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Block heaters

S

SVcummins

Well-known Member
Ive burned up two in a week only after I started plugging into the barn . Can to low of voltage kill a block heater?
 
yup #1 cause of burnt out heaters. Generally a block heater extension cord should be 12 gauge wire. There are exceptions, but if a cord is warm enough to melt into snow, you're pulling the voltage down. Anything under 115v is causing harm, its just a matter of how long it will take it. I have our power leaving the transformer at 130volts, so that helps a fair bit, most places start at 120. Ontario Electrical code says anything more than a total loss of 5% is unacceptable.
 
I doubt it. They're simple resistive devices; the lower the voltage the less heat they put out.

Consider plugging in a <a href=https://www.harborfreight.com/kill-a-watt-electric-monitor-93519.html>Kill-a-Watt meter</a> between the outlet and heater. It will tell you exactly what the voltage is under load and how much power the block heater is drawing.
 
Thats what I thought Ive been running the heater no problem for 6 months at the house on the same size cord its a 14 its the same 14 gauge cord Ive been running my 1500 watt tank heater on for 4 years now . now Im plugging the truck into the barn with a different cord and its burned up two heaters in the truck this week . Ive got a 1500 watt stock tank heater running on 250 feet of 12 gauge and the last 50 feet Is 14 gauge heater is on its second year burned the last one up when I let the water in the trough go low a d exposed the heater element to air
 
Mornin SV, to your question Can to low of voltage kill a block heater?

With a pure resistive heating element (unlike a motor) type of device I = V/R so if the voltage is low it simply draws LESS current and produces LESS heat, which in theory should NOT harm a heater.

If an intended immersion type of resistive heating element isn't encased in full water/coolant it can overheat and be damaged !!!!!!!!!!!!

Regardless I like to use quality cords even 12 Gauge when using such devices.

John T
 
Are you sure it is completely immersed in coolant? If there is an airlock all bets are off.

DITTO EXACTLY it could overheat and can burn up if not immersed in water/coolant to transfer heat off the element

John T
 
I am familiar with that problem of not being immersed seems like I forget to check the stock tank and burn up a heater once a year
 
SV, Thanks for the update, If that's the case alls well as far as that issue goes.....Back to square 1 lol

John T
 
Were both heaters the same brand?

Possibly a run of defective heaters.

Most heating appliances have a safety overheat link, a troublesome one time fail device. Common to fail for no reason.

I doubt voltage drop is the cause. Is everything else working ok? Lights burning steady, no flickering or surging?
 
I wouldn't think so, low voltage should make them last longer, less power, less heat! Incandescent light bulbs last much longer if the voltage is low.
 
(quoted from post at 10:32:23 02/19/22) I wouldn't think so, low voltage should make them last longer, less power, less heat! Incandescent light bulbs last much longer if the voltage is low.
Click to expand...

Likely you aren't but, running an engine with a block heater plugged in can burn the heater out in a short time.
 
Two things I have run into.
If the element touches metal in the block it can create a hot spot and burn out.
Some elements have to be installed with a certain side up to avoid burn out.
 
I measured the depth with a dial caliper the element is almost an inch from the block same type of heater as the oe
 
(quoted from post at 05:55:23 02/19/22) Ive burned up two in a week only after I started plugging into the barn . Can to low of voltage kill a block heater?
Click to expand...

Are there any other relatively "large" loads at the barn or on the wiring that feeds it?

If there are significant loads on the other "leg" AND there's a poor connection in the neutral circuit the voltage on the other "leg" will float UPWARDS with respect to the neutral.
 
Wow, I've had block heaters in everything from small Chevy V-8's, 300-6 Ford's, a Pontiac V-8,couple FARMALL
tractors, H&M, and my 7.3L IH PowerStroke that I started hundreds of times with the block heater warming and
at 20+ years old and 300,000 miles still has the factory heating element, but I replaced the cord a couple
times. I gave the truck to my Son, he didn't like the Hassel of plugging/unplugging it, or having instant heat
and defrost after the truck started.
 
I ran a truck with a Cummins 903 and if you tried to start that engine with the block heater plugged in it would burn out the heater. I feel sure it had to do with vibration of the engine. I don't know if the block heater had some design feature which wouldn't withstand the vibration. I still don't start things with the heater plugged in.
 
They are both from Napa zero start brand . I got a bad one several years ago took it back got another one and its been fine ever since
 
SV are we talking a block heater or the JD heater on the right side of the engine there with a hose to each top and bottom? If a regular block heater just because it clears depth wise does not mean it could not touch rotational wise in the block. Some have to be is a certain soft plug and certain position to not touch. If this is the Deere heater on the side for get the previous. I also don't think they are made as heavy on some heaters. We had a lower radiator hose heater in the 574 for many years and now I have trouble with them over about 2-3 years not heating enough to start. I have a block heater in another tractor that needs looked at too.
 
These are straight thankfully. Its a cummins block heater. Seems like nothing is made to last thats for sure .
 
Not really a couple small lights and an electric baseboard
heater . If I can find my meter Ill do some testing but I cant
seem to remember where I put it .
 
I have an old block heater that I found I think I should have one more going to hook it up and put it in water and see if it works for now .
cvphoto117963.jpg
 
Now Ima thinkin since low voltage shouldn't harm it, you say its fully immersed in coolant and not touching the block MUST BE A BAD BRAND/QUALITY OF HEATERS

John T
 
How did you determine your heaters are bad? Just because your engine doesn't seem to warm up, or did you ohm out the suspect heaters and compare their resistance to a good one? A 500 watt 120V block heater should measure about 30 ohms. I'm wondering if you have a bad connection someplace, maybe an arc'ed outlet.
 

They say it is possible for air bubbles to collect/form around the heater when the engine is running. I know some get away with it just fine, but I have seen some that fail where that seems to be the likely cause. I was mechanic for a fleet of concrete mixer trucks at one time. Had three trucks with the same engines and I installed the same block heaters in them. One of the three failed two heaters in a short time. No failures in the other two, even when plugged in the same cord as the one failing heaters. The only difference was it turned out was two unplugged their heaters when checking the oil. The third was unplugging when he was ready to load, so he was running it a half hour or more at times while the truck warmed up. Stopped his doing that and I didn't have to replace that heater again. Just my experience in one case.

Also, too rich an antifreeze mixture can be a problem; straight antifreeze is a no no in all heaters I believe.
 
Maybe it's inductive loads only but on AC as the voltage goes down current goes UP. I've observed this with the rooftop AC on my camper as I tried to run it on an inadequate extension cord. Voltage got down to 92 and then the breaker tripped.
 
> Maybe it's inductive loads only but on AC as the voltage goes down current goes UP. I've observed this with the rooftop AC on my camper as I tried to run it on an inadequate extension cord. Voltage got down to 92 and then the breaker tripped.

That's true of induction motors, which want to run at a certain speed and will draw whatever current is necessary to generate sufficient torque to run at that speed. In a low voltage situation, the motor will draw more current than normal, which in turn results in even greater voltage drop. At some point the motor stalls, overheats or trips a breaker.

It's not true, however, of simple resistive loads like heaters. Their behavior is governed by Ohm's Law, which states that as voltage drops, current drops as well.
 
I know the heaters are bad because when they work you can hear them . Also the truck doesnt want to start
 
> Found my meter . This look about right ??? Thats ohms across the two pins

27 ohms would be about right for a 500 watt heater. Is that a known good heater or a suspect one?
 
127 volts is a bit high, but probably not enough to blow a heater. Is that the voltage at the outlet with nothing plugged in? Or did you measure it with a heater plugged in? I would expect the voltage to drop a few volts under load.
 
> I know the heaters are bad because when they work you can hear them . Also the truck doesnt want to start

Just because the block heater doesn't warm up sufficiently doesn't mean it's defective. A bad connection can cause a good heater to appear to be bad.
 
Im not sure Jim I think 750 watt with my truck meter I finally
found I did some checking hopefully this spare heater I found
is still good ? So the breaker tripped at the barn this time had
to drive my other truck after I found voltage there I came
home plugged the one with the block heater issue and sure
enough I could hear it working right away . So Im still not sure
why the first heater quit working though Just poor quality i
guess
 
This is a spare heater I had I think they are 750 watt . The voltage is at the outlet nothing plugged in
 
(quoted from post at 09:05:11 02/20/22) Im not sure Jim I think 750 watt with my truck meter I finally
found I did some checking hopefully this spare heater I found
is still good ? So the breaker tripped at the barn this time had
to drive my other truck after I found voltage there I came
home plugged the one with the block heater issue and sure
enough I could hear it working right away . So Im still not sure
why the first heater quit working though Just poor quality i
guess
Click to expand...

Just like anything, sometimes they just quit.

As for your ohm readings on heaters here are the approximate ohm readings and amp draw values you should see for some of the different wattage 120 volt heaters.

500 watt 28.8 ohms 4.2 amp draw
750 watt 19.2 ohms 6.25 amp draw
1000 watt 14.4 ohms 8.3 amp draw
1500 watt 9.6 ohms 12.5 amp draw
 
> This is a spare heater I had I think they are 750 watt . The voltage is at the outlet nothing plugged in

Can you dig one of your failed heaters out of the trash and see how many ohms it is? I'd expect it to be open.

You really want to check your voltage under load, since you could have a bad connection someplace that won't show up until you start drawing current. Ideally you want to check the voltage as close to the load as possible. One way would be to insert a <a href=https://www.homedepot.com/p/Leviton-Grounded-Triple-Cube-Outlet-Adapter-White-R54-00692-00W/100356925>cube tap</a> between the outlet and heater cord (or between the extension cord and heater cord), then read the voltage at one of the other outlets on the tap. I think you'll be surprised how much voltage drop you get when the heater is plugged in.
 
(quoted from post at 11:12:57 02/20/22) &gt; This is a spare heater I had I think they are 750 watt . The voltage is at the outlet nothing plugged in

Can you dig one of your failed heaters out of the trash and see how many ohms it is? I'd expect it to be open.

You really want to check your voltage under load, since you could have a bad connection someplace that won't show up until you start drawing current. Ideally you want to check the voltage as close to the load as possible. One way would be to insert a &lt;a href=https://www.homedepot.com/p/Leviton-Grounded-Triple-Cube-Outlet-Adapter-White-R54-00692-00W/100356925&gt;cube tap&lt;/a&gt; between the outlet and heater cord (or between the extension cord and heater cord), then read the voltage at one of the other outlets on the tap. I think you'll be surprised how much voltage drop you get when the heater is plugged in.
Click to expand...

Multimeter calibration may be off as well.
 
(quoted from post at 09:14:02 02/19/22) Thats what I thought Ive been running the heater no problem for 6 months at the house on the same size cord its a 14 its the same 14 gauge cord Ive been running my 1500 watt tank heater on for 4 years now . now Im plugging the truck into the barn with a different cord and its burned up two heaters in the truck this week . Ive got a 1500 watt stock tank heater running on 250 feet of 12 gauge and the last 50 feet Is 14 gauge heater is on its second year burned the last one up when I let the water in the trough go low a d exposed the heater element to air
Click to expand...

Are you sure you didn't have a air lock? Air will burn it up in a few seconds.

Also, never start the motor while it's plugged in.

This post was edited by J.Wondergem on 02/20/2022 at 07:36 am.
 
I dont know but the first heater lasted 6 months I cant figure
an air lock being in there that long ? Luckily the heaters have
a year warranty
 
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