| Author | Message | ||
| quantum merlin (Quantum500)
Registered Member Username: Quantum500 Post Number: 23 Registered: 8-2007 Posted From: 67.41.221.134 Rating: N/A |
I've been researching heating methods and none of them really suite my needs and my pocket book at the same time. Any type of diesel fired heater is expensive and uses just as much fuel as a generator. So my question; Can I build a water jacket for the exhaust manifold on the generator and pull all the heat out of the genny? Seems to me if I'm burning fuel I might as well be putting it to work. | ||
| Douglas Wotring (Tekebird)
Registered Member Username: Tekebird Post Number: 266 Registered: 10-2004 Posted From: 71.59.75.212 Rating: N/A |
A webasto airtop unit uses no where near the fuel a generator would | ||
| quantum merlin (Quantum500)
Registered Member Username: Quantum500 Post Number: 24 Registered: 8-2007 Posted From: 70.57.21.17 Rating: N/A |
No it doesn't but I'm already plumbed for water/baseboard heat exchangers. With a airtop I'm out out $2k thats quite a lot of fuel through the generator. Being really pessimistic at $5 a gallon diesel thats 400 gallons. In my particular situation it makes more sense to run the generator. The only thing I'm not sure of is if it will indeed make enough heat. I haven't been able to find any total BTU figures, but I'm assuming it should figure out to equal out to the amount of fuel that is burned. I think the trick is to capture as much exhaust heat as possible. Plus it sounds like a fun project. | ||
| Jim Wilke (Jim Bob) (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 204 Registered: 2-2001 Posted From: 12.8.169.106 Rating: |
Depending on which engine you have on the genset, it may be possible to get a water cooled exhaust manifold if the engine is used by a company that builds marine generator sets. That would be way cheaper and more reliable than tinkering around to put a jacket on your existing manifold & will capture more heat. The bad news is that with the genset lightly loaded, there will not be enough heat (less fuel injected so less manifold heat). So you will need to keep the genny decently loaded to make a decent amount of engine coolant heat. You can do this by getting part of your heat from electric heaters. You would want to keep the genny decently loaded in cold weather anyway to prevent cold issues. As far as how much heat, engine heat is "rejected" to the atmosphere in 3 ways. One is heat rejected through the exhaust gas. Second is to the cooling water (or air if air cooled) and the third is heat radiated from the engine itself (like a hot stove.) Often the engine manufacturer can provide these numbers. Remember that normally these numbers will be calculated at full load. If you don't stay a lot in cold weather, this would be a good system. If you will spend winters in Minnesota you will need to do something else like an LP RV furnace, etc. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 274 Registered: 8-2006 Posted From: 76.168.69.233 Rating: N/A |
QM, Jim has pointed you in the right direction concerning available heat. Two more things to think about though. A gallon of LPG has 94,600 BTU, gas & diesel, 144,000. So, if you burn a gallon of propane an hour through an air cooled gen, at least half of that will go away thru the cooling air, maybe leaving you 50K? Taking that much heat out of the exhaust will lower it below condensing temperature, so everything will have to be stainless steel, and you will need a condensate drain to get rid of the water which has a ph of vinegar! Google a company called "Polar Power" out here in LA, as they were going to make some very high efficiency engine driven heat pumps using both the jacket water and a water-cooled manifold as additional heat sources. Jim also mentions electric load required... Bottom line? I think you will have made a "mechanical furnace" that you can't run during certain hours in campgrounds, and will wear out long before a diesel boiler. IMNSHO, "Won't fly Orville." | ||
| quantum merlin (Quantum500)
Registered Member Username: Quantum500 Post Number: 26 Registered: 8-2007 Posted From: 71.33.238.169 Rating: N/A |
I doubt I will ever stay in a campground, or at least one that is worried about my "mechanical furnace". I would use it a couple times a year during the winter months dirtbiking in the moab area. Thanks for the tip on the condensation drain. Hadn't thought of that. | ||
| Richard Bowyer (Drivingmisslazy)
Registered Member Username: Drivingmisslazy Post Number: 1997 Registered: 1-2001 Posted From: 75.108.77.39 Rating: N/A |
If you are going to run the gen set anyhow, forget about the heat exchanger idea. Just use a few electric heaters. The gen set runs much more efficiently and unloaded gen sets do not like that type operation. The engines have a bad habit of fouling up very quickly. Personally I used a freestanding propane heater for temporary heat when I first started going to the desert at Glamis. Cheap and easy. Richard (Message edited by drivingmisslazy on October 22, 2007) | ||
| JJ Woden (Jj_woden)
Registered Member Username: Jj_woden Post Number: 34 Registered: 10-2006 Posted From: 216.161.223.60 Rating: N/A |
Use an electric water heater along with the heat exchanger. Route the water to the exhaust first, then to the heater and use all your hydronic system. Also use it to heat your diesel engine on cold mornings. If this works or sounds like it should, keep us informed. JJ | ||
| quantum merlin (Quantum500)
Registered Member Username: Quantum500 Post Number: 27 Registered: 8-2007 Posted From: 67.41.221.134 Rating: N/A |
I think it has potential. I'm probably pissing in the wind though, like several replys have stated in not so many words. The coach is basically all electric so if I want to cook or really use any thing other than the fridge and maybe one light I'm gonna have to run the genny. I also have a roof top ac unit with heat in it. So when I run the generator I can give it a pretty good load to make heat. I'd probably be farther ahead just putting propane in it and going that route, but in the long run that will actually add complexity to the whole thing. I hope my thought process makes sense. The idea of an electric water heater would work well too. That way it would give the generator a fair load all by its self. Thanks! I also thought some more about the condensation drain and came up with the solution of just pointing the exhaust down so it automatically drains. It should work well once I get it put together. | ||
| quantum merlin (Quantum500)
Registered Member Username: Quantum500 Post Number: 29 Registered: 8-2007 Posted From: 71.216.90.94 Rating: N/A |
Here is a pretty interesting page off of the polar heat web site that puts thing in perspective http://www.polarpowerinc.com/products/heat_exchanger/heat_exchanger.htm | ||
| Robert Fischer (Rbt137)
Registered Member Username: Rbt137 Post Number: 10 Registered: 7-2006 Posted From: 71.111.98.121 Rating: N/A |
These machines (just the coach by it self) are already complicated machines so we are really discussing how much more complicated do we want it to be. Being practical this is always a cost/benefit issue. My 7KW PowerTeck gen set and the Webasto exhaust into a six foot heat exchanger and then are connected into the vehicle exhaust. The Webasto exhaust circuit has a one way valve in it to prevent generator/8V92 exhaust from exiting through the burn chamber of the Webasto The heat exchanger is five or six inch steel tubing. Inside this tube are sixteen 3/4" copper tubes. Half of the copper tubes carry drinking water and half carry coolant. This steel tube is enclosed in a sightly larger steel tube which is connected to a blower which circulates warm/hot air into the forward bay. The generator exhaust at the exhaust header is 350 F. The Webasto exhaust is 250 F. When in the transit mode, coolant from the 8V92 can heat hot water (20 gal). ((up to 180 F which can be dangerous)) When boondocking ((often well above the snow line)) the generator coolant is connected to the heat exchanger and to the coach heating system. The coolant is monitored and when up to temperature, waste heat is then pumped inside. The coolants for all (8V92, Webasto, coach heat) are all tied together through 24 volt valves. Have I mentioned that this is unGodly complicated? All of this is built (the heat exchanger) so that it can be isolated and waste heat dumped overboard if necessary. (Summer time) The genset radiator is normally completely blocked. (((winter time))) On occasion when the generator is necessary for more than its nominal two hour run (to charge batteries) inside coach temperatures have exceeded 80 F. Solution: open roof vents & turn on the fans. With six roof vents, no problem. Often this will occur when everyone wants a shower. It's not necessarily a bad thing to exit the shower with 80F air as long as the generator is within its operating range. On rare occasions, usually due to a cockpit error, there have been over temperature shutdowns on the generator. There have been times where I've spent half a day looking for problems when a switch in the wrong position. One pump is capable of circulating hot coolant to the 8V92 as it will not spin up in <35 degree weather. Heat source can be either the genset or Webasto. If necessary, this circuit (the 8V92) can be activated and used solely as a large heat sink although this has never been necessary. Winter time, high elevations, full throttle climbs, the radiator of the 8V92 is a comfty 180 degrees. While the 8V92 is operational, it is a interior heat source, once shutdown, this same pump will pull heat from the 8V92 and provide interior heat for another hour. Condensation in the exhaust may be a problem. I have seen 3" of ice drop out of the exhaust behind the left rear tire . I do not like the ice pushing up on the exhaust system and have modified the heat exchanger so that it can dump overboard bypassing the rest of the exhaust. If I expect to be stationary for seven days, this modification is engaged. This is the ultimate in heat transfer systems. It is unGodly complicated. Is it worth it: nope. Will I remove it: nope. Does it make me feel bad when it's cold outside: nope. As fuel passes three dollars a gallon, do I feel better: maybe. FWIW |
