I had forgotten about my conversation with Kyle Brant about AC in Timmonsville till I saw his excessively flattering post in reply to my post about my new ductless split. But now I recall I was, at the time of the conversation, convinced that I was going to give up on the portables and replace them with a ductless split but was trying to decide wether to stick with a 120 volt unit and be forced to accept 12,000 BTU/h or take the risk of using a transformer to make 240volts out of 120volts to gain an extra 50 % of cooling & heating capacity. I wrestled with this decision for a long time, and sought advice in many places including our conversation. Well as all now know I finally decided the extra capacity and efficiency were worth the gamble so I tried to reduce the risk of failure by deliberately oversizing the transformer and choosing the type of transformer that performs best under overloads, such as that which occurs under compressor start up. And it worked!
I'm still amazed and p---d at how dishonest the specifications of the portables have turned out to be. Though they were rated as having a 10,000 Btu/h capacity, 2 of them would only cool the whole bus about 10 degrees with the outside temp at 90. Yet the new unit rated at 18,000BTU/h cools the whole bus 22 degrees by running 80 % of the time with the outside temp at 90. When running the new unit uses exactly the same amount of power as the 2 portables. My quick calculations say the portables were only actually delivering about 1/3 of their rated cooling. That's rather serious fraud. There is no governmental supervision or regulation of portables but ductless splits are regulated by the EPA and FTC & others. In some cases government regulation helps. Now I'm a bit curious as to how honest the ratings of roof airs really are. Does any governmental agency take interest in roof air ratings?
Regards
Jerry 4107 1120
Hi Jerry,
No, there are not any regulations on the roof unit companys. But, the RV industry demands a certain proformance within the 115v/20amp window.
I think this keeps them in the ballpark for the specs.
Nick-
Nick,
I'd bet there's quite a bit of overstating capacity in roof airs. My 18,000 btu/h split running 80% of the time is about 15,000 BTU/h. How many single 15,000 BTU roof tops hold an entire 4107,well insulated but not very well like some are, at 68 deg f while sitting the sun on a 90 degree day? And of course the next question how many do it 11 amps or less?
Regards
Jerry 4107 1120
Fraud and Government ???
You thought they were TWO Different things ?????? ::)
;D
By "Portables? , do you mean the king in your windows ??? or the lil one you Roll around from room to room... ??
Paul...
Superpickle,
I guess if your chosen party is in power they are different but if the other party is in control then they are surely the same.
Meanwhile, by 'portables' I meant the kind that are on casters. I understand that window AC units are subject to regulation and the kind of dishonesty I encountered would not happen in the window AC marketplace.
Regards
Jerry 4107 1120
Quote from: Jerry Liebler on May 28, 2007, 03:42:40 PM
Superpickle,
I guess if your chosen party is in power they are different but if the other party is in control then they are surely the same.
Meanwhile, by 'portables' I meant the kind that are on casters. I understand that window AC units are subject to regulation and the kind of dishonesty I encountered would not happen in the window AC marketplace.
Regards
Jerry 4107 1120
Thanks Jerry ;D, i was wondering about that..
And. My party is NEVER in power... The People... ;D
I feel they are ALL out to make a Buck off you and i at Anyexpence. I'll just Ride along till it Hits something ;)
Quote from: Jerry Liebler on May 28, 2007, 03:12:48 PM
Nick,
I'd bet there's quite a bit of overstating capacity in roof airs. My 18,000 btu/h split running 80% of the time is about 15,000 BTU/h. How many single 15,000 BTU roof tops hold an entire 4107,well insulated but not very well like some are, at 68 deg f while sitting the sun on a 90 degree day? And of course the next question how many do it 11 amps or less?
Regards
Jerry 4107 1120
Hi Jerry,
You may be correct.... Then again, a "British Thormal Unit" might even be incorrect, who knows!
Nick-
Nick,
Someday I may try the test of 'temporarily' removing my front 'Maxifan' and dropping a 15,000BTU/h roof wart in place and let her run on an appropriate day. Same bus, clear comparison easy to interpet results. Do you think any roof top manufacturer wants to supply a unit for this experiment?
Regards
Jerry 4107 1120
I've always been skeptical about what marketing has to say about their own product. Even more so after working with marketing. :(
I'm guessing the gross cooling is close to their claim, however, they neglected to subtract out the negative impact of having the condenser inside & the makeup air. Net cooling is a more usefull rating, but then you probably wouldn't have bought the units if that number had been available.
The split system is more efficient due to the nature of the design - the hot stuff is all outside & only the cool stuff is inside.
BTW, I didn't think my post was 'excessively flattering' :D I learned a lot from you & really enjoyed talking buses with you. I like the way you approach finding solutions to problems.
Kyle,
I thank you for the flattery! I've done some research on how rooftops are tested vs how house AC is tested and have found part of why rooftops don't do as well in actual use. The indoor wet bulb temperature at which rooftops are rated is 71 deg f. while the housholds are tested at 67, both use 95 drybulb outdoor conditions. It's much easier to move a given amount of heat energy over the smaller temperature difference between indoors and outdoors. The same website showed that a Coleman 15,000 btu rooftop uses 2117 watts under those conditions. My 18,000 BTU split is rated as using 1480 watts moving more heat up a bigger temperature hill.
I also did a 'cool down' test of sorts. The outside temp is 86, the inside of the bus is 80 and I start the split. 20 minutes later the inside is 73 but seems to have quit falling. After 40 minutes the unit's thermostat cycles off and the inside temp is 70. I look under the drain line and there is quite a puddle, it dawns on me what happened. I don't have a wet bulb thermometer but I'd bet I started at about 73 degrees wet bulb and that last 3 degrees involved removing lots of water. The moral of this story any outside air entering the bus plays H with cooling ability because it's carrying lots of water. And despite my efforts to supply outside air to the condensers of those portables they were pulling in outside air.
Regards
Jerry 4107 1120