High limit switch

Originally Posted By: kmcmahon
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Did an inspection yesterday on a 31 year old Luxaire furnace that’s limit switch was set to 210 degrees. The bathroom register was directly above this unit and I was getting 195 degrees out of the register! icon_eek.gif The register was leaking into the vanity cabinet and when I opened it up you’d think I was opening up an oven!!! Holy crap was that hot!!



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Originally Posted By: phinsperger
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Quote:
The register was leaking into the vanity cabinet and when I opened it up you'd think I was opening up an oven!


That's where I would grab my towel from after coming out of the shower. ![icon_smile.gif](upload://b6iczyK1ETUUqRUc4PAkX83GF2O.gif) ahhh that warm feeling.


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Hinsperger Inspection Services
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Originally Posted By: rsummers
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Wow what was the temperature rise of the unit and was it with in the operating parameters of the manufacture. The usual rise is between 30 and 60 degrees it would have had to been very hot in home to get a supply temp that high. How was the air flow in the home? I suspect there is something that needs a professional evaluation thats HOT!


Originally Posted By: John M Borchers
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Thats way to close to getting water to boil! 180 F Max normally recommended. Steam in lines can build up tremendous pressure. Normally ends up setting off relieve valves and getting water all over the place!


Originally Posted By: Blaine Wiley
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Steam? I must be somewhere else. I thought he was talking forced air. I have seen many limits marked 210 -25 with duct air at the plenum in the 160-180 range.


Originally Posted By: phinsperger
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kmcmahon wrote:
I was getting 195 degrees out of the register!


Pyrolysis of wood starts to occur at 250. In Canada in order to maintan a margin of safety 90 deg C (194 deg F) is considered the maximum allowable temperature to which combustibles should be exposed for long periods.


--
.


Paul Hinsperger
Hinsperger Inspection Services
Chairman - NACHI Awards Committee
Place your Award Nominations
here !