TRACTOR PARTS Allis Chalmers Case & David Brown Farmall & International Ferguson Ford & New Holland John Deere Massey Ferguson Massey Harris Minneapolis Moline Oliver & Cockshutt Kubota / Yanmar

TRACTOR MANUALS

Allis Chalmers	Case	Farmall IH	Ford 8N,9N,2N	Ford
Ferguson	John Deere	Massey Ferguson	Minn. Moline	Oliver

Tractor Talk Discussion Forum

OT furnace fan limit switch question??

Welcome Guest, Log in or Register

Author

PhilcaseinWPa

10-24-2006 11:41:02

Report to Moderator

Well it's getting cold so like everything else I do I decided at the last minute to check to see if the furnace would run (natural gas, forced hot air). I cleaned out all the cobwebs and dust, set the thermostat and turned on the furnace. Started up just fine but the blower fan never came on and the furnace eventually stopped. Then tried to start again and would run a few seconds and shut off over and over. I found the fan limit switch for the blower and by turning the dial a little I was able to get the blower to kick on and run. Got the house a little warmer. But when the furnace kicked on again the blower wouldn't start unless I turned the limit dial by hand. Finally I got my glasses and a flashlight so I could see the dial clearly and there were 3 adjustable pins on the dial along with temp indicators and words limit/ off fan/on /off. I set the bottom pin (fan off I think) to about 75 degrees, the middle pin (fan on to 110) and the limit off to about 170. I started the furnace and it seems to work ok. I watched and the dial would turn as the furnace heated up, when it got to about 100 -115 the blower would kick on, when the house thermostat got to its setting the gas would turn off and the blower continue to run until the furnace cooled to below 70 - 75. So I guess I fixed it but I don't know what the heck I'm doing. Does anyone know the correct settings for a Honeywell fan / limit control? This is a Sears 145000BTU input,forced draft furnace. I'm asking this OT questions here because there always seems to be a lot of good information about everything on this board. Thanks.

Phil

[Log in to Reply] [No Email]

you

10-30-2006 18:49:38

Report to Moderator

Re: OT furnace fan limit switch question?? in reply to PhilcaseinWPa, 10-24-2006 11:41:02

[Log in to Reply] [No Email]

PhilcaseinWPa

10-24-2006 13:40:52

Report to Moderator

Re: OT furnace fan limit switch question?? in reply to PhilcaseinWPa, 10-24-2006 11:41:02

Thanks for all the help guys. I may try to up the settings a little and watch it and also check my filters. I regularly change those so I think it is ok. After the blower kicks on I can watch the dial drop until it reaches about 90 and then it holds steady there til the burner shuts off. Then it drops to the fan shutoff and the fan goes off. I keep the house at less than 65 because we are hardly ever in there. Sweaters are cheaper than natural gas. LOL

Phil

[Log in to Reply] [No Email]

Matt Kane

10-24-2006 14:34:55

Report to Moderator

Re: OT furnace fan limit switch question?? in reply to PhilcaseinWPa, 10-24-2006 13:40:52

I saw in the paper that natural gas customers were looking at a 130.00 drop from last year. propane is also predicted to drop about 2 percent, While fuel oil and electricity are going up. But your right sweaters are cheap.I keep my house at 75 to 76 all winter long with wood.

[Log in to Reply] [No Email]

Hefty Heifer

10-24-2006 22:50:26

Report to Moderator

Re: OT furnace fan limit switch question?? in reply to Matt Kane, 10-24-2006 14:34:55

How much wood do you use in a winter? What does anyone think of those newfangled corn stoves?
HH

[Log in to Reply] [No Email]

Matt Kane

10-25-2006 02:14:41

Report to Moderator

Re: OT furnace fan limit switch question?? in reply to Hefty Heifer, 10-24-2006 22:50:26

About 5 to 6 cords. 150+ year old home. 2400 square feet.

[Log in to Reply] [No Email]

Matt Kane

10-24-2006 13:13:35

Report to Moderator

Re: OT furnace fan limit switch question?? in reply to PhilcaseinWPa, 10-24-2006 11:41:02

I am hearing now that some are saying to kick on the furnace a little lower, at about 125 degrees, and off at 90. This way it comes on sooner to extract more heat, and shuts off later to extract all of the heat it needs. I have a woodfurnace that uses a control limit to trigger my main furnaces blower. I have it set at 135 on and off at about 85. The difference is the gas furnace will shut off when the temp is met, and the woodfurnace will keep running all day till the fire goes out, or the temps are out of range. I would up the settings a little. And like what was said, check your furnace filter. The furnace could overheat due to restriction and shut down, then to just cycle again.

[Log in to Reply] [No Email]

Bus Driver

10-24-2006 12:16:06

Report to Moderator

Re: OT furnace fan limit switch question?? in reply to PhilcaseinWPa, 10-24-2006 11:41:02

Sometimes there are two switches and sometimes one with two functions. The fan control starts the fan when the heat exchanger temp gets up to the preset ON temp. This is so that the fan does not blow cold air for the time that the heat exchanger is warming up. If the system is designed and installed correctly, the fan will carry away the heat as fast as the furnace can create it. Clogged filters, undersized ducts, slipping fan belt, things like that can mean that the heat continues to build. The second switch and/or function is the high limit which will shut off the burner if the heat exchanger temp reaches that value. It is possible that some furnaces regularly cycle on the high limit without the occupants being aware of it. The second function of the fan control switch is to stop the fan when the heat exchange temp drops to the lower/off setting. This lets the fan get a bit more stored heat from the unit after the burner stops, increasing efficiency.

[Log in to Reply] [No Email]

Jay (ND)

10-24-2006 12:05:24

Report to Moderator

Re: OT furnace fan limit switch question?? in reply to PhilcaseinWPa, 10-24-2006 11:41:02

Yep, that's a good sign - safety is working.

The low one should be set at about 100 - anything less and the air will feel cold coming through the registers. The mid should be 140-150 and the top one about 200.

This is common for the to stick like this over the damp summer. Usually just sliding the limits, as you did, will take care of it.

[Log in to Reply] [No Email]

Janicholson

10-24-2006 12:01:16

Report to Moderator

Re: OT furnace fan limit switch question?? in reply to PhilcaseinWPa, 10-24-2006 11:41:02

The fact that the bonnet control limit activated the burner shutoff, is a good thing. That means that even if you do something wrong to the fan control side of things it will not have a melt down, (you tried that at first accidently). I think your settings are reasonable and will work. I do not know the factory spec. Make sure the filter stays clean, and the registers are open to all rooms so that the fan upper limit never gets used. If it fails to operate consistently, I would purchase a new fan switch and R7R tho old one. JimN

[Log in to Reply] [No Email]

[Options] [Printer Friendly] [Posting Help] [Return to Forum] [Log in to Reply]

TRACTOR PARTS	TRACTOR MANUALS

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]

Home | Forums

Copyright © 1997-2023 Yesterday's Tractor Co.
All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy

TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters

Website Accessibility Policy