Anyone ever use a Soleus Mini-Split Heat pump for both your AC and heat? Kenny
using on project now..only problem is condensate tank drain un level and leaking when not level or in motion..solution get one that has drains on both ends of tank or build a catch tank around unit and drain from it..don't know if the brand your looking at has dual drains.conquer that problem and they are great...several members have them and have had no problem with drains..Including a close friend in his MCI 8 and he is a HVAC guy..Pay attention to drains .wether one or two and I think you will be happy...he used two twelves and said in 90 plus weather they are not maxed out.Bob
Bob, are you or your friend using the Soleus brand heat pump? If not, whose are using?
Kenny
LG-brand; don't know if there is much difference..just what our local supplier has..cheaper than internet..
we are using a mini split air and heat system 12500 btu made by ramsond. cost about 750.00 draws 8amps, works great. been in mid-west and southren states all summer.has one drain hose, no problems. ron
Twocnusa: Where do you mount the outside unit? What about ventilation?
Kenny, we have been buying heat pumps for our apartments in Ketchikan, Alaska. Most of the Chinese units have been fine, but some don't have as good of performance.
The Soleus is one of those brands that we avoid. The low ambient ratings are worse than most, and if you have been checking around, the market is about flooded with them.
To get good units, do not accept any that use heat strips or show a low ambient rating above 19 degrees F. The R410A really improves the low temperature heating capability. Our 19 degree units have worked down to 11 degrees, and didn't quit.
You can buy a better unit that uses less power and is rated down to -4 F. For running on a generator, you will probably much prefer inverter units, as they will change generator load gradually, where the non-inverter designs turn on and turn off, changing the generator load with large swings.
The better units will generally be quieter, but be sure to check the ratings. Most of ours are in the low 40s for sound ratings, and there are some models that carry ratings in the high 20s. This makes them a lot quieter.
We won't accept any if the seller will not disclose all the specs that matter to us. If you go by that and check out the specs that you are furnished, you should get a handle on them.
For what it's worth.
Tom Caffrey
Tom, Great feedback. Was thinking about the inverter unit for smooth operation. Want a unit with a small condenser box. Any recommendations on price vs performances?
Kenny
I have 2 Mini-Split Heat pumps. I have a Sanyo 12K BTU in the front, it has the inverter compressor. It is a very quiet unit, I have had it installed for 2 years with no problems. The compressor is mounted under the bus and also draws air from under the bus and exhausts through a vent on the side. The condensation pan has a drain on both sides so there is no issue with leaking. It is a very nice unit although rather pricey ($1500).
I also have a Klimaire 12K BTU Mini-Split HP in the bedroom. I just installed it 2 weeks ago. I put the compressor where some of the stock coach equipment was located on the top rear of the bus. It is concealed by the stock fiberglass cover. It does not have the inverter compressor and was half the price of the sanyo. So far I am pleased, with both units running I can get the interior temp down in the 60's on a hot summer day. Neither unit draws more than 10 amps and I have yet to have an issue with the generator cutting out (Onan 5K Watt).
I chose to go this route because I did not want to mount anything on top of the bus. I prefer the look of a clean roof. (I also prefer the look of a painted bus, but I am not quite there yet)
where i mounted my unit. look at our blog: ourbusandus.blogspot.com When u get to our blog look at the left side, scroll down until u come to aplir. click on April and u will see where we mounted the inside and outside unit and much more. ron
Could someone explain how these work, or direct me somewhere where I can read more about it?
I am considering a bus conversion where I would use the OE evaporator and condensor, replacing the DC fan motors with 240 volt AC motors, and run a small residential air conditioning compressor, about a ton or so capacity, for cooling. I imagine it wouldnt be that hard to reverse the flow and make it a heat pump? Any advice for or against, or if it would even work would be kindly accepted.
from one newbie to another (ha ha) hi artvonne, look up acworld.com then look at mini-split system's. it will tell u how they work and i found they had the beat price. ron
Artvonne- About the only way you'll be able to use the stock bus A/C's evaporator and condenser is to run the A/C with a 10ton electric compressor-which would be out of line with what you need.
A little on A/C basics-the sizing of the evaporator, condenser, and compressor have to be all balanced to work properly together. Using the giant condenser, may not be a problem, but trying to us the giant evaporator with one or two small compressors would create a cold spot at one corner of the evaporator and not really much of any cooling coming from it. The OEM A/C equipment is both very large, very expensive to keep up and entirely too large for what we do (unless the entire system is still operational).
On my bus, with 2.25" of sprayed insulation (I have a 40x102 transit with large windows) I can keep the bus cool running two of the three roof top air conditioners when running down the road. Insulation is the key.
Instead of experimenting with trying to keep the on board existing A/C, I would suggest you rip it out and install either conventional roof top airs (which really work well and are cheap), use RV style basement air (which keeps the roof clean, but takes basement space), or create your own with mini-splits, or like what I'm going to do-use the Duotherm Penquins as basement airs since they are the only roof top air that has a squirrel cage blower for the condenser that can be ducted. Then you have a cheap roof top air in the basement out of site. Good Luck, TomC
Thanks for the insight Tom. Years ago I learned that a large condensor was a big key to keeping cool. Sizing the evaporator I didnt know about, but it makes sense. I am curious though what some are calculating for heat loss/gain values. The original AC system was capable of removing the heat of 40 plus passengers while running through the Arizona desert in 110 plus heat. These busses were poorly insulated and do have a lot of glass, but were only talking about roughly 300 square feet of living space. Remove 4 windows on each side, close off the rear glass, and double insulate it all with high performance insulation, it would seem a 10,000 btu air conditioner should be more than sufficient, but its not. Many are claiming 35,000 btu furnaces are only good down to 0-10F. Where is allthe heat going??? Are you guys insulating under the floor?
Tom, did you know Duotherm has a combination AC/Heat pump that is priced reasonable? Don't know though if it has the ducting needed to put in the basement.
Kenny
I am enjoying this thread. I would love to see some more pictures of these installed on buses, in addition to Ron's (alias twocnusa).
Thanks in advance!
as to where the HVAC goes in a coach...
The coach may be easily calculated for stationary HVAC loads, as existing residential calculators may be adapted to our use.
However, these calculations are pretty much useless for a coach that is underway.
Air intrusion is the biggest loss beyond any other, and a coach is leaky. Every seal, every opening, every crack, are all put under either pressure or vacuum while moving, sucking or blowing the conditioned interior air out and replacing it with unconditioned air from outside.
Somewhere in the past when we had the engineering experience on these boards, IIRC, it was suggested that an opening of 8 square inches was all it would take to completely overcome the big 80 000 BTU stock coach HVAC.
Add up all the little openings and it isn't hard to reach a total that will overcome a pair of roof tops.
So, a religious crusade must begin: seals have to be fresh and adjusted, all cracks and holes chased with the spray foam.
Then, there are the lesser issues of greater sunload through glass/ceiling/walls and the high heat transfer materials that the coach is typically constructed from.
And, for a driver sitting facing the sun, ambient temp in the coach isn't enough, the driver needs a steady stream of cool air to feel comfortable.
Due to the air intrusion variable, it would be very difficult to have a calculator that would for all coaches in the condition that ours are in.
So, go big, or plan for additions if you try for small?
happy coaching!
buswarrior
I can tell you that BuddyDawgs front A/C works well and is very quiet too!Jack
I am not a AC guy but I heard the new freons run under extremely high pressure that would make me a little nervous with high pressure and vibrations from a bus using a house type system ?
good luck
Cliff, you're right, but that is what makes the performance so good on the modern units. We got involved because the cost of fuel heating was too high and these draw most of the output heat from the outside air. For us, it means that we can heat for about 1/3 the cost of fuel.
A background item was that we do not have enough power to put everything on electricity, so we need a way to keep people off of electric heat. These units accomplish that.
R410A evaporates at around -80 F at atmospheric pressure, so it can work down pretty low.
For what it's worth.
Tom Caffrey
Kenny, stick to the one ton units, and they should only about 24 inches tall and run on 120 V. However, a lot of the inverter units require 240 V.
Good luck.
Tom Caffrey
Quote from: pvcces on September 03, 2010, 07:28:37 PM
stick to the one ton units
Mr. Tom: Please excuse my ignorance: What is "one ton" in BTU's?
Thanks in advance!
12,000btu -Mci 8 tin tent uses 2 ea 12,000btu and they work great in high 90's with stock insulation..40 ft coach..
Thanks, Mr. Robert! How about a couple of PIX?
Robert is right; one ton is 12,000 BTU per hour. The one ton term comes from freezing units that produced one ton of ice in 24 hours. That's 288,000 BTU per day.
To compare it to something simple, an electric heater of 1500 watts produces 5120 BTU per hour if it runs on high without cycling on and off.
One KWH is 3413 BTU.
One horsepower hour is a little over 2500 BTU.
A 35,000 BTU RV furnace uses .38 gallons per hour of propane. They are rated as 75% efficient, so the output will be about 26,000 BTU. You can get a comparable amount of heat out of about 5 electric heaters.
The mini-splits will use about 1 KW per rated ton of heating or cooling.
I hope some of the above is of some help.
Tom Caffrey
by the above calc if you pay 17cents per kWh for elect and use LP at $2 Gal times .38 it would cost 76 cents for the same amount of heating...BIG difference 17 compared to 76... I do know there are differant SER (efficiency ratings) for ac units and that the larger the # the less energy a unit uses...please correct my memory but are nor most roof tops around 9 and are not the mini splits starting at 13 and going up to around 20...this is why I decided to go with Mini-split plus they are much quieter. Bob
Robert, I have never seen the SEER ratings for an RV air conditioner, so I can't help you there. Since we are needing them for heaters more than cooling units, we are looking for the HSPF. The 13 SEER units come out about 7.7 to 8.0 as heaters, and we have seen claims as high as 11 or so.
In any case, I have heard reports of suspicions that the output ratings are not reliable. From what I've seen of the air conditioner business, not much would surprise me. We know of rooftop units drawing right at 15 amps and of some rooftop units that draw around 11 amps. That's a whopping difference in efficiency if the output is similar.
Perhaps, someone with more knowledge about these units can shed some light on this subject.
Tom Caffrey