Can I take the heating system water lines from the engine, that are used to provide interior heat for the coach, and somehow use the same heat distribution pipes that provide interior heat and use the water from the generator (when the engine is not running)?
I was thinking that being able to interconnect, somehow, the coolant systems would also keep the non-running engine warm, and if both were running, the coolants could simply share the heat.
I am using heat exchangers for heating domestic water while drivng, but is there a way I can do something similar between the two diesels (engine and generator) so the domestic hot water can also be heated by the generator?
There will have to be valves (similar to the thermostatically controlled valves in the heating system controls), or high tech plumbing done, to separate the systems to protect in the event of a system leak. These valves would have a driver controlled override to shut them off manually in the event of a problem.
I thought about installing solenoid valves to shut off the interior heating coils from whichever engine (main or generator) is not running, with small bypass hoses to deal with water expansion.
Am I totally crazy? or can it be done?
While that sounds good on paper, the generator does not produce anywhere near the heat that the main engine does. If you did hook up the generator to your heating lines, you would end up with luke warm water going through the lines and a generator running to cool. I would suggest just keeping the heating lines hooked to the main engine and if you want heat when the big engine is stopped, get a Webasto Diesel fired coolant heater. Good Luck, TomC
I don't see why it can't be done. The old 4104 had the air conditioning engine tied into the coach cooling system, they each had their own radiator and fan.
My concern would be with keeping the generator running hot enough, especially since you would not be putting as much electrical heating load on it. Probably the worse thing you can do to a diesel generator is under loaded and over cooled.
Thank you - but perhaps I should mention that the generator is a 75 HP four cylinder diesel with a radiator as big as the entire bay door, so I could cut off some of the air flow to raise the water temperature.
I already have an exchanger to use the hot water to heat the interior heating system, and, when the engine is running, to heat the domestic water.
Does that information make a difference in your thoughts?
Sorry, I forget to mention those specifications.
Unless I'm missing something here - which wouldn't be the first time - the generator temperature will be controlled by the generator thermostat. It will just see the house cooling loop as a very big radiator but that won't change the operating temperature of the generator engine. The generator won't provide much if any heat to the house but I don't see how it will affect the operation of the generator engine.
Thank you Bob,
The generator does operate at the usual 160F (71C for you, Bob), so it does have the temperature to heat the coach, and it has the radiator size to keep that temperature. I could put a higher temperature thermostat in to increase the available heat.
The size of the radiator was to say that there is sufficient volume of water, and heat created during operation, to make a good dent for the interior warmth, I think.
It is the interconnecting that I have never done before. I am trying to get these cooling systems to share the warmth with the interior in an easy to operate or switchable manner, and find the pitfalls of interconnecting the two independent systems.
Quote from: PCC on December 11, 2009, 08:04:05 AM
Thank you Bob,
The generator does operate at the usual 160F (71C for you, Bob), so it does have the temperature to heat the coach, and it has the radiator size to keep that temperature. I could put a higher temperature thermostat in to increase the available heat.
The size of the radiator was to say that there is sufficient volume of water, and heat created during operation, to make a good dent for the interior warmth, I think.
The thermostat rating won't change the waste heat available to heat your coach. You are right though that a large radiator would seem to indicate that there is waste heat available. My point was that the thermostat will attempt to keep the generator at the correct operating temperature. The heat you have available for the coach is limited to what would normally be wasted through your radiator. As far as your generator is concerned the coach hydronics are just a really really big radiator.
My personal opinion is that you won't get much usable heat out of your genset but that is just an opinion. I have looked at interconnecting my generator & engine cooling systems - in my case the goal was to get rid of the genset radiator entirely. It seemed to me that the risks and expense of interconnected systems outweighed any potential benefits but again - just my opinion.
Changing the thermostat does not change the heat available; the heat available is a funcation of the engine and load. The thermostat controls the coolant temperature by metering coolant into the cooling system when the coolant temperature inside the engine has reached the set point of the thermostat and shutting off the coolant into the cooling system when the temperature has dropped below the set point. Ideally the cooling system is sized to the engine's needs and the thermostat stays in a midpoint of opened and the heat generated matches the cooling available; if the cooling available is not enough for the heat generated the temperature will rise and the thermostat will go the full open but the temperature will continue the rise but because the temperature of the coolant in the cooling system (generally the radiator) now has a greater delta to the exchange medium (air with a radiator) the cooling system gains a little more capacity and the temperature may stabilize at this higher temperature (above the thermostat's rated temperature) if not the temperature rises above the coolant's boiling point. When the coolant boils (converted to steam) it provides a great deal of cooling as the convertion the steam takes a great deal of heat but with a limited amount of coolant available this cooling does not last very long. If the cooling system is larger than the engine's needs the thermostat closes completely and the coolant in the cooling system has a significant drop in temperature before the thermostat reopens and very cool coolant enters the engine which may cause thermal shock to the engine. This is why you see the big rigs with most of the radiator covered or shutters closed. Anyway those are engineered systems and I would proceed with caution.
Depending on the fittings in your genset, perhaps it would be easier to plumb a separate heater core to your genset and then just take advantage of that heat when the it's appropriate. That is what I plan to do with mine. Good luck!
Glenn
I wonder with a 75 horse generator, how are you going to keep enough load on it to even get to normal temperatures?
The generator will maintain a basic continuous load on it, between 10 Kw and 16 KW (+/-), when parked and occupied.
When running all the A/C systems, the load will be at about 30 Kw. When running with everything on. I will need about 42 Kw.
I figure it will be able to stay warm.
And no, it is not a hybrid bus !! (LOL)
It is a working home, and will have a lot of electrical appliances that will run almost all the time.
The generator has the heater hoses already connected to the engine, so it is an engine designed to be used with a heater. That is what gave me the idea that I could find heat for the interior from this engine.
I hope it runs cool, for the generator's sake, but I hope it runs warm enough to bring the engine coolant temperature into the coach.
Am I wrong to presume that a thermostat set for 160F will warm the engine up to that temperature before opening to the radiator, and then keep it about there?
If that is so, then would that (160F) not be the average/minimal water temperature fed into the coach for heat?
Is that not hot enough?
If not, would not a higher temperature thermostat raise the generator engine's water temperature even more?
Are my presumptions all wrong here? Do I need to rethink the system completely?
I await your inputs.
The thermostat will crack open at 160F and reach full open at about 175 F. In between it will regulate flow.
Assuming the genset is under light load, the thermostat could remain virtually closed causing no flow to go through the genset radiator.
The bus heat will get coolant flow regardless of thermostat opening. The cooling effect of the bus heaters could be enough to cause the engine to run below 160F
If you put some kind of a thermostatically controlled valve on the link between your genset and your hydronic system to restrict the outward flow of engine coolant when the engine temp is below 160 then I don't see a problem. Otherwise I think you are going to run your genset cooler than it is designed to run but again, that's just my opinion. What you want to do is mimic the operation of the engine thermostat with another thermostat that regulates access to the "really big radiator" which is in fact your hydronic system.
Keith,
One thing that puzzles me in yer post is you mention;
"When running all the A/C systems, the load will be at about 30 Kw. When running with everything on. I will need about 42 Kw.
I figure it will be able to stay warm."
Uh isn't heating and cooling at the same time counter productive?
Just curious.
;D BK ;D
btw I still haven't took pics, I loaned my mom my digital camera and she won't be back w/it until monday!
BK - I was just trying to show the anticipated load of the generator - Hopefully, the heat and the A/C will not be operating simultaneously, but then it might, if the humidity is too high.
Looking forward to the pics.
Thank you
Bob - Thank you for another example of making a design better. If I thermostatically control the flow to the heating system at a temperature below the thermostat, then I can hold the water at a temp that will prove to be both good for the engine, and supply noticeable heat.
Good idea - I like it.
Using the main engine heat to keep the hot water hot (heat exchanger) has been a real saver for me, as I have hot water without running the generator to keep it that way.
Thank you all for sharing your genius with me.
PCC, your genset is going to be able to do a nice job of heating your coach anytime it is warm enough outside. The problems begin when it gets cold enough outside that there is no longer an appreciable amount of heat to waste into the coach.
I noticed that you seem to be mixing up temperature and heat; 160 degrees may be a good heating temperature, but it wont do any heating if no volume of it can be fed to the coach. If you feed a volume to the coach in cold weather, your generator may run pretty cold.
All this ignores the waste heat that may be produced inside the coach from using all that power. 30 KW is about 40 horsepower, which will require burning around 2 gallons per hour. If that is a constant load, you're talking 48 gallons per day or over $100 per day for your electricity.
Also, that much power, if used entirely within the coach will produce over 100,000 BTU, which is equivalent to three furnaces running full blast. I can't envision a case where you would actually set up a system that would cost you that much or produce that much heat inside the coach.
Is it possible that you didn't do these calculations?
Good luck.
Tom Caffrey
Tom,
The genset is a 50Kw diesel. It is run on a generac four cylinder diesel, and they say that the consumption will be about 1.5 gal per hour, not that I am questioning anything you have said. I am aware of the cost of operating this unit, but I also know how much it would cost to run the 8V92 to keep heat in the coach, so the genset will cost less to operate than the DD, I think.
There will not be many situation where I will be able to obtain a shore power connection, so I am left with the genset, so I can either heat electrically, or use the hot water coolant, or maybe both?
I am not understanding the difference that you have pointed out between heat and temperature, so, if I may, would you outline the specific differences so that I may understand?
If the generator runs at a constant temperature of 160, and I thermostatically control any feed of the heated water to maintain that temperature, will that not be useable to heat the coach, or might I have to consider adding some electric heat as well?
I have never had any problems providing heat to a coach I have converted before, but this time I have all of you showing me things I may have overlooked.
Let the school continue !!
PCC- the kind of load you're talking about is equivalent to 2-3 houses. Most houses have 100 amp service at 240vac-which is 24kw. I think refiguring your load requirements might be a good idea-unless you're operating a mobile Xray lab. Good Luck, TomC
I have about 200 amps @ 240VAC, and I know that I will be using that much - not a mobile lab, nor will I be using electricity to move the bus (hybrid).
I will be using the coach for purposes that will consume a lot of power (not a grow op, either), and that is why I need to have sufficient heat for comfort while stopped.
So my calcs are reasonably correct, though I tend to always shoot high so that I do not find myself short.
A lot to think about with this one !!
You are all making sure all my 'T's are crossed, and 'I's dotted !!!
It might get the skeptics amongst us involved in constructive ways if you tell us what on earth you are stuffing into a coach that will consume all this power?
And, as noted, why you will need heating at all, if those loads are inside?
We want to help, but cat and mouse games don't proceed well on here.
I'd like to help.
happy coaching!
buswarrior
One of the uses for this coach will be to get out and travel (probably the most personally (for me) motivating).
However, having said that, I also plan to record and document the travels, and the places travelled to, so this vehicle will have a lot of electronics, as well as the equipment to record and produce the documentaries, and hopefully uplink the material from anywhere I am able to connect.
That will be the main power consumption load - lights, equipment, and passenger comfort, 24/7.
A 42KW gen will be almost as big as the bus!!
This generator fits under the bus in one bay - fills it completely. I was amazed that it did, but it was measured at least a dozen times to be sure.
It measures 36" H X 38" W X 77" L and has a 200 AMP main breaker.
With all that generator capacity I'd save all that work and go with electric heat. My coach is all electric with a 15 kw gen set and a electric heater built into each of my 4 hydronic heaters so I can choose which one to use and electric works very well except in the coldest of temps.
BTW-My generator is tied into the buses cooling system so what you want can be done.
PCC, if you are using coolant for hydronic heating, and it is waste heat from the generator, you are going to encounter two problems.
One, your generator is almost certainly going to be underloaded, which is very hard on it's durability. And anytime you are in cold enough weather, the engine will have trouble keeping itself warm, let alone you. A simple way to produce enough heat is to ADD electric heating load when this happens.
Then, you get the heat from the electric heater, and the additional load warms up the generator.
If you start using all that power inside the bus and you are not in very cold weather, you will be needing an air conditioning system as big as the original equipment over the road system to keep you from overheating. This can be demonstrated by doing your BTU calculations.
An easy rule of thumb that will help you is to figure that about 1/3 of the BTU in the generator fuel will turn into electric power. 1/3 will turn into heat in the cooling system and 1/3 will turn into exhaust heat. If you burn a gallon of 140,000 BTU fuel, you should get around 45,000 BTU of electricity. Divide that by 3.4 and you will get watts. In this case, about 13 KWH.
If you capture the available heat from the coolant, you will get some part of that amount in heating the inside of your bus. Since only a few furnaces in buses are larger than 45,000 BTU, you can see that the first gallon per hour ought to be enough to keep you warm in most weathers.
You will probably want to have some way of heating your coach other than the generator just in case the generator goes down.
For what it's worth.
Tom Caffrey
Quote from: buswarrior on December 12, 2009, 07:15:41 AM...It might get the skeptics amongst us involved in constructive ways if you tell us what on earth you are stuffing into a coach that will consume all this power?...
Quote from: PCC on December 11, 2009, 09:47:53 PM...I have about 200 amps @ 240VAC, and I know that I will be using that much...
Quote from: PCC on December 12, 2009, 02:33:41 PM...I also plan to record and document the travels, and the places travelled to, so this vehicle will have a lot of electronics, as well as the equipment to record and produce the documentaries, and hopefully uplink the material from anywhere I am able to connect... ...lights, equipment, and passenger comfort, 24/7...
I'm unfortunately still finding myself in the "skeptic" category... but maybe that makes for some constructive questions about the application...
I work at one of the two companies that makes the super high-end graphics cards for real-time editing and rendering applications - I'm building an uber machine for my home use using all of the highest end gear I can cram into it (dual Xeon 3GHz CPUs, 32GB of DDR3, 2x 32GB RAMdrives in RAID-0, 15x WD CAviar Black RE4 2TB drives in a LSI-powered RAID-6 array, 4x of the new next-gen "Fermi" cards (not yet shipping) with the HD-SDI input/output, a BlackMagic HDMI Capture card, and 32-channel firewire audio interface with 2x 30" Dell 2560x1600 LCD displays. This "uber machine" (of which I build one every ten years or so, and it stays pretty "fast" for that whole decade), still only draws about 1.7kW total at the wall (120V-AC). It is fast enough to do RED-one 4K resolution on AVID/Premire NLE without breaking a sweat. I can also do multi-channel audio mixing and orchestration in ProTools if I need.
This is a full-tower and requires a 5' wide desk (for the monitors and work surfaces).
A professional Live-satellite-uplink would still be less than 10kW... They run these out of normal sat-trucks with only 20kW gens including the power for Air-Cond. (with an 8' dish on the roof by the way...).
Even a 5MP 24HZ H.264 PoE camera is less than 25W (I have one attached to a microscope on my workbench).
I can do that whole setup of of one very heavily loaded 20AMP 120V breaker in my appartment. Even with four 500Watt on-stage flood lights, I can still run that from a 12kW gen and run a bunch of extra stuff. You are talking about 4x that power!!!! Are you running a computer animation render farm in there (72"-rack with 20 servers)? Broadcast is only up to 1920x1080 @ either 24/30fps, I can't imagine you needing more than a Dell Precision Mobile workstation running Adobe Premire to edit/publish video from a Canon Solid-state HD-HandiCam going into the laptop via firewire, and some foam and a good mic to turn your shower into a temporary Voice-over-booth). Then a 3G card to upload that video to an FTP (which won't require an uncompressed-video satellite uplink). This can all be done with less than 200Watts...
Another question for the curious - Have you tried running that 240V/200Amp generator yet? I'm going to guess that it's very, very, noisy (>80dB-A @ 1Meter)...
[Edit]
I guess it boils down to me/us not understanding your intentions - most on this board try to find ways to "sip" power (the .177cal pellet solution) you're talking about a "wet T-shirt contest at a water park" use of power in perspective (the H-Bomb solution), it's way higher than we're used to hearing about here... so we're getting stuck on the genny/power-draw aspect of this. Heating/cooling seems like the least of your worries...
[/Edit]
-T
I havn't read much of the above postings, 'cause I was kinda shocked when I got to
""When running all the A/C systems, the load will be at about 30 Kw. When running with everything on. I will need about 42 Kw.""
What makes me wonder is, when I'm running my camp at Burning man, in 105 degree heat, I bring a 32KW generator and it's associated powergrid that successfully powers
18 RV's and motorhomes. That's EIGHTEEN full sized RV's with their a/c's running all day, and everything else (sound systems, lighting, electric vehicle battery chargers etc)!!! WE do this so that they will not use their own generators, which
makes for a very quiet and very nice non-smelly camp.
So.... if I can power eighteen RV's with a single 32KW genset, how on earth are you using 42KW in one vehicle??
Oh, one last thing... when running this kind of load during the day, and reducing it to around 7KW during the nights, the gene eats drinks around 350 gallons of diesel in a week's period. Do you really have that kind of consumption in mind and a place to store that much fuel?
I, like others, am TOTALLY dumbfounded...
Ok. I'm a belt and suspenders guy. I won't mix cooling systems. You could use a heat exchanger to transfer the heat and maintain seperate systems. The thought that a busted hose on the generator would cause a loss of engine coolant just sends shivers up the spine. I know, people do the interconnect all the time without any problem. However, having spent some years riding submarines I'm in the 'lets not make a problem' camp.
Bill
I have decided not to mix my cooling systems (you have given me enough reasons not to), but I do use heat exchangers to heat domestic hot water heat from the engine while driving. This exchanger will also provide heat to the engine, on cold days, by electrically pumping the coolant through the same exchanger. That was my original question.
I did not see my post, to answer those who question the amount of power I will use when fully loaded. If it is still there, I missed it, so please forgive the repeat.
The system is set up for more than 12 - 500 watt floods for stage and audience lighting, and up to three 1000 watt follow spots. Add to that, 12+ ton of A/C, and the power required to maintain the electronics including cameras, sound board, computers, etc.
Then there is the vehicle with its electric hot water, electric stove, fridge, freezer, interior lighting, air compressor, hydraulic pumps, wheelchair lift, and a number of other accessories, my total came to about 41.7 Kw under maximum load (not likely to happen), but still giving me a margin.
I also have the capacity to add should someone else need some power, but you will remember that the generator was a steal for the price (not telling), and I was happy about that.
So if it fits and more than meets my needs, I am not complaining, though I know it is a monster.
The more I read the input from those who are sharing with me on this thread, the more I am happy about both the caring from those who share this place, and the fabulous technical support I continue to receive.
Thank you to those who talked me out of interconnecting my cooling systems, and to those who kept me from relying on generator coolant for interior heat. I have learned a lot.
Thank you all.
Interesting application... Here's a suggestion though: put in a smaller genny for non-"production" loads. When you kill those follow spots and floods, the load on the genny will drop by around >=25%... Since you mentioned follow spots I'm guessing that you are also planning on running some live sound reinforcement amps/speakers. Those systems draw >1KW meaning your design peak power draw is probably way higher than your average draw...
So it may be in your interest to run the cooking, heating/cooling (HVAC&R), internal lighting etc from a 6-12kW genny and wire your extra cooling/heating to the large genny so it'll run when your roadshow loads are running (I still can't get over the moster system you're putting in ;) - I thought mine was big...).
-T
Again, I have to lean heavily on the "steal" of a deal that I got on the generator itself. It fits under the bus, and will power everything.
Yes, there will ultimately be a major P.A./sound system, and having been a recording and concert sound engineer, I will want more available amplification than I need. (Turn my system up with some old time gospel while driving next to some of those loud cars !!). Traveling as a sound guy is where the bus bug bit me over 40 years ago.
The two generator idea has crossed my mind, but I am running out of bays to put more equipment, so I may have to stay with the big one and let 'er rip, no matter how much it will cost to run. (I might be able to drop up to a gas-powered 5 Kw in a corner somewhere, like behind the former washroom tanks door. Another good idea, thank you.) I have no plans for any propane.
That is why I have been trying to figure out ways to heat/cool the coach with a system that would allow multiple ways to turn the A/C compressor - from the engine and also an electric motor, but how big an electric motor would I need to turn the 12.5 ton A/C compressor? That may not be possible, but we are talking about it. I have always wondered if a system can have two independent compressors working the same plumbing for evaporators and condensors. Seems that that is not possible, as far as I know at this time.
I hope to be using my short bay over the drivers as the heating/cooling unit by insulating it completely, sealing it from outside air, and installing the evaporators, hot water (coolant) radiators, electric heating coils, and the fans into this compartment - and it is big enough to fit it all. I am waiting for the final component specifications to confirm that it will all work.
All I know is that the system cannot go on the roof, so I have to fit it underneath, and that one bay is the least intrusive into my overalll designs.
Thank you, and have a great day.
***********
Yes, there will ultimately be a major P.A./sound system, and having been a recording and concert sound engineer, I will want more available amplification than I need
***********
With amps like the I-Tech and Digam series along with the new LED stage lighting your power requirements for "mobile" off the grid SSL are a fraction of conventional systems - FWIW
40-50 HP to run the OTR compressor. I would put the small genset in the bus and rent a bigger one if needed at the venue. That is what we did .I once did remote recording and live sound for gospel music venues. We typically ran 10,000 watts for amplification . With everything powered up we could run the system with 5Kw with no problem.
James77, which OTR compressor do you mean?
The entire stock HVAC system in the MC7/8/9 and early 102, was considered to be 20-25 HP load at most, compressor and electric combined.
I'm having a hard time keeping track of this thread, so I apologize if I've missed something.
happy coaching!
buswarrior
B Warrior,
If you say it only took, say, 30 HP max, to run (load) your A/C compressor, then would a 30 HP electric motor not also turn that compressor?
I have a motor builder who works to build and rebuild electric anything (motors, generators, alternators, welders, etc.) that works with me (friend/contractor), and he could build me a motor to drive my OEM A/C compressor for when I am not running the main engine?
More ideas???
A 30 hp motor will run you around 2K new, and they are heavy. Then you have to have 240V to run it, 480 would be more efficient. Where are you going to find that kind of power in a bus?
Paul
Yes, Paul, I am the crazy person with the 240 v., 50 Kw generator on board, it fits and was inexpensive, so I have the power. I do not have 480 VAC, though I could wish !!
But am I correct, did you say that the 30 HP motor would run the OEM 12.5 ton A/C compressor? 2K is still less expensive than the cost of the completely new all electric A/C - heat system that I have been considering.
The only consideration would be the start-up load when that 90+ amp motor starts up. I would have to start the motor first, with a heavy flywheel, then connect it (electric clutch) to the compressor, so the motor it is not starting up under load.
Keep talking, I am listening.
It sounds like you need an electrical/mechanical engineer to figure what you are trying to accomplish. That I'm not......... ;) I usually try and run with what I have because it's already been engineered for the purpose. That's just me. ;)
I do wish you luck and I'll continue to read the thread to see the outcome! ;)
Paul
For this exercise, you'd want to know a closer answer to the HP requirements, as you don't want a 30HP motor when a 15HP might do. You'll have to go to original equipment manufacturer for the specs.
In my above 20-25 HP estimate, that includes the stock AC having between 2 and 3 HP worth of electric fans running. So the total combined load to the engine, compressor and alternator loads, are suggested to be 20-25HP.
Not difficult to rig controls so that the load comes on after the electric monster motor is running, if that will be a problem.
happy coaching!
buswarrior