Anyone good with the HVAC?

[Missourian]

I think i'm going to have to pull the elements today.

I was really thinking one of the "thermocouples" high heat limit switches were bad.

But...after sone research last night and this morning...I discovered that there is a fusible link in the coil itself...

"Secondary High-Limit Control​

Secondary high-limit protection is provided by a fusible link in each electric heating element (Figure 14-8). This device is designed to shut off the current when temperatures in the furnace become excessive. It functions as a backup system in case of limit switch failure."

​

This is for a trane...

But when I go to the HKA page...it has them too...

Goodman HKA-20C 19.6 Kilowatt Heater Coil (68,200 BTUs of Heat)

www.alpinehomeair.com

Also...and I don't know if this means exactly what it sounds like to me...but it sounds like a break in this fuse WOULD initiate a "fan on" condition when power to the heat was attempted...

"Furnace fan limit switches also include a maximum temperature function that will disable the standard heating process if the furnace overheats. Lastly, the furnace fan limit switch may also be accompanied by a Manual On switch that allows you to keep the fan activated continuously throughout the day in your home to improve air flow"

What is a Furnace Limit Switch? How it Operates & Troubleshooting

The furnace fan limit switch is designed to activate and deactivate the furnace blower assembly. This component is responsible for transmitting warm air throughout the home.

www.wmhendersoninc.com

So that's where we're at today.

Going to start with a little tappy-tap-tap to the limiting switches to see if one is stuck open.

 

[Missourian]

yes, if the t-stat works & coil pulls in, blower works etc , which appears the case

exactly why i own one

meaning the actual heating coil element in the unit ? continuity may be somewhat problematic due to high R , but if you do get 238V to it and it's not heating (drawing power) it would be indicative of a burnt out one. ~S~

I'm pulling it out today. I envy you guys knowledge on this.

Thanks. I appreciate your help.

 

[Missourian]

More likely to be in the control area you're looking right at. Fuses, breakers, bad connections, wires, discolored catalytic

This is where I'm at too. I'm hoping anyway.

Appreciate the help.

 

[Missourian]

Worth mentioning is that so long as the heating element is connected to the circuit, continuity or ohmage measurements there are likely worthless or at best misleading in testing the state of the actual element as even if open, the meter then would simply read the resistance of the circuitry upstream behind it, whatever that is and may still appear good to the meter.

Short of disconnecting one side of the element which may be hard to do without really getting in there as these are meant to carry a high current, if these are difficult to reach in order to check if voltage is present (which would only be high / 220VAC if the element is open anyway I would think), you might get a couple of long wood or plastic sticks and tape the test probes to them to give yourself better and safer reach to probe around.

Good idea. I'll give that a try before I tear everything apart.

Even so I can only get to one or two.

Thanks for helping, I appreciate it.

 

[sparky]

I'm pulling it out today. I envy you guys knowledge on this.

Thanks. I appreciate your help.

that 'fuseible link' might be worth a look Missourian ....

best of luck & play safe
~S~

 

[toobfreak]

that 'fuseible link' might be worth a look Missourian ....

Might I point out that all this stuff about fusible links and limit switches were listed as high suspect places to look at first in the article I linked here last night about 6 best places to look first?

 

[sparky]

Might I point out that all this stuff about fusible links and limit switches were listed as high suspect places to look at first in the article I linked here last night about 6 best places to look first?

Yes you may, & thx toob dude

~S~

 

[Missourian]

I have cheated.

Since the furnace is modular, we ordered a new heat kit assembly for $229 from Amazon, which arrived today.

Going to install it tomorrow...then I can go thru and check everything, get parts and fix the old one and vacuum seal it with some oxygen absorbers and put it up until it is needed again.

Mrs MO and I talked it over and with the way things are going with China...better to have an extra.

 

[Missourian]

Heat is working again...but the old heat kit is MUCH more robust than the new heat kit.

Old on the left.

Installed...

Now I have to figure out what has failed ... because I'd rather have the robust unit installed and keep the new unit as a backup.

 

[Grumblenuts]

Heat is working again

Congrats!

 

[Missourian]

Congrats!

Thanks.

Appreciate all the help.

 

[toobfreak]

Heat is working again...

That is really the main thing!

Old on the left.

Pretty obviously so.

Now I have to figure out what has failed ...

That is what I'm interested to hear, what the actual failure was, because I'm not sure what exactly is all in a "heat kit" and I can't make out much of anything in the photo past a bunch of wires.

 

[Missourian]

That is really the main thing!


Pretty obviously so.


That is what I'm interested to hear, what the actual failure was, because I'm not sure what exactly is all in a "heat kit" and I can't make out much of anything in the photo past a bunch of wires.

I'll get ya some better pics if you're interested.

My money is now on the high heat switches now that I understand more how they work.

But I have to do a multimeter refresher video tonight to remember how to do these tests without power.

 

[toobfreak]

I'll get ya some better pics if you're interested.

Not if it is any bother at all.

My money is now on the high heat switches now that I understand more how they work.

I think that may be a good guess.

But I have to do a multimeter refresher video tonight to remember how to do these tests without power.

What kind of test is that?

 

[Missourian]

Not if it is any bother at all.


I think that may be a good guess.


What kind of test is that?

Sequencers unbolted

Heating elements, fusible links and heat limiters etc...

From behind...

 

[Missourian]

Found the problem...

Element B1037520 discontinued.

Going to have to keep an eye on Ebay or search the second hand market.

 

[toobfreak]

Found the problem...

That'll do it. Differential stress caused by the insulator.

 

[Grumblenuts]

Science!

 

[Grumblenuts]

Goodman HKR-20CA Electric Heat Kit For Air Handlers 20KW heat | eBay

Find many great new & used options and get the best deals for Goodman HKR-20CA Electric Heat Kit For Air Handlers 20KW heat at the best online prices at eBay! Free shipping for many products!

www.ebay.com

"Out of stock" -- I know, but just suggesting to search by the model number rather than the part number.

 

[Missourian]

Goodman HKR-20CA Electric Heat Kit For Air Handlers 20KW heat | eBay

Find many great new & used options and get the best deals for Goodman HKR-20CA Electric Heat Kit For Air Handlers 20KW heat at the best online prices at eBay! Free shipping for many products!

www.ebay.com

"Out of stock" -- I know, but just suggesting to search by the model number rather than the part number.

Damn... That's a good price too.

I'll do that... Thanks.