| non gmc- 240V water heater in 50 amp Class A [message #354842] |
Mon, 18 May 2020 13:32  |
hertfordnc
Messages: 1164
Registered: September 2009
Location: East NC
Karma: 0
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Sometimes google is no help and you just have ask smart old guys.
Helping a friend convert his water heater in a mid 90s pusher. He wants an electric tankless. Is it possible (and safe) to bring both legs of his 50 amps service to a 240V water heater?
thanks
Dave & Ellen Silva
Hertford, NC
76 Birchaven, 1-ton and other stuff
Currently planning the Great american Road Trip Summer 2021
It's gonna take a lot of Adderall to get this thing right.
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| Re: non gmc- 240V water heater in 50 amp Class A [message #354856 is a reply to message #354842] |
Mon, 18 May 2020 22:25  |
Rick Staples
Messages: 126
Registered: May 2014
Location: Johnstown, Colorado, USA
Karma: -1
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Dave,
You asked " Is it possible (and safe) to bring both legs of his 50 amps service to a 240V water heater?" Assuming he wires it properly (main panel, breakers, and wires), I'd say yes. However.... Remember, if he is plugged into a non 240v/50A outlet, either a standard 30 amp or 20 amp outlet, or even a "50 amp" outlet that's wired like the GMC's internal power outlet, then the water heater simply won't work at all. ie: he will have 0 volts across the heater. Sort of limits where you can camp and get hot water. Of course if he has a generator that can supply 240 volts (unlike the GMC's Onans), and it's wired properly to his electrical panel, then he's good to go.
HTH
Rick Staples
Rick Staples, '75 Eleganza, Johnstown, CO
"Advice is a dangerous gift, even from the Wise to the Wise, and all paths may run ill." -Tolkien
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| Re: non gmc- 240V water heater in 50 amp Class A [message #354860 is a reply to message #354842] |
Tue, 19 May 2020 08:58 |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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He should also consider that tankless water heaters consume alot of electrical power. Just reading some on-line reviews and it seems 6.5Kw plus is the minimum to be happy with the hot water temperature/quantity. 50A @ 240V = 12kw so that's just over 1/2 of your available power. The 6.5kw tankless will be pulling ~30amps on each leg when operating.
So a pusher usually has 2 A/C units which take 20amps to start and near 15 amps to run so that takes to 45 amps (assuming one A/C on each leg). So you are at your limit right there. Plus you will other loads like fridges, microwaves, coffee maker, electric skillet, hot plate, toaster, RV's power converter to run 12v and charge the batteries...etc.
Yes I know the tankless will rarely operate, but consider breakfast or dinner. You have the coffee maker going, toaster and microwave running... then you turn ON the hot water in the kitchen sink, or someone is in the bathroom... suddenly the current jumps by 30 amps and if either leg exceeds 50Amps by much, the main breaker will trip and everything goes dead... or reverts to inverter.
So consider the ramifications.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: [GMCnet] non gmc- 240V water heater in 50 amp Class A [message #354876 is a reply to message #354874] |
Tue, 19 May 2020 14:30 |
Dolph Santorine
Messages: 1236
Registered: April 2011
Location: Wheeling, WV
Karma: -41
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J.R.
Ohm’s law.
It’s not just a good idea. It’s the law!
It’s a resistor. Turning electricity back into heat (likely where it started).
It’s not taught in school science courses anymore, so the understanding of the effect of the lower voltage is missing.
Dolph
DE AD0LF
Wheeling, West Virginia
1977 26’ ex-PalmBeach
Howell EFI & EBL, Reaction Arms, Manny Transmission
“The Aluminum and Fiberglass Mistress”
|[ ]~~~[][ ][] \
"--OO--[]---O-"
> On May 19, 2020, at 3:13 PM, John Wright via Gmclist wrote:
>
> The HOT tip here is to use a 240 volt 4000w heating element. They are less expensive than the 120V heating elements and will heat somewhat faster and is more durable. It is not that you use 240 vVAC, but it works well with 120 VAC. I don’t under stand the mindset to spend many unnecessary dollars to make a so called improvements. For about $9 your water will heat faster and use less energy. You don’t need to change the world to make it work better.
>
> J.R. Wright
> GMC Great Laker MHC
> GMCGL Tech Editor
> GMC Eastern States Charter Member
> GMCMI
> 78 GMC Buskirk 29.5’ Stretch
> 75 GMC Avion (Under Reconstruction)
> Michigan
>
>
>> On May 19, 2020, at 12:13 PM, roy keen via Gmclist wrote:
>>
>> I would only consider 120 volt. 50 amp service isn’t always available in which case if he is connected to a 30 amp source he would have no hot
>> water.
>> --
>> Roy Keen
>> Minden,NV
>> 76 X Glenbrook
>>
>> _______________________________________________
>> GMCnet mailing list
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| Re: [GMCnet] non gmc- 240V water heater in 50 amp Class A [message #354903 is a reply to message #354874] |
Tue, 19 May 2020 23:53 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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[quote title=powwerjon wrote on Tue, 19 May 2020 12:13]The HOT tip here is to use a 240 volt 4000w heating element. They are less expensive than the 120V heating elements and will heat somewhat faster and is more durable. It is not that you use 240 vVAC, but it works well with 120 VAC. I don’t under stand the mindset to spend many unnecessary dollars to make a so called improvements. For about $9 your water will heat faster and use less energy. You don’t need to change the world to make it work better.
J.R. Wright
GMC Great Laker MHC
GMCGL Tech Editor
GMC Eastern States Charter Member
GMCMI
78 GMC Buskirk 29.5’ Stretch
75 GMC Avion (Under Reconstruction)
Michigan
> On May 19, 2020, at 12:13 PM, roy keen via Gmclist wrote:
>
> I would only consider 120 volt. 50 amp service isn’t always available in which case if he is connected to a 30 amp source he would have no hot
> water.
> --
> Roy Keen
> Minden,NV
> 76 X Glenbrook
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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[
[ maybe I’m reading it wrong but he said both legs of a 50 amp supply for a tankless heater in a diesel pusher? As far as a 240 heater for a 6 gallon Heater I agree a 240 is the way to go that is the way I have done it as it is less likely to burn out.
Roy Keen
Minden,NV
76 X Glenbrook
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