Relay for control of circ pump doesn't make sense


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Old 10-25-14, 10:43 PM
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Relay for control of circ pump doesn't make sense

Hi everyone, new to the forum, first post. This forum has been immensely useful to me since I moved into my new place and took possession of a Beckett oil burner with Weil-McLain boiler; mixture of radiator and in floor between joist heating. One of the Honeywell zones valves was sticking in the open position so I went to change it and realized that they all have auxiliary switches on them that were wired in a circuit to a relay which looked like it should control the circ pump. However the circ pump runs continuously whether the zones are calling for heat or not. The aux switch circuit does seem to be correct and energizes to 26 volts when the zone valves are calling for heat. There is a little green test button on the relay that when pushed does stop the pump running. Here are some pics that I hope illustrate the situation.

It would be nice if this pump only ran when the infloor was demanding heat. I suppose the relay probably needs replacing. Is there some way to test it?

Thank you.
 
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Old 10-25-14, 11:09 PM
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Welcome to the forums.

I've posted a diagram of your relay.
Terminals 2 and 7 are the 24vac coil.
Terminal 1 is common,
Terminal 3 is normally open
Terminal 4 is normally closed

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Your "load" is connected to terminals 1 and 4 which means with no power to the relay the circuit is closed. When you apply 24vac... terminals 1 and 4 will open.

That is backwards from the way it should be. The end switches in the zone valves close with a call for heat which should cause the relay to activate. You should be using terminals 1 and 3 for the pump.
 
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Old 10-25-14, 11:44 PM
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That makes more sense. I tries it and now the pump runs when the test button is pushed and goes off when it's released. However the pump does not activate with a call for heat? Bad relay. Remove and replace?
 
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Old 10-26-14, 05:49 AM
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when zone valve is open do you have 24 volts across terminal 2& 7?, if not end switch or 24 volt transformer may be bad.
 
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Old 10-26-14, 08:27 AM
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The aux switch circuit does seem to be correct and energizes to 26 volts when the zone valves are calling for heat.
What saves asked... your statement above means that when a zone is calling for heat you have that 26 volts across 2 & 7 ?

Do you hear the relay 'click' when the 26 VAC is applied?

If not, it does sound like a bad relay and someone 'band-aided' it by moving the wire from 4 to 3.

You obviously have a multimeter if you're measuring volts...

Do you know how to use it to measure OHMS?

Remove one of the wires from either 2 or 7 and measure the resistance between 2 and 7.

Spec on the relay says it should be 80 ohms. If it's 'infinite' or 'open', the relay coil is fried.
 
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Old 10-26-14, 12:58 PM
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Yes, there is 26 volts across 2 & 7 when the zone valves are calling for heat.

I'm not hearing any clicks or seeing the relay move at all when the 26VAC is applied.

I refreshed my memory on reading OMHS, changed the battery in my multimeter (it was low), tested it on some dc resistors I have kicking around, all good readings.

I measured the resistance between 2 and 7 and my multimeter reads 0.L. Not completely sure what that means, my multimeter's manual doesn't explain.
 
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Old 10-26-14, 01:18 PM
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my multimeter reads 0.L. Not completely sure what that means, my multimeter's manual doesn't explain.
OL = "Open Loop" which is basically what you should see when you aren't measuring any resistance.

It means the coil on the relay is open... bad relay.
 
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Old 10-26-14, 01:35 PM
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Ok, great, thank you, I should be able to pick up a new relay tomorrow and try it out. It would be nice if that circ pump only ran when required, it would save me a few bucks in electricity. I'm owner of this place for only 3 months and really want to understand the system as we slide into heating season. I live at 62 North, we get -40 degrees here sometimes.
 
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Old 10-26-14, 01:50 PM
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Siemens is one manufacturer of that relay that I use a lot.... part # 3TX7120-1DC13
Amazon carries them. Not sure who has the best price.
 
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Old 10-26-14, 02:40 PM
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I live at 62 North, we get -40 degrees here sometimes.
Two seasons right? Spring and Hockey?

There are a number of manufacturers that make that same relay. Potter and Brumfield would be another.

KRPA 5AG-24 <-- single pole

or

KRPA 11AG-24 <-- double pole

The relay you have is a TWO POLE DOUBLE THROW (aka 2 FORM C) , but you are only using one pole so you could use the SINGLE POLE relay as well.

KRPA-5AG-24 TE Connectivity | KRPA-5AG-24-ND | DigiKey

KRPA-11AG-24 TE Connectivity | PB167-ND | DigiKey

The double pole is less than half the price of the single pole, probably because of demand... go with the double.
 
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Old 10-26-14, 03:21 PM
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Well I'll see what my local supplier has before I go shop online. I have lots more questions about how best to operate the system, like are programable thermostats worth installing, but I'll start a new thread for that. One quick question though, after I changed the zone valve it has been leaking ever so slightly from one of the flare fittings even after reinstalling it and re-torquing it. How much torque do these fittings need? They should not require any tape? Is that correct?

Thanks
 
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Old 10-26-14, 03:30 PM
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I'll start a new thread for that.
You could, but I don't see any reason not to keep one thread going...

leaking ever so slightly from one of the flare fittings even after reinstalling it and re-torquing it.
You have flare fitting zone valves? Asking because we don't see them very often.

It's possible that the copper tubing has got an imperfection on the flared part.

How much torque do these fittings need?
Not really a 'fixed' number for this. I guess the answer is " enough so that they don't leak ". But if you've got it real tight, and it's still leaking, then there's something else going on. The copper tubing is ductile and the fitting must be tight enough to form the copper to mate with the cone. In some cases, the tubing must be cut back and a new piece spliced in with a new flare on it.

It takes some skill and a quality tool to get a good flare on copper tubing. Those big box flaring tools are often not worth the metal they're made of.

They should not require any tape? Is that correct?
Yes, that's correct. Tape won't do any good on a flare fitting. The seal is between the copper tubing and the cone on the valve, metal to metal.
 
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Old 10-27-14, 03:27 PM
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Success, I picked up a new relay, stuck it in and everything works perfectly. Carlo Gavazzi model for $10.42 in Canadian pesos. Even has an indicator led on it to tell you when the pump is running. Also reinstalled the zone valve one more time and no leaks this time. And yes all the zone valves are flare fit, that seems to be the standard around here. Thanks for all the help.
 
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Old 10-27-14, 04:48 PM
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I live at 62 North
Wow, I live at 42 deg north. You are (62-42) x 60 = 1200 nautical miles (1,400 statute miles) north of me.
 
 

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