Mystery ...

Ok .. now this is a real mystery. My EFM 700 runs fine most of the time. However, during times when there is no call for heat for an extended period of time ... say an hour or two, the power to the furnace (this includes the power to the stoker, the timer, and the circulator... basically everything) suddenly won't work. When I go down and flip the on/off switch ... it will suddenly come to life. I had thought it was a breaker switch ... but it does not matter whether I flip it off and on at the breaker .. or at the furnace itself .... so it can't be the breaker.

This has me very puzzled .... I've caught it just in time a few times e.g. there was enough fire left for it to get going again ... but there are times when it will just go out because there is no power.

I would try bypassing or replacing the switch in question.

Timer motor is dying or needs some fixing?
Trippers are too much for the weak motor to trip...cycling the power gives it the umph to push it through until next time.

McGiever wrote:Timer motor is dying or needs some fixing?
Trippers are too much for the weak motor to trip...cycling the power gives it the umph to push it through until next time.

It does not matter if I flip the switch off and on at the breaker ... or if I use the switch on the furnace, or the other switch that I have on the wall... flipping either of them on and off restarts the furnace mechanisms ... basically the aquastat clicks on and so does everything else. The aquastat ... I assume it is a magnetic mechanism, where the metal flange pops/clicks when there is power .... I'll go down to the basement and the furnace has no power....Then I simply flip any on/off switch to the off position, then to the on and the flange in the aquastat clicks open (or closed .. whichever) as the power comes on. I had thought the aquastat might be bad ...... I still don't know. It just seems that all power is cut ... even though all switches are in the "on" position... then a simple flick to the off position and back on ... on any of the switches ... brings back power. If this is not a common thing that someone else has encountered .... I may have to start testing.. but how? Bypass the switches ... as suggested .. but would a switch that was in the on position (these are switches that look like light switches and are fairly new), for some unknown reason simply stop making a connection ... that is reconnected with a on/off flick? Also, this only happens maybe every 2 days or so. I remember it happened once a year ago ... but then never happened again. Strange ... truly.

They are normally fully mechanical not magnetic. Not sure what you are hearing when you do that. It sounds like something will not engage and when you cycle it it catches. I would have to agree with the timer or relay that drives your feed

Catch it when it goes down and find someone that is qualified to safely use a voltmeter on live wiring to check the circuit in order to determine exactly where the open is located. Replace the part. Mike

Sleeper735 wrote:They are normally fully mechanical not magnetic. Not sure what you are hearing when you do that. It sounds like something will not engage and when you cycle it it catches. I would have to agree with the timer or relay that drives your feed

Well, actually, there is a built in magnetic relay in many aquastats.

Over-loaded 24 volt control transformer, maybe?, is it overly hot? Are any zone valves going bad? They are 24 volts, and only can run 3 valves per 40va transformer.
Another cause with your same symptoms would be a loose or dirty contact/connection/splice.
This makes a high resistance connection which lowers the voltage through and generates heat at the connection point. Find a hot to the touch connection.

Just a shot in the dark,
Is the control circuit wired 120VAC or 240VAC?
If it is wired 240VAC you could have a bad contact in the switch on one leg of the wiring, been there done that on a well pump wired for 240VAC. A couple of wore nuts corrected the problem at the time and a new switch was installed the next day.
If it is wired 120VAC than most likely you have a bum connection within the controls themselves. Disconnect the power (turn off the breaker) and the switches. Then one device at a time and one connection at a time disconnect the wiring clean and reconnect it. Check the contacts in any device that has a set of contacts for damage (wear, burnt or corroded points), replace any suspect devices. While disconnecting the wiring pay close attention to the tightness of the connection, as a loose connection can be caused by thermocycling over time. Cleaning the connections might lead to discovery of a loose neutral, check all connections including wired nutted ones.
I have also found broken wires this way on a couple of machines over the years, the solid wire had been scored by someone using the wrong hole on the wire strippers when the machine was first wired.
In the end I am would almost bet your timer is the culprit. It is either worn enough it is hanging up or the drive motor is too weak to overcome the resistance of the switch.
Dan.

My bet is on a bad connection at L1/L2 in the aquastat, or in the switch itself.

Do as Dan suggests and carefully check/clean/tighten all the connections.

Thanks fellas. I did as suggested... but I'm not a technician ...

I did not notice any loose connections ... this was installed last year ... has seen now 2 seasons of use .. and all switches, timer, et was all refurbed or new. STill, it is likely what Dan had suggested because after checking everything .... I must have tightened something ... as it is not doing it anymore. Crossing my fingers ... season nearly over now .... probably gonna shut her off end of April.

Strange ... but I burned more coal this year than I did last year ...

If there is a relay in the system, the contacts might be starting to get burned. Turning off the power and then back on might be resulting in a small voltage spike higher than operating voltage. The spike may be burning off just enough of the crud on the contacts to get it to work again until the next few times they arc opening and closing ?

The click you hear when the power is turned back on is likely the points closing.

Paul

Sunny Boy wrote:If there is a relay in the system, the contacts might be starting to get burned. Turning off the power and then back on might be resulting in a small voltage spike higher than operating voltage. The spike may be burning off just enough of the crud on the contacts to get it to work again until the next few times they arc opening and closing ?

The click you hear when the power is turned back on is likely the points closing.

Paul

Well, that makes sense.... I'll go you one even better .... I don't have any of this stuff covered ... I don't know why, but the dirty coal and ash laying on everything (increased because the pot auger had been worn - not replaced when refurbed, but now replaced with new) .... perhaps the level of dust (both white and black.. ha) ... increased the likelihood that you may have discovered the issue. Thanks

If they are not burned up, or badly pitted, an old electrical engineer taught be the best way to clean relay and ignition points contacts is to drag a dollar bill between the contact buttons as you hold them closed against the bill. The paper used in money is ideal for cleaning them. The newer, stiffer the bill, the better.

Don't use any kind of abrasive like sand paper. Fine grit can embed in the contact faces and cause increased resistance and arching, or worst yet, an open circuit.

Paul

Don't use any kind of abrasive like sand paper. Fine grit can embed in the contact faces and cause increased resistance and arching, or worst yet, an open circuit.

Or worse fire, the Linen in a bill is a soft clean, but replacing the relay is better to be sure..