Automag Relay Question
Hi All, new to the forum.
I recently purchased a home with an older Automag zone valve system. Oil furnace, hot water baseboard heat.
A recent problem has come up where all zones are heating when one zone calls for heat. I know that these automag zone valves fail open so I am thinking that this is an electronic problem as opposed to all of the valves being non-functioning. I have even replaced a few of the valve heads with new ones to confirm that and no change.
My question is I cannot seem to figure out what this separate relay is, it is on the side of the control board. It is hooked up to the hot water tank which I believe is the priority zone.
Here are some photos of the relay. There are no markings on it. The only similar relay that I was able to find is the Automag CNV84 ( picture attached)) which is a 3 wire to 2 wire relay. Is this what I should be changing out?
I dont think the problem is with the main control board, as thermostats are working correctly and kicking on/off furnace when it calls for heat. The problem is that power is not going to the valves to close them, and that the hot water tank is not regulating a constant temperature.
Thanks for any help or guidance you can give.
Comments
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0 -
That looks like a standard run of the mill relay. 24 volt coil 24 volts to terminal 1 & 3 powers the coil.
contacts 2 & 4 are normally closed with no power to the coil
contacts 5 & 6 are normally open with no power to the coil
The contacts reveres operation when the coil is powered. Look closely at the relay the terminals are usually marked
I think the 24 volt coil is the two white wires. Terminals 4 & 6 are connected internally. It is a single pole double throw relay
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you have to trace things with a meter. there could be a transformer or fuse that is bad or something like that or a wire that is broken off somewhere. that type of wire will snap off really easily if you nick it when you strip it. i can't really think of a reason why there would be a single relay in front of all of the zone valves. the relay that is screwed to the framing might turn off all of the heating zones when there is a dhw call.
that is just a standard inexpensive hvac relay, it has nothing specifically to do with thermostats.
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i don't think there are any electronics there, i think that is just a set of insulated bus bars from the telecom or alarm industry repurposed to wire the zone valves.
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Some information here.
Apparently those zone valves need power to close, and they stick easily, they also may run on DC current instead of AC current like most modern zone valves do.
Your black plastic box looks like a relay with a date code 8943 (43 week of 1989), and the crimp connections look pitiful.
These may be relays also.
I suspect the thermostats energize the zone relays and the zone relays then cut off the power to the zone valves so they open allowing the water to flow.
I also suspect for DHW (Domestic Hot Water) priority it is controlled by an aquastat or DHW thermostat that controls the black plastic relay and it simply may disable power to the space heating thermostats or the zone relays' coils, so they can't be energized to shut off the DC power to the zone valve coils.
Not sure where the AC to DC conversion is, maybe in the junction box. What is under the cover of the junction box ? I suspect the relays are all AC powered but that is just a guess.
More pictures of the whole control system may help.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System1 -
pretty sure these are bus bars, don't see how the screws are insulated from the metal.
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It looks like this may be a full wave bridge rectifier, the AC to DC conversion. If the yellow wires are the 24 VAC and all the zone valve control equipment may be after the rectifier and all the relays may have DC coils.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
there aren't any relays other than the one that is probably doing dhw priority(or firing the boiler from the end switches). those are the busses that supply the zone valve and thermostat for each zone and the combining of the end switches. the rectifier could be bad and keeping the zone valves from closing but the end switch fires the boiler.
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Yes that would make sense and the thermostats open for a call for heat, the black plastic relay is for DHW priority, it interrupts power to the upper bus bar.
I've seen older equipment where the whole base plate is the insulator like the plastic relays are now, however I like the bus bar theory. Makes more sense with the wiring and screw count.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System1 -
What model is the main control board? And what model are the zone valves.
Can you post pictures of each ?
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
I think these are basically a solenoid type valve, powered close.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
Thanks all for the replies, much appreciated. During my research I did find that this is a standard SPDT relay. I have one on order that will be here Tuesday. I will update once I change that out. I will also take photos of the control board.
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Would that rectifier be easily removed and replaced if once I change out the SPDT relay and still have same problem? Hopefully there is a model# on it to help find a replacement. It seems as this entire system is somewhat obsolete. I am not crazy about the open fail scenario, that seems more appropriate for a dump zone than having them for every zone valve.
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There are two versions of the Automag zone valve the AA is a DC, they offer an AC version also.
So if you start changing components be sure they are all "on the same page" regarding current and voltage.
It looks like a bit of a homemade wiring and power source for those zone valves?
Maybe the electrician worked for "Ma Bell" at some point based on the wire and terminal block :)
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
I kind of doubt the full wave bridge rectifier for the AC to DC conversion is defective. If it is defective it would probably short out and that would probably cause the 120 VAC to 24 VAC transformer to fail. Diodes and bridge rectifier like that rarely fail open like a blown fuse.
You really need a multimeter and figure out what is really going on. Rolling the dice and saying I'll replace this may be a waste of time and money. So far the only thing I see that I don't like is the crimps on the push on connectors to that relay. But since you have moved that relay all around you may have noticed a poor connection there.
Does any part of the control system seem to work normally or show any signs of life ?
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
One thing I don't like about the 'open fail scenario' is you are paying for electricity to shut the heat off. So all summer long unless you shut the system down you are paying to have those zones to not have heat. You probably can't shut it all down if it is also used to make your DHW too.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System1 -
I for sure plan on changing out the connectors to that relay, Previous job was poor at best. Good to know about the rectifier. System seems to work fine other than all zones heating when calling for heat, and the priority hot water tank not regulating it self. All zones seemed to have failed open so heat is going to all zones anytime there is a demand. I am hopeful it is the relay but if it ends up being something more severe I will be ripping it all out and going to an standard Taco normally closed system. Thanks for your input!
0 -
Thanks for sharing hot_rod. I have the AA valves. I have bought a few extras and swapped them out as my first thought for repair was changing out the zone valve head. But no change. They are not closing and are in a failed open scenario.
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You mentioned a main control board. Does it have relays ? Picture, model ?
" I dont think the problem is with the main control board "
Since the zone valves 'fail safe' is open providing heat is there power to the zone valves ?
If that black relay is for DHW priority (I'm not convinced) I would think if it failed you would have normal heat or no heat or just DHW priority or no DHW priority depending on what failed inside the relay. You seem to have multiple symptoms.
OR you have multiple issues.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
Fail safe is a bit of a misnomer, if power goes out in a building, there is a pretty good chance the boiler or source of heat will go down also. So it is not 100% fail safe.
Also I'm guessing there are more non heating hours in a year than heating. So N.O. valves probably consume more energy.
8760 hours in a year, maybe 2000- 2500 heating hours, in a midwest climate region?? Energy efficient homes 1000 hours??
@Jamie Hall passive home designs 10 hours :)
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream
1 -
have you tried getting a multimeter yet…
it is a little messy and made out of scrounged parts but it isn't bad(someone other than the original owner may have worked on it and not put things back when they were done). maybe they worked in an industrial setting that used those valves.
it isn't impossible but it isn't likely that a relay would fail in that particular application, it has enough load to keep the contacts clean but not enough to wear them out.
0 -
Depending on what is actually wrong, I would think a repair is a lot less expensive than replacing all the zone valves and starting over. However some good troubleshooting has to be done to determine the actual defects.
Lets say that some or all of the space heat zone valves are sticking open even though the DC power is applied to all of them. Since the DHW priority is electrically controlled, you have lost DHW priority control if any of the zone valves are are sticking open. Does that seem like that is whats going on ?
It may not even be an electrical problem.
Not sure if you can get rebuild kits for those zone valves.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
Seems like the Zone valve repair kits are available.
https://www.automagzonevalves.com/automagrepairaccessories
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
If it were me I'd turn down all the space heat thermostats, let the pipes cool a bit, run the DHW water to force a DHW priority (boiler running), feel if hot water is leaking by any of the space heat zone valves and measure if the 24 VDC is present at any space heat zone valves that are leaking by.
If the 24 VDC is present, hot water leaking by, the zone valve needs repair or replacement.
The zone valve coil resistance should verified too. An open coil will cause the valve to not close. It appears replacement coils are available too.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
I have replaced the zone valve heads. It is not the zone valves malfunctioning.
When I say " fail open" I mean if the zone valve does not have power it reverts to open. They are a normally open coil. Obviously if the power is out it doesn't matter, but based on heat dynamics the residual heat will continue to flow from hot to cold, so I understand that there is a basis for a fail open valve. To me it makes more sense for dump zones, not having every zone that way.0 -
I have tried that scenario. no demand from thermostats. I turned up the thermostat on the hot water tank to call for a demand, and furnace does not kick on. All coils / zone valves are open. any time there is a demand and furnace kicks on, it sends heat to all zones.
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My point is, is the water part of the valve sticking (apparently there is a history of that happening), I'm thinking changing the head does not repair a leaking or stuck open valve. Or is the DC power to the zone valve actually missing ?
Loosing control of the space heating zones (for any reason), you loose control of the DHW priority.
With zone valves that are normally open (power to close) makes the troubleshooting more interesting.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
Another test. If you understand the black relay's switching you can temporally disconnect the switching wires and do the switching manually to see if it restores the normal system functionality.
I would venture to say it is a SPDT (Single Pole Double Throw) relay.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
i'd start with seeing if there is power to those bus bars with a dc voltmeter
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I agree, but somehow I get the feeling the OP is not really interested in a multimeter.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System1 -
I have taken the zone valve apart, checked for a blockage, and changed the head. Not sure what else to do as far as a mechanical failure. In my opinion it has to be electrical. Yes I can check voltage with a multimeter. I am not "against that" I am just trying to figure out what the most likely candidate is. My multimeter is missing in the pile of boxes as I just moved in here. Thanks for the help, even with the subtle digs.
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if none of the zone valves are working right the most likely cause is that they aren't being powered so really the only practical way to troubleshoot it is with a meter or maybe a test light but if something like half the rectifier shorted then burned open if there was enough available fault current you'll need a meter to see that the valves are powered but not with enough voltage to close them
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Not a dig, you just seemed not interested. Some folks have no interest in a meter. To me taking voltage measurements is way easier than taking a valve apart. As much as electrical properties were mentioned you just seemed uninterested. I think a few minutes with a meter the problem may be obvious. Then you could just repair the actual defect instead of all of us just guessing. Test don't guess, is what I try to do whenever possible.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System1 -
Ill keep looking for the multimeter and will update. Thanks for advice everyone. I really do appreciate it.
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multimeters have become very affordable if your search does not turn up yours. Home Depot example
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
I use a multi-meter every day at work, I have more than my fair share at home. If my Boss told me I had to do my job without a meter I would probably quit.
With troubleshooting, one strategy is to eliminate what is working normally and move on. System power is high on the priority list, if there is no power or the power is incorrect expecting the equipment to work normally is silly and will give you an incorrect troubleshooting direction. If there is actually no power to any of the zone valves when there should be, yet system power is good that may be a huge clue and basically eliminated the zone valves as an issue as far as system control is concerned. An example; The black relay's basic functionality could be verified quickly, bad replace it, good move on.
You are here for assistance, I think everyone here wants you to resolve the issue as efficiently as possible. We only know what you tell us about your system and your troubleshooting resources, and your troubleshooting strategies may be different from ours.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0
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