Need help bypassing circulating pump relay on Weil-McLain PCG-5


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Old 10-21-15, 11:35 AM
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Need help bypassing circulating pump relay on Weil-McLain PCG-5

Hi, and thanks in advance for any help I can get!
Heat stopped coming into my house and through lots of testing (using forums like these) I have narrowed down my problem to probably being the circulating pump relay, or the pump itself, which is why I want to bypass the relay to confirm if it is indeed the relay or the pump. (However, I am pretty sure it is the relay because when I power the entire boiler down, then back up, it seems to run through a series of checks and the circulating pump usually runs for a few seconds.)

I've read on many other forums how to jump things to test them, but I could never find the things they were referencing on my own unit, hence the post for some individualized help!

Here is a picture of what I am working with: http://s22.postimg.org/f0nwibvf5/box2.jpg

I am hoping that someone looking at this knows what they are seeing and can tell me how to jump past the relay. Each point has it's own letter designation, top left is "C", Middle is "G", bottom left is "R" and the other two are unused (top right and bottom right).

Thanks!
 
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Old 10-21-15, 12:50 PM
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You need to give us more information because I am not comfortable with the diagnosis.

In other words, we need to start again from the beginning.

Please find the Pressure and temperature gauge on the boiler and take a clear picture of it so we can see what it's reading.

The problem might not be the pump.

Did this problem just up and alla sudden happen?
 
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Old 10-21-15, 01:28 PM
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Thanks for the reply.

I was out of the country for about 6 months, when I came back is when I noticed the problem, so unfortunately I wasn't there when it started to act up.

I'm not home right now so I can't take a pic, but I can tell you that the pressure is at 15#; the temp has been fluctuating a bit since I have been turning the boiler on and off trying to troubleshoot.

I first tested the thermostat, whenever I went above room temp I could clearly hear an audible "click" at the boiler. Even so, I decided to eliminate all thermostat variables and unhooked it and connected the two wires at the thermostat.

I tried to test the aquastat with a multimeter, but I wasn't exactly sure where to do that; on the aquastat itself there were three screws, the top two had the red and white wire coming into it and the third and bottom one was empty. I tried using the multimeter on the top two, where the wires were coming in, and I got "0" whether the thermostat was open or closed. Just for the heck of it, I went back to where the thermostat itself is (that I unhooked) and I tested those wires and I got a reading of 26 VAC.

My understanding (admittedly limited) is that the aquastat regulates the temperature of the water and will shut off the boiler when it reaches it's max heat; and that appears to be exactly what would happen. After the whole thing was shut down, I would connect the thermostat wires, turn on the boiler and the boiler would run until the temperature reached the max level, then it would shut down. If I keep it in this state, with the thermostat wires connected, after the water temp drops the boiler will again come on until the water reaches max heat then go off again. During this whole time however, the circulating pump would not come on. BUT there are a few times (I've done this many times) where the circ pump will come on, and when it comes on and starts pushing the water it seems to run just fine, but the pump doesn't stay on for long, maybe a min or two usually. Then the aquastat shut the boiler down again as the max temp is reached.
 
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Old 10-21-15, 02:31 PM
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The reason you couldn't find the things to measure is because you have a boiler that uses a different control scheme.

You are going to need to measure the voltage going to the pump if you have not yet done that.

I don't want you replacing the pump if a $20 relay replacement will do the job. Takes about 5 minutes or less.

The thing on the left in this picture is the relay. If you flip that wire bail over, the relay unplugs.



You have been measuring the LOW VOLTAGE 24VAC circuits, but the pump runs on 120 VAC and you must be CAREFUL! because 120VAC can kill you.

You don't have access to the pump terminals with the type of control that you have.

What model pump do you have? Taco 007 ?
 
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Old 10-21-15, 02:35 PM
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Please find the 'data plate' on your boiler and take a READABLE picture of that.

If there is a wiring diagram pasted to the inside of the cover, please take a clear picture of that as well.
 
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Old 10-21-15, 02:48 PM
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I'm not sure what the data plate is, but I'll look for it when I get home and also check the inside cover for a diagram.

You don't have access to the pump terminals with the type of control that you have.
I assume that means I couldn't jump the terminals to get past the relay?

What model pump do you have?
It is a Bell and Gossett, I'd have to check for the exact model

Yeah basically at the end of the day I'm just trying to figure out if it's the relay or the pump, whichever way gets me there. Thanks for the help. I won't be home till after tomorrow but I'll definitely post a reply once I do!
 
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Old 10-21-15, 03:10 PM
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not sure what the data plate is
All boilers have a metal plate on them with model information. Weil-McLain has had MANY versions of your boiler so I want to know exactly what version you have. The SERIES number in particular... but if there's a wiring diagram inside the cover and you can get a good shot of that, it's all I will need.

I assume that means I couldn't jump the terminals to get past the relay?
No, not easily... and make one little mistake inside there and you can fry the whole works and yourself. It's MUCH safer to test for power to the pump and it tells you what you need to know. In this way you are also checking the wires as well.

I won't be home till after tomorrow but I'll definitely post a reply once I do!
Ok, we'll be here, God willin' and the creek don't rise.
 
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Old 10-21-15, 03:33 PM
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Ok, we'll be here, God willin' and the creek don't rise.
In my rural area of the Midwest, that would be "crick," and spelled c-r-i-c-k. But, I know what you mean.
 
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Old 10-21-15, 03:55 PM
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Some folks think that Hank Sr. meant the Muskogee (aka Creek) native Americans when he used to say that.

But we dahgress y'all.

"It's pronounced 'Raymond Luxury Yacht', but it's spelled 'John Smoke Too Much'. - MP
 
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Old 10-26-15, 11:15 AM
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but if there's a wiring diagram inside the cover and you can get a good shot of that, it's all I will need.
Here is the picture of the diagram: View image: IMG 20151023 111401332

You said you'd only need the diagram, but the series number is "7".

Thanks for your help!
 
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Old 10-26-15, 03:02 PM
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That's it? The whole thing?

Now I'm confused about something... you said:

when I power the entire boiler down, then back up, it seems to run through a series of checks and the circulating pump usually runs for a few seconds.
There is nothing in that boiler that will run 'checks' on power up.

You don't even have 'rollout' or 'blocked vent' safety switches!

How old is that thing?
 
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Old 10-26-15, 04:11 PM
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Old 10-26-15, 05:13 PM
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There is nothing in that boiler that will run 'checks' on power up.
Don't read too much into my usage of the word "checks"; It was really just more of a thought I had as opposed to any real technical checks that were actually being done.

The boiler is probably quite old; but, considering how cold it is going to be getting here in Ohio I am definitely hoping someone can at least help me figure out how to narrow down if it is the relay or the pump; unfortunately I'm not in a position to have a tech come out and take a look at it.
 
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Old 10-26-15, 06:58 PM
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How do you feel about hooking up a cord and power the pump directly from a wall outlet in order to test it? Do you have that in your bag of skills?

For $20 just replace the relay.

I can't find a parts list on line for the PCG boiler, but I'm reasonable certain that this relay will work:

510-350-223 - Weil Mclain 510-350-223 - Plug In Relay w/ 24V Holding Coil
 
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Old 10-26-15, 07:28 PM
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I found an old parts list and you have the relay number correct.
 
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Old 10-26-15, 08:16 PM
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How do you feel about hooking up a cord and power the pump directly from a wall outlet in order to test it? Do you have that in your bag of skills?
I would feel comfortable doing it if I can get some instructions on how to do it?
 
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Old 10-26-15, 09:08 PM
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Very important... turn the boiler power off.

Ok.... you know where the circulator is.
Look where the flex cable connects and you should see a removable plate or cover.
Open it and note where the two wires are currently connected. Most likely a white and black wire.
Disconnect those two wires.
Take an old cord with just a plug..... old extension cord, old computer cord, old equipment cord...... connect the two wires, should be white and black but may not be, to the two motor wires. Polarity for this test is not important. DON'T use the green wire in a three wire cord.
Plug it in. Does the pump run ?
 
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Old 10-26-15, 09:34 PM
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Awesome, thanks. Will report back. I already have an extension cable that my dog chewed through a few years ago that I think I still have laying around somewhere, never thought I would actually get to use it again!
 
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Old 10-27-15, 07:37 PM
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Yep, the pump ran when I gave it power. So, I'm going to order the relay and hope that fixes the problem. Thanks for the help.
 
 

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