Obby Posted February 11, 2004 Share Posted February 11, 2004 I hope someone know's the answer to this one... Sounds simple, but I'm no "tool time" house mechanic when it come to this stuff. Here it goes... I replaced my furnance fan due a failure with the original part. Now the furnace fan keeps going on-and-off all the time. Yes the heat is on, but due to the new fan problem it takes forever to heat the house. Any ideas guys/gals? -Obby :???: Quote Link to comment Share on other sites More sharing options...
Canada0937 Posted February 11, 2004 Share Posted February 11, 2004 that happened to me a couple of houses ago...I consulted a heating specialist and he said the motor/blower wasn't powerful enough, therefore the home wasn't reaching temperature. This caused it to run almost constantly. So he replaced it with a more powerful motor/blower. Worked perfectly and the home heated up much faster. Hope this helps. Quote Link to comment Share on other sites More sharing options...
vetteman Posted February 11, 2004 Share Posted February 11, 2004 i've never ran into that problem. if its what joel said then you may just need to rewire the motor. some fan motors are multi-speed, different wires for different speeds. might be worth a shot. good luck. Quote Link to comment Share on other sites More sharing options...
SwampNut Posted February 11, 2004 Share Posted February 11, 2004 That's an odd one, but if it worked it worked. Is this gas? If so, there's a temp trigger to make the blower come on only when the furnace is hot, then shut down when it cools. Could be that sensor is bad, or corroded and not reading properly. That would be the first place I'd look, and it's simple. But I'm no expert, just understand how they generally work. Quote Link to comment Share on other sites More sharing options...
N1K Posted February 11, 2004 Share Posted February 11, 2004 But I'm no expert Do you even have a furnace Carlos? :fingers: What for? Those 'cold' whorey nights that get down in the 50's????? We might have covered this before but I'm willing to bet that if I lived in your climate I would not need a furnace.... Then again... living in that AZ sunshine might turn me into a pussy too! :razz: :razz: :razz: :razz: It'd probably take a couple years, but eventually as I got pussified, I might need one. :razz: :razz: :razz: :razz: :razz: Quote Link to comment Share on other sites More sharing options...
azxr Posted February 11, 2004 Share Posted February 11, 2004 But I'm no expert Do you even have a furnace Carlos? :fingers: What for? Those 'cold' whorey nights that get down in the 50's????? We might have covered this before but I'm willing to bet that if I lived in your climate I would not need a furnace.... Then again... living in that AZ sunshine might turn me into a pussy too! :razz: :razz: :razz: :razz: It'd probably take a couple years, but eventually as I got pussified, I might need one. :razz: :razz: :razz: :razz: :razz: Even though this was intended for Carlos, I will answer. Yes we do have furnaces. It got down to 19 a couple of weeks back and my friend even had his water freeze. Granted it warms up to the 50s or 60s during the day. However, I grew up in NE PA and spent a year in Alaska and loved the cold/winter. However, after being down here 20 years, 19 degrees does feel cold to me. So Nik, you are right, all of this warm weather probably turn you into a pussy, it did to me. :wink: FYI - My thermostat is set at 70 and the furnace came on a lot last night. Quote Link to comment Share on other sites More sharing options...
SwampNut Posted February 12, 2004 Share Posted February 12, 2004 Do you even have a furnace Carlos? I've got a heat pump, does that count? Don't imagine heat pumps, like swamp coolers, would be any good where you live. Quote Link to comment Share on other sites More sharing options...
Obby Posted February 16, 2004 Author Share Posted February 16, 2004 Sorry for the delayed response everyone, work has me spinning circles lately. No time for an actual life. I will make certain that this is not true come spring/summer (prime riding months). Swampy. Yep, the furnace is gas. I replaced the original fan with a slightly larger one. The furnace comes on, fan starts to blow... then, after 30-60 seconds, it stops... then restarts again in the same time. Over and over this go's until the the temp. is reached. Maybe the replacement fan I bought is too big? Quote Link to comment Share on other sites More sharing options...
SwampNut Posted February 16, 2004 Share Posted February 16, 2004 Ok, I think what's happening is that it is cooling the furnace to where the blower sensor sees that it's too cold, and shuts it off. However, maybe the sensor is bad, or improperly adjusted. You could try adjusting it to colder temps, but if you're really over on the blower your efficiency will go down. Is the motor configurable for speed? IE, does it have a fuckload of wires coming out of it, or just two? Try obstructing the return register about half-way with some plastic or something. Try to get it so the flow is what it used to be, and see what happens. DO NOT let it keep running that way forever, you'll stress the motor and kill it, but it will give some answers. Quote Link to comment Share on other sites More sharing options...
afd44 Posted February 17, 2004 Share Posted February 17, 2004 Carlos is right it is called a "fan limit switch" it senses the air teperature coming off the heat exchanger, if you installed a larger or more powerful blower motor it is cooling the heat exchanger off too much and therefore the limit switch will shut it down until the temperature comes back up to where it needs to be and then will allow it to come back on. I would say that you have too much blower speed!!!!! also as Carlos said depending on the motor that was installed there should be a way to slow down the fan by changing the wires, most of the blower motors that are installed these days are what is called a "multi-tap motor" you can change speed or even voltage depending on which way it is wired. I am not an expert because I have only been in the HVAC business for 10 years :oops: But I would say that is what your problem is. Hope this helps, Later Lonnie Quote Link to comment Share on other sites More sharing options...
Obby Posted February 17, 2004 Author Share Posted February 17, 2004 Thanks for all the advice guys... The old fan's bearing wore out, that's why I replaced it. The furnace worked fine, but made a knocking noise as the fan moved around (clunk...clunk...clunk... when starting and stopping). After replacing the fan, with a slightly larger one at Home Depot (that was the closest match), I started experiencing this on-off problem. The new fan definately blows a little harder that the old one. I will take a look at the new fan's wiring again. Maybe I can slow it down like you guys suggest. Better get a fire extinguisher ready for this one :oops: ... I hate playing around with wiring, otherwise I would have done the Yamaha R1 regulator/rectifier mod on my bird. I think I'll just be buying an extra one and keeping it onbord for a quick swap out when needed. Quote Link to comment Share on other sites More sharing options...
afd44 Posted February 17, 2004 Share Posted February 17, 2004 Shouldn't be much playing around they should have given you directions, i.e. which color goes where to do what. it's not a big deal but until you get it slowed down you are gonna experience this problem, It could cause other problem's down the line. Later, Lonnie Quote Link to comment Share on other sites More sharing options...
Guest Posted February 17, 2004 Share Posted February 17, 2004 I think Carlos has got this one solved! Too much fan will cause your High Low limit switch to shut down your furnace if it cannot mantain an open cerciut. The H/L switch is telling the furnace that everthing is O.K. as long as it's hot, when it cools down too fast, it's telling the furnace that you have lost your flame or that it is done heating and that the whole unit needs to shut down. Plus... the air is flowing past the manifold so fast that it doesn't have time to warm-up and therfor cannot heat your house. You really need to get this fixxed immeadiatly...... if this continues to much you may end up cracking your manifold by not allowing it to cool properly. You can have the same problem with heating in a car/motorcycle motor if you take the thermostate out..... it will either never warm up or it will never cool down. Too much flow is a bad thing. I hope that helps. Quote Link to comment Share on other sites More sharing options...
EVLXX Posted February 17, 2004 Share Posted February 17, 2004 Damn! I did it again posted with-out loging in first! Quote Link to comment Share on other sites More sharing options...
dsanders Posted March 18, 2004 Share Posted March 18, 2004 I hope your problem is fixed by now. First the fan motor needs to be the same RPM as the old one. It can be a larger Horse power, but it the speed is too high it will cool the exchanger down too fast. Especially if the house is already cold. Now if it is a multispeed motor, generally you will use the lowest fan speed for heat and highest for air conditioning. The lowest speed is generally a red wire. The highest is usually black or blue. If you have this backwards you will have problems in the summer time. (That is why I decided to go ahead and respond in the off chance you will come back to this post.) From the days I used to work on gas furnaces (which has been about 7 years ago), the only two things that come to mind about a motor coming on and off is: The exchanger is getting too cool--which is due to a cold inside temp air, fan speed too high, or fan temp low limit set too high. Or two, motor going out on overtemp. This can be caused by not having enough air resistance--this is unusual, unless you went alot higher in horsepower. (Which would usually mean the motor won't even fit in the blower assembly. If you still have problems PM me and maybe I can help you some more. Good luck.. Quote Link to comment Share on other sites More sharing options...
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