Roof A/C

[Michael Kauffman]

[size=18]Hello, has anybody replaced their Dometic A/C unit(s).  Mine are 600-315C's.  I was just wondering what to replace the bad rear one with?
Thanks, Mike[/size]

[Richard And Babs Ames]

We replaced ours a couple of years ago with the Dometic Penguin 15000 heat pumps and switched to the digital thermostats at the same time. We now have the option of two heat sources (aqua hot or AC unit) and an increase of over 10% in cooling capacity. .

[Michael Kauffman]

[size=18]Richard did you have to re-wire anything for the added heat strip?  That sounds great.  Do you have the exact part numbers by chance?  Thanks   [/size]

[Joel Weiss]

If they still sell heat strips that can be installed in the regular A/C I think I'd rather go that route.  IMHO heat pumps are trouble-prone devices.

[Michael Kauffman]

I think that you are right Joel.  I have 2 A/C's that run separate from one another, front and rear.  I found this set-up at what looks like an OK price (see link).  It looks like you can run the A/C, Heat Strip, or Funace (Hurricane) from the stat without re-wiring anything.  Does anybody see why this wouldn't work for me?

http://www.americanrvcompany.com/view_cart.asp

Thanks for the help, Mike

[Richard And Babs Ames]

http://www.dometic.com/enus/Americas/USA/RV-Products/climate/ac-display-page/?productdataid=99493

Is the AC and I do not think any rewiring was required.

[Michael Kauffman]

[size=14]Richard I was looking at that one per the guy at Dometic.  So you went with the heat pumps.  Have you had any problems with them?  How cold a temp can the heat pumps work in before they need the Hurricane to back them up?

Thanks, Mike[/size]

[size=14]Found out that it works down to about 40 degrees before it kicks in the furnace heat[/size]

[David T. Richelderfer]

My understanding is heat pumps, whether at your house or coach, steal heat from an outside source, usually from outside air.  So for a heat pump to operate efficiently there must be heat in the outside air.  When outside temps get close to freezing, then heat pumps don't work well because there is little heat in the outside air to steal.  As a note - I know a fellow who put a heat pump into his house and uses it exclusively, even in much colder temps than near freezing.  His key was his ground water table was near the surface.  He plumbed into the ground water to deliver that warmer ground water to his heat pump.  The result is his heat pumps do the job and he did not need a backup heating system.

[Joel Ashley]

When our roof heat pumps encounter outside ambient temps below about 36F they stop.  In theory they supposedly cut off around 40F.  It's just too much work electrically to turn 40 degrees into 72.  But it takes a little load off the hydronic system if the heat pump is within its operating parameters and useable.  On cool nights, watching TV in the front, we often turn on the rear bedroom heat pump, lessening the noise that interferes with the TV.

Ours are Duo-Therm.

Joel

[Richard And Babs Ames]

We have had no problems with the units in about 4 years of use. We live and travel in FL so rarely see low tempatures that make them not work. The old heat strips puts out about 6000 watts of heat so is less than half the capacity of the heat pump.

I have a son that is a AC service tech in the AC business and the only thing that can go wrong is a valve that can stick from non use.

[Joel Weiss]

We have had no problems with the units in about 4 years of use. We live and travel in FL so rarely see low tempatures that make them not work. The old heat strips puts out about 6000 watts of heat so is less than half the capacity of the heat pump.

Actually, the heat strips put out ~1600 watts of heat which is roughly 6,000 BTUs/hr.  That's the same as the typical small space heaters you can buy.  We know from experience that 2 heaters will keep us warm down to ~40F at which point we'd rather turn on the Hurricane.  If I can get just as much heat from heat strips in my A/C's then I could ditch my heaters.  At least at temps around 40 the heaters are working fine whereas the heat pump is struggling to provide heat.  Just my opinion, but the cost of a new A/C with heat strip is roughly half the cost of a heat pump unit.

[Edward Buker]

I would like to have another heat option also, seems like a good idea at times. I noticed on this site a universal heat strip kit for Duo Therm Air units, but it mentioned for non ducted only in bold letters. Is that a fit or fire issue, any insight? I assume those that are using ceiling air heat strips have ducted systems. I wonder if only the heat pump versions are recommended with ductwork given they run at lower temps. Fire could be an issue if the fan quit and the heating element stayed on. The heater looks like it has one wire feed, although there is some assembly near the element.  I do not see an over temp sensor wire feed nor is it mentioned. Anyone have any insight on this issue?

http://www.pplmotorhomes.com/parts/rv-air-conditioners/duo-therm-heat-strip-kit.htm

Later Ed

[Michael Kauffman]

[size=14]Ed I've been digging around on the internet, and it seems that Dometic has a plastic and a metal distribution box.  It depends on what is installed on your RV.  If it's metal, you'r OK.  If it's plastic, Dometic says "no heat strip, fire hazard".  I don't know at this point what Beaver put in my Patriot in '98.  I still don't know which way I'm going.  I like the heat pump efficiency, but it doesn't work in freezing temps.  We don't really use the RV much in the winter.  I would like to leave it set at 40 to 50 in the winter, when it gets down to the teens around here, and not burn diesel. [/size]

[Edward Buker]

Maybe someone will know what was used for a distribution box in the Beaver builds. Not sure how much would have to come apart with ducted air to install the heating element. Sometimes just an immediate form of heat when it is not too cold out would be nice from the exisitng systems without firing up the burners. I would not change out a working air system just to have a heat pump option that is more limited than a heat strip. If someone takes this on let us know how it goes.

Later Ed

[Michael Kauffman]

[size=14]Thanks everybody for the input.  I've decided to go with the heat pump style after all.  My A/C is shot in the bedroom, that's what started this whole thing.  I didn't even know you could get heat from the A/C when I started looking for a new A/C.  This is what I went with if your interested.  I'll just run plug-in supplemental heaters when it gets really cold while in storage in the winter.

http://www.americanrvcompany.com/view_cart.asp[/size]