# Bad or failed heat strip. Any ideas why.



## 50juan (Apr 21, 2010)

So I have a 2 ton air handler I just got going for this winter. I do not yet have the Heat pump portion of it so I was using the heat strip for my heat. I had an HVAC co. come and wire the air handler up to make sure it was done right.(so I hoped. 

The heat strip is a 10kw Nordyne and it was new along with the air handler. I used it for about 3 weeks keeping the thermostat @ 73. A couple days ago I noticed cool air was coming out of the registers. Called HVAC Co. and they came out. He removed the air handler panel and 1st thing he pointed out was the control board was missing a jumper. He put it in and said that should fix the problem and buttoned it up. We checked the air and still cool air coming out. He again removed the panel and removed the heat strip and found it was burned up. The coils had broken and melted. 

I asked what would cause this and he said it could be a bad sequencer or a wire. 

Of course they offered to fix for the heat strip $300.00 and I passed on that offer. they did however charge me $94.00 for coming out and finding the issue. 

My question is would a missing jumper be more likely to cause the failed heat strip.


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## Doc Holliday (Mar 12, 2011)

Not the jumper wire, no. What did it or is it supposed to jump too, from where to where? 

Can you take some pics?


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## Doc Holliday (Mar 12, 2011)

If there are sequencers than perhaps one got stuck and continued the call for heat to the strip after the blower quit. It's either that (which means you stand the chance of burning up another one until after the sequencer is replaced), a contactor to the strip which acts in the same manner as a sequencer if that is what you have or it's an air flow issue such as a blocked (dirty) filter or poor duct design.


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## Doc Holliday (Mar 12, 2011)

What you are wanting to know is if the first company is responsible for the replacement due to this mysterious missing jumper wire. No, they are not. The wire that is missing on a control board (of which I'm not even sure is missing as usually there is no jumper on control boards but rather in the thermostat) is used to bring power to both heating and cooling mode, if I'm thinking correctly. 

So again, from where to where is this jumper supposed to connect to and from and can you take some pictures?


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## 50juan (Apr 21, 2010)

Doc, Thanks for fast reply. Here are a couple pics of heat strip. I will take pic of control board when I get home. The jumper he put in was in the thermostat control board, but Ill get the pic. 

I dont have issue paying for a new heat strip if a mistake was made on there part, But if they did make an error, sucks they charged me $94.00 for less than 10 minutes :laughing:


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## 50juan (Apr 21, 2010)

2nd pic


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## Doc Holliday (Mar 12, 2011)

Had they been the ones who purchased and then installed the air handler they most likely would not have charged you for that service call but since you had it and simply paid them to install it or wire it in then they are going to charge each time they come out. I would do the same, my company and the next as well.

Again, the wire missing has absolutely nothing to do with the element burning up. It could be that it has too much voltage to it or either of the other two circumstances previously stated, stuck sequencer/contactor or air flow issue.


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## 50juan (Apr 21, 2010)

Here is pic of board, where he placed a jumper. Thanks for all the insight. So this doesnt occur again, what do you suggest I do to make sure all is good.


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## 50juan (Apr 21, 2010)

*pic of system*

pic of system overall.


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## Doc Holliday (Mar 12, 2011)

Okay, the jumper is between first stage heat (one heat strip) and second stage heat, both strips on. 

What he did was call for both strips to come on in regular call for heat, not staging first and second. They both come on in call for heat. If you really need both is another question entirely as usually first stage is more than enough. With two stage heating capability (W1 being first stage and W2 being second) you need a stat that can determine if and when you need second stage. That jumper wire is not the problem, nor is it mandatory in the manner it's wired, you were not missing anything) in any way concerning the burned up strip. However, the voltage supplied to the strips and how long it's supplied (stuck sequencer?) and/or air flow restrictions can cause the heat to simply accumulate and thus build up and burn out the strips. I see the pics of the ducts but without knowing the size of system and what the external static pressure is across the entire system (air flow measurement) and most importantly the temperature rise I can't really say why it burnt up. I would have to assume a higher than normal voltage fed to heat strips and again, how long (as in if a sequencer is stuck closed and constantly supplying voltage even after set point is satisfied and t-stat cuts the call for heat off, blower off) and/or an air flow issue.


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## Doc Holliday (Mar 12, 2011)

Beenthere, please feel free to jump in at any time.


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## Marty S. (Oct 31, 2009)

Make sure your thermostat is set up for electric heat,which brings on the elements and fan at the same time.


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## carmon (May 8, 2010)

The jumper did not cause the element to burn...... sometimes it just happens.....


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## beenthere (Oct 11, 2008)

Looks like fusible links may have blown. Fusible links are safeties to prevent more damage happening from a fire.

The missing jumper from W1 to W2 didn't cause the problem. And it being jumped won't harm anything. Don't think it needs jumped on that furnace.

You may have a low air flow issue. Or the board may have not called for the fan soon enough one time, or the relay for the strips may be stuck closed.


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## yuri (Nov 29, 2008)

Marty S. said:


> Make sure your thermostat is set up for electric heat,which brings on the elements and fan at the same time.


This is the best method. You need an higher quality electronic tstat which has this feature as not all do. The Honeywell Focus Pro and higher end units do.


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## 50juan (Apr 21, 2010)

Thanks all for help. So How would I make sure air flow is suffice. I have ordered a new heat stip. Im going from a 10kw heat strip to 15kw. Will my 6/2 wire still work and do I need to change the current 60amp breaker. line travel to breaker box is less than 25ft.


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## 50juan (Apr 21, 2010)

yuri said:


> This is the best method. You need an higher quality electronic tstat which has this feature as not all do. The Honeywell Focus Pro and higher end units do.


This is what I Currently have.

http://www.ritetemp-thermostats.com/60XX/6080.html


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## HVACDave (Oct 16, 2007)

If your current conductor is #6 AWG copper then it would be capable of carrying approx. 65 amps at full capacity depending on temp. rating of the wire. You will be close to exceeding 65 amps with 15KW plus your fan motor. Depending on what kind of breakers you are using they won't likely hold with the 15 KW unit. The problem with maxing out your wire capabilities is that when you upsize your breaker you are no longer protecting your wire. You should check with an electrician as to your local codes for amperage ratings and breaker sizing. In my area we would have to upsize the wire and the breaker to do what you are planning to do.

If it were my heating strip, I would restring the ones you have by buying new element coils and inserting into the old rack. (much less than a whole new unit) of course you should check out the sequencer end and be sure nothing is stuck "on" or you may experience the same problem as before.


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## Technow (Nov 12, 2010)

50juan said:


> Thanks all for help. So How would I make sure air flow is suffice. I have ordered a new heat stip. Im going from a 10kw heat strip to 15kw. Will my 6/2 wire still work and do I need to change the current 60amp breaker. line travel to breaker box is less than 25ft.


 
Why are you going with 15kw in a 2 ton airhandler? :huh:


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## 50juan (Apr 21, 2010)

Technow said:


> Why are you going with 15kw in a 2 ton airhandler? :huh:


GOOD damn question HAHA. Someone suggested it and I went with. I will keep 10k after that thought lol.


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## beenthere (Oct 11, 2008)

You might not even have enough air flow for 10KW let alone 15.

After you install the new 10KW, check your temp rise.


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## 50juan (Apr 21, 2010)

beenthere said:


> You might not even have enough air flow for 10KW let alone 15.
> 
> After you install the new 10KW, check your temp rise.


Now I keep hearing the subject of air flow come up and when the HVAC Co. set up and installed the 9 registers I noted the air coming out was not a whole lot. To feel air I had put my hand up to register. I inquired with HVAC Co. and was told that was fine. I'm for sure going to remain with a 10k, so how do I check that airflow is appropriate, should I call HVAC co back to have them take care of. 

thanks


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## yuri (Nov 29, 2008)

get a stick type cooking thermometer. check the temp about 2 feet downstream of the furnace in the duct and subtract the temp in the return duct by the filter or the house temp. should have a temp rise range on the model # sticker. ie: 35-65 degF.


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## beenthere (Oct 11, 2008)

Temp rise check is best way. Best done at unit, with a probe stuck in the return right at unit, and then in the supply duct 2 to 3 foot from plenum.

Temp rise/CFM

20-------1580 
25-------1264 
30-------1053 
35--------903 
40--------790 
45--------702 
50--------632 
55--------575 
60--------527 
65--------486 
70--------451


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## 50juan (Apr 21, 2010)

So I have been digging into my heat strip issue further. I did not initially mess with the blower board switches and let the HVAC co. take care of it. Well today I was looking at wiring diagram/ settings. The switch board has 8 on/off switches on it. The switches were set at, 1-3 ON 4,5& 6 OFF, and 7,8 were ON. Now I'm 80% pretty sure I'm reading diagram correctly, still leaves me with 20% to worry about. So with that said am I correct to assume they were wrong and now good. 

per diagram I changed and placed 1-3 to ON. 4-5 OFF. 6-ON and 7,8 I left as is(ON). I've attached pics, mine is cabinet B.

2 ton air handler with 10 kw heat strip.. heat pump not yet attached. 

Much appreciated . THANKS


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## beenthere (Oct 11, 2008)

The normal CFM setting they had was ok. Higher then needed, but the min electric CFM was too low.

Generally, you wouldn't want more then 900 CFM when the heat pump i running in heat mode.


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