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Urgent generator fan question
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No OTR I see . Send me a email alperna@yahoo.com and i will send you pics of our set up , maybe it will help . You can then load them up here as i can not load pics on my computer to share .
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Today, next we will,plug radiator fan into alternate source via extension cord again without genset running measure drawn amps, the take access door off (surrounded by the blue tape photo above) and check amps drawn If amp drawn with access door off, them
n original design fails to provide inadequate air flow pulled by fan blower thru radiator, or radiator is too plugged for the proper air flow to keep fan motor from working too hard aka pulling more amps which creates hest, which eventually under a good load causes fan to heat up that bewitching ambient air temp cut off point
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A fan dealing with restricted air flow, for whatever reason will work less and draw lower amps.
If you want to test this use a vacuum cleaner and stick your hand over the end of the hose. You will hear the motor speed up significantly because the motor is working less. Measure the amps with an open hose and then with a blocked hose.
If you are going to make decisions regarding the re-engineering of your generator radiator fan, make the decisions for the right reason.
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Jon
our test showed amps drawn by blower fan sourced out showed 9.7 amps pulled. When we opened the access door, amps drawn was 11.4 ish. So what you described above with your vacuum cleaner analogy proved true.
The main problem remains, the squirrel cage fan/motor assembly housed in this sealed box pulling hot air thru the radiator iscawash in “hot air”. This hot air per our installed thermometer shows with ambient temperature of 85 F, it took 19 minutes for box interior to raise to 104-5 degrees, which is when electric fan motor inside squirrel cage fan QUITS due to its spec of 104F degrees shut off. -
The point that needs to be considered is every fan motor with a 104 degree cutoff in every coach is going to stop running. Obviously if that is the case this and every other forum would be filled with posts and threads about the problem.
But since this is the first time I have ever seen this issue discussed to tells me Vantare has done something that prevents shut down. There is no way a coach is going to avoid high air temps. Driving down the highway in the summer with the generator running very hot air is drawn into the fan. In most of the nation in the summer the road is heated by the sun and is radiating that heat up. That is why Cruisairs struggle in the summer.
So the solution is to find out what Vantare did to prevent that problem. My guess is they added a jumper across the thermostatic switch or temperature sensing device to keep power to the motor, or they use a higher temperature motor.
Cutting holes in your coach has to be a last resort.
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Wait a minute, if the vacuum motor has to work harder wouldn’t the amp use be higher?
You will hear the motor speed up significantly because the motor is working less.
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Jon, defeating the temperature shutdown of the fan blower motor was our first thought since every electric single phase 115 v motor on Grainger’s website and others like Zoro, has ambient temperature shutdown at 104
We bought a new $6320 assembly from Grainger since the old motor shaft had been so distorted at the end, we could get old squirrel cage fan off shaft. Easier to buy new
A couple of small local electric motor shops here in town told good luck finding higher ambient temp rated motors
ive found a number of 220v motors with much higher temp ratings, but thatcwont work.
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I don’t have a dog in this fight. But …
Did the local electric motor shops have an opinion on running an electric motor at higher than ambient temps of 104*F? I’d think there are quite a few commercial and industrial applications (especially in the South and SE US) where the ambient temps around the electric motor are above 104*F. Working in banking all my life I’ve only been to an electric motor shop a few times, but I was always amazed of how knowledgeable those guys tend to be.
I’m with Jon. The converter likely had a bypass of the high temp cut-off or devised its own high temp cut off (with a cut-off at a higher temp) and wired that into the motor.
Good luck. Keep us posted.
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Yes Dick, thats the most sense. Featherlite didnt indicate that when i spoke to them
We are going to clean the radiator today. Reading, there dhould be 30 degree difference of the coolant between inlet and outlet. Perhaps air is restricted from tears of grit slowing air flow hence heating it up. Stay tuned
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Tom,
It seems counterintuitive but subjecting a fan motor to an area of less pressure reduces the load on the motor.
We have countless examples but there are two easy ones that prove the situation. First as mentioned above and as confirmed by Coloradobus is to block air flow and the motor will speed up since it is doing less work. block the hose your vacuum and you hear it speed up.
But our coaches from the olden days used that principle to save fuel. When a radiator has shutters such as coaches of 30 or more years ago, when the shutters closed the engine driven fan was doing less work, and thus reduced the load on the engine and saved fuel. Shutters also decreased warm up time and acted to an extent like thermostats, but their true purpose was to save fuel.
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OK. Here we go
remove generator blower fan cover box and inner access panel on genset side to expose both sides of radiator
sprayed both sides of radiator with A/C condenser cleaner then rinsed
reassembled, let it dry then started it up. 25 minutes later the new motor stops again but not at 104 F in the blower box but at 120 degrees
so, took off blower box access panel, experimentally fashion a four inch piece ductwork, thru temporary access panel cover to electric blower motor air intake. System ran for almost two hours with no shutdown BUT, coolant temps rose from the before 25 minute run before shutdown at 180F to 205F ea time with 4 rooftop a/c units blasting. Blower box temp 122F with ambient 80 F outside fed to motor air intake
turned two A/C off and fan box temp lowered to 116. Coolant to 190-195
Shy pulling radiator, rodding it, and repositioning it by laying facedown with blower fan mounted on top blowing thru radiator and having bay doors loovered, we are at a loss.
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Bottom photo. Radiator all clean except for a leaf that just got sucked up
top photo is temp access door with experimental air intake for electric motor
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Our bus has a PowerTech 17.5kw generator w/Kubota engine. Water temperature runs at 165*f winter or summer. It has 13,300 hrs on it.
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Lonestarace, we replaced our thermostat last fall from powertech directly. . Its a 180F thermostat
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