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| water heater wire gauge [message #105766] |
Fri, 12 November 2010 09:06  |
jknezek
Messages: 1057
Registered: December 2007
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anyone know, off the top of their head, what gauge wire is running to the oem electric water heater? i'm considering replacing our oem with a new electric tankless (we have no propane in the coach) and figure I'll have to replace the wire, but I'm curious what gauge they originally used. Thanks.
Thanks,
Jeremy Knezek
1976 Glenbrook
Birmingham, AL
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| Re: [GMCnet] water heater wire gauge [message #105767 is a reply to message #105766] |
Fri, 12 November 2010 09:39  |
powerjon
Messages: 2446
Registered: January 2004
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Jeremy,
The Factory 120 VAC drawings say that it is 12-2 with ground type wire.
J.R. Wright
GMC GreatLaker
TZE Zone Restorations
77 Eleganza Custom (For Sale)
1975 Avion (Under Reconstruction)
Michigan
On Nov 12, 2010, at 10:06 AM, Jeremy wrote:
>
>
> anyone know, off the top of their head, what gauge wire is running
> to the oem electric water heater? i'm considering replacing our oem
> with a new electric tankless (we have no propane in the coach) and
> figure I'll have to replace the wire, but I'm curious what gauge
> they originally used. Thanks.
> --
> Thanks,
> Jeremy Knezek
> 1976 Glenbrook
> Birmingham, AL
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: water heater wire gauge [message #105771 is a reply to message #105766] |
Fri, 12 November 2010 09:52 |
rwbmitiopt@comcast.net
Messages: 189
Registered: April 2005
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Jeremy
The water heater, on my 75, is supplied with a 12ga wire and 20 amp breaker and is original. The size wire and breaker on your new heater will depend on the manufacturers specs: usually 20 amp draw requires 12ga, 30 amp draw = 10ga. My electician friend says if there is a single appliance on a circuit then the wire size can be downsized by one ga. If you need 30 amp and you have 12ga existing I would check with a local electrician on the "single appliance" rule.
JWITIK
Randall
| jknezek wrote on Fri, 12 November 2010 07:06 |
anyone know, off the top of their head, what gauge wire is running to the oem electric water heater? i'm considering replacing our oem with a new electric tankless (we have no propane in the coach) and figure I'll have to replace the wire, but I'm curious what gauge they originally used. Thanks.
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Randall Burns
Sammamish WA
75 EX GB
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| Re: [GMCnet] water heater wire gauge [message #105772 is a reply to message #105766] |
Fri, 12 November 2010 09:57 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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I know that somebody has already answered that
12 gauge, 2-wire with ground is what is shown
in the factory manual, but this might NOT be
adequate for your proposed "instant hot water"
replacement. You would need to compare the
current (Ampere) requirements to be sure.
Personally, I would be inclined to use #10 gauge
as a minimum size.
* * * * * * * * * * * *
* D C "Mac" Macdonald *
* Amateur Radio K2GKK *
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> To: gmclist@temp.gmcnet.org
> From: jtknezek@hotmail.com
> Date: Fri, 12 Nov 2010 09:06:22 -0600
> Subject: [GMCnet] water heater wire gauge
>
>
>
> anyone know, off the top of their head, what gauge wire is running to the oem electric water heater? i'm considering replacing our oem with a new electric tankless (we have no propane in the coach) and figure I'll have to replace the wire, but I'm curious what gauge they originally used. Thanks.
> --
> Thanks,
> Jeremy Knezek
> 1976 Glenbrook
> Birmingham, AL
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
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| Re: water heater wire gauge [message #105775 is a reply to message #105766] |
Fri, 12 November 2010 10:24 |
jknezek
Messages: 1057
Registered: December 2007
Karma: 5
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Senior Member |
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Thanks everyone. That's exactly what I was looking for. Odds are I'd replace the wire anyway since I tend to do that unless it's completely unfeasible. I think I'd rather go to a 10 gauge with a 30amp breaker even if I get a small water heater that registers as 20-25 amps. We don't use the hot water much since we rarely shower in the wetbath but our OEM heater is probably on its last legs and I really don't want to go a tank style again. Good thing the GMC has 50 amp service...
Thanks,
Jeremy Knezek
1976 Glenbrook
Birmingham, AL
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| Re: [GMCnet] water heater wire gauge [message #105783 is a reply to message #105775] |
Fri, 12 November 2010 10:59 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Jeremy,
You are already wired for 20 amp with a 20 amp breaker. I would
suggest that you find out the power requirements before making any
changes. It makes no sense to spent extra money on a project unless
the change is necessary. You're going to find that changing out the
wire from the breaker box to the HWH will not be that easy and working
with 10 gauge wire will be more difficult to work with and finding a
30 amp breaker that fits the box might be a challenge too. JMHO
J.R. Wright
GMC GreatLaker
TZE Zone Restorations
77 Eleganza Custom (For Sale)
1975 Avion (Under Reconstruction)
Michigan
On Nov 12, 2010, at 11:24 AM, Jeremy wrote:
>
>
> Thanks everyone. That's exactly what I was looking for. Odds are I'd
> replace the wire anyway since I tend to do that unless it's
> completely unfeasible. I think I'd rather go to a 10 gauge with a 30
> amp breaker even if I get a small water heater that registers as
> 20-25 amps. We don't use the hot water much since we rarely shower
> in the wet-bath but our OEM heater is probably on its last legs and
> I really don't want to go a tank style again. Good thing the GMC has
> 50 amp service...
> --
> Thanks,
> Jeremy Knezek
> 1976 Glenbrook
> Birmingham, AL
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: water heater wire gauge [message #105786 is a reply to message #105766] |
Fri, 12 November 2010 13:05 |
jknezek
Messages: 1057
Registered: December 2007
Karma: 5
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The chart at the bottom of this page indicates it would take considerably less. The Mini3 runs on 120V. I've seen similar requirements from several vendors for 120V products.
http://www.e-tankless.com/stiebel-eltron-mini-tankless.php
Like I said, we hardly ever use the hot water heater. I'd imagine we could get an 80 degree navy shower going if we had to from 60 degree water. Mostly though, it's for washing hands, dishes, or hosing down the baby. The mechanic I use has this unit installed and says mostly it draws 15-20 amps and makes for tolerable hot water.
Thanks,
Jeremy Knezek
1976 Glenbrook
Birmingham, AL
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| Re: [GMCnet] water heater wire gauge [message #105790 is a reply to message #105786] |
Fri, 12 November 2010 14:28 |
Marsh Wilkes
Messages: 155
Registered: January 2004
Karma: -3
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Hi Jeremy,
I checked their figures for the mini 3 at 75 degrees .68 GPM, the figures
are correct.
The unit draws 25 amps, half of the available power.
We are working with the same figures (there is only set), I used 40 amps to
get you around 1 GPM for the example.
To put it in perspective, this water has 2/3 the power of a standard home
electric tank water heater, therefore it will produce 2/3 of the hot water a
standard home water heater does after it "runs out of hot water".
Yes you could get a good navy going if you have the flow rate very low.
To give you a better idea of the performance to expect, filling the large
side of a GMC sink 3 1/2 inches deep with 115 degree water (starting at 60)
would take about 7 minutes.
I just didn't want you to be surprised or disappointed.
As long as you don't expect too much from the water heater, go for it.
Marsh Wilkes
Perry Fl
----- Original Message -----
From: "Jeremy" <jtknezek@hotmail.com>
To: <gmclist@temp.gmcnet.org>
Sent: Friday, November 12, 2010 2:05 PM
Subject: Re: [GMCnet] water heater wire gauge
>
>
> The chart at the bottom of this page indicates it would take considerably
> less. The Mini3 runs on 120V. I've seen similar requirements from several
> vendors for 120V products.
>
> http://www.e-tankless.com/stiebel-eltron-mini-tankless.php
>
> Like I said, we hardly ever use the hot water heater. I'd imagine we could
> get an 80 degree navy shower going if we had to from 60 degree water.
> Mostly though, it's for washing hands, dishes, or hosing down the baby.
> The mechanic I use has this unit installed and says mostly it draws 15-20
> amps and makes for tolerable hot water.
> --
> Thanks,
> Jeremy Knezek
> 1976 Glenbrook
> Birmingham, AL
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] water heater wire gauge [message #105791 is a reply to message #105786] |
Fri, 12 November 2010 14:43 |
Marsh Wilkes
Messages: 155
Registered: January 2004
Karma: -3
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Senior Member |
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Hi Jeremy,
I just reread the part of your last post about your mechanic saying his is
drawing 15 to 20 amps. The water heater the manufacturer is specifying WILL
draw 25 amps at 120 volts, their figures and mine are based on that. If for
some reason the voltage was so low that the water heater was only drawing 15
amps then the performance would be less than half the figures we have been
discussing. At that point it gets a little complicated and is not a straight
ratio.
Marsh
----- Original Message -----
From: "Jeremy" <jtknezek@hotmail.com>
To: <gmclist@temp.gmcnet.org>
Sent: Friday, November 12, 2010 2:05 PM
Subject: Re: [GMCnet] water heater wire gauge
>
>
> The chart at the bottom of this page indicates it would take considerably
> less. The Mini3 runs on 120V. I've seen similar requirements from several
> vendors for 120V products.
>
> http://www.e-tankless.com/stiebel-eltron-mini-tankless.php
>
> Like I said, we hardly ever use the hot water heater. I'd imagine we could
> get an 80 degree navy shower going if we had to from 60 degree water.
> Mostly though, it's for washing hands, dishes, or hosing down the baby.
> The mechanic I use has this unit installed and says mostly it draws 15-20
> amps and makes for tolerable hot water.
> --
> Thanks,
> Jeremy Knezek
> 1976 Glenbrook
> Birmingham, AL
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: water heater wire gauge [message #105792 is a reply to message #105766] |
Fri, 12 November 2010 15:06 |
jknezek
Messages: 1057
Registered: December 2007
Karma: 5
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Senior Member |
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Marsh -- I appreciate it. I think the difference is that I don't expect to get 115 degree water. I expect to get about 80 degree water from 60 degree water at a rate of about 1gpm, or about half my pump rate. I do realize this is not traditional for a home shower, but... we are camping in a 35 year old, 26 foot motorhome with a tiny, cramped side wetbath. I don't actually expect all the comforts of home! Otherwise I'd have to buy one of those 250K 40 foot monsters with a washing machine...
As for the draw, I'll have to ask him again. He had a multimeter on it for a while after he first installed it to see how much it was drawing as both of us were curious and I remember him telling me he never saw it go over 20 amps. That being said, I never asked him if he upgraded the wiring, hence my original question. Kind of wish I could find one that would run on 15 amps. I could wire it completely seperate and use it at the increasing number of campgrounds that offer the 15 in addition to 30 and 50 amp service...
Thanks,
Jeremy Knezek
1976 Glenbrook
Birmingham, AL
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| Re: [GMCnet] water heater wire gauge [message #105810 is a reply to message #105792] |
Fri, 12 November 2010 20:55 |
Marsh Wilkes
Messages: 155
Registered: January 2004
Karma: -3
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Senior Member |
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Hi Jeremy,
60 to 80 at 1 GPM is exactly what it will do. You did mention washing
dishes hence the sink filling example. As for the wire size it would be #10
copper. If you found one to run on 15 amps it would do .6 GPM.
Hope the information is helpfull.
Marsh Wilkes
Perry Fl
----- Original Message -----
From: "Jeremy" <jtknezek@hotmail.com>
To: <gmclist@temp.gmcnet.org>
Sent: Friday, November 12, 2010 4:06 PM
Subject: Re: [GMCnet] water heater wire gauge
>
>
> Marsh -- I appreciate it. I think the difference is that I don't expect to
> get 115 degree water. I expect to get about 80 degree water from 60 degree
> water at a rate of about 1gpm, or about half my pump rate. I do realize
> this is not traditional for a home shower, but... we are camping in a 35
> year old, 26 foot motorhome with a tiny, cramped side wetbath. I don't
> actually expect all the comforts of home! Otherwise I'd have to buy one of
> those 250K 40 foot monsters with a washing machine...
>
> As for the draw, I'll have to ask him again. He had a multimeter on it for
> a while after he first installed it to see how much it was drawing as both
> of us were curious and I remember him telling me he never saw it go over
> 20 amps. That being said, I never asked him if he upgraded the wiring,
> hence my original question. Kind of wish I could find one that would run
> on 15 amps. I could wire it completely seperate and use it at the
> increasing number of campgrounds that offer the 15 in addition to 30 and
> 50 amp service...
> --
> Thanks,
> Jeremy Knezek
> 1976 Glenbrook
> Birmingham, AL
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: water heater wire gauge [message #105811 is a reply to message #105766] |
Fri, 12 November 2010 22:09 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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But you loose the free preheat function of the original coolant warmed system if that matters. I think the factory setup is best of both worlds great.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: water heater wire gauge [message #105821 is a reply to message #105811] |
Fri, 12 November 2010 22:42 |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
Karma: 0
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| JohnL455 wrote on Fri, 12 November 2010 20:09 |
But you loose the free preheat function of the original coolant warmed system if that matters. I think the factory setup is best of both worlds great.
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I would agree. On mine, when I had it, I changed the heater element to a 2000 watt one at 120 volts. That way I could heat the water in the tank to the shut off limit in about 15 minutes. Reduced the generator run time to heat water by half over the original 1000 watt element. The #12 wire will support a 2000 watt element and still be within the code rating, assuming it does not run for more than 3 hours at a time, which is highly unlikely.
Rob Allen
former owner of '76 x-PB
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