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Heater rheostat shot

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0123 Mike D
Biddulph, Staffs, UK   GBR
The thickest wire that fits give the best result.

Max continuous current through a red fitting is 10 amps.
Use 22AWG to 16AWG wire for red fittings.


Max continuous current through a blue fitting is 15 amps.
Use 16AWG to 14AWG wire for blue fittings.

Max continuous current through a yellow fitting is 15 amps.
Use 12AWG to 10AWG wire for yellow fittings.

Fuses have different functions.
You can fuse your circuit at a higher rating than the current rating
Say 50% higher for general car work.

I guess your wipers and heater will run happily using red fittings.
And a 15 amp fuse.

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0123 Mike D
Biddulph, Staffs, UK   GBR
pvr Avatar
pvr Paris VonRabenau
Reynolds, GA, USA   USA
1952 MG TD MkII
1960 Morris Minor 1000 "EMMA"
I see Mike, I have all those tools including crimpers. I fully capable of tearing down an engine and putting it back together again.
The same for an Alternator or heater or anything mechanical. But I am a duce at wiring. (slow)
I also get it what you are telling me. I didn't think of that when considering that part.
Simple was my angle, and here in the states, it comes with the wires. (actually China)
But Mike, now that we are along this far; please explain why the heater needs a relay? What does a relay do anyway?
I understand the fuse.
Butch contacts" that's a good one.



Too soon old, too late smart, Dad always said.

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pvr Avatar
pvr Paris VonRabenau
Reynolds, GA, USA   USA
1952 MG TD MkII
1960 Morris Minor 1000 "EMMA"
Thank you Mike for educating me by forcing me to look up my own questions.
I just looked up why use a relay.
In my words; the purpose is to balance the load when the heater is turned on especially when using a rheostat for varying the speed of the blower.
And for shutting it down with 0 flow of voltage after turned off.
I'll get the relay Mike.
A fuse on the hot lead side.



Too soon old, too late smart, Dad always said.

0123 Mike D
Biddulph, Staffs, UK   GBR
A heater needs a relay cos the ign switch wasn't built to run a heater Paris.

A relay is a butch switch
that switches a heavy current on and off
when a wimpy little switch tells it to.

That starter solenoi you have is a good example.

Think of a switch as a tap.
and the wire as a hose.

A small tap reduces the pressure at the jet as the end of the hose.

A small switch reduces the voltage (electrical pressure) at the end of the wire.

The ign switch is just butch enough to run the ignition and the perhaps the wipers.
At least, it was when it was new.

When it also runs the heater, it's a hiding to nothing
the electricity can't flow through it quick enough
to get a decent spark.

pvr Avatar
pvr Paris VonRabenau
Reynolds, GA, USA   USA
1952 MG TD MkII
1960 Morris Minor 1000 "EMMA"
Thanks, Mike, photos coming later of my installation.
Darn good analysis too.



Too soon old, too late smart, Dad always said.

0123 Mike D
Biddulph, Staffs, UK   GBR
In reply to # 33932 by pvr Thanks, Mike, photos coming later of my installation.
Darn good analysis too. Exactly 50% of it was below average Paris

pvr Avatar
pvr Paris VonRabenau
Reynolds, GA, USA   USA
1952 MG TD MkII
1960 Morris Minor 1000 "EMMA"
It seems appropriate when you are teaching a retard.
Keep it simple. (Smiling)



Too soon old, too late smart, Dad always said.

0123 Mike D
Biddulph, Staffs, UK   GBR
I'm about as good at teaching as a
collander is for catching farts Paris smiling smiley

John in Eugene Avatar
John in Eugene Platinum Member John Quilter
Eugene, OR, USA   USA
In reply to # 33931 by 0123 A heater needs a relay cos the ign switch wasn't built to run a heater Paris.

Well my two dead stock 1960 Minors came with Smiths heaters from the factory which were wired via the ignition switch. Fifty eight years and 190,000 plus miles later and they're still working fine as are the ignition switches.

John F. Quilter
Eugene, Oregon USA

0123 Mike D
Biddulph, Staffs, UK   GBR
In reply to # 33941 by John in Eugene
In reply to # 33931 by 0123 A heater needs a relay cos the ign switch wasn't built to run a heater Paris.

Well my two dead stock 1960 Minors came with Smiths heaters from the factory which were wired via the ignition switch. Fifty eight years and 190,000 plus miles later and they're still working fine as are the ignition switches. John, please would you kindly measure: -
The voltage at the coil when wipers and heater are running with the engine at say 3000 rpm.
The voltage at the coil when ancillaries are not running

Temp at the switch when wipers and heater after they've been running with the engine at say 3000rpm for 10 mins.
Temp at the switch when wipers and heater are not running, and haven't been running for say 30 mins.



John F. Quilter
Eugene, Oregon USA



Edited 2 time(s). Last edit at 2018-12-19 04:36 AM by 0123.

0123 Mike D
Biddulph, Staffs, UK   GBR
Here's the current ratings for a couple of typical starter switches.

Anyone know the amps through a heater please?

Ditto through the wiper motor please?

Ditto through the ignition circuit please?


Attachments:
Ferd002.jpg    54.2 KB
Ferd002.jpg

emjay Jim English
Etters, PA, USA   USA
Mike, simply using relays will not magically increase the amount of voltage available for the coil. You may be moving the load off the ignition circuit but the dynamo is still the limiting factor and now it also must supply these new relays. Now if you also install an alternator, then you are getting somewhere.

Remember, the driver's handbook advised to charge the battery when you get home after using the wipers and heaters and lights because they new the dynamo was up to the job.



Edited 1 time(s). Last edit at 2018-12-19 05:55 AM by emjay.

0123 Mike D
Biddulph, Staffs, UK   GBR
I daresay we'll get a definitive answer when John
posts voltages for his dynamo cars Jim thumbs up

Or when someone else does please smiling smiley
I will be very happy to be proved wrong thumbs up

I don't have a dynamo car, so I can't help there sad smiley

According to Green Earth: -
Automotive Relay Guide | 12 Volt Planet
https://www.12voltplanet.co.uk/relay-guide.html
This completes the 'high' current circuit between the terminals and the relay is said ... According to DIN 72552 the coil should be fed with +12V to terminal 86 and ... The current draw of the coil is not normally shown but is typically 150-200 mA ...

pvr Avatar
pvr Paris VonRabenau
Reynolds, GA, USA   USA
1952 MG TD MkII
1960 Morris Minor 1000 "EMMA"
The rheostat is working and ready to install. To be clear, the black wires (2) go through the small hole in the plastic housing. From there they run down the side where they are secured to the metal shroud that houses the heater coil. At the base, you will see both the white wire and the two black wires of fan motor. One of the blacks goes to ground. Both blacks go to the rheostat switch in the plastic top.
The fan propeller is inside the plastic shroud where the switch is. The plastic shroud is clipped directly to the heater coil. Hook the 6" X 5/8" metal clips into the plastic shroud grove provided then with both hands push on the spring and guide over the base of the heater coil. It is difficult at first but with practice, you will get the hang of it. I have five clips with my heater plus two spring hooks welded to the outside of the heater core metal shroud. These 2 clips help to hold the heater coil assembly in place while the side shroud section joints are screwed together (4) screws.
[url=]MM1000 Heater assembly[/url]
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On a humorous note: the PO cut the white wire to the motor very short. My attempt to attach a connector failed, making the wire even shorter. I disassembled the motor from the coil, removed the fan blades and opened the motor housing, I removed the rotor which popped the carbon contacts and springs. I added a connector to the white wire and threaded it through the motor casing with the black wire. Then with surgery clips held the carbon contacts back so I could get the rotor back in between them. Very hairy. I was afraid I'd break the tiny meshed copper carbon wires. I pressed and pushed the casing back together carefully and tested. Not a job recommended for anyone short on patience or with fat fingers.
My motor is working now.



Too soon old, too late smart, Dad always said.

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