What the heck do I do with this?

[WoodenBoat]

I've only owned my new (to me anyway) Prevost H3-45 for about three weeks now. I'm still getting to know it.

It has been serving first as a casino bus and then a church bus. But I've started going through the deconstruction phase having removed the seats and most of the interior.

I have questions about this Prevost HVAC system that is occupying the fourth bay back on both sides. I honestly do not know what to do with all of this stuff. Do I take it out? I don't think it will heat or cool unless I'm running down the road. Am I correct?

If I take it all out, am I going to cause other problems that will bite my butt later on?

[Jim Blackwood]

Sort of a prickly issue. Convention says rip it out, but... What you have there is about a 1 ton AC unit on each side that just needs a compressor and a condenser to use when parked. Just like the inside bits of a split-mini AC. So if you aren't afraid of AC work you can do a lot with that, as well as the dash unit which is another ton or so.

Jim 

[richard5933]

This seems to be an eternal debate in the conversion world. Our current bus as well as our previous one still had the over-the-road (OTR) HVAC systems in place. They worked great going down the road to keep us comfortable. There is no comparable system that can easily be put in place to heat and cool as well going down the road, especially the cooling part.

Others may disagree with me on this. Heating can be accomplished a bit easier than A/C while OTR, but a properly-functioning OTR heating system is hard to beat. Air conditioning is more difficult and I have seen no good alternative system for keeping the bus cool in the summer that doesn't require running the generator, and to me that just doesn't make sense. I know others do it, but I don't see it. I've read about running a roof-top A/C unit from an inverter while going down the road.

If you are going to take the OTR HVAC systems apart, be careful to plan it out carefully before you start ripping things apart. The A/C system is the one most commonly torn out, replaced with roof A/C units run from the generator. Most of the time the heating system is left in place, and if not the entire heating system then at least the defroster system as having a working defroster system is a safety issue.

Lots has been written about this in other threads, so you might set aside a few hours and read through some of that before starting the removal.

[bronson]

Jim, speaking of mini splits..... I know you are in the area where some of these auctions are and might be interested. Have you heard of Fast Track auctions? https://www.bidfta.com They seemed to have mini split systems either complete or partial pretty regularly. I just watched one sell for $275 complete. If they are listed as appears new and you get there to pick up and find damage you dont have to take it and they will refund your money. If the damage doesnt bother you but you still want it, show them and they will knock money off the price you paid. If the auction listed as open box you have to take it as is. They do have times to preview in advance but it is hard to located the items sometimes. I havent bought a mini split but have bought quite a few items and have gotten some super deals. Most of the items are Amazon, wayfair and other store returns so there is some risk but Its worth looking into. They have warehouses here
A1, Johnson City TN
Amelia, Amelia OH
Broadwell, Cincinnati OH
Chandler Drive, Walton Kentucky
Don Tyson, Springdale Arkansas
Edwin Moses, Dayton OH
Elizabethtown, Elizabethtown KY
FTA Columbus, Columbus OH
Latonia, Latonia Kentucky
Manchester, Manchester Ohio
Phillipi, Columbus OH
Rogers, Rogers AR
School Road, Cincinnati OH
Seymour, Cincinnati OH
Washington Court House, Washington Court house Ohio
Waycross, Cincinnati OH
Webster Street, Dayton Ohio, Dayton OH
Wellston, Wellston Ohio

[WoodenBoat]

Believe it or not, I think you folks may have given me just what I needed. This is because I'm all about doing the least amount of work if there is a system already in place that I can put to good use. I have no desire to reinvent the wheel. And a guy only needs to look in the bays to see that this stuff is dripping with Prevost quality - something that continues to amaze me everytime I work on anything.

Also, this darn bus is SO tall anyway that I've really been getting squeamish about putting more and more stuff on the roof. I've parked it already at truck stops and rest areas next to OTR trucks and my bus is everybit as tall as many of them. If I were to run this under something too low, I would much rather smash off my satellite dish instead my satellite dish, five AC units, my cell phone repeater, solar array and so on and so on. LOL

I will pour through all of this forum to glean out what I can find. But thanks. If there is anyway I could use these while NOT having to run down the road, such as when I'm boondocking, I'm all for it.

[Geoff]

You should measure the height of the bus-- 13'6" is the legal height limit so that height is fine for truck routes, but not for areas with low bridges.

So roof airs are probably out, and the OTR ac/heat is expensive to maintain, and no good for camping.  I see mini-splits and a Webasto, et al, in your future.

[Jim Blackwood]

Here's what I'm thinking about on my DL: Keep the OTR air. Nothing is going to work better. And if work on it is needed in the future I'm not afraid of getting my hands dirty. Thankfully you can still buy 30lb cans of r-134. I can find a way to pump it out and back in in order to work on the plumbing.

Now, while boondocking the 3 small units should be enough most of the time. That's at minimum 3-1/2 tons of A/C (TXVs on the OH units are 1 ton each, on the dash it is 1-1/2) so all I really need to do is provide a suitable compressor and condenser. The stock condenser is way more than enough, that leaves the compressor. So what if I could find a way to declutch the stock compressor and belt an electric motor to it to run it at, oh let's say about 25% speed? I do believe that would do it. Add a solenoid valve to shut off flow to the main evaporator and I'm in business. That requires drawing down the system, recovering the refrigerant, some plumbing, evacuation, and returning the refrigerant to the system. Well, I have a spare A/C compressor which with an appropriate motor should handle those chores just fine and the rest is plumbing and fabrication. Seems feasible enough to me. How big a motor do I need for the main compressor? I'd say 5hp with suitable speed reduction might work, it's the suitable speed reduction part that could be a little tricky, finding space for it, and then not overspeeding the motor when operating OTR. But these are just technical issues and can be overcome. In the end the actual current draw may be less than 5hp, meaning I could either reap the benefits of lower current draw, or belt up for a faster compressor speed. Either way I think it should be feasible to stay below a 30 amp single leg draw provided the right motor can be found, and if a single phase 5hp motor is unobtainable then a VFD can be used to run it and a 3 phase motor can be used. Doing that, I could maybe even switch in the main evap, cut off the other three, overspeed the motor by about 20% and get enough out of the system for those hot days.

That's my basic plan anyway.

Jim

[WoodenBoat]

Thank you Jim, you've given me some serious food for thought. But I need to think tank it some more.

[richard5933]

If you keep the OTR HVAC system in place and use it only for OTR, there are still options for you other than roof top units. Mini-splits are an option that some go with, but there is also a system similar to what Custom Coach did on their coaches back in the day.

Ours uses a commercial refrigeration unit (compressor, condensing coil, controls) in a bay and a blower w/evaporator coil in a cabinet upstairs. The units (we have two) were built with off-the-shelf pieces and parts. The guy that works on ours says it was most likely built from components normally found keeping a walk-in beer cooler cold. A little creativity and something like this could be installed in any bus - a rock solid system that will turn any bus into a meat locker (or beer cooler, if you want.)

[luvrbus]

If you keep the OTR HVAC system in place and use it only for OTR, there are still options for you other than roof top units. Mini-splits are an option that some go with, but there is also a system similar to what Custom Coach did on their coaches back in the day.

Ours uses a commercial refrigeration unit (compressor, condensing coil, controls) in a bay and a blower w/evaporator coil in a cabinet upstairs. The units (we have two) were built with off-the-shelf pieces and parts. The guy that works on ours says it was most likely built from components normally found keeping a walk-in beer cooler cold. A little creativity and something like this could be installed in any bus - a rock solid system that will turn any bus into a meat locker (or beer cooler, if you want.)

The bays on the H-3 are huge lot of the entertainers bus us a mobile home package unit Ac/Heat pump combo OTR Air is hard to beat but cost a arm and a leg to keep it up the 2 electric motors on the outside when they go and they do it is a 5 grand lick for new ones BTDT

[lvmci]

Dave, what part of the country are you located?...

[bandsaw]

Dave, I am in the process of  converting a 1998 H3-41.  I kept the bus air conditioning system. It did not work when I bought it.  This was the first A/C system I had worked on and I was able to fix myself.  There were 8 leaks and the compressor oil was low. One of the condenser fans was frozen.  It has held a charge for the last 6 years. I would highly recommend keeping the bus air.  You will need a cylinder of nitrogen, a couple of vacuum pumps, a gauge set, and a big tank of 134.  I probably spent $1,000 on A/C tools and $1,500 on condenser motors. I could have rebuilt the condenser motors for a couple of hundred instead.

I installed 3 roof airs.  2 will barely keep up with 100 F weather.  Shade from the awnings makes a big difference.

I installed full length Girard awnings on roof brackets. These are almost as tall as the roof air conditioners. I really like the awnings.

I have broken a couple of the Girard wind sensors that pull in the awnings. There are several trees hanging over the road in my town.  They trim but they don't go high enough.

My wife loves the washer and dryer.

I think my height is just over 13 foot.

Have you found any sliding windows?  They make a big difference when it is pleasant outside.
I installed 3 factory sliding windows and I have several more that will be installed later.

Do you have framed windows or frame-less? Peninsula glass can make sliding windows from the framed windows.

The heat gain from the huge windows is hard to deal with without plenty of A/C.

The H3's tall bays make the conversion work tolerable. You can sit upright on an old milk box and go to work.

We should figure out how to talk on the phone.

There a few other guys I know in the process of converting H3's. You picked a nice rig to convert.

I really like my bus, it is a great project.

As you add weight to the bus the ride will improve.

Take Care, Bandsaw.

[Jim Blackwood]

If the fan motors are that expensive, I think I'd be looking at alternatives.

3 phase motors are pretty inexpensive overall. Even to spec out and buy new something in the hp range needed to drive that fan is probably not going to be over a couple hundred dollars and can probably be picked up on ebay for less than 50. Shouldn't draw more than 1kw at the very most so about any inverter should be able to handle the load easily, then to get the 3 phase you buy a small VFD, set up a thermostatic speed control with a probe in the condenser and use your original power lead to switch it on. Should be able to do this with all new parts for under $1k, NOS or used for a couple-three hundred. You end up with better control of the fan, on-demand usage, variable speed dependent on temp, and overall less current draw. You could do the same with the main evaporator to reduce power requirements. Everything required is available, ain't industrial surplus great?

Jim

[TomC]

Number one is insulation. I have 2.25" of sprayed in insulation, 3-13,500btu roof airs on my 40ft transit. Going down the road, 2 a/c's normally keep the interior at a comfortable 75. Over 100, I kick on the third. Never been hot. Same roof airs that I installed in 1993 (Coleman). Simplest.
As far as over height, Duotherm Penquins are the lowest made. 3 or 4 will cool just fine. Notice most all motorhome manufacturers are back to using roof airs-why? Easy to service, out of the way, easy to replace, about $1,000ea. Good Luck, TomC

[WoodenBoat]

If you keep the OTR HVAC system in place and use it only for OTR, there are still options for you other than roof top units. Mini-splits are an option that some go with, but there is also a system similar to what Custom Coach did on their coaches back in the day.

Richard, I hate to have to admit this but I don't know what a "mini-split" is.

However, I've come to a decision and that is to leave anything Prevost in place if at all possible. And let me explain my reasoning.

I've worked in construction of all types for over 40 years. I've built everything from pole barns to mansions - from cedar strip canoes to Chris Craft style mahogany runabouts. I'm a superb cabinet builder and spent quite a few years taking on frame carpentry and a LOT of hardwood flooring and that included the sanding and finishing. Tools fit my hands extremely well! But in just taking apart the parcel shelves in this bus I have to say that Prevost never intended this bus to come apart. I have never in my life seen anything so difficult and frustrating to deconstruct as this danged bus! I believe that Prevost wanted to build a bus that was so indestructable that, if you were to run one off of a 300 ft high cliff, you could roll it back on its wheels at the bottom of the chasm and drive it away.

I'm dead serious. For example, you can remove every screw, every bolt and every rivet you can find. Nothing even budges. So, after doing some exploratory research, you find several dozen more hidden screws, bolts and rivets and you twist yourself into all sorts of contortions and remove them all.... finally! Nothing budges. So then you find some brackets that are riveted in from the outside. There is no way to get to them from outside so obviously, you need to grind the backs off of the rivets. But you can't get your grinder in there. Ok wait.... let's see.... if you can get a crow bar and bang on it with a hammer, you might be able to wedge the crow bar in enough to pop those rivets.

NOPE, Prevost rivets are impervious to hammers and crow bars. If you get a bigger hammer and really wack that crow bar, you're going to have a crow bar that will bounce out and hit you in the head. It's not important how I know that.

Hmmmmm

WOW, I do LOVE LOVE LOVE this bus! Anything with this sort of build quality has got to become my best friend down the road. Oh yeah, it's pissing the dickens out of me now but this will be worth it if I will just stay the course!

Number one is insulation. I have 2.25" of sprayed in insulation, 3-13,500btu roof airs on my 40ft transit. Going down the road, 2 a/c's normally keep the interior at a comfortable 75. Over 100, I kick on the third. Never been hot. Same roof airs that I installed in 1993 (Coleman). Simplest.
As far as over height, Duotherm Penquins are the lowest made. 3 or 4 will cool just fine. Notice most all motorhome manufacturers are back to using roof airs-why? Easy to service, out of the way, easy to replace, about $1,000ea. Good Luck, TomC

Hello Tom, I have been able to see the insulation that Prevost put in this puppy from the get go. It's identical to that best foam I've seen everyone rave about so I'm not messing with it.

But also, you are correct. The proper way to go is to put three roof units on and then do just like you said. I will use the roof units when I'm hooked to shore power or dry camping and running the genset. But running down the road, it will be Prevost all the way.