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Adding heating element to roof top air


hunkaman

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can anyone provide info regarding adding an optional heating element to a Coleman Mini Mach model #6727-739 roof top a/c unit ? i have the original instruction paper work,  it says this model is a 7000 btu unit and speaks of an optional "ELECT-A-HEAT" element. it goes on to say this is not a substitute for a furnace, but used to just "take the chill off", i would consider adding it assuming it is effective and not too expensive, and available. any help, and/or advice would be appreciated. thanks joe from dover.

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6727 is a very old model (1978/79). Before spending alot of money on a heating element, you may be better off buying a new unit with the heating element included.

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thanks for all the input, since the roof top air is working fine, i really don't feel the need to replace it with a unit that has a heating element . the advice you have given about  buying a small heater to accomplish the same thing seems to be the way to go. my friend suggested the same thing. he has a 1986 winnie, and bought a small ceramic heater that has two settings , 750 watts and 1500 watts with a fan only feature as well. he only spent $20.00, and said it really works well. i bought the same heater and tried it out the other night and it worked great. situation solved!  not having much experience with motorhomes , it is such a blessing to have all of you out there to guide and direct with your vast knowledge and suggestions. thanks again. joe from dover

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I have a small ceramic heater that works well.  If I do not have electric I put water in a pan and heat in on the stovetop, high heat till boiling then lower the flame.  Has worked down to 42 degrees. Have to keep an eye on water so pan does not boil dry. 

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I too have a small heater I use when on shore power. I used the 1500 watt setting a couple of times and some 14 gauge wiring melted in a junction box under the rear bench. Close call there. The 750 watt setting works well enough for the space and has given me no problems. Please DO NOT use the 1500 watt setting.

Allan

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thanks allen, my friend had advised me on that issue. when i tried it the other night i only used the 750 watt setting. it really did perform well. thanks for your concern and input. joe from dover

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The circuit should handle 1500 watts. The circuit is rated 1800 most of the little heaters usually are 1000-1200 watt just for that reason to not be too close to max. If you have melted wires it's usually is from a poor connection otherwise it would trip the breaker. I would check the rating on the heater 1500 watts sounds high to me.

8 hours ago, jjrbus said:

That works but it also puts stuff in your air that may not be real heathful in a closed camper.

 

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50 minutes ago, Maineah said:

If you have melted wires it's usually is from a poor connection otherwise it would trip the breaker.

I'd also go through all your wiring and check that all is good. Like almost everything, these were originally built to the lightest, lowest standards and add time taking it's toll (plus possible DPO mods), a good check is a good idea. :)

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Thermal imaging test equipment is the best way to go, but most of us do not have it. I go over my system and house electrical when the mood strikes me with a non contact IR gun.

Bad connections cause heat and may be detected with an inexpensive temp gun, amongst a million other uses for one! A temp gun would certainly pick up a connection about to melt the wire.

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I agree it's not a good idea to load a circuit continuously that close to max. The heater I was using at the time had 500/1000/1500 watt settings. 750 watts is the low setting setting on the heater I use now. I don't remember what the high setting is as I don't need it that high and only use the low setting.

 

Allan

Edited by Allan
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13 hours ago, jjrbus said:

  If I do not have electric I put water in a pan and heat in on the stovetop, high heat till boiling then lower the flame.  Has worked down to 42 degrees. Have to keep an eye on water so pan does not boil dry. 

Not a real good idea for a continuous flame, make sure your monoxide detector is up to speed. Another not so good idea is a clay flower pot upside down. It has more mass and you can heat it up and turn off the stove and coast to take off the morning chill. Open a window a bit and leave the flame on low works for longer periods. Do not go to sleep with the stove on!!!!

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9 hours ago, Derek up North said:

I'd also go through all your wiring and check that all is good. Like almost everything, these were originally built to the lightest, lowest standards and add time taking it's toll (plus possible DPO mods), a good check is a good idea. :)

Very true vibrations marginal stuff to begin with takes it's toll.

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9 hours ago, jjrbus said:

Thermal imaging test equipment is the best way to go, but most of us do not have it. I go over my system and house electrical when the mood strikes me with a non contact IR gun.

Bad connections cause heat and may be detected with an inexpensive temp gun, amongst a million other uses for one! A temp gun would certainly pick up a connection about to melt the wire.

It is not for nothing all new homes have to have ark fault breakers. However it's a little hard to check outlets and wiring inside of a J box. with a temp gun.

Edited by Maineah
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15 hours ago, Maineah said:

It is not for nothing all new homes have to have ark fault breakers. However it's a little hard to check outlets and wiring inside of a J box. with a temp gun.

Maybe I am misunderstanding, you seem to be saying that it is not a good way to test.  What would you suggest instead?

My outlets were all in poor condition, particularly the fridge recepticel so I replaced them all except one as I ran out of time.

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The RV outlet are made so that any one can assemble them they are not the best. A bad connection hiding inside of an outlet or a J box would be very hard to find with out disassembling them they will not get hot until a load is applied that is enough to cause heating. So if a 500 watt load works it may not get hot a 1000 watt load might get hot. Usually the fridge one is the better wired one because it has to be hand wired the coach outlets work kind of like a scotch lock the are friction fit with a terminal that cuts the insulation instead of a screwed down terminal. Just saying it would be hard to check with a thermal device with out access to where it might become hot. It maybe a better shot in a duplex outlet with a voltmeter and a load and check for voltage drop. Ark fault breakers can detect arking at a poor connection that is why they are now code in many home circuit locations.

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what I have done with the same heater is I never plug that in my rv outlet . the rv park had 30 , 50 and 20 amp plugs plug rv in 30 or 50 with a 30 to 50 step down. use a long heavy extension cord out a crack front door window. plug into 20 amp plug or even 30 amp with adapter. that way you wont overload old rv wiring.

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Hey 5Toyota, that's exactly what I do also. As previously posted I used a heater set on low  (750 watts) and after running it for awhile I touched the outlet the heater was plugged into and it was Extremely Hot!! I'm glad I didn't go to sleep with it connected to the coach outlet or I would have awakened to melted wires no doubt!  Luckily I had an extension cord to use the camps shore power which I will Always do now. I plan on replacing all my outlets next spring but will never plug a heater into ANY of them again! Mark

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Fix the outlet correctly and use it. That's what they are for.

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for a mere $300 and an iphone  you can get a flir and see exactly whats going on without taking anything apart.

The flir attaches to the iphone and uses its retina display to show heat in camera mode. I've been wanting to get one for a while now. If not for anything else but to look for insulation leaks etc.

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I'm sticking to an extension cord for safety reasons! Even with all new 20 amp outlets the wiring in my 85 Granville is 31 years old! Use your outlets if you want WME but not me Sir. Won't need to worry about melting wires anywhere else. Can't afford $300 Totem but cool idea. I'll be safer and my wallet still intact spending $20 on a heavy duty extension cord:-)!

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5 hours ago, markwilliam1 said:

I'm sticking to an extension cord for safety reasons! Even with all new 20 amp outlets the wiring in my 85 Granville is 31 years old! Use your outlets if you want WME but not me Sir. Won't need to worry about melting wires anywhere else. Can't afford $300 Totem but cool idea. I'll be safer and my wallet still intact spending $20 on a heavy duty extension cord:-)!

What do you think will happen to your extension cord with a heater if it isn't at least a #12 wire and no greater than 25'? A good extension cord for a camper is about $100. A 20 amp outlet with a #14 wire is asking for trouble, why because you can plug a 20 amp load in, with a 15 amp outlet you can't. A 20 amp outlet is no better made than a 15 the difference is the configuration and the #12 wire feeding it instead of the #14 for a 15 amp.

8 hours ago, Totem said:

for a mere $300 and an iphone  you can get a flir and see exactly whats going on without taking anything apart.

The flir attaches to the iphone and uses its retina display to show heat in camera mode. I've been wanting to get one for a while now. If not for anything else but to look for insulation leaks etc.

Or you could buy a thermal imaging camera like the fire dept. uses or go cheap and use a B&W video camera it's not insulation leaks you are looking for it's bad connections. If you want to check your insulation use a Megohm meter.

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I'm just using a heavy-duty 10' outdoor extension cord for the heater plugged into the 110 shore power outlet @ the camp site. When I checked the extension cord power plug where it was connected to the shore power outlet it remained cool with the heater set on low (750 watts) after several hours. Isn't this a safe alternative instead of using outlet plugs in my RV which overheat presently? Thanks!

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BTW, my converter fan never turned on when running the heater using the RV outlet leading me to believe it wasn't overheating like the outlet was?? Most definitely going to replace all the outlets this spring! Is the wiring adequate in these old rigs to handle 750-1000 watts using a quality replacement outlet? Thanks!

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Your converter has NOTHING to do with the outlets, its for 12v. Do you have a roof AC?? if so your running a 2000w load on your "old" wiring. Copper wiring is not the problem, the problem is a 30 year old cra**y outlet. 

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Thanks WME! I thought about that....power draw from the AC using the "old" wiring. I have roof AC and the AC also has the optional heater element installed. Don't know the wattage of the heating element.  The wiring must be good as they both work well. So your saying that after I replace the old outlets I should be good to go using the heater connected to the coach outlets? Any recommendations for the outlets? Home Depot has a Levington 20 Amp outlet for around $7.00. Is that overkill Sir? I got scared @ how Hot the old outlet became using the heater set to low! 

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20 hours ago, markwilliam1 said:

I'm sticking to an extension cord for safety reasons! Even with all new 20 amp outlets the wiring in my 85 Granville is 31 years old! Use your outlets if you want WME but not me Sir. Won't need to worry about melting wires anywhere else. Can't afford $300 Totem but cool idea. I'll be safer and my wallet still intact spending $20 on a heavy duty extension cord:-)!

What do you think will happen to your extension cord with a heater if it isn't at least a #12 wire and no greater than 25'? A good extension cord for a camper is about $100. A 20 amp outlet with a #14 wire is asking for trouble, why? because you can plug a 20 amp load in, with a 15 amp outlet you can't. A 20 amp outlet is no better made than a 15 and they both will handle 20 amps. The difference is the configuration and the #12 wire feeding it instead of the #14 for a 15 amp. The RV outlets are rated 15 amps the RV wiring is rated 15 amps the breaker is 15 amps that should tell you some thing. Putting in a 20 amp outlet does not increase the camper wiring capacity or make it run any cooler. If you have not dealt with an RV outlet you are in for a surprise there is no excess wiring and there is no box that will fit inside the wall.

23 hours ago, Totem said:

for a mere $300 and an iphone  you can get a flir and see exactly whats going on without taking anything apart.

The flir attaches to the iphone and uses its retina display to show heat in camera mode. I've been wanting to get one for a while now. If not for anything else but to look for insulation leaks etc.

Or you could buy a thermal imaging camera like the fire dept. uses or go cheap and use a B&W video camera it's not insulation leaks you are looking for it's bad connections. If you want to check your insulation use a Megohm meter.

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I'M with Maineah on this NO 20 amp breaker. A lot of the older units have 2-15 amp breakers with a 20  amp Main, 20  amps on a leg is a problem looking to happen.

Just replace the bad outlet and test things out before jumping off the deep end.

this  http://www.ebay.com/itm/RV-Designer-S815-Self-Contained-AC-Dual-Brown-Outlet-with-Cover-Plate-/111283418332?hash=item19e90234dc:g:nt4AAOSwsB9V-VnW&vxp=mtr

or this http://www.ebay.com/itm/RV-Designer-S805-Self-Contained-AC-Dual-Brown-GFCI-Outlet-with-Cover-Plate-/131120678899?hash=item1e8766c7f3:g:UMkAAOSwiLdV-Vlq&vxp=mtr

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I appreciate the advice Gentleman and the recommendations on proper outlets to use! Will be my 1st project when Grannie comes out of storage next Spring. Best, Mark

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  • 1 month later...

I would get something like this:  https://www.walmart.com/ip/Fan-Heater-Black/53017087

I have the heating strip upstairs - the little heater works just as well without all the noise.  My Honda 2000 can pull the little heater - not even working hard on the low heat setting and easy to pull the middle setting.  It can pull the high setting but it seems to be working hard. 

 

If you are plugged into shore power, I think it could help a lot if run all night in moderate cold.

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Thanks Dan, I already have a nice little portable heater and also the optional heater in the AC unit. Both run well with my Honda 2000 also. I did purchase all new outlet plugs as WME suggested for install in the Spring. Can't wait!

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