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I ran into one of these several years ago, went through 3 sequencers before I figured out it was the air flow that was keeping the sequencer engaged. The back panel was hot where the sequencer mounted. made some changes with duct work sealing some holes and cleaning the coil and magic, no more problem.

Originally Posted by kls-ccc

The unit was designed to work properly with the sequencer in that location. You should not have to do anything to the sequencer unless it's bad. Fix the problem not the symptom.

Thnx, but I replaced the sequencer, and the furnace runs like new for about 2 weeks. Today I'm going to check the element(yep, there's only 1) and the limit switch to find out what's overloading the sequencer or shorting it out.

Originally Posted by Puzzle50

I'm working on a downflow electric furnace about 20+ yrs. old. The heat wouldn't shut off, and t-stat checked out good. I replaced sequencer, then I get same call 12 days later and same problem.
It's only a 30,000 btu furnace.
Would the limit switch cause the overheating of sequencer?............. Tomorrow I will try a continuity test on limit switch and elements.
ANY SUGGESTIONS OUT THERE?

Sometimes a bad blower relay can cause the same symptoms as a stuck sequencer. An amp meter in the right spot will tell you for sure. A lot of times when you shut the power off, a stuck relay or sequencer will unstick for a while.

Originally Posted by Puzzle50

I put my thermometer inside compartment and close the cover to see what it reads. I've never ran into that in 18 yrs. I was thinking on putting a small piece of ceramic tile between the base of sequencer and the furnace wall.
The blower is on Medium for heat and high for cooling right now.

The unit was designed to work properly with the sequencer in that location. You should not have to do anything to the sequencer unless it's bad. Fix the problem not the symptom.

Thnx

Originally Posted by gravity

If you have low airflow and the electric compartment is too hot, it could keep the sequencer in the energized state

I put my thermometer inside compartment and close the cover to see what it reads. I've never ran into that in 18 yrs. I was thinking on putting a small piece of ceramic tile between the base of sequencer and the furnace wall.
The blower is on Medium for heat and high for cooling right now.

If you have low airflow and the electric compartment is too hot, it could keep the sequencer in the energized state

I'm working on a downflow electric furnace about 20+ yrs. old. The heat wouldn't shut off, and t-stat checked out good. I replaced sequencer, then I get same call 12 days later and same problem.
It's only a 30,000 btu furnace.
Would the limit switch cause the overheating of sequencer?............. Tomorrow I will try a continuity test on limit switch and elements.
ANY SUGGESTIONS OUT THERE?

Normally there are 2 60A double breakers. One set controls the blower and the 1st stage of heat strips, the 2nd set controls the 2nd stage of heat. Air handlers typically use W1 and W2 for heat, one terminal per bank of heat. A 2 stage thermostat can bring on W1 most of the time, and only kick on W2 when W1 can't keep up.

Originally Posted by 54regcab

Peak demand is figured over a 15 minute period, not at any one instant. It only affects those who have smart meters with peak pricing plans and certain commercial customers. IMHO it's better to split the heating load into stages controlled by the thermostat.

To clarify what i was saying the post i commented on didnt mention staging. And as you said electric plans vary we dont know this homowners plan, nevertheless sequencers werent designed to keep breakers closed since theirs no difference on start up amps so i assume their designed to control peak wattage. Plz correct me if im wrong but most pairs of resistance heaters are on a separate breaker than the blower.

Originally Posted by 54regcab

The ideal solution is to use a thermostat with multistage capabilities that would only bring on the extra banks of heat strips as needed. The 1st 10KW could be brought on by one contactor through W1, the 2nd 10KW contactor brought on by W2.
If a multistage thermostat isn't practical time delays or outdoor thermostats could be used to control when the 2nd bank of heat is activated.
Another strategy with heat pumps involves setting up one 10KW bank of heat connected to W1 of the thermostat and the other 10KW bank being activated by the defrost board of the heat pump. If the heat pump can't keep up the thermostat will call for 10KW heat, when the heat pump goes into defrost the other 10KW will come on. Once the heat pump catches up electric heat is dropped. A simple wiring change achieves this, no additional parts required.

Im not disagreeing with a word you just said. Your obviously more knowledgable on the subject than me. I was commenting on a earlier post in the thread were someone said they always change seq. with contactors when theirs a problem. I wouldnt thank thats a good idea especially when you suspect ambient heat is preventing the seq. from opening.

Originally Posted by Core_d

I know this is an old tread but, are you telling me when a seq. is being closed by ambient heat replacing it with a contactor and being done with it in no way affects the customers energy bills compared to determining the actual fault and fixing it. Peak pricing was not the only effiency issue in this situation

The ideal solution is to use a thermostat with multistage capabilities that would only bring on the extra banks of heat strips as needed. The 1st 10KW could be brought on by one contactor through W1, the 2nd 10KW contactor brought on by W2.
If a multistage thermostat isn't practical time delays or outdoor thermostats could be used to control when the 2nd bank of heat is activated.
Another strategy with heat pumps involves setting up one 10KW bank of heat connected to W1 of the thermostat and the other 10KW bank being activated by the defrost board of the heat pump. If the heat pump can't keep up the thermostat will call for 10KW heat, when the heat pump goes into defrost the other 10KW will come on. Once the heat pump catches up electric heat is dropped. A simple wiring change achieves this, no additional parts required.

Originally Posted by Core_d

i thank alot of ppl do have smart meters i know i do i also have a peak pricing plan. I delieave in my neck of the woods peak pricing is determined by kw used in an hour

Depends on your plan. Plan very GREATLY, be sure to look your up. In our area consumers can pick from 3 summer plans. Standard, TOU, and VPP. Everybody is on standard during winter months so heat sequencing doesn't matter to power bills. Smarthours is the plan that our utility is pushing right now.

I know this is an old tread but, are you telling me when a seq. is being closed by ambient heat replacing it with a contactor and being done with it in no way affects the customers energy bills compared to determining the actual fault and fixing it. Peak pricing was not the only effiency issue in this situation

Originally Posted by 54regcab

Peak demand is figured over a 15 minute period, not at any one instant. It only affects those who have smart meters with peak pricing plans and certain commercial customers. IMHO it's better to split the heating load into stages controlled by the thermostat.

i thank alot of ppl do have smart meters i know i do i also have a peak pricing plan. I delieave in my neck of the woods peak pricing is determined by kw used in an hour

Originally Posted by Core_d

manufacturers use them to save the homeowner on energy bills. Starting tomany components at once can raise your price on kwhs for the rest of the month and anyways if its so hot the seq. wont open its not a very efficent system wouldnt you say?

Peak demand is figured over a 15 minute period, not at any one instant. It only affects those who have smart meters with peak pricing plans and certain commercial customers. IMHO it's better to split the heating load into stages controlled by the thermostat.

manufacturers use them to save the homeowner on energy bills. Starting tomany components at once can raise your price on kwhs for the rest of the month and anyways if its so hot the seq. wont open its not a very efficent system wouldnt you say?

I wonder what the surface temperature was at the location where the sequencer was mounted? Also at what temperature does the sequencer contacts close..... This calls for an all out investigation using the scientific method.

Question: What is causing Sequencers contacts to be closed and allowing completion of circuit to heating elements

Hypothesis: Excessive heat from cabinet is transferring, in the form of conduction, directly to the bi-metal of sequencer thus causing contacts to close

Prediction: Heating the mounting base of the sequencer shall ,at certain temperature, close contacts allowing conduction of electricity to flow through contacts

Testing: Take the sequence at fault and clamp temperature probe to base of it, place multimeter leads across M1 and M2 and set meter on the ohms scale, preferably audible scale, then proceed to heat the base of sequencer with external heat source and record at what temperature the contacts close. Record your analysis and repeat test 3 more times. Also conduct this test on new sequencer out of package. Then with furnace running measure the surface temperature where the sequencer mounts in cabinet and record your readings via#2 pencil.

Data: place your analysis here:

Conclusion: State your final conclusions here and present graphs and table charts to confirm your findings.

I don't like sequencers, but the manufacturers use them for price I guess. I almost always replace with contactors.

i would have to guess a temp. issue if both terminals are staying closed and the replacement did the same thing why its to hot is another issue do amp amp draws on the wires that would be my humble

Originally Posted by Core_d

let me clarify how many heating coils is it controling?

2 heating coils. Replaced seq. did same thing.