Tempstar 90+ condening furnace (help !) - http://www.hvacmechanic.com/ Forums
Original message
| mike14411
|  "Tempstar 90+ condensing furnace (help !)"
, posted Tue 25 Oct 15:17:  
I have a question for a Hvac Technician. I have had a problem with my furnace heating efficiently. The 1st problem I had was corrected where the burner would only run for 5-7 seconds and after cleaning the electrode on the spark ignitor and pilot assembly and cleaning the burners and burning chamber and so on the burner is now operating correctly. I had thought the comb. Fan/Limit switch was bad because it kept kicking out on high limit @ 200 degrees, This was not the problem I had choked down on the gas supply to the furnace by closing the valve somewhat lowering my burner flame from 1" to 1/2" and this helped with stoping the burner kicking off on high limit. Is there a good posibility that the plenum could be to short causing the heat to radiate back down through the heat exchanger and causing the burner to go out on high limit? If so what can be done to correct this because I really do not want to keep the gas choked down .I was thinking about taking a cold air return and converting it to a supply because I feel this might help by allowing the heat to flow more and taking away the load on the plenum and I have more than enough returns on my system . I would have 3- 12x14 return air lines left. I realize this cant hurt to try! The furnace is a Tempstar (Whirlpool)
Output 75,000 btu/hr
Input 66,000 btu/hr
Temp Rise 35-65 degrees I have a supply Temp. 128 degrees and a return of 66 degrees giving me about 62 degree Temp Rise.
If anymore information is needed please let me know.
Thanks
Mike
HVAC Tech. In Training !
[this message was edited by mike14411 on Mon 24 Oct 17:43]
Replies:
Xenos
"Re(1):1987 Tempstar 90+ Induced Draft Furnace" , posted Sat 22 Oct 22:50
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If there is an A/C on this I bet the coil is blocked, If not, you better look at why the air flow is so low.
Xenos.
The best way to escape a problem is to solve it.
mike14411
"1987 Tempstar 90+ Induced Draft Furn. NO A/C" , posted Sun 23 Oct 10
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the air supply is not low, I am getting more than enough return air and supply air . The problem is more with the temp. The furnace I have does not have a A/C Coil The plenum is only 15" high. That's why I was asking to see if I could get a professionals input on what to try next.
Thanks
Mike
HVAC Tech. In Training !
[this message was edited by mike14411 on Sun 23 Oct 14:58]
mbales
"Re(1):1987 Tempstar 90+ Induced Draft Furn. N" , posted Mon 24 Oct 16:24
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If that temp rise is at the max, then it's time to increase the fan speed.
mike14411
"Re(2):1987 Tempstar 90+ Induced Draft Furn. N" , posted Mon 24 Oct 17:42
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Fan Speed is running @ MH and I tried to adjust the speed to slow the fan down so I could open the Gas valve all the way and this made no difference it still wanted to kick out on High Limit. The Plenum on the top of this furnace is only 15" high. The temp. Rise is suppose to be between 35-65 degrees and this furnace with the burner flame choked down is giving me about 76 degrees (138 at plenum and return at 62)way off the mark. I have tried all kinds of different settings for the Fan/Limit switch and my HVAC instuctor said to set this at 110 degrees off and 130 degrees on. and it still does not make a difference no matter the fan speed but as long as the gas is choked down it runs without kicking out on limit. Anymore ideas besides a new furnace?
Mike
HVAC Tech. In Training !
[this message was edited by mike14411 on Tue 25 Oct 15:18] |
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"Re(1):Tempstar 90+ condensing furnace (help !"