Emerson 24A34-5 Electric Heat Sequencer, 3 Switches

Worked as it should and saved me from paying $900 for the furnace guy to do it! The hookup is super easy, just need a screwdriver.

I work on some really old heaters and use these to replace the “black box” sequencers and individual old stuff. These are much easier and safer to use and are cost efficient. I have used them for years as retrofit for the older models and have never had issues or problems yet and have not had to replace one yet. They’re a good product.

for now, i am happy i bought this sequencer. long story short, i needed a sequencer with 3 switches for an old lennox furnace that originally had three separate relays for each of the three elements. i have a 1970's vintage furnace and in the past 30 years all i've had to do to keep it running is to replace some wiring and also periodically replace the sequencer. my old sequencer finally failed and one switch was stuck closed, so i had a runaway furnace to deal with that could only be turned off from the breaker. since about 2000 when i started keeping track, this is perhaps the third or fourth time i've had to replace the sequencer. each one seems to last a few years, plus or minus. i used to be able to get a replacement from a local shop, but new ownership requires that they send a tech out rather than sell to the public. ugh. the item i received was a ningbo yuanfang sequencer, and not an emerson t-o-d as shown in the advertised pic when i ordered it, for $16.05 last month. these sequencers have a limited life. we'll see how long this one lasts. for now, i am going to order another so i have it on hand. price is reasonable. but, as i have discovered in the last few days, the offers on amazon can change quickly, in terms of suppliers and prices.

These devices in older air handlers and forced air furnaces, like in mobile homes, are well known for failing. These are basically time-delayed-on/-off relays, that start up the furnace in "steps", avoiding a large current surge on the main house breakers and the line transformers, and also shut down the secondary heating coils prior to the primary coil and fan, allowing a little "cool down". This is a simple device to replace if you are familiar with electrical testing and repair. Just be SURE you have turned off the breakers in the load center before starting on the replacement. Many furnaces have a 60 amp AND a 30 amp breaker. Be sure you turn off BOTH. I have had to problem with this sequencer since I installed it. Now I get all the heater coils turned on, so the air out of the vents is warmer and the fan runs less.

Fixed my furnace.

Perfect replacement. We have heat again !

The blower on my Coleman furnace had intermittently stopped blowing during a call to heat. I could see the elements getting (very) orange hot through a crack in the case, but no blower. Internet research seemed to indicate that this was due to a failing sequencer. I purchased this to replace my stock model 3115-357. After I wired it in, but before turning back on the breakers, I noticed that all the "M" connections were flipped flopped from my original. M1 had traded placed with M2 and vice versa. Not wanting to mess anything up, I called Emerson for assistance and the tech suggested that I rewire it and follow the labeled connections. So I rewired it to respect the "M" connections - so old M1 went to new M1 even though it was on the opposite side of the sequencer. I turned on the breaker and immediately the fan kicked on even though the thermostat was still off. Ut oh. I guess the Emerson tech was incorrect. I rewired it again to the follow the locations of the original sequencer and after turning on the breakers, everything worked as before.

Had issues with my furnace not heating my home. Did all the checks, determined that only two of my three elements were coming on. Checked everything and found out my sequencer was bad. Order this one, got it within 3 days, and was easy to install. Just plug and play. Now furnace is operating as it should.

c l'un des meilleurs séquenceurs pour la fournaise

Exactly what I needed. Installed it myself. Fraction of the price electrician wanted.

Works well as a replacement for my old (and failing) 15S21 sequencer, this one is labeled with 15HS21 but appears functionally identical. The M1-M2 and M3-M4 contacts do turn on well before the M5-M6 contacts as they should. Also the M5-M6 contacts turn off before the others when cooling.

The only thing is that they sent the wrong switch. The one they sent was the next model up, so it stilled worked i just had a spare switch. But still a quality product.

We are happy with our order. It was the right part, shipped quickly, and worked.