Chattering coming from burner control?

[loudram]

Hello everyone, Just a new guy here with a question. There is a chattering coming from my burner control on start-up. It sounds like a relay chatter. (BTW...I'm an electrician) It's coming from the small box next to the terminal strip for the t-stat. What is that? Can it be replaced? Do I need to call a service tech? It's still under warranty but if I can replace it for less than a service call, I'll do it. The controller is a Beckett R7184B. Hopefully the pic turned out good. Thanks for your help.

 

[Redox]

Looks like you have central air on that bad boy. You might be getting feedback from somewhere else in the system. Try disconnecting the W wire and see if that stops the chatter. Then try jumping the R and W terminals together and listen again (this will bypass the thermostat and start the burner). I suspect you may have a programmable thermostat that is drawing too much idle current. They use the heating circuit to keep the battery charged, and I have seen some of them pull enough current to keep a burner running when the stat opens, but that was an extreme case.

If it is still under warranty, the installing contractor should probably replace it without charge, if it really is bad. They probably go for around $100 new.

Chris

 

[heaterman]

Thermostat would be the first thing I'd check also. Test your voltage from R to ground. It should be 24-28VAC. Now turn the thermostat up to call for heat and test W to ground. It shouldn't be more than a couple 1/10th's less than what you saw on R.If it is, you probably just nailed the problem. Some of these new electronic stats will do weird stuff. Stick with a battery powered model.

 

[Redox]

Thermostat would be the first thing I'd check also. Test your voltage from R to ground. It should be 24-28VAC. Now turn the thermostat up to call for heat and test W to ground. It shouldn't be more than a couple 1/10th's less than what you saw on R.If it is, you probably just nailed the problem. Some of these new electronic stats will do weird stuff. Stick with a battery powered model.

Or one that is system powered. They will have a C terminal to run the stat.

 

[loudram]

Thanks alot guys, I'll check it out tonight.
BTW...The t-stat is a battery powered, digital, non-programmable one and I installed it when we got the new heater last year.

I take it from your advice that if lifting the W lead or jumping the W&R;terminal solves the problem, replace the t-stat...correct?

 

[Redox]

The thermostat closes the W and R terminals to start the burner. If you jump these at the burner and the burner starts and runs normally, then the box (primary control) is good. Also try jumping R and W at the thermostat to rule out a wiring problem in the wall. If this works normally, then the problem is in the thermostat. Does the chatter occur at the beginning of the cycle, or the end. Is it quiet when it's off?

If you have to replace the stat, and you don't want a programmable one, I suggest going back to a mechanical model. I never had a complaint with the old T87 (round) Honeywell thermostats in all the years we put them in. I haven't been too impressed with the cheap electronic ones. Just because they are digital doesn't make them any more accurate or reliable.

Chris

 

[loudram]

It chatters at the beginning. I'll let you know what I find.

Thanks again for your help.

 

[loudram]

I think the problem is solved. I went out and bought a new Honeywell t-stat. The round mechanical type. It still chattered. I jumped it to bypass my t-stat. It still chattered. Then I jumped it from my controller and no chattering. Looks like I found a bad wire. I had four spare conductors in the wire going from my t-stat to where they spliced past an old York MaxiMizer. So I took one of the wires off to change it over and the wire came out of the wire nut. It was broken inside the wire nut and making intermittent connections. I re-spliced it and every thing works fine so far.

Thanks again for all your help guys.

 

[mtfallsmikey]

Does your 'stat have RC and RH terminals? These are isolated to keep the xmfr's in the 7184 and your fan relay center from bucking

 

[loudram]

It does have an R and an RC terminal. The directions say keep the jumper in unless there is a wire going to both. I only have one wire so I left the jumper in. My wife did say she heard the noise again but it is no where near as bad as it was. I'll have to listen for it. If it comes to it, I'll just run a new t-stat wire. Not a big deal.

EDIT: I just cut back and re-spliced all four wires. Lets see if that does the trick. I did hear the chattering when I was wiggling the wires so hopefully something else was loose in there.