Boiler firing with thermostats off


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Old 04-30-12, 08:21 PM
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Boiler firing with thermostats off

Before I call in a pro I thought I'd post on here to see if anyone can help me understand what's going on. I'm in a new to me house with a ~14yr old boiler, Weil McLain model CG-4-PIDN series 12, that is used to heat the hot water baseboard radiators. There is no hot water heater off of the boiler, it is separate. The boiler was also recently serviced within the last month. The system functions correctly in that if you set a temperature in one of the two zones it will come on and turn off as expected.

The issue is that when the system is not being called on, including when both thermostats are turned to off, it will periodically fire up until it hits it's upper limit temp then turn off which is usually only 15-45 seconds each time. No water is being circulated to the zones at this time, the pumps do not come on nor do any of the zone lights on the Taco relay come on indicating a zone is requesting the heat.

I have noticed that this happens only when the water temp falls below ~140 or 160 degrees then it goes until it hits the upper limit and turns off until the temp falls again. This happens more often, as you'd expect, when it's colder in the basement as the temp falls quicker.

I've checked the wiring on both the boiler wiring diagram and the Taco SR503 relay diagram and all appears as it should be as far as my untrained eye can tell. Links to pictures of the system and wiring are below as well. Any help would be appreciated, let me know if additional information is needed too.

Thanks in advance.

Pics: http://www.dropbox.com/gallery/54263...oiler?h=68972f
 
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Old 05-01-12, 03:23 AM
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the water in the boiler cools down enough (standby loss) where the aquastat lower limit is reached & starts the burner, fires, then the upper limit is reached and the burner shuts off. This occurs regardless of zone heat demand.

It would be nice for you to harness that heat energy somehow rather than having it transfer up the flue and heat the outside.
 
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Old 05-01-12, 05:14 AM
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Thanks for the response. The only thing I can't find is if the aquastat has a lower limit, I only see it referencing the upper limit.

I did find that when the boiler was first installed the water heater was off the boiler but it no longer is. When the new water heater was put in they also put in the Taco relay as well. Maybe it still thinks there's a boiler off of it?
 
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Old 05-01-12, 06:29 AM
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The aquastat has a a differential setting, no?

Is your water heater an indirect type or tankless coil type?
 
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Old 05-01-12, 08:51 AM
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Not sure on the differential setting, the only thing on the aquastat I see is setting the high temp limit on it which you can see in the pics.

The water heater is just a stand alone gas heater, not connected to the boiler at all now. The old water heater appears it was run off the boiler but was taken out in 2010.
 
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Old 05-01-12, 04:07 PM
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Just to add to this, I noticed that the black wire on the left of the aquastat has power to it when this is occurring. I'm not sure if that's normal or not but thought I'd point it out if it helps.

The thermostat wire coming from the taco relay is not powered. I was wondering if the aquastat is getting a signal that heat is being requested all the time hence why it's firing up when the temp dips down.

It's driving me crazy trying to figure this out
 
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Old 05-01-12, 04:29 PM
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Where does the black wire come from? It sounds like you have a warm start boiler, but your aquastat doesn't appear to be that way.
 
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Old 05-01-12, 04:58 PM
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The black wire is coming off of the Y on the transformer.
 
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Old 05-01-12, 07:38 PM
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Are there ANY other control boxes wired up to this system?

You MIGHT have a 'stuck relay' ... doesn't sound typical though...

Tomorrow I'll see if I can dig up a wiring diagram and help further.
(remind me if I forget, kinda busy lately...)

Do you own and know how to use a multimeter? (you mentioned voltage measurements, so I'm thinking yes)
 
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Old 05-01-12, 07:47 PM
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I just took a quick look and I can't locate the control supplement manual for your boiler on the W-M site.

There should be a schematic diagram on the inside cover of the boiler.

Can you take a high res photo of that and post so I can view?
 
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Old 05-01-12, 07:48 PM
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The only control box wired to it is the taco sr503. I do have a multimeter that I can test with as well.

I do have the wiring diagram for it so I can try and scan it or take a picture of it, I have ones for the boiler and the taco. The taco does have 2 diagrams, one for use with a hot water tank and one without but it's definitely wired correctly. Everything else follows the diagrams too, I was hoping it would be a simple wiring issue but so far not seeing one.

The search continues! Thanks for the continued help with this.
 
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Old 05-01-12, 07:55 PM
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Ok I just uploaded 4 pics of the schematic http://www.dropbox.com/gallery/54263...oiler?h=68972f

Let me know if you need more info. Thanks!
 
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Old 05-02-12, 02:53 PM
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Let's start with reviewing how is SHOULD work:

The wires from the endswitch should be going to the G and the R terminals on the relay control in the boiler.

When the endswitch closes, the relay should energize.

When the relay energizes, one set of contacts on the relay should start the circulator (120 VAC!)

The OTHER set of contacts should send 24 VAC to the Y terminal which will then open the flue damper, after which the burner will fire.

OK...

There should never be 24VAC at the Y terminal (referenced to the C terminal) if the relay is not energized and the circulator is not running.

An easy test to start with would be to pull the wire coming from the TACO to the G terminal. Wait and see if the boiler fires. If it DOES, the problem is in the boiler, if it does NOT the problem is external to the boiler.

There should be no other wiring going to G and R from the outside ... if there IS, trace it and see where it goes.

When the thermostats (and thus the TACO) are calling for heat, you should see 24VAC between the C and the G terminals. If the boiler fires and there is NOT 24 VAC there, something is probably wrong with the relay.

It is possible for only one set of the contacts to be 'stuck' together. That relay is a plug in job. Pull the relay and under a bright light examine the contacts to see if they are pitted and cruddy.
 
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Old 05-02-12, 04:25 PM
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Thanks for the info! I disconnected the wire at the G terminal and it still fired so I guess we know it's in the boiler at least.

I then pulled the relay but I can't tell if the contacts are good or not, it looks like it's from 2005-2006 so I'm not sure how long they usually last.

Of course I don't have batteries for my multimeter to confirm the 24VAC however I do have one of those voltage detectors and when I put it on the Y terminal it's confirming power even when no heat is being called for. So maybe the relay is toast?
 
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Old 05-02-12, 08:10 PM
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It sounds like it... if it's still calling for heat with voltage on the Y terminal, and the circulator is NOT running, and the wiring is removed from the G terminal... and all other possibilities have been thought of and dismissed... (like a shorted wire somewhere in that rats nest of wiring) ... then it pretty much has to be the relay.

Those can be had for about $20 or so... I think it's one of the flavors of the R8222 Honeywell relay, probably a Double Pole Single Throw (DPST) .
 
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Old 05-03-12, 05:14 AM
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So I decided to have someone come check it out so I thought I'd post here with the info.

Apparently it's working as intended as it's set up as a warm start boiler due to the first configuration with the hot water heater being off of the boiler. The explanation was also that if it were a cold start boiler it would state that in the manual...

The only options are to turn it off during the warm months or have the control changed out to be a cold start. Not 100% buying that but I guess I will since I wasted that money for them to tell me
 
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Old 05-03-12, 07:22 AM
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I would not by that. There is no control that I see that would make it a warm start boiler. The aquastat is only a high limit. Did they tell you what makes it a warm start?

I would call them back, and or get your money back. Any warm start boiler can be made cold start if the control is there.

Can you take additional pics of the boiler. Possibly there is an aquastat installed in the piping somewhere, where the indirect was?

Troopers theory sounds plausible with the relay, but I would not think that's the issue, but would be the only and absolute thing if there are no other devices.

The wiring looks fine in regards to priority jumpers, and where everything goes from what I can tell.

And I would think when this boiler fires up on its own it goes through the whole process of lighting, such as vent damper opens, ignition sequence,...etc?

Mike NJ
 
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Old 05-03-12, 08:13 AM
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The only thing the guy said and that's on the service receipt is that the control is warm start only, not sure what makes it that way. I did point out the aquastat and that it only has a high limit etc.

I've looked all over the boiler and I don't see any additional equipment, no aquastat anywhere that I can see. The TACO is in the spot where the old boiler use to come off of but I don't see anything left over or extra.

As far as the process when it fires up, it does do the whole process of damper opening, ignition then full flame. Demonstrated that to the guy 3 times while he was here but I just wasn't getting that good feeling that I was being told the right stuff, I even tried asking it a few ways.
 
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Old 05-03-12, 09:47 AM
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Demonstrated that to the guy 3 times while he was here

How long was the guy there for?

Do you mean that the boiler lost all that heat and fired up sporadically 3 times?

My boiler in an outside shed with no vent damper does not loose that much heat!!! It may take an hour or so to drop 10 degrees with no circ running.

I did re read your post and the boiler heats very quickly you say?

I would have to rule out a leak and the fact that cold water may be constantly filling the boiler. But just wanted to through that out there.

What is the pressure in the boiler, and what temp does it shut down?

I see you may be at 190f on the aquastat. Thats high. Possibly a test you can do is turn the aquastat down to 170f. Then see if it kicks on and at what temp it kicks on. This is to see if it follows. Meaning will the boiler know kick on at 110f?

If the pressure is good in the boiler (12psi) turn off the boiler feed for a while and watch the pressure.

Let us know and take more pics. Possibly we can see something you cant. All pipes in and around the boiler.

Mike NJ


 
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Old 05-03-12, 10:44 AM
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Here is the wiring diagram in PDF.

http://www.weil-mclain.com/en/multim...ams/cg-118.pdf


I think your problem is here with the taco control. ( See link at bottom of page) Read the warning below the schematic. Even though it may seem the wiring is correct you need to follow these instructions.

And since it controlled an indirect it was wired with the alternate wiring diagram.

Stand tight...The wiring guys such as trooper will be on shortly to decipher this information for you.

Here is what it says.

Note: When using Alternative Wiring diagram, the boiler operating controlís ZC terminal will see the load of the circulator(s).



Warning: When using Alternative Wiring diagram, wiring instructions must be followed so power originates from the boiler aquastat. Failure to
follow these wiring instructions may result in a secondary source of power being connected to the boiler that may activate it under certain circumstances,
causing injury or death.

http://www.taco-hvac.com/uploads/Fil...ry/102-168.pdf


Mike NJ
 
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Old 05-03-12, 10:51 AM
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The guy was here for about 30 mins, during that time we forced the temp to go down by turning on the thermostat and letting the heat drop then shutting it off before it would trigger.

It usually triggers around 160 and right now it's set back at 180 for the high limit. I'll check on the pressure but I believe it was around 12 last time I looked.

As for the wiring of the TACO, that was never in play when the direct boiler was there. It was added in 2010 when the direct boiler was removed and a stand alone was added. I did confirm it's using the normal wiring set up per the schematic you referenced.

Hope that helps, let me know what else you need and I'll check on the boiler pressure. I appreciate all the help with this!
 
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Old 05-04-12, 09:29 AM
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Yer getting a line of BS.

There's nothing in the design of that boiler that allows it to be set up as a warm start.

Unless someone has 'customized' the control, it is a COLD START boiler, no matter if the manual says it or not.

If you've got a tech that needs the manual to tell him if it's warm or cold start, you should probably start shopping for a new tech.
 
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Old 05-04-12, 09:46 AM
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Is there ALWAYS 24VAC on the Y terminal? I'm thinking not, because you would notice that the damper was always open if so.

Follow that black wire from the Y terminal, it should only go to the spill switch on the atmospheric hood. From there to the limit control, and from there to the rollout switch down near the burner, and from there to the damper connector. There should be no other wires tied in anywhere on this route.

In this photo:



is there TWO pairs of wires to the left of the flue pipe?

On second look, that appears to be a SHADOW on the wall ?


NEXT:


The RED and WHITE wires from the TACO on X1 and X2 ... those should go directly to the G and the R terminals on the relay control in the boiler. Do they? There should be no other wires joining them along the route. Are there ?
 
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Old 05-04-12, 10:00 AM
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I'll have to check on the Y terminal, I need to grab some batteries for the multimeter and see. The damper is definitely not always open but maybe that's because the aquastat is shutting that off once it hits it's high limit?

In the pic that is a shadow, there is only 1 pair of wires to the left of the flue pipe. I do need to take some more pics tonight.

The wires from the TACO, those come in and go to the yellow wire nuts you see in the one pic of the wire nest. I'm not at home so I can't see what, if anything ties into them, but from there they go to the G and R terminals. I'm pretty sure something else ties in there that needs that terminal so they used one connector and the wire nuts to combine the wires.
 
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Old 05-04-12, 10:14 AM
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I'm definitely feeling like I got ripped off by the tech that came out. Sadly I just don't have enough info yet to contact them and call them out, though I too can't find any information that this boiler is in any way a custom build to be a warm start.
 
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Old 05-04-12, 10:21 AM
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maybe that's because the aquastat is shutting that off once it hits it's high limit?
Yes, yer right. Still need to test the Y for CONSTANT 24VAC though.

I'm pretty sure something else ties in there that needs that terminal
Yes, probably the R terminal... but I think the G terminal should be all by it's lonesome. If there's something else on the G , follow that wire and tell us where it goes.

Do you hear the relay in the boiler 'click' when it starts up on it's own?
 
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Old 05-04-12, 11:11 AM
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I know the wire going to the G terminal does go into one of the yellow wire nuts but I can't recall if anything else is tied in there so I'll check that tonight as well.

I do hear the click when the boiler starts up on it's own.
 
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Old 05-04-12, 01:14 PM
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I do hear the click when the boiler starts up on it's own.
If you hear that plug-in relay click (don't mistake it for anything else clicking) then it means that there has to be something closing that connection from G to R ... which means that there may well be something else unseen as yet tied in there.

BUT... didn't you say that when you pulled the wire from the G terminal, the boiler STILL started on it's own?

I think I know what it is... You've got BGs ! BOILER GREMLINS!
 
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Old 05-04-12, 01:31 PM
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lol that could be.

I'll double check everything tonight and ensure the click is the relay one more time. Definitely fired up with the G terminal wire unplugged though. I can probably get a quick video of the whole process too if that helps.
 
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Old 05-04-12, 06:00 PM
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Ok the wire from the TACO is going to the G terminal, no other wires combine with it. I listened for the relay and I believe it's clicking, there were a few clicks and it was hard to say 100% it was coming from that.

I can see where the old water heater was coming off the boiler which is the right side, no wires going to or from that side anymore though. Could it be that the boiler was ordered with a control that was for having the water heater off of it and it still thinks it's there or would that be something obvious in the wiring?
 
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Old 05-05-12, 08:11 AM
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OK, let's take a step back and recap everything...

There's really only TWO WAYS that the burner can fire when it should not.

1. If something is triggering the relay to close.

2. If something is causing 24VAC to be applied to the Y terminal.

We need to get definite answers on these points before proceeding.

================================================

1. Place multimeter set for AC volts, 24 V range between G and C.

Monitor this point when the boiler fires up on it's own.

You should NOT see any voltage on the G terminal as long as the Taco is not calling for heat.

Voltage should only appear at the G terminal when there is a call for heat.

If you do see voltage when you should not, then something else is tied in somewhere, somehow, that is causing the relay to close and fire the burners.

==Only proceed to step 2 if you do NOT have voltage on G when you should not==

2. Place multimeter set the same as above between Y and C.

Monitor this point when the boiler fires up on it's own.

You should NOT see any voltage on the Y terminal as long as there is no call for heat.

You've already told us that you DO see voltage there when the boiler fires on it's own ( and of course you would HAVE to, else the boiler would not fire! )

The question now becomes : Is that voltage there ALWAYS?

If it IS there ALWAYS: Short circuit in the wires? Stuck relay? Wiring error?

If it is NOT there ALWAYS: Trace wiring and find what is telling the burners to fire. Something else is tied into the Y terminal that is calling for burners to fire.
 
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Old 05-05-12, 08:14 AM
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Could it be that the boiler was ordered with a control that was for having the water heater off of it and it still thinks it's there or would that be something obvious in the wiring?
You should be able to see it. There would be another aquastat control on the boiler somewhere that monitors water temperature and fires the boiler when it drops below setpoint. This would be something tied into the Y terminal on the other control.

The HIGH LIMIT control that's there now, correct me if I'm wrong, only has TWO wires on it, and is wired per the schematic diagram on the boiler.
 
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Old 05-05-12, 08:21 AM
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One other thing that might be worth mentioning...

The relay control you have is an R8285 Honeywell part.

It is possible that there are some extra connections INSIDE the box that it's mounted on. Keep that in mind as you troubleshoot. Are there any other wires going in and out of the box itself that don't belong there? Are there any frayed or shorted wires?

Here is the Honeywell product data sheet. It is called a 'fan control' but W-M (and others) has used them for many years for this purpose. It's basically just a transformer and a relay with a terminal strip attached.

http://customer.honeywell.com/techli...it/68-0088.pdf
 
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Old 05-06-12, 06:24 PM
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I finally had a little bit of time to fool around with this but I don't have all the info yet. I did look at the R8285 and I don't see any wires coming in or out of it that shouldn't be. Coming out are just 3.

As for the aquastat, it does only have the 2 wires that you can see in the pictures and no others.

I did check with the multimeter on the C and G terminals when the boiler fires on it's own, nothing showed on that. When I check on the Y and C terminals there's definitely power there as it sparks but I couldn't get a good reading, not sure why. But both as it's running and when it shuts off I'm still seeing power to the Y terminal.

Maybe the relay is stuck and it's causing the constant power to it? Any way that the relay or transformer could have been wired to deliberately do that for when the hot water heater was attached?

I did check with some neighbors who have the same set up, all put in originally by the same builder and none of theirs run when it shouldn't however none of them originally had a hot water heater attached to it.
 

Last edited by Matty33; 05-06-12 at 06:40 PM.
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Old 05-07-12, 09:13 AM
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So the relay is model 91-112006-11000 which doesn't look like they make anymore. I think the replacement to that is 90-340 which appears to be pretty cheap before shipping.

I'll see what you guys think and if there's a chance it's the relay it might be worth the $10 to grab one and swap it in.
 
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Old 05-07-12, 02:49 PM
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And when you pull the relay out and measure Y to C ? What then ?

Your meter needs to be set up to read AC VOLTS ... there should be no sparking when you touch the meter to the terminal.

Maybe the relay is stuck and it's causing the constant power to it? Any way that the relay or transformer could have been wired to deliberately do that for when the hot water heater was attached?
That's been my diagnosis all along... did you physically trace the wire from the Y terminal ? If you remove the plate with the relay and transformer from the j-box, is there anything 'jumpered' or 'spliced' inside, under the relay? Those colored wires come off the relay socket and up to the top. There should be nothing else connected to those.
 
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Old 05-07-12, 03:07 PM
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If you know how to use the OHMS scale on your meter, you can look at the PDF for the 8285, determine which two contacts you think may be sticking and measure for continuity, if you need some confidence that the relay really is bad.

There are two sets of Normally Open contacts on that relay. The pairs should be 1 & 3, and 4 & 6. One pair USED TO run the circulator, but since you've got the Taco panel they won't be used. The other pair switches the 24VAC to the burner.

With the relay pulled you should NOT measure continuity between either of those pairs.

The White-Rodgers part number you gave is not what's listed in the parts manual for your boiler, but that doesn't necessarily mean it's wrong. W-M shows:

91-322000-11000

There are thousands of varieties of these relays and many will 'cross' to a different part number.

I guess you could use the 90-340 if you wanna save a few bucks, but me personally would stick with the Honeywell.

The Honeywell replacement part number for that relay is:

R8222U1006

and that has been replaced by this:

Patriot Supply - R8222U1079
 

Last edited by NJT; 05-07-12 at 03:23 PM.
  #38  
Old 05-07-12, 03:12 PM
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By the way, here's the PDF parts list for your boiler series, your series 12 is near the end.

http://www.weil-mclain.com/en/multim...-boiler/cg.pdf
 
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Old 05-07-12, 04:41 PM
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I have a pic of the relay, I just need to upload that, it has the 91-112006-11000 number on it so that's why I was going with that one. Didn't check the parts list though so it's good to know the one you listed would work.

Not sure what was going on with the multimeter, it's a cheapo harbor freight special and was set correctly (even checked the manual afterwards lol). I'll see if i can pull the relay again tomorrow and measure the ohms. Not so sure about taking off the panel and looking at the wires inside, I want to do that but just concerned I'll mess something up and make things worse but probably something that needs looked at.

I did contact the weil-mclain and they confirmed the boiler is a cold start and I called back to the hvac company to let them know that their answer seems like BS right now...they're going to call back so we'll see what they say too.
 
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Old 05-11-12, 05:45 AM
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So in further troubleshooting this issue I've come across another interesting thing or two. What I've been doing is shutting off the boiler during the day because it's nice out, upon doing so I've been noticing that the pressure relief valve has been dripping some water. I did turn off the boiler and open and closed the relief valve a few times to flush some water out incase it was some debris but it's still dripping a bit.

I then checked the expansion tank to make sure it wasn't the issue and the pressure in it is about 15psi so I think that's ok. I did turn off the power and the water to the boiler and tested releasing the pressure and also drained a little water from the valve under the circulating pumps, weird thing is that the pressure showing on the boiler never moved...not even a slight bounce. I would assume that it should have moved at least a little doing that right?

Wondering if I have more than 1 issue at hand here. I did see the sticky about making your own pressure gauge so I might try that too.
 
 

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