14-09, 08:45 PM
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It might!

If it doesn't, and since it sounds like yer a 'unit repair' kinda person, the 'microswitches' in those valves are replaceable if you can find the correct one.

Mouser Electronics, Digikey, should have an appropriate part that will work. They have websites... others on here have done this, and perhaps they will have part numbers they can chip in.
 
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