| Author | Message | ||
| gillig-dan Rating: N/A |
I need help (anyone posting another air conditioning thread needs some kinda help or medication). Here is the basic plan... I have a Carrier CM2 and EM2 condensor and evaporator modules along with a York (CCI) 210 compressor. This is a skirt mounted condensor and a ceiling mounted evaporator. The compressor is a 10 cubic inch model rated to 6000 RPM, 4000 RPM reccomended. I gathered these components at a very reasonable price so, I would like to make use of them, unless someone can convince me that I'm not right in the head. I would like to use a large, 2hp+, 110VAC, 1750 +/- RPM motor to drive the compressor. Sometime, down the road, when I get a pocket full of round tuits, I may add the ability to run the compressor from the bus motor using a hydraulic drive. Anyway, I would like the system to be flexible enough to plug into as little as 20 amp shore connection. I would use the generator going down the road which can deliver up to 50 amps. By my calculations, it would take about 22 Amps for full load on the motor. So, here are the points I'd need help with: - If I use step pulleys to change the motor ratio, what would be my best selection of ratios. My thoughts were to have three ratios 2:1, 1:1 and, 1:2. That way I could determine the best ratio based on conditions and what was available at the power pole. - The condensor is rated up to 30kbtu and the evaporator to 20kBTU. How much does the efficiency change based on compressor RPM? (I know my car cools fairly well at idle) - I may add a second evaporator in the dash if I need more air up front when I'm driving. My hose connections will be fairly short to run the main system. If I add the dash air, I will need to branch off a long run from the rear of the bus to the front. How will this affect the system's operation? - Does anyone know how much power I'd loose running off a modified sine wave inverter vs. pure sine wave inverter? I'd like real numbers not speculation please. When I finish the system, I'll report back here on its performance and how I connect it all together. Gillig-Dan '70 Gillig 636D, Cat 3208 | ||
| John that newguy Rating: N/A |
Hey Dan.... I don't know nuttin 'bout nuttin, but the first thing the gooo-rooos are going to ask (or should ask), is: "what kind of refrigerant are you going to be using". | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
Have you, or anyone else considered utilizing a VFD (Variable Speed Motor Drive) to control motor RPM? I did some work several years ago and found that I could vary the RPM from about 1200 to 2000 rpm with no problem. These devices really do not care about the input as they rectify the AC to convert it to DC then using PWM (Pulse Width Modulation) convert it back to a variable AC output. These devices are typically over 95% efficient. Also I found that I could satisfactorily use a device designed for three phase input and output, they worked great on single phase input or output. If I were to do this, I would input single phase 240 volts and output 240 volts three phase. Three phase motors are much more efficient than single phase motors. In addition to variable output frequency, the VFD provides a soft start so that starting current never exceeds full load running current. Richard | ||
| gillig-dan Rating: N/A |
I had thought about the VFD but, the one in my garage is only rated at 1/2 horsepower. Unless I could find one gathering dust at work, I couldn't justify the expense. This is just the family camper. I think the step pulleys will be efficient also. I may even get fancy and put a solenoid tensioning system on the belts to select a speed from inside. For now, KISS applies and I'll manually change the belts to different settings. The soft start sound good also. Can I put in a slow acting solenoid (air) valve on the compressor from the intake and discharge lines if I find I need a softer start? Gillig-Dan | ||
| gillig-dan Rating: N/A |
JTNG, I haven't decided what refrigerant to use. I figured 134a or Freeze12. Comments anyone? Gillig-Dan | ||
| FAST FRED Rating: N/A |
Due to patent protection laws , at one time boats attempted to cool the fridge with a setup of clutchable York conpressor with either engine or AC as power source. It worked techanically , but the owners went beserk if the unit switched on after bed time. The auto stuff is not as quiet as canned house stuff , so the racket was easily heard. Try a bench run to see if this will be a problem for you. FAST FRED | ||
| gillig-dan Rating: N/A |
Thanks Fred, I hope this thing is not as noisy as the air compressor in my garage. That can wake me in the middle of the night if I forget to turn it off. I plan to isolate it from the bus chassis by building a separate cradle to mount the motor/compressor and use isolation dampers. Gillig-Dan | ||
| FAST FRED Rating: N/A |
The engine space on most boats is very well sound proofed , usually with Soundown 2# lead 2in foam, and it didnt work there. Perhaps your softer mount (no engine drive) may help , but there not Quiet. FAST FRED | ||
| gillig-dan Rating: N/A |
If the compressor doesn't work out, I may have to switch it to a sealed unit. I'd be out the $25 I paid for it though  Thanks for bringing up the noise factor Fred, that was something I didn't even consider while concocting this scheme. The compressor will be in my engine compartment which is, of course, right below the bedroom. I could move the compressor to the generator bay (front) but, that would mean longer hose runs. I'll try it on the bench first... Gillig-Dan | ||
| Tom Caffrey (Pvcces)
Rating: N/A |
Gillig-Dan, if you are wanting to be able to run 22 or 23 amps on a 20 amp shore cord, the only inverter I know of that will work is a power supplementing Trace, such as the SW or PS line. If there are any other power supplementing inverters, I would like to hear about it, because with the right setup, I think it would be the cat's meow. I just haven't been willing to pay the going rate for one. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher |