I seen a remark or post on here about mini splits then seen a video of incredabus, (which by the way was way cool) and he mentioned mini splits also. Can you guys tell me more about them please.? how they work, setup and cost or anything else you feel is pertenant
Ron:
We've put these in kitchens where the house has no AC, client doesn't want to spend the $$$ for whole house AC and they certainly don't want to use a window unit.
The condensor sits outside -- usually small in scale (subject to the over cooling needs). A small air handler (evaporator) is mounted inside on the wall -- lineset between the two. They often have a (TV-like) remote control since the indoor unit is usually mounted high. They work well, they aren't cheap. Although I do like them, I personally wouldn't use this type of system on my own busconversion. I'd still use slim profiled rooftop ducted units -- but that's just me. If I were using a system design for a home, I'd use a conventional home-type heat pump system (1 or 2 of them) with the bus being ducted throughout with conventional indoor air handler.
Jerry H.
"I'd use a conventional home-type heat pump system"
Are there any conventional units that are 110 volt? I'm am planing mini-splits in our new project because they are available in 110. That and I don't want to listen to any more roof top airs.
Problem with mini splits that are made for home use is that they are not designed for vibration and movement of the bus. The systems that come to mind that are made for buses are CruiseAir-compressor and condensor underneath and various kinds of evaporators available. Then at WWW.Tundra.CC are splits that are designed for over the road truck use-can't get any worse than that. One is a true basement unit with all in one and then duct the air too and from the inside. The other is a split system with the condenser outside and the compressor/evaporator inside-typically mounted on the floor with a duct going up to the ceiling. The compressor box is insulated and cannot here the unit when just a few feet away. Granted there are cheaper units, but not with the strong design of these units. Good Luck, TomC
Of course there's always the Cruisair Split systems, designed for Boats and RVs. I have a few in the shop now and am about to install one.
These look like very nice systems, although pricey. But to me, put the "blow boxes" in an upper cabinet or corner and they'll do the job well.
A bus I've been working on, a 45 foot Prevost, had 4 of these setups 2 in living room, 1 in kitchen and 1 in bedroom. For heat it has a Aquahot with registers all throughout - a nice setup if you can afford it, I know I can't.
Todd
One advantage to the mini-splits is the heating and cooling capacitiy is about the same.
I have two miuni-splits with 12,000 btu cooling and 12,000 btu heating capacity.
With rooftop units you usually have to install more heat.
Ed
Quote from: Don4107 on January 09, 2007, 08:42:57 AM
"I'd use a conventional home-type heat pump system"
Are there any conventional units that are 110 volt? I'm am planing mini-splits in our new project because they are available in 110. That and I don't want to listen to any more roof top airs.
I am curious about that as well. I know of a coach operator in FL who builds there lease units with home-type heat pumps. There's decent logic as to the 'why' ... Gensets are capable of producing the needed 240vac ... and in their situation, I am fairly sure they DON'T use shore connections as they're entertainer coaches.
Jerry H.
Don,
It is possible to use a 240 volt unit on 120 volts by adding a transformer. I'm in the process of installing a 240 volt minisplit (18000 BTU/h) with a transformer. The heat pump I have requires a minimum 'ampacity' of 9.5 amps at 240. I have an isolation transformer that's rated at 11.5 amps output that I'll use to 'create' the second half of the 240 volts. The 'running' current of my heat pump is 6.4 amps at 240 so the 120 input to the transformer will be about 13 amps. I'll be running the heat pump through my SW2512 which will supply the starting surges (from house battery) and should enable running the unit on the road from coach engine power.
Regards
Jerry 4107 1120
Jerry, 240 consists of two 'legs' of 120 that are out of phase by 180 degrees. Just stepping up the 120 with a transformer to 240 will only give you single phase 240 which I don't think the motors in the air conditioner will like. I would at least test it before you install it in the bus. If the mini split has ANY solid state components, I think you will fry them with your plan.
Good luck.
Don,
You are misunderstanding what I'm doing. I'm using a 120 to 120 isolation transformer to reverse the phase of one leg while the other leg is passed straight through. The result is 3 wires, a neutral and 2 hots. The neutral and one hot are the 120 input, the second hot comes from the transformer secondary, which has it's other lead connected to neutral, and is 180 degrees out of phase with the input. From neutral to either hot is 120 but between the hots is 240.
Regards
Jerry 4107 1120
Does a mini-split need a neutral? Normally 220 volt is just two hots and a ground. Usually only applicances like dryers use 2 hots, a neytral, and a ground. The neutral is for the 110 volt parts of the dryer.
Brian
Quote from: belfert on January 11, 2007, 08:15:46 AM
Does a mini-split need a neutral? Normally 220 volt is just two hots and a ground. Usually only applicances like dryers use 2 hots, a neytral, and a ground. The neutral is for the 110 volt parts of the dryer.
Brian
Brian, you are correct, and you can use any 120 to 240 volt transformer to get the proper voltage. Most step up transformers will also have a center tap to give you a neutral if you need it.
Richard
Jerry,
Glad to hear you have it covered. In my world an "isolation transformer" is used to isolate equipment that uses an internal hot ground for service/safety. Just did not want a a fellow 4107 owner "tuning for maximum smoke". ;D
Are you using just the one air? I'm am thinking a 12K in front and a 9 or 12K in back of our 4107. Our current bus has poor insulation all over and is a dark color. That and the added heat from the engine on a travel day makes the bedroom hard to cool for a good nights sleep. I think I may use the space where the OEM air conditioner compressor was for the rear condenser. It will be tight but I think it will work.
I think that everyone should have bought an already converted bus as we did to find out what you like and don't about the conversion. I know it has given me some very definite ideas and plans that would not have been obvious without that experience. My main lessons are insulation, insulation, insulation and no such thing as too much cooling.
Heres to no smoke,
Don 4107-501
PS What brand mini split did you settle on?
Don,
I'm using the 18,000 BTU/h heat pump for the front of the bus and I have a 10,000 BTU/h window AC through the rear cap to cool the bedroom. And I have a Webasto for heat when it gets too cold. The rear unit does a real good job keeping the back of the bus cool and it's actually quieter than any roof top I've heard.
The minisplit is replacing two 'portable' heat pumps that simply did not perform up to their specs. I'm putting the outside unit in the area that used to be the AC condensor. The indoor unit will be above the living room windows on the road side of the bus.
Regards
Jerry 4107 1120
Jerry, I put my window air in like yours. I have not yet ducted the intakes out the side as you have, don't want to burn up closet space if I don't have to. Can I use the recirculating feature with success? my unit I have now does not have that but will trade up.
Actually 240 VAC is 120 Deg. out of phase. It is two of three available legs from a three phase system.
With an exception, I'm told, on a 240 VAC genset. I've heard that they are 180 out of phase.
If so, the 240 V motors don't seem to mind.
House current might also be 180 out since there is only a hot and a neutral going to my house transformer.
Ed
Captain Ron,
If you want it to do any air conditioning you need to have air flow over the outside (condensor) coils. These units normaly have all but the front 5 or 6 inches hanging outside. When they are hanging out a window the outdoor fan draws air in through louvers on the sides and top of the metal case and pushes it through the condensor then exausts it out the back. When one puts one into a bus most of the designed air flow has to be maintained for it to work. In my case I have a plenum behind the cabinets to provide air into the top and sides of the AC unit, with air flowing into this 'plenum' from louvered vents on the sides of the cap. I also have a duct from the rear of the unit through the rear surface of the cap and a louver in the rear opening in the cap. I designed my rear cabinets to create the 'plenum' by making the cupboards, on each side of the air conditioner, relatively shallow, leaving over a foot behind their rear wall. I have Drawers under the air conditioner and these are much deeper. Because of the window type air conditioner I really have no closet space over the engine. This wasn't a big deal to me as I have plenty of closet space in the 'rollback' closet over the bathtub.
Regards
Jerry 4107 1120
Quote from: Kristinsgrandpa on January 11, 2007, 03:38:00 PM
Actually 240 VAC is 120 Deg. out of phase. It is two of three available legs from a three phase system.
With an exception, I'm told, on a 240 VAC genset. I've heard that they are 180 out of phase.
If so, the 240 V motors don't seem to mind.
House current might also be 180 out since there is only a hot and a neutral going to my house transformer.
Ed
Ed, you are correct. Generally two hot legs are brought into a home. These two legs are 120 degrees out of phase with the third phase of a three phase system.
The odd thing is that if you look only at the two legs brought in, they are actually 180 degrees out of phase with each other, so the 240 volt power in your home is always 180 degrees out of phase with each other.
Richard
Richard,
While 2 phase conductors are brought into a residence they are 2 phases of a 240 volt line to line delta connected three phase transformer set AND the transformer has a center tap that's grounded, it's the neutral. The third phase conductor would be 208 volts to ground or neutral and it would be 120 degrees ahead of or behind the lines used by the residence.
Regards
Jerry 4107 1120
I have never lived in an area where the public utility company distributed low voltage three phase, especially to residential. I have always had three phase at high voltagae (commonly 25kv) feeding the distribition transformers. The voltage on any winding is always 180 degees out of phase at opposite ends so each secondary winding pair of whatever voltage is 180* out of phase and may have a center tap. You are only concerned with phase to phase angle if you want to use the three phase and use more than one winding. If you take one leg of three phase, the two wires are 180 out of phase with each other. I can't figure out how you can get two wires for single phase that are 120* out of phase and then try and run a single phase motor on it. If you put a scope on these two wires, what do you see? Possibly two half cycles that overlap or have a space between them, both positive half cycles or both negative half cycles. I hope someone can explain this conundrum to me because I have never seen anything but a sine wave of a public uility system.
Quote from: Stan on January 11, 2007, 05:40:04 PM
I have never lived in an area where the public utility company distributed low voltage three phase, especially to residential. I have always had three phase at high voltagae (commonly 25kv) feeding the distribition transformers. The voltage on any winding is always 180 degees out of phase at opposite ends so each secondary winding pair of whatever voltage is 180* out of phase and may have a center tap. You are only concerned with phase to phase angle if you want to use the three phase and use more than one winding. If you take one leg of three phase, the two wires are 180 out of phase with each other. I can't figure out how you can get two wires for single phase that are 120* out of phase and then try and run a single phase motor on it. If you put a scope on these two wires, what do you see? Possibly two half cycles that overlap or have a space between them, both positive half cycles or both negative half cycles. I hope someone can explain this conundrum to me because I have never seen anything but a sine wave of a public uility system.
Quote from: DrivingMissLazy on January 11, 2007, 05:04:49 PM
Quote from: Kristinsgrandpa on January 11, 2007, 03:38:00 PM
Actually 240 VAC is 120 Deg. out of phase. It is two of three available legs from a three phase system.
With an exception, I'm told, on a 240 VAC genset. I've heard that they are 180 out of phase.
If so, the 240 V motors don't seem to mind.
House current might also be 180 out since there is only a hot and a neutral going to my house transformer.
Ed
Ed, you are correct. Generally two hot legs are brought into a home. These two legs are 120 degrees out of phase with the third phase of a three phase system.
The odd thing is that if you look only at the two legs brought in, they are actually 180 degrees out of phase with each other, so the 240 volt power in your home is always 180 degrees out of phase with each other.
Richard
This makes my head hurt!
I know this about electricity:
If I try to strip the wires on a lamp cord with my teeth while its still plugged in, it lets the smoke out of your head. (Long Story)
If I stick my finger in the light socket to remove the base of the broken bulb, it turns your finger nail black for a loooong time.
If you believe your friend that he shut off the power to the irrigation system while you are on an aluminum ladder, in the mud working on a 480V motor, you are a really big idiot! (It feels like someone hits you in the armpits with 3" iron pipes).
Quote from: Kristinsgrandpa on January 09, 2007, 05:55:03 PM
One advantage to the mini-splits is the heating and cooling capacitiy is about the same.
I have two miuni-splits with 12,000 btu cooling and 12,000 btu heating capacity.
With rooftop units you usually have to install more heat.
Ed
FWIW, I have two Dometic rooftop heatpumps and they work very well. 15K cooling and 12K heat per unit. These units work fine down to freezing. One unit heats my bus....but I have a open floor plan..a narrow area between the front and rear of the coach would require two units running to heat and cool.
They are 110VAC and one will operate on a 20A outlet. They use more power on heat than on cool...about 15A @ on heat....11A on cool. I don't understand this but that's the way it is.
The strip heat Colemans and Dometics were almost useless for heat...but, those are not heatpumps.
Downside to rooftops is noise (ducted rooftops are not noisy), and raised roof coaches.
I would be surprised if any small heat pump works efficiently at much below 30*...with home style heat strips they would...with a good 240V supply.
JR
Stan,
I lived on a farm that had 3 phase power available, we used it for irrigation pumps. It was 240 volt line to line, delta connected and there was a 4 th wire that was grounded, it was a center tap between two of the phase conductors. Between the grounded connection and 2 of the phase conductors was 120 volts but between the grounded conductor and the third phase was 208 volts. There are three phase 'Y connected systems where there is a common point(neutral) at the 'center' of the 'Y and the voltage from this common to any of the phase conductors is 120, this system gives 208 volts line to line and there is a phase angle of 120 between any 2 line to neutral voltages. The Y connection is often found on generators and can be rewired to provide 2 120 volt wires that are at 180 degrees to each other.
Regards
Jerry 4107 1120
Quote from: Jerry Liebler on January 11, 2007, 05:16:30 PM
Richard,
While 2 phase conductors are brought into a residence they are 2 phases of a 240 volt line to line delta connected three phase transformer set AND the transformer has a center tap that's grounded, it's the neutral. The third phase conductor would be 208 volts to ground or neutral and it would be 120 degrees ahead of or behind the lines used by the residence.
Regards
Jerry 4107 1120
The center tap that is grounded at the center of one winding, for example between phase A and Phase B. This provides two 120 volt legs that are from each end of one winding so they are 180 degrees out of phase.
Richard
Ron
I have two mini-splits heat pumps 12000 btu each, we are very happy with them.The units are 120 volt ,and they are very quiet inside as well as outside. I was able to get mine from United Refrigeration about 2 yrs. backfor aprox,$ 530.00 ea. I know the price has gone up as it has with copper , and everything else . My bride an I both agree this is the best spent money on our bus yet!!! These units are not made in the states ,but they are made very well. Most all mfg. use a rotory compressor . You may want to check e- bay at one time ther was a seller on with a complete line of these. Hope this helps !
Dwayne M.
Gerry: I think you and I both understand three phase distibution but just explain it differently. There are comments on this thread that indicate that some others do not (" 240 consists of two 'legs' of 120 that are out of phase by 180 degrees. Just stepping up the 120 with a transformer to 240 will only give you single phase 240 which I don't think the motors in the air conditioner will like" also "Actually 240 VAC is 120 Deg. out of phase. It is two of three available legs from a three phase system.")
Your farm service three phase came from distribution transformers either on farm or down the road to a point where several farms were fed from one location. I now live in a city with underground service. The primary is 25kv three phase and each distribution transformer serves eight houses. Single phase 240 goes to each house and if I wanted three phase I would have to pay for the underground installation from the transformer location. Transformers can be wound to give any voltage desired and distribution transformers usualyl have taps for voltage adjustment and to get the configuration (single phase 240 and Delta or Y three phase) that is required. Your explanation of the Delta and Y connection is quite clear and to simplify the phase relationship on the Y connection, just visuslize the the points where you take off 240 volts as one long winding with a center tap.
If everyone can remember that opposite ends of a winding are 180* to each other and no matter how many taps you put on the winding, between any two taps there will be a sine wave with 180* beteen them. Using some other point as a reference means nothing. Your reference point has to be one of the conductors you use for the load.
Dallas: If this makes your head hurt, try and visualize this three phase wave in three dimension.
Hey, Thanks guys for the actual info on mini splits. ;D It's kinda hard keeping up with the latest "PHASE" of this topic and I'm sure it will turn "180 degrees" and go into another "PHASE" in the near future. ;D Have fun guys I'll check back periodically to see if there's any more useful (for me) knowledge on Mini Splits. ::)
Ron: Sorry your thread got hijacked, but got off on a tangent as frequently happens. As soon as someone started posting about minisplits using 240 volts, a lot of confusion showed up and I was trying to clarify the situation. Maybe I did a poor job on the electrical explanation, and not needed by you, but you were lucky enough to get a lot of info on minisplits. There was even a couple of suggestions on how to run 240 volt units on 120 volts.
Quote from: Stan on January 12, 2007, 05:59:44 AM
Gerry: I think you and I both understand three phase distribution but just explain it differently. There are comments on this thread that indicate that some others do not (" 240 consists of two 'legs' of 120 that are out of phase by 180 degrees. Just stepping up the 120 with a transformer to 240 will only give you single phase 240 which I don't think the motors in the air conditioner will like" also "Actually 240 VAC is 120 Deg. out of phase. It is two of three available legs from a three phase system.")
Your farm service three phase came from distribution transformers either on farm or down the road to a point where several farms were fed from one location. I now live in a city with underground service. The primary is 25kv three phase and each distribution transformer serves eight houses. Single phase 240 goes to each house and if I wanted three phase I would have to pay for the underground installation from the transformer location. Transformers can be wound to give any voltage desired and distribution transformers usually have taps for voltage adjustment and to get the configuration (single phase 240 and Delta or Y three phase) that is required. Your explanation of the Delta and Y connection is quite clear and to simplify the phase relationship on the Y connection, just visualize the the points where you take off 240 volts as one long winding with a center tap.
If everyone can remember that opposite ends of a winding are 180* to each other and no matter how many taps you put on the winding, between any two taps there will be a sine wave with 180* between them. Using some other point as a reference means nothing. Your reference point has to be one of the conductors you use for the load.
Dallas: If this makes your head hurt, try and visualize this three phase wave in three dimension.
Very good explanation Stan. It is really hard to explain the differences with words only. Really need an electrical diagram to show everything.
One thing I would like to make clear. To my knowledge there is no such configuration as a 240 volt three phase
Wye connection. At least in my 50 years of work in the commercial electrical field, I have never seen it. Any time a Wye connection is discussed the phase to phase as well as the phase to neutral voltage should be listed.
For example in the low voltage area the nominal voltage is 208/120 volts Wye. Any phase to phase voltage is 208 volts, and any phase to neutral is 120 volts. In the higher voltage it is 480/277 Wye. The higher voltage being the phase to phase voltage and the lower voltage being the phase to neutral voltage.
If there were a 240 volt Wye configuration the voltage would be 240/139 (I believe) and that line to neutral voltage would be of no use for any known application.
Richard