Mixing/connecting cooling systems

[PCC]

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.

[pvcces]

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

[PCC]

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 !!

[TomC]

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

[PCC]

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 !!!

[buswarrior]

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

[PCC]

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.

[gus]

A 42KW gen will be almost as big as the bus!!

[PCC]

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.

[Damn Yankee]

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.

[pvcces]

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

[Tim Strommen]

...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?...

...I have about 200 amps @ 240VAC, and I know that I will be using that much...

...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

[boogiethecat]

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...

[Bill B /bus]

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

[PCC]

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.