Good Source for Roof Top A/C Units????

[Highway Yacht]

Anyone know of a good source for new Roof Top a/c units at a decent price? I've did some searching and they make it really complicated with the "This not included" or "This must be bought seperate" or $99 shipping price for each unit. I will soon need (2) 13500 btu non-ducted roof units. Heat strips is not a have to nor is a remote wall thermostat, but I do need everything else for an installation. This would be for a new installation and not a replacement.

[happycamperbrat]

Im not sure about the price, but this is non ducted and best of all is that is 18,000 btu and designed to run from solar power http://www.solarpanelsplus.com/dc-air-conditioning/

[JohnEd]

I would suggest you consider two things.....A heat pump will sub for a furnace efficient heating if you have the AC.  Why are you going for a 13KBTU instead of a 15KBTU? If you have thought thru these options the some would benifit from your decision process.

Nick sold these a while back  Not sure if he still does.  He might be able to save you some money....might ask.  Check EBay, check Craigs...check everywhere.  Camping World had them on sale a while back and there prices wasn't so bad.

Good luck with your search and install.

John

[JohnEd]

Splits are way more efficient and versital.  I do not like it that that mfr did not specify his SEER rating.  Not at all.  he does have all the right hardware though....variable speed mtr and the blower inside should also be variable.  He didn't spec the interior unit's noise/db numbers and that is a critical choice point.  You can get AC powered units at low prices.  Try to  fit a Split into you choices.

HTH,

John

[belfert]

The inside portion is often not included because there are multiple versions of the inside unit depending on if you want ducted or not and sometimes there is a version that will use a regular thermostat.  Dometic has multiple versions of the top unit depending on if you will use their wall mount thermostat or not. 

Shipping is $99 because these units are large, bulky, and heavy.  If you're confused, any RV dealer can get you the right parts, but you'll pay a lot more generally.

[bevans6]

A few minutes browsing google will find you the best price.  As stated, it's going to cost a lot to ship a couple of hundred pounds of anything, so $99 is reasonable to me.  As noted, the inside panel is separate so you get the flexibility of ducted or non-ducted, you just have to choose the simple non-ducted stand alone version.  Most all of the internet suppliers have staff that can help you choose what you need.  15K units use a few more amps than 13.5K units, but that aside I don't know why you would choose the smaller one for the main rooms in your bus.  I do think that for the bedroom, which is usually smaller and somewhat separated from the rest of the bus by doors or hallways, a small unit might be a very good choice.  I am personally thinking of adding a 7K or 9K unit for the bedroom, advantage is far lower amps and quieter.  The Dometic Brisk-air shown here is exactly what I have - http://www.adventurerv.net/dometic-duo-therm-brisk-air-conditioner-15000-btu-p-1119.html  (I just randomly grabbed that link from google).  I have model 59516 and am pretty happy with it.  When I was choosing it seemed to have more CFM of air than some others, and it does blow up a storm inside the bus but is correspondingly noisy, although I have no comparison to other similar units.  If you want to avoid shipping then just buy locally from your RV store, but maybe spend more.

If you are in the construction/planning stage of your conversion, ducted or split AC's can easily be integrated into the design.  If you are adding to existing, stand-alone rooftops are dead easy to install.  Split AC's seem to cost more than stand-alone for the same capacity, should be quieter, but there is a big advantage if you have a catastrophic failure of a roof top on the road, it's a matter of a few hours to toss the old one over the side and install a new roof-top in the Camping World parking lot...

Just my thoughts...

Brian

[Sean]

Im not sure about the price, but this is non ducted and best of all is that is 18,000 btu and designed to run from solar power http://www.solarpanelsplus.com/dc-air-conditioning/

I would not put any value on the "solar" aspect alone, as you're not going to be able to air condition a bus with solar power -- the math just does not work.

A DC-powered system may seem tempting, because we already have batteries, chargers, etc. (and possibly even solar panels), however this unit is 48 volts.  You'd either need to have a completely separate DC system just for this, or you'd have to have a 48-volt house system instead of the more common 12- or 24-volt system.  While 48-volt inverter-chargers are common, alternators are not, so you'd be giving up over-the-road charging.  On top of that, 48-volt systems mandate conduit and all the other provisions of the NEC, which become applicable as soon as you get above 30 volts.

If you have to convert between DC voltages, you lose any advantage over just running AC-powered units from a high-quality inverter.  Couple that with the fact that these units are not designed for RV use and are not particularly convenient to install for that purpose, on top of any price premium they are commanding for the DC motors, and it all adds up to them being a poor choice for a conversion.

If you are a serious boondocker, you are better off arranging your solar panels and house system to match your alternator voltage, so they can be most productively used for more conventional loads, as you'll need to get the power for your air conditioners, if needed, from fossil fuels anyway.

JMO and FWIW.

-Sean
http://OurOdyssey.BlogSpot.com

[muddog16]

The lowest price isn't always the best deal, you have to shop around!  I purchased 3 dometic low profile heat pumps from Nick, to make this short.....someone fell in love with one of the units before they were delivered, I called Nick, he said don't accept this shipment they will be sending you three new units by the end of the week (which they did).  I purchased all three with a central digital control, two remote temp sensors, ducted units and the system is capable of running a 4th heat source (hurricane heater) from the same control!  Shipping and all was less than 2,500 delivered and backed by Nick, you can't beat that! I'm sure the prices have changed its been awhile.  Before this I had purchased two basement units, changing my mind midstream for reasons that suit my installation and later expenses if there are problems. I've shopped and bought at the cheapest source before and ended up regretting it later, but I know we all have to do it our way!  Good luck! ( Just a added note, never worry about holding the delivery guy up, open the boxes and count the contents, protect yourself )

[happycamperbrat]

Sean I agree with all you said but this would obviously be a stand alone system because it doesnt even use an inverter (which is one of the main reasons that it says it can be done on solar with 48 volts of batteries). It could not support a house battery set up.

[Sean]

Sean I agree with all you said but this would obviously be a stand alone system because it doesnt even use an inverter (which is one of the main reasons that it says it can be done on solar with 48 volts of batteries).

Umm, no, it could not be a "stand-alone" system, at least not in a bus.  You'd need an alternative way to charge the 48-volt batteries, which would mean either a charger, or an inverter-charger, plus a generator of some sort.

The A/C unit involved draws 1,800 watts, the same amount of power that an equivalent-sized RV air conditioner would draw.  In the most optimistic of worlds, if you needed air conditioning at all, you'd run an air conditioner at perhaps 50% duty cycle, for, say, eight hours.  That would require 7.2 kWh of power (or 150 amp-hours at 48 volts).

In order to generate that much power with solar alone, you would need a minimum 2,400 nominal watts of solar panels, and a bank of eight 150AH batteries.  If, instead, you needed to run the air conditioner 16 hours at 50%, double all that, so 4,800 watts of panels and sixteen batteries.

To put that in perspective, 2,400 watts of panels would completely cover the roof of a 40' bus and cost around $7,000.  4,800 watts of panels can't be done on a bus alone, you'd need to set half of them up on the ground, and would cost around $14,000.

Now, I don't know about you, but I'm seldom anywhere where I can get away with air conditioning "just a few hours."  It's usually either a 16-hour or 24-hour proposition.  Also, while 18,000 BTU/hr might keep us cool on a moderate day, we generally need 2-3 times that amount on a hot humid day; here in Florida where the heat index has been in the 110s for the last three weeks we've been running two 13.5 units full tilt 12-14 hours each day, and a single unit overnight.  FWIW, that's about 56 kWh of power and would require over 18,000 watts of solar panels to keep running, even here in the low-lattitude sun -- five times the size of the bus.

Nothing wrong with running an air conditioner from batteries; we do it all the time.  But on a bus, you can not expect those batteries to be charged entirely with solar power.

Realistically, most people will run their air conditioners from shore power most of the time.  And on shore power, this DC unit is actually 10% less efficient than an AC unit of similar size.  Also true for generator use, unless your generator is a 48vdc model.

This system is designed for off-grid applications such as a remote cabin.  There not only will you have the real estate to mount so many panels, you will also have the ability to mount them at an optimal angle for collection.  For that application, it might make some sense (although I would argue otherwise on a number of grounds, including the efficiency losses involved in transmitting DC power from the point of collection to the point of use).

We are a bit far afield of the OP's question here, as I am certain the roughly $10,000 cost of doing solar air conditioning does not square with the notion that $500 roof airs are expensive.  If folks want to debate the merits of solar air conditioning we should probably start another thread, although I'm pretty sure we've already done so here before.

-Sean
http://OurOdyssey.BlogSpot.com

[Len Silva]

Just to add one more little tidbit here.  We generally park in the shade as much as possible.  You have to consider the increased cooling load when you park so as to get the most solar.

[Highway Yacht]

Sorry if most of you guys took my original question as someone trying to locate the cheapest a/c available or a $500 unit with free shipping. That was not my intention at all. What I was asking if anyone knew of a "Good Source for Roof A/C's at a Decent price". That meant a fair price for an equivalent unit from a reputable source that doesn't rape you on the shipping. I'm sure many of you have already gone down this road before and could offer some good advice as some of you already have. I know all so well that the cheapest is usually far from the best route and I'm sorry my question sounded that way. I appreciate the advice so far and will definitely use it especially bumping one a/c up to 15K if not both and checking for any damage before signing the shipping bills.

[JohnEd]

Sean,

Well done!  We are going to call that Sean'd from now on.

Len,

I don't see your reservations.  With all the solar panels he needs to cover the entire roof he will be in perpetual shade.  Not to mention top heavy and overloaded with the other panels he will carry along.  Just kidding here.

John

[JohnEd]

The higher capacity units can be operated on a lower speed and that will translate to a quieter unit.  That really does matter.  Talk to Nick direct and seek his advice as he can provide thoughts on stuff we haven't even imagined.  His service is superb.  Like I have told so many merchants here where I buy local, and Nick is local wherever I am, "you don't have to be cheaper, only sorta close".

Good luck with the adventure,

John

[Sean]

... What I was asking if anyone knew of a "Good Source for Roof A/C's at a Decent price". That meant a fair price for an equivalent unit from a reputable source ...

I thought you got some good answers to your original question, so I did not chime in.  Since you're asking again, though, here's the skinny:

Roof air conditioners are heavy, so having one shipped is always going to be expensive.  For this reason, finding units locally is almost always the cheapest option.  In our case, we bought them from Northwest RV Surplus near Eugene, OR, but that was convenient for us.  I don't know what, if any, RV surplus places might be near where you live, but that's where I'd start.

The other option is to look at junk yards and used RV dealers.  Often the dealers will have take-offs, or junk yards will have entire rigs with working units.

Camping World can have good prices if you join their President's Club, which is worthwhile if you are going to buy a couple of air conditioners.  If you wait until the end of the season, they often have them on sale as well.

As was written earlier, you can find deals on the Internet, and sometimes you'll find one cheap enough where the total cost with shipping will be favorable.  Some on-line vendors have the product drop-shipped from the manufacturer.

Sometimes your local RV dealer will also have these on sale, so hunt around.  It helps to know what you want ahead of time; as you now know, all roof airs are sold in at least two parts, the unit itself (outside part) and the inside piece which is either an Air Distribution Box (ADB) or a duct header.  For the ADB style, there is a further choice between remote and local controls (ducted units are always remote).  Spend a little time on the Dometic and Coleman-Mach web sites picking out what will work for you, and have the part numbers handy while you shop.

HTH,

-Sean
http://OurOdyssey.BlogSpot.com