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Topic: Roof air heat question (Read 703 times) previous topic - next topic

Roof air heat question

Being new to rving i'm On a steep learning curve as I have said before. Last nite the rear roof air would not get hot, only blows cool air, not cold like the ac was on.. I am somewhat mechanical is this something I could do myself or should I leave it to the professionals? I know nothing about the unit other than it is a heat pump... any info is greatly appreciated...
The selected media item is not currently available.Keith & Jo
2003 U320T 4025 PBBS Designer series
Build 6203    Cummins 500hp
2000 U320 4010 WTFE / Build 5762 —Sold—
Motorcade #18070   
Pasadena, Texas
2015 Jeep Wrangler Sahara-Sunset Orange pearl coat
Don't argue with a fool, people watching might not be able to tell the difference.

Re: Roof air heat question

Reply #1 –
I would look into the thermostat to see if it is talking to the rear unit or dead, before taking it to someone that most likely knows less than you do in how the HVAC system works in these coaches.

Mike

Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Roof air heat question

Reply #2 –
If it was below 45 degrees you will not get much heat from the roof mounted heat pump
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Roof air heat question

Reply #4 –
As a previous answer stated if below 45 degrees not much good. I  don't like using them, like the ac they are noisy.
1995 U320 40', 2013 chevy sonic toad, my real love are corvettes have owned 30

Re: Roof air heat question

Reply #5 –
Here it texas it very rarely gets below 40* especially in April. It was in the mid 50' at nite
The selected media item is not currently available.Keith & Jo
2003 U320T 4025 PBBS Designer series
Build 6203    Cummins 500hp
2000 U320 4010 WTFE / Build 5762 —Sold—
Motorcade #18070   
Pasadena, Texas
2015 Jeep Wrangler Sahara-Sunset Orange pearl coat
Don't argue with a fool, people watching might not be able to tell the difference.

Re: Roof air heat question

Reply #6 –
Quote from: hdff –
Here it texas it very rarely gets below 40* especially in April. It was in the mid 50' at nite
Interesting fact, especially if you pay for the electricity you use. A heat pump  can supply over 12000 btu's of heat and use 13 amps at 120 volts. Best a electric resistance heater [which is basically all portable electric heaters] can do, is 5100 btu's using 13 amps at 120 volts
."Electric resistance heating is 100% energy efficient in the sense that all the incoming electric energy is converted to heat. ... If electricity is the only choice, heat pumps are preferable in most climates, as they easily cut electricity use by 50% when compared with electric resistance heating."
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: Roof air heat question

Reply #7 –
At 50 heat pumps are very efficient at that temp, most output 3x or more than the amount of energy that they consume. Unless they have to defrost, which I don't think the RV units are even capable of doing. Average winter temperature in KS where I live is about 47 IRC. Granted they make noise, and many people feel that they are drafty due to the discharge air temperature being lower than the body temperature. But efficient.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Roof air heat question

Reply #8 –
Quote from: Old phart phred –
At 50 heat pumps are very efficient at that temp, most output 3x or more than the amount of energy that they consume. Unless they have to defrost, which I don't think the RV units are even capable of doing. Average winter temperature in KS where I live is about 47 IRC. Granted they make noise, and many people feel that they are drafty due to the discharge air temperature being lower than the body temperature. But efficient.
Newer models claim a low of 32 f. I imagine not a lot of heat at that temp.
https://comnet2.newmarcorp.com/instance1env99newmar/html/images/SS2011DometicAC.pdf
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.
 

Re: Roof air heat question

Reply #9 –
Jim - you can get modern inverter heat pumps that even go down to -14 they just burn more and more energy to go thru the defrost cycle which they can now sometimes detect when the outside coil is frosted. At temps less than about 37 ambient humidity starts freezing on the outside coil depending on your location and load on the coil. Can't fool mother nature and the COP drops below 1.0. past that point it's a game of liars poker with the deep pocketed Asians able to win every hand. Lots of politics, slick marketing and graft. JMO.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake