Circulator Pump Relay Wiring - Honeywell R845A

reghi

I need help with wiring a relay. I have two boilers and four separate zones with four circulator pumps. I had 3 zones on one boiler and 1 on the other. I now moved one of the three zones to the boiler with the one zone so now I have two boilers with two zones each and I need help in figuring out the wiring.

How do I wire these relays. I am attaching pictures.

Additionally, how do I troubleshoot these relays as it seems that one of the relays is not turning on the circulator pump. If I jump the two T terminals that should make the circulator start, right? As I can turn on the circulator by pressing on the contactor, however turning on the thermostat does not turn on the circulator pump.

How do I test the relay to see if it's good or if it needs replacing.

Also how do I wire the relay, to get power for another relay?

JohnNY

If closing the t-t circuit doesn't pull in the pump relay then I'd replace the whole relay.
Wiring goes like this, basically, but you shouldn't share terminals if you can avoid it. Use a wire nut to gang wires:

Each relay needs its own power leads and the "T-T to boiler" leads can be wired in parallel to close the T-T circuit when either unit calls for heat.

JohnNY

If I were you i'd simplify the whole situation and get a Taco SR502.

JohnNY

marked up here

GW

I don't see your 5 and 6 terminals wires up, these honeywells call on the burner?

reghi

First of all, thank you to everyone. Please tell me if the following is correct or not?

I don't need this relay, as it is only controlling one circulator pump, I can get the spst version. I don't want to spend the money on the 2 zone taco, but I am leaning toward the one zone taco. When my bell and gosset circulator pumps go bad, I replace them with the Taco circulators, as they are much cheaper, do not need yearly oiling and take less space.

I need to run power (from boiler switch) to terminal 1 (hot) and 2 (neutral). The best way to accomplish the above I believe is by pigtailing the incoming hot to terminal 1 and 4 and to the outgoing power to the second relay. Pigtailing a a neutral to terminal 2 with all of the other neutrals (pump, cirulator power 2 and incoming power).

To test functionality, I can jump the t terminals and test if terminal 3 is hot (as long as terminal 4 is powered from 1.

I do have a couple of questions.

Why does terminal 1 need to get power, why isn't terminal 4 powered directly, as terminal 4 is what powers the cirulatror.

What other tests can I perform on the various terminals. This is just for my knowledge as I really want to understand what how the relay works.

Thanks again to everyone you guys are a great help.

reghi

Last question.

There is no way to wire these relays, to get run off two separate thermostats to control 2 different circulator pumps, right?

Then if the above is true, why do these relays have a second (5,6) power going out? Is that for a situation when one thermostat runs two zones? Or is that for powering the aquastat on the boiler?

The aquastat is running off of a low voltage transformer currently, which is powered by the main boiler switch.

If the aquastat is low voltage, then line 5,6 would have to be wired to a low voltage transformer and then the burners would only go on when the thermostat is calling for heat and there will be a delay in heating but saving in the boiler not keeping the water hot at all time, similar to a water heater?

GW

Your questions seem to have multiple answers depending on the goals or restraints. 5 and 6 are simply a contactor. You need to unthink this a bit. Think of 5 and 6 as a light switch on your wall.

What powers the aquastat isn't related to what powers a relay control. If you're running pumps you need 120v. You're trying to combine too many thoughts. The two controls handle different duties and they each have their own trans

It's been years since I've wired an 845, but I believe 3 and 4 are the same a 5 and 6. Simple contactors. It's generally assumed you're using this for a circ, hence jumping power from 1 to 3. Again, it's just a light switch, able to pass 120 or 24.

Two stats controlling two different circs? No, one 845 can not do that.

Bob Bona_4

Yes, 3 and 4 are dry contacts.

Paul48

As are 5 and 6. You use 5 and 6 for the T-T contacts on the boiler. When the stat attached to the 845 calls for heat, the 3-4 contacts close and start the circ, and the 5-6 contacts close and start the boiler.

Bob Bona_4

Right. And 1 and 3 are jumpered in that scenario to send power to circ.

BigMak

I have a similar issue with my R845A honeywell relay switch. something or multiple things went wrong.
1st: when I engage tstat, relay doesn't engage. Aquastat is set well below boiler temp, so i know that isn't an issue, (I think). I jump T-T still no relay trip. if i push down on relay, to engage contacts, I here/see it trip. then it sends power to circ, but circ just humms. no motor movement. It was working previously. then i re-piped and replaced circ. at first it was working, but now it is not. In fact, the motor was rotating although briefly. everything is old, A-stat, relay, circ. I tested the load at #1 & #4 when i manually engaged the relay, and it reads 125V.

Is it the circ, relay or both?
1. why doesn't the relay engage when Tstat calls? ( how to test?)
2. why isn't the circ rotating when receiving V? (I'm thinking impeller is stuck, because i do hear a humm when i manually engage)

thoughts?

thanks in advance.

PS, I see the electrical tape, I inherited it.

EBEBRATT-Ed

Sounds like you have multiple problems.

First use a cut off extension cord to power the circulator. You have a bad pump , stuck impeller or bad motor or something. Troubleshoot that first

Back to the relay. You need 120 volt power on terminals #1 & #2. #3 & #4 are just a set of contacts that make and break to start the circulator....like a light switch

The circulator hot should be hooked to #4. #3 needs 120 volt power (usually a jumper from #1 The circulator neutral (white wire) gets hooked to terminal #2 or to the incoming neutral wire.

With power (120 volts) on terminals #1 & 2 and a jumper on T & T the relay should pull in and start the pump. If it doesn't the relay is bad

Remove the T & T jumper and connect your thermostat wires. If it doesn't work then you have a ad thermostat or thermostat wires

BigMak

EBEBRATT-Ed I will try trouble shoot. if the relay is bad, i was thinking i could hook up to a taco SR503-EXP, I have one zone open on it. I have to review instructions, but i think each circ needs its own transformer. and then off to removing replacing/ repairing circ. when it rains, it pours!!!

thanks

BigMak

UPDATE:

So I solved the multiple issues; circulator & R485A relay switch. Circ was jammed by a piece of metal. Looks like a piece of the boiler. I'll attach a pic. And the Relay must have been shorting out. I changed the wiring, previous was dry rotted. I bench tested the circ, so I was confident about putting back. But
didn't know how to test the relay, luckily it was the wiring.