| Author | Message | ||
| ChuckMC9 (Chucks)
Registered Member Username: Chucks Post Number: 1091 Registered: 10-2003 Posted From: 68.166.204.142 Rating: N/A |
You won't have to sit thru a long story about the trials I've had trying to figure out wiring requirements for wall thermostats on rooftop ACs. Turns out the units I'm planning on (Carrier Heat Pumps) don't have provisions for *any* external thermostats at all. Hmmm. Grrrr. Heck I'm not even sure I need external control, but before I put the ceiling back together I'm planning on the ordinary 6? conductor regular old thermostat wire, might be better than not putting anything up there. Can you "hack" thermostatic control to a unit not designed for them? Seems to me you could just parallel an external unit to the one built in on the ceiling control? Something tells me it would be a *really good thing* to be able to control the compressors independently for some kind of load management. I think I've read a few of you hinting that you'd done something like this - any thoughts? | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 691 Registered: 7-2006 Posted From: 64.136.49.228 Rating: N/A |
I see no need for wall thermostats...ya got a low,med & high cool & a warm to cold scale...when it's hot outside,turn it on high...if it gets too cold (yeah ...sure )...turn it down a little | ||
| Len Silva (Lsilva)
Registered Member Username: Lsilva Post Number: 86 Registered: 12-2000 Posted From: 71.30.245.136 Rating: N/A |
I'm not familiar with the Carrier units but it is likely that the thermostat as well as the fan swith on the unit is line voltage. You would have to add some relays to make it work with a remote stat. (Message edited by lsilva on February 14, 2007) | ||
| bill chisholm (Billybandman)
Registered Member Username: Billybandman Post Number: 109 Registered: 2-2001 Posted From: 198.236.64.22 Rating: N/A |
You can get a thermo, like the ones for electric baseboard heaters, for 120vac and wire your whole a/c through this. It will work only turn your unit on/off. | ||
| Jerome Dusenberry (Jerry32)
Registered Member Username: Jerry32 Post Number: 6 Registered: 1-2007 Posted From: 148.78.243.50 Rating: N/A |
The thermostat in the A/C may be mechanical and no way to paralell the thing. The better kind of units have fan and compressor controlls with a sensor in the unit . and then you can use an electronic thermostat that will run everything including the furnaace. | ||
| Dale Waller (Happycampersrus)
Registered Member Username: Happycampersrus Post Number: 300 Registered: 7-2005 Posted From: 66.82.9.53 Rating: N/A |
I had the same questions and this what the guys helped me with. Check out this thread. http://www.busconversions.com/bbs/index.php?topic=1303.0 HTH, Dale | ||
| ChuckMC9 (Chucks)
Registered Member Username: Chucks Post Number: 1092 Registered: 10-2003 Posted From: 68.166.204.142 Rating: N/A |
Thanks, everybody! That link to the other board is a good one. Unless I figure out something differently I'll probably do it that way, and then when the warranty runs out, perhaps try hacking!  And Bob, I'll probably agree. I don't need a lot of fancy stuff, but just didn't want to kick my own *ss for not running the right wires once I got the ceiling up. I definitely do like the idea of some kind of compressor interlock though. Awhile back someone (JtNG?) posted a link to a camping world unit that did some rudimentary load management, but I think it's discontinued. | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 191 Registered: 7-2006 Posted From: 66.217.105.58 Rating: N/A |
FWIW: These will (or can) allow you to turn on/off electrical devices remotely. There's isn't any reason a remote thermostat couldn't be used to trip the remote sending unit, in turn tripping the actual AC unit.. Kinda' Rube Goldbergerish, but hey... 30-Amp Appliance Relay Module Specialty Vehicle Electronics The item Chuck was referring to was a unit that allowed two air conditioner units to be run with a 30 amp system.... It did the trick by automatically switching from one AC unit to the other... "Pulse Air" (unit item #9320) If you're thinking of doing anything "later", install a conduit and a pull string, for future use... | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 536 Registered: 1-2003 Posted From: 67.45.244.133 Rating: N/A |
Chuck, We wanted to use the least-expensive type of roof air, the kind without the external thermostat. But we also wanted to control them with wall thermostats, for three reasons. (1) We wanted the convenience. (2) We wanted to "sense" the temperature down where we were living, not up in the unit itself at the return plenum. And (3) we did not want the circulating fan running when no cooling was being caller for. Our solution was to use cheap household thermostats available at Lowes or Home Depot. (Get the electronic kind, without the mercury-type switch inside, which is incompatible with a moving vehicle. We got fully programmable ones.) We connected these to relays with 120-vac contacts rated for at least 20 amps, and simply ran the AC supply power for the units through these relays. An important feature of these electronic household thermostats is that they have a built-in delay: if the 'stat has been calling for cooling, and then stops calling for it for any reason (temperature goes below set-point, or user intervention), then it will wait a fixed time, usually around five minutes, before calling for cooling again. Without this feature, stopping the unit by interrupting the supply power, then trying to restart it quickly, can lead to compressor overload and a tripped breaker. To make this work, use your low-voltage coach system to operate the relays. Our coach is 24 volt, so we bought relays with 24-volt coils. Run your low-volt line out to the 'stat, then back to the relay, which would go in a junction box between your AC panel and the roof unit. Then wire the unit normally, except through this j-box, with the relay in-line in the hot side of the circuit. Voila! Remote-controlled AC on a budget. And the best thing is that the thermostats cost maybe $30-$60 each, depending on how fancy they are, and you can replace 'em at any hardware store. We went one step further, and use the same thermostats to control both our AC and our heat, plus we have "zoned" the bus such that two thermostats, one in front and one in back, control all three roof units and all seven heaters. You can see a diagram of our relay control unit here: http://odyssey.smugmug.com/gallery/63883#2228266-O-LB HTH, -Sean (Message edited by sean on February 14, 2007) | ||
| Jim Smith (Jpsmith)
Registered Member Username: Jpsmith Post Number: 2 Registered: 1-2001 Posted From: 189.164.128.33 Rating: N/A |
Chuck not sure which Carrier you have. I found manual at http://bryantrv.com/docs.html http://bryantrv.com/docs2/docs/airv.pdf It appears that they all support external thermosats Hope that this helps | ||
| ChuckMC9 (Chucks)
Registered Member Username: Chucks Post Number: 1093 Registered: 10-2003 Posted From: 68.166.204.142 Rating: N/A |
Thanks again, everyone. Jim, I did see those docs and it *appears* that you can do that, but from what I understand for some reason the heat pump units are different in that they don't take externals. I finally called Carrier (an exercise in phone-tree hell) and a "technician" told me that. But looking at the schematics, they really aren't that different. The external control will suffice, and actually it might have an added benefit in that if you wanted to keep things 'stock', you could just turn the external thermo all the way down so that the relay always stays closed and let the units work as the mfg. planned, with no mods to the units themselves. Sounds like a plan. Thanks for the elaboration and step-by-step, Sean! and once again, thanks again all! ...and John, as one rubester to another, it's good to have a reunion after all this time. All the best, Chuck | ||
| Jim Stewart (H3jim)
Registered Member Username: H3jim Post Number: 280 Registered: 10-2004 Posted From: 68.6.175.166 Rating: N/A |
I used the carrier low profile units. You can buy the inside piece as ducted units or non ducted. Teh upper is the same either way. The ducted units are $100 more and have a remote control with a thermostat. The unit has a small pair of wires that you can hook up to your heater relay so it works for both heat and cool. very easy to use. |