Block heater problem

202 watts, so would I have 200 watts at the heater or 100 watts?

200 W at the heater.

When the power meter was being fed with from the rectifier, the RMS voltage wasn't being measured correctly. If the mains voltage was 125 V, the RMS current when half-wave rectified would have been about 88 V.

Some hair dryers have a low power setting that has a diode in series, so power meters like that are expected to work correctly with loads like that. Having the rectifier after the power meter is the way to take the readings.

I would expect readings to be about:-
Voltage 125 V
Current 2.3 A
Power 202 W (as you already told us)
Power factor 0.71

Without the rectifier I would expect
Voltage 125 V
Current 3.3 A
Power 414 W (as you already told us)
Power factor 1.0

If you are getting those readings, they would be consistent with the rectifier working perfectly. The readings with the power meter after the rectifier are just an anomaly from using the power meter in a way that it's not intended to be used.

I appreciate your input in helping me understand how this works.
Nothing left to do but get it installed and hope it will last longer than the previous heaters.

KevinW said:

I was just looking at a dimmer, 500 watt, 6 amps, even if I worked down to 200 watts I expect the element might last longer.
I thought the timer might help, I guess I could set it to come on for five minutes then off for two then cycle again.
Too tight for an inline hose heater.
Thanks for your response.

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Your best solution would be to use a simple dimmer. By using an AC, amp meter, you will be able to set the voltage to anything between 0vac and 120vac. To drop it down to about a 100 watts, You will need to set it at about 0.8 amps AC.
Simply using a timer to turn it on and off. I will not give you longevity to the heater, but the dimmer switch method will. Also I assume that there is no corrosion present and the failure is not being caused by corrosive properties.
All the best,
Don

Too cold to install it right now but in a few days I'll get a picture of the cavity in the block and the heater itself to show how restrictive the space is around the element.

A dimmer could be anywhere in the supply, as could the diode. Either could be inside the house.

I wouldn't use a dimmer and a diode.

DHolub said:

Your best solution would be to use a simple dimmer. By using an AC, amp meter, you will be able to set the voltage to anything between 0vac and 120vac. To drop it down to about a 100 watts, You will need to set it at about 0.8 amps AC.
Simply using a timer to turn it on and off. I will not give you longevity to the heater, but the dimmer switch method will. Also I assume that there is no corrosion present and the failure is not being caused by corrosive properties.
All the best,
Don

Click to expand...

I installed the new heater today, ordered one from EBay for my tractor and was sent the wrong one, unfortunately I had drained all the coolant and removed the defective heater before I found out the one sent was the wrong size.
Anyway here's the cavity in the block and the heater that was removed is the one on the left, the one on the right is the wrong one sent.
You can see there isn't a lot of wiggle room around the element.
I just found out the newer engines have the larger heater with more space around the element which is why they sent the wrong heater for my tractor.

Just a follow up, the heater is doing its job at half the wattage.
I can tell the tractor starts well with it and not so well without it on cold days.
Thanks for helping me with this project.

KevinW said:

Just a follow up, the heater is doing its job at half the wattage.
I can tell the tractor starts well with it and not so well without it on cold days.
Thanks for helping me with this project.

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How cold are your cold days at the moment

We're heading towards spring, and it's usually low single degrees (centigrade) in the mornings, and 'iffy' if the car is frosted over or not.

We are about the same here in northern Ontario.
-5C to+7C.
Nice to see the sun again!

KevinW said:

We are about the same here in northern Ontario.
-5C to+7C.
Nice to see the sun again!

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If it was down to -5C we'd be getting worried