Munchkin Troubleshoot

[Deleted User]

You get the Sherlock Holmes Award. Trouble shooting skills are developed, not inherited. It's obvious you've been honing yours.

I got fiddle faddled by the fickle finder of fate yesterday, and it was MY own finger.

Was called out to a phantom outage problem we'd already spent a lot of time trouble shooting. You know the call. Mrs. So-n-So called, she has not heat or hot water.. You send your best, they get there and pull the cover off the aquastat relay box and BOOM, it starts working again. Check for loose wires, none found, cover it back up, and a week later the phone rings again, Mrs So-n-so...

So yesterday, no one is available, and I decide to try my dusty trouble shooting skills. I get to the job site, go into the boiler room, shut off all the lights, pull the cover off the boiler using the Hellen Keller method, and carefully start wiggling wires. Isee an ARC and the boiler fires up. I turn on my headlight, and its the damper interface wire where it plugs into the relay aquastst board!.

I order a new one (relay aquastat), pick it up, install it, and as I'm rewiring it, I realize that the guys had used the contacts on the SR502 to power the pumps, and that they were just sending 120 volts over to the relay aquastat for bringing the boiler on. No problem. Except I'm getting too old to read the small print on the circuit boards... I put the power to the pump output contacts. I get done, turn it on, and NOTHING... I jumper out TT and still NOTHING. I'm getting mad about now, due to a defective parts sale... I stop, take a deep breath and ask my self..."What are the chances of getting a defect right out of the box...?"

Funny thing is, when I manually pull the relay in, the boiler takes OFF and fires! Makes me scratch my head even harder. I finally get my squatty body down close enough to read the fine print on the relay board and realize I put the 120 volts onto the load size instead of the source side. DOH!!

I switch the wiring, and BOOM it takes off like it's supposed to.

Don'tcha hate it when you are your own worst enemy? It's hell to get old...

GOod job Paul!

ME

Paul Rohrs

I was a Hydronic Sherlock Holmes yesterday.

I was called out to a job yesterday to troubleshoot a M80 munchkin boiler with zone pumps. Seems this boiler was cycling every 3-5 minutes and the HO (A plbg contractor) had $200.00 a month LP bills just to handle the DHW.

He had zone pumps being controlled by a B&G ZT series pump relay. One zone of Hydro-air, one in-active zone of radiant floor heat, and DHW. I kept thinking on the 1 hr drive up that it was wiring or programming.

There is no Vision 1 kit on this system so and DHW should take about 5-6 minutes for the boiler to ramp up to full fire, so the 3-5 minute cycle time was a real head scratcher.

I pull the cover off of the pump relay and that wiring looks pretty solid. The homeowner was adamant about leaving the Burnham Indirect on Priority since it was a 40 gallon model with a fixed 5 degree differential. 4 people in the house and they would occasionally run out of hot water.

Here is where it gets interesting. The only way the HO said he could get the system to work, was to wire-nut the two grey boiler TT wires together. Okay...that explains the cycling. The boiler was in constant call for heat and would come on, get up to 180F and then stop firing, but the boiler pump would send heat out slowly via the copper pipes as well as the boiler being a heat emitter, drop the 20F where the differential was set, and fire back up again. So I watched as this beast consumed small but very frequent sips of LP.

I took the wire nuts off of the two grey wires and the cycling stopped. Then I lost power to the pump relay until I jumpered the XX end-switch. Huh? I didn't have power to the pump relay until the boiler TT is jumpered.

Really odd. I start Multi-metering out power, switch, and loads ( Ala Carol Fey) and find that all power comes in to the boiler j-box. Power then goes into the boiler and then thats it. Where is my power source from the pump relay? Pump relay is dead unless the boiler is jumpered and calling for heat. Turns out that the power being supplied to the pump relay was wired in with the boiler pump. Orange-Hot and Brown-Neutral is where the pump relay got its power.

Re-wired thru the switch so that the pump relay had dedicated power and problem solved.

It was so strange standing there with a boiler that wouldn't turn on without the TT jumpered, and even more strange when the pump relay was dead until I jumpered the XX end-switch of the relay and it would spring to life. By jumpering the end-switch, I would complete the circuit that allowed the boiler to call for heat which would turn on the boiler pump, which would then power the pump relay into a call for heat.

Kind of sad how 2-wires caused this family $$$$ of LP and a system that wouldn't function correctly.

I found out later that a rep ( I don't know who) said he had plugged in the laptop and he had registered about 1200 F09 codes.

On one final note, I noticed a pile of 8-10 igniters and flame-rectification probes in the corner. Seems he was going thru quite a bit of those as well. I had just stopped at a hardware store on the way up to this job and had picked up a small wire brush wheel that I could insert into the Dewalt cordless drill. I took it out and buffed the igniter until it was new looking. Pretty simple fix (albeit temporary) if you are in a pinch and don't have a spare igniter.

It was pretty gratifying to figure this one out.


Have a Happy Thanksgiving everyone.

Regards,

PR





Biggerstaffradiantsolutions.com

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kevin coppinger_4

gotta love it....

when you are the hero...good work. Thanks for sharing. kpc

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