Visit our Popular Forums

85Sovereign · 01-24-2007, 06:03 PM

Does anybody happen to know how many amps a heater fan would draw in a 25 foot, 86 Sovereign? I am currently measuring a draw of 25 amps when it is running. Is this within an acceptable range?

Thanks,

Greg

Condoluminum · 01-24-2007, 06:30 PM

Can you clarify if that is the draw at 12V from Suburban Propane Furnace, or if that is an electrical heater added and running on 110V? It sounds high for the furnace fan, but I suspect others might have better data. The furnace manual as part of owner manual pkg should also specifiy electrical loads when running.

SilvrSausage · 01-24-2007, 07:59 PM

I was furnace shopping recently, and the highest number I remember was 8 point something, on Atwood units. 25 amps is out of the ballpark! If the blower motor bearings are drying out, that might be the issue, and lubricating them might help, if that is even possible on that particular motor.

Do be sure you are measuring ONLY the heater draw, not everything in the coach.

85Sovereign · 01-24-2007, 09:52 PM

This is the stock, propane fired heater. The measurement would flux between 22 - 26 amps. I used my Trimetric meter to gather the data. Nothing else was on in the coach. It blows air really good and it is not a noisy fan.

Also, I don't know if this matters, but when the heater is running, it seems that the exhaust coming out of the port to the left of the door is hotter than what is being put into the coach. The heat coiming out of the vents in the coach is still warm. But, the exhaust seems very hot.

Thanks,

Greg

**azflycaster** · 01-24-2007, 11:16 PM

The exhaust will be very hot, it is the heat from the flame in the furnace. The warm air in the trailer is a result of blowing air over the plates that are heated by the flame. It is a transfer system that keeps all the fumes and CO outside of your trailer.
The 20+ amps is way out of line, I would expect 4-6. It you are running on battery power, that amount of draw will drain them in a few hours. Something is wrong and I would suspect the fan motor.

85Sovereign · 01-26-2007, 09:11 PM

Well, you were right. I managed to get the fan motor out of the furnace unit. It was a real treat. To get to the fan, you have to pull the entire furnance unit out from underneath the cabinet. When I spun the shaft of the motor by hand, it felt like the bearings are made of gravel. I figure I'll try to find a source for a new motor. Anybody else repalce a fan motor from a Suburban furnance.

Greg

William_Mc · 01-27-2007, 10:38 AM

Congratulations on getting the fan motor on your suburban furnace out! You've found the problem! When you get it installed after the bearings/or motor are replaced, please do us a favor and publish the amperage pulled by the good motor. Many of us are following what you are doing.

Can you tell if it would be possible to get oil or grease into the motor bearings or are they sealed?

Suggestion, In most areas I've lived, there were electric motor rebuilding companies that could rebuild your present motor or will have one on hand ready to go in exchange. Of course, Suburban will be able to help as well.
Try looking on the Web for Electric Motor rebuilding.

Keep us posted, THANKS, William_Mc

markdoane · 01-27-2007, 11:09 AM

Here is a chart that shows the general amperage draw of Suburban furnaces. http://www.bryantrv.com/docs2/docs/suburbantech.pdf

doorgunner · 01-27-2007, 11:13 AM

This truly is a GREAT forum! McMaster car has a web, most of the time if they don't have it you don't need it.

William_Mc · 01-27-2007, 11:19 AM

I followed the advice to search the Web for electric motor rebuilding and found several sources. Also, searched Yahoo for 'Suburban Furnace parts'. This brought up a wealth of companies that could help.

The one I chose was Marks RV. The URL is Marksrv.com/suburbanparts.htm#motors. This will list the Suburban Dynatrail Furnace Parts. The 12Volt blower motor section list motors that can ship in one to three daysfor furnace models NT12L-LE-LEC-S-SC-SE-SP and Models NT16LEC-SE-SP-SW. These are all part # 0232877 for a price of $97.50.

There is a sec ond motor for Furnace models NT16L-S-SC and NT20L-LE-S-SE-T under part # 0232878 for a price of $96.75.

I printed the whole list of parts for Suburban Furnaces which is just about everything. A total of eight pages. I saved the list for future reference and inclusion in my trailer repair manual

My trailer is a 1986 sovreighn so it will have about the same motor and parts as your '85.

Thanks in advance for your reply, William_Mc

85Sovereign · 01-28-2007, 07:45 AM

Before I put the unit back in the trailer, what is the best way to clean the furnace?

Greg

Smokin Camel · 01-28-2007, 08:32 PM

My NT20 drew amost 3 amps when I measured if after installation. The NT 24 that it replaced was drawing about 8 amps. That seem typical for those models.

Before cleaning, obtain a manual for that model:

Basic cleaining of the burner and vicinity can be done by carefully vacuming and brushing with a small paint brush. Look over the heat exchanger when you do that. Make sure you have no obvious cracks or pin holes. Nozzles can be softly blown out with compressed air. Try not to put anything through if you can help it. If you need to clear a nozzle be gentle and careful. Clean your ignitors with cotton cloth and then with light emery if necessary...then wipe again with the cotton. Mainly just get the dust out and clean the ignition is half the job.

While you are at it check to see the exhaust and intakes are clear of mud dauber nests, mice and whatever else can get in there. Check you internal hot aird ducts as well.

Take a small plastic water bottle and make some very saopy water with dish soap. Use a large atrist brush or similar insturment to put a lot of saopy water over your gas fittings. If there is a bubble formed you may need to tighten the fitting.

It is good to clean the furnace every year. After you clean the beast, test it. You can by-pass the thermostat by disconnecting the two blue wires and holding them together. Flame it for a few minutes and make sure the system gets fully heated up. Notice if the fan motor sounds clean and if the burner has a smoothe buffered hiss. If there is a sight glass, most Suburban and Atwoods burn a nice clean blue flame.

It is best to have someone that is competant (like a steam fitter or service tch) look at it every couple of years. The pros tend to notice the little things the rest of us may miss. The good ones provide some education along with a furnace service.

Before I forget....check your LP detector (if you have one) by venting a small propane torch at it (without lighting the torch!). If you smoke or have a friend that does they can test the smoke detector and CO detector (cigarettes will often set these off if the hot end of the butt is near the detector).

Remember have a pro look at it onec in a while.

85Sovereign · 02-02-2007, 02:32 PM

I could not find anybody to rebuild my old motor. So, I ordered a new one. I installed it today. I am still measuring 25 amps when the motor is turning. Am I reading the my Trimetric meter incorrectly? It has the 500ma shunt connected to it. Any guesses?

Greg

Condoluminum · 02-02-2007, 03:07 PM

Greg-

The Suburban Data sheets linked above suggest the motor should draw around 3 Amps, and if you're reading 28, and motor is new, I'd be suspicious of meter reading unless motor were making some strange noises...

I'm not familair enough with that brand of meter to answer question about shunt or settings, but I'd be suspicious...

John McG

85Sovereign · 02-02-2007, 03:47 PM

Thanks for the advice. I'm thinking I just spent $100.00 for nothing.

Greg

doorgunner · 02-02-2007, 10:14 PM

post #6 you indicate the bearing felt like gravel was in them. Maybe you got lucky here and avoided a breakdown when you needed heat the most. I'm still interested in the resolution of the high amp reading.

Smokin Camel · 02-02-2007, 10:38 PM

Just out of curiosity, turn everything off; try disconecting the positive terminal and putting a voltemeter meter from the positive terminal to the line. There should be no draw. See if the installed meter has a reading. Then try various appliances/lights etc. one at a time. Turn each off before progressing. Repeat readings from volts to amps for each source. If there is a bad meter reading you will fugure it ourt real quick. If there is something shorting the high reading should show up somewhere. If you find it get out the service manual and track down that wire from the panel to whatever caused the spike in amps. I wonder if your ampmeter was hooked up correctly?

Poprivet · 02-03-2007, 01:49 AM

Try reading a know load such as a 12 volt light bulb. Current = watts / voltage. I sounds to me that your meter reading is off by a factor od 10 which would make the heater fan draw 2.8 amps or right on target. If the meter is anolog, make sure you are reading the right scale. This can be a little tricky if your unfamilar with the meter. If the fan turns freely, I'm betting on either your on the wrong setting for the meter or your reading the wrong scale.

lewster · 02-03-2007, 05:30 AM

Quote:

Originally Posted by 85Sovereign

I could not find anybody to rebuild my old motor. So, I ordered a new one. I installed it today. I am still measuring 25 amps when the motor is turning. Am I reading the my Trimetric meter incorrectly? It has the 500ma shunt connected to it. Any guesses?

Greg

Greg,

I would suspect your meter as being part of the problem. A/C compressors generally draw 12-14 amps while running, and a fan motor should be in the 5-7 amp range, similar to what the furnace should draw. You did the right thing in changing your motor if the bearings were noisy.......that is a prelude to motor failure and lock-up!

I would dump your meter (as far as amp measurements go) and go to Sears and get one of their $50 AC/DC amp clamp meters. They are accurate enough to measure most applications and you just clamp it around the wire you want to measure. I use one as a back-up to my $500 Fluke meter.

85Sovereign · 02-03-2007, 09:47 AM

I sure hope it is not the meter. It cost $200.00 and is supposed to be very reliable. I'm using the digital Trimetric meter. It is multifunctional and monitors volts, amps, and percentage full of the batteries. It also has programable reminders for other battery issues. I know that when I turn on one 12 volt light, the meter registers 6-8 amps. Is that a correct reading for one light bulb?

Thanks again to everybody for your help in trying to resolve this matter. I'm sure we can solve the mystery.

Greg