4-zone, Boiler, electrical issues...help?

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Old 01-08-09, 04:02 PM
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Exclamation 4-zone, Boiler, electrical issues...help?

4 Honeywell T87F thermostats controlling 4 Honeywell V8043F zone valves, with a newly installed Honeywell L8142E 1016 Triple Aquastat running an ancient boiler. Relay on old Aquastat stopped working so replaced the unit today. New unit works but pump runs constantly unless water temp drops too low. The zone valve wiring was all screwed up so I redid it per Honeywell diagram. No change in how pump runs, either before or after change in wiring. If I disconnect the feed to the transformer (from TH-TR and TR) the pump does not stop. If I disconnect the feed from END and SWITCH to power, the pump stops. I have long had questions about my thermostats, and the system had screwy wiring for ten years, so some or all of the attenuators may be fried. I'm fairly certain at least one the thermostats doesn't work at all. Another one seems to trigger the valve at times that don't make sense. If I have a bad zone, I can work around that, but why is the pump on constantly? It looks like we made the T, C, L, and B connections to the Aquastat correctly. Thanks for any suggestions...
 
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Old 01-08-09, 04:22 PM
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You should have no connections from the transformer to any of the end switch wiring.

All endswitches should be wired in parallel and then on to the T and TV on the 8124.

I suspect the ZV wiring is still screwed up and that you are 'backfeeding' the thermostat connections on the aquastat with the 24 VAC from your transformer.

What happens when you disconnect the T and TV wires from the aquastat?
 
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Old 01-09-09, 07:26 AM
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You should have no connections from the transformer to any of the end switch wiring. (I was unclear in what I wrote. Transformer is fed from TH-TR in parallel for one wire, and TR in parallel for the other wire.)

All endswitches should be wired in parallel and then on to the T and TV on the 8124. (Yes, that's what I did. Is it possible to get T and TV backwards on the 8124?)

I suspect the ZV wiring is still screwed up and that you are 'backfeeding' the thermostat connections on the aquastat with the 24 VAC from your transformer. (Don't know what ZV wiring is. The Z connector on the 8124 is not being used. I wired the new 8124 based on the old one, but the whole system has never been quite right.)

What happens when you disconnect the T and TV wires from the aquastat? (I may get a chance to try this later today. Is this still your first suggestion based on what I just said above? Thanks.)
 
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Old 01-09-09, 03:05 PM
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Is it possible to get T and TV backwards on the 8124?
No, either/or is fine.

Don't know what ZV wiring is.
Sorry, shoulda defined: ZV = Zone Valve

Is this still your first suggestion based on what I just said above?
Yes. We need to determine if the problem is with the zone valve wiring, or the aquastat itself.

When the wires are removed from T and TV, the circ pump should be shut down... the burner may still fire based on the LO setting. If you place a wire jumper between T and TV, the boiler should turn on... depending on the temperature of the water in the boiler at the time, and the settings of the aquastat, the circ pump may or may not run, but when the temp rises above the LO + (DIFF - 10) the circ should run.

If the circ pump never runs with T and TV open, then the problem is either with the zone valve itself, the endswitches, or the zone valve wiring. If the circ pump runs at any time with no connection to T and TV, then there's a problem with the aquastat.

How is your understanding of how the triple aquastat is supposed to operate? And what settings do you have on the HI, LO, DIFF knobs?

Double/triple check the wiring of the endswitches.

Take a look to see if one of the zone valves is hanging open (not closing). This could cause a continuous 'call for heat'. If the MANUAL OPEN/CLOSE lever moves freely, rather than with a little resistance, the valve is open ...

If you find a valve OPEN, double/triple check the wiring to the zone valve motor connections. If there's an error in wiring, the valve might be energized all the time, rather than being mechanically/physically 'stuck' open.

Do you own a multimeter and know how to use it?
 
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Old 01-09-09, 03:55 PM
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Sorta, I've re-read your original post... a few more questions:

Since you said you have no connections to the Z terminal in the aquastat, you are not powering the zone valves from the transformer in the aquastat, and have a separate transformer.

As such, there should be no jumpers from either of the endswitch terminals to the TH terminal. The only thing on the TH term should be one wire from each thermostat.

All the TR terminals are going to one side of the transformer, and the other side of the transformer is going to all the TH-TR terminal, along with one wire from each thermostat. Yes?

If after you do the previous tests on the aquastat, remove the wire from each thermostat to the TH terminal on each zone valve. All the valves should be CLOSED, and there should be no call for heat. The circ should not be running.

If any of the valves are OPEN with the TH terminal OPEN, and the circ still runs as though there's a call for heat, that zone valve is defective.
 
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Old 01-11-09, 03:12 PM
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OK. Extremely helpful. Based on what you have said and my Honeywell diagram, I'm quite confident the wiring is right and that I'm OK on the aquastat (low setting 140, high setting 180, DIFF about 18. And the pump DOES shut off, for example, when the system has been off for a while, I turn on the main power switch, the boiler fires up, the pump kicks on, and the COLD water in the pipes begins to flow back into the boiler, lowering the temp. Then the pump kicks back on at about 150).

What I was beginning to suspect was that bad zone valves may be causing my always-on problem. Pretty sure I have two of those out of four. They are noticeably older than the other two. They have brass-colored SYNOCHRON cylinders inside while the newer ones are something like aluminum. So I'm going to try cutting to the chase and completely bypass those valves in terms of wiring, while keeping the wiring logic intact for the remaining two valves in terms of END/SWITCH and TH-TR/TR connections. Then I bet the system behaves normally. If so I will manually open the two bad valves (they may already be stuck open), and run the house in two zones. Not the end of the world until I want to bring someone in to hassle with draining the system and replacing the valves. I know this means that whenever either of the two good zones are on the bad zones will also get heat, so I might experiment with limiting the water flow in those zones via the faucet-type valves (name eludes me at the moment).

I'll keep you posted...
 
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Old 01-11-09, 04:10 PM
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When I remove the wiring from the two valves that seem bad, I end up with one thermostat being able to open/close its valve and control the pump. The other thermostat opens and closes its valve, but does not affect the pump. I've re-checked all the wiring on that valve. Does this make any sense?
 
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Old 01-11-09, 04:20 PM
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Does this make any sense?
Yes, sorta, Sorta...

If you are totally convinced that the wiring is correct... in that the ONLY connections to the ENDSWITCH terminals are those that run to the T and TV terminals on the 8124 ... and those endswitch terminals are all wired in parallel, and continue on to the a'stat... then:

It seems that you have only ONE out of four zone valves operating properly. If the two that you disconnected were always firing the boiler, and removing them both solved that problem, then the one that DOESN'T fire the boiler has an endswitch that is not MAKING contact...

Those ZV 'heads' are easily replaceable. You don't need to drain anything in order to do so... however, if the 'old' ones are very old, there's always the possibility that product changes will make a new head incompatible.
 
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Old 01-11-09, 04:27 PM
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Here's how I would isolate the 'always on' zone valve (in lieu of a multimeter on the OHMS scale):

Turn ALL t'stats all the way down.

Disconnect ONE of the endswitch wires from each zone valve, so that you have four wires hanging near the terminal.

Make sure all the zone valves are CLOSED.

Touch one of the wires to it's endswitch connection. Boiler should not fire.

Repeat for each of the four endswitches.

If one (or more) of them fire the boiler with the t'stat down and the valve closed, that switch is 'stuck' shut for some reason.

Connect the other 'good' endswitch wires back up.

Turn each t'stat up in turn and verify that each one is able to fire the boiler.

This will test two conditions, either stuck shut, or stuck open.
 
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Old 01-11-09, 04:31 PM
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One more thing... by keeping a zone valve manually open, not only will those zones receive heat when one of the other zones calls for it, you may also find that those open zones receive heat when NONE of the other zones are calling for it... due to gravity flow. Cool water sinks, hot water rises...
 
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Old 01-11-09, 04:39 PM
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OK, TWO more things...

It is possible for the MOTOR to be OPENING the zone valve, but the SWITCH to not operate. That appears to be what you are seeing on at least one of your valves.

It's unusual for the SWITCH to be stuck closed though, without the VALVE being stuck closed.

When you push the t'stat up for the two 'older' valves, can you SEE/HEAR the gears turning? If the valve is actually opening and closing, and the switch is indeed 'stuck' closed, if you remove ONE of the endswitch wires and tape it up, you can continue to allow the valve to operate, it just won't fire the boiler.

Do you have a multimeter?
 
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Old 01-11-09, 07:16 PM
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Great. I'll get to all this when I can -- the system is already much more functional than 24 hours ago.
 
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