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-   -   How hot can I make it with gas furnace (http://www.diychatroom.com/f17/how-hot-can-i-make-gas-furnace-69383/)

rgesner 04-19-2010 02:56 PM

How hot can I make it with gas furnace
 
This is an unusual post. We have bedbugs. Nasty creatures.

The safest, most environmental, surest treatment is to raise house temperature to 120 - 130 degrees for about 4-6 hours.
Commercial exterminators will bring in electric or propane heaters to accomplish this, charge me $1000+ and not even guarantee results.

I've calculated heat loss and determined that it would require 45 to 55,000 BTUs/hr at most, and it occurs to me that my Carrier Infinity gas furnace outputs 60,000 or more, so I'm considering a DIY solution: bypassing the thermostat and forcing the furnace to run continuously until I reach desired temp, then monitoring and manually cycling it as needed to maintain temp for 4-6 hours.

My questions are whether the furnace is likely to have any return air monitoring or other circuitry that would prevent me from doing this, or whether it could damage the furnace?

If there are any HVAC specialists who can answer this, I'd certainly appreciate it.

Please, no conjectures or random opinions from other DIY-ers; I can make plenty of those myself :wink: but if you have specific technical info, please respond.

Thanks

DangerMouse 04-19-2010 03:14 PM

You should keep an open mind. In your case especially... Us "diyers" are the best source of info!
For instance, I (and others here) know ways other than heat that will rid your home of those nasty things, but since I'm not a pro, you're likely not interested? I'd rethink that last comment.....

DM

rgesner 04-19-2010 03:17 PM

Thanks, but I have already researched all the other ways of dealing with them, and here I'm really looking for expert information on the furnace.

Quote:

Originally Posted by DangerMouse (Post 430697)
You should keep an open mind. In your case especially... Us "diyers" are the best source of info!
For instance, I (and others here) know ways other than heat that will rid your home of those nasty things, but since I'm not a pro, you're likely not interested? I'd rethink that last comment.....

DM


DangerMouse 04-19-2010 03:26 PM

That's fine, I'm sure someone will come along shortly to help you.
However, Please remember, you may not pick and choose who responds to your threads here.

*Good Luck!* and "kill 'em all!"

DM

tpolk 04-19-2010 03:52 PM

how would you do it mr mouse?

DangerMouse 04-19-2010 04:57 PM

Well, (just between you and me, tpolk) I don't think just the furnace will be hot enough, long enough. I'd be inclined to add ceramic heaters and/or other sources as well. Intensified in the trouble areas. AFTER removing anything likely to be affected by the high heat. (My "under the pillow chocolate stash" comes to mind.)
Although I have to shudder a little to think what that kind of extended heat can do to the structure, drywall, paint, etc. But what do I know? I'm just a mouse.....

DM

Yoyizit 04-19-2010 05:23 PM

$1000 with 50% likelihood of success = $2000 with 75% likelihood of success. Maybe you can find some company who offers you better odds for your money.

The companies know their odds, but they may not tell you. If 100 homes are treated and 50 people complain, there are probably more than 50 who are unhappy with the job.

No company can probably do much better than industry-wide odds.

http://www.faqs.org/patents/app/20090145019
How much CO₂ you have on hand?

yuri 04-19-2010 06:20 PM

If you have 120 degF in the house and returning to the furnace then the furnace will cycle continuously on the limit control and damage it as well as overstress the heat exchanger and plastic collector box etc. I would not try it. A couple of 5 kw 240volt construction heaters and some ceramics might do the job. BEWARE, running those heaters for a long time will eventually overheat your house wiring and could cause a fire. I would let the insured, bonded licensed Pros do it rather than risk a visit from the local fire dept.

beenthere 04-19-2010 10:23 PM

Some where on your Infinity furnace. It has a max discharge air temp rating.

With a return of 120 to 130. You would most likely exceed that temp.
Normal temp rise through a furnace is generally between 40 and 70 degrees. So if your furnace is at a 70 degree rise already. At 120 degree return temp, that would give you a 190 supply air temp. Don't recall seeing any new gas furnace rated for that.
The furnace's high limit will trip long before your house gets to 120.

If the rise is only 40 degrees. And you exceed max discharge air temp.
The first part of the heat exchanger would become too hot. And become brittle. And have a short life span.

The inducer motor and wheel may over heat. The wheel might warp.
The motor has a safety in it. But i wouldn't reply on it.

If its a 90% or better efficient furnace. You'll end up destroying the coating on the secondary as Yuri said.

The secondary will end up having to be replaced.

The PVC on the flue of a 90% will become soft. And will warp/bend at the horizontal runs that are supported. Causing condensate to be trapped there in the winter. When you want to use it for heat again. And cause you to have no heat.

Your blower motor may only be a 50C rated motor(If its an ECM, you definitely DO NOT want to risk it, real big money $$$$ to replace it and its module). If it is only rated for 50C, then it will not last long with a 130F return temp(probably be higher, if your manually controlling the burner/furnace).


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