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One of the last systems I've not figured out is the Webasto heating system. There is plenty of documentation but there is some mental block that keeps the light from going on.
In the coach, there is a panel that has two switches: One says Engine preheat pump on/off, the other says burner/exchanger/off.
In the heater bay, there are pipes and valves running everywhere. The diagrams help sort out where they go and what the valves control.
Here is what I think I need to do.
1) Open the valves on the pipes going to the MSR fan heaters in the coach and bays.
2) Open valve leaving Webasto DBW300 and leading to manifold that connects pipes to fan heaters
3) Find expansion tank and check fluid level
4) Turn up theromstats.
5) Flip switch to burner
Check if pump starts up, burner lights up, and feel for heat in the pipes.
Here is a couple images;
coach heater switch panel - https://www.dropbox.com/s/iiwlx87b5n69vsh/IMG_20171212_163830.jpg?dl=0 (https://www.dropbox.com/s/iiwlx87b5n69vsh/IMG_20171212_163830.jpg?dl=0)
Webasto DBW300 heater and pump - https://www.dropbox.com/s/mhs12wqigk477rh/IMG_20171212_163939.jpg?dl=0 (https://www.dropbox.com/s/mhs12wqigk477rh/IMG_20171212_163939.jpg?dl=0)
Pipes and valves - https://www.dropbox.com/s/q23ebqur3pk6mxe/IMG_20171212_163945.jpg?dl=0 (https://www.dropbox.com/s/q23ebqur3pk6mxe/IMG_20171212_163945.jpg?dl=0)
Heater plumbing diagram https://www.dropbox.com/s/h0bhsadltt2t2sc/IMG_20171215_181709.jpg?dl=0 (https://www.dropbox.com/s/h0bhsadltt2t2sc/IMG_20171215_181709.jpg?dl=0)
another diagram - https://www.dropbox.com/s/6qoy7pwrrvm0blc/IMG_20171215_193425.jpg?dl=0 (https://www.dropbox.com/s/6qoy7pwrrvm0blc/IMG_20171215_193425.jpg?dl=0)
Other configurations I can deal with later such as loops pushing webasto heat thru the fresh water heater and the 8v71 heat exchanger. Not even sure if it is designed so the engine heats the coach or the webasto is supposed to heat the motor via the exchanger. LOL
A webasto is not a system that i consider a reliable heat source.
I appears that your pump is on the return side of the system. Probably ok, but not my choice, though I understand why they did it this way. Also looks like you have two gate valves on the supply and return. Both will need to be opened.
You're steps seem reasonable.
The heat exchanger seems to have a pump on it. I would assume that is an engine preheat pump. You probably don't need that while driving. If plumbed to the engine correctly, the engine should circulate through the exchanger loop while driving and you should be able to neat the domestic water with that. Probably need to circ pump on, though as the exchanger is a closed system with the engine. I doubt that heat exchanger will be big enough to heat the coach off the engine. You'll need to use coach heat or run the Webasto while driving to heat the coach.
Can't really tell where that 3-way valve goes. Seems to be cut off on the bottom of the schematic.
Quote from: gumpy on December 15, 2017, 07:40:42 PM
If plumbed to the engine correctly, the engine should circulate through the exchanger loop while driving . . .
Is that from the 1"-threaded outlet on the driver-side thermostat housing on a 6V92?
John
Quote from: Iceni John on December 15, 2017, 07:53:57 PM
Is that from the 1"-threaded outlet on the driver-side thermostat housing on a 6V92?
John
That would probably work well.
On mine, I tapped into an existing line coming out of the block on the passenger side. Might be the air compressor coolant line. Don't recall offhand. The return goes into the coach heat return line next to the mounting rails in the MC9. Works fine. Obviously it's going to be the hottest.
I've seen them tapped into the coach heat lines inside the tunnel, but that was too confined for me to feel comfortable cutting and soldering in there.
Quote from: eagle19952 on December 15, 2017, 07:17:24 PM
A webasto is not a system that i consider a reliable heat source.
I would have to disagree. Like any other device a Webasto needs maintenance. From the experience of hundreds if not thousands of conversions with a Webasto or Espar or Hurricane system these diesel powered heat exchangers are reliable and fuel efficient. All of them however require exercising on a regular basis because the most likely trouble spot is the nozzle that gets plugged from the waxy substances in fuel if not used routinely.
There are other items that may occasionally need attention such as cleaning the electronic "eye" or making sure the points for the igniter are set correctly but generally speaking Webasto and other similar heaters are pretty reliable.
Your 1st time use have someone tune the system and walk you through how the system works money well spent IMO
nice looking set up . with mine I just turn on the boiler switch and set the thermostats and all is good + it heats the hot water
I agree about getting someone with experience walk you through the set up
dave
Quote from: sledhead on December 16, 2017, 05:49:43 AMnice looking set up . with mine I just turn on the boiler switch and set the thermostats and all is good + it heats the hot water ...
dave
Do you also have a way to transfer heat to the engine block for engine preheating, Dave? IWSTM that that's pretty much a perfect home run for a heat source. Also, a system set up like that should give you OTR heat in the coach and "endless/free" hot water (from engine coolant).
We had a nearly identical setup on our previous coach. It had not been run in some time and needed maintenance. I finally admitted defeat and sent it to Lloyd De Gerald, who is a trained tech on these units. He went through the unit, cleaned it and did maintenance, and sent it back quickly. Best money I spent getting the heating working again in the coach. He's got the test unit for the Webasto control box so he can confirm that everything is working properly. Send me a PM and I'll forward you his contact information. Lloyd will also walk you through the steps to be sure that the Webasto is getting proper power in the proper places.
When working properly the unit should make enough heat to keep you toasty. Whether you run it while on the road depends on whether or not your OTR (factory) heat is still in place. If it is still there then you won't need to use the Webasto while on the road.
The engine preheat is used only when you want to get the DD warmed and ready to start. One ours the Webasto heat was not sent to the engine unless the switch is flipped. Otherwise, you'll be throwing your heat overboard and out the back of the bus needlessly. On ours, the engine pre-heat switch turned on a secondary pump which diverted the heated fluid through the loop going to the engine. Looks like yours might use a valve to open the engine heat exchange loop.
You can also check your thermostat to be sure that it's functioning properly, as that can cause the whole works to stall. Same with the two main fuses that power the Webasto.
There is dozen of ways to skin the cat on those heating systems I have seen neat installs by owners with no valves and I have seen some cobbled up systems with valves and pumps.Parts for those are expensive and you can screw one up if not careful because they are touchy lol I have 2 units laying in the shop now owners have screwed up
Quote from: eagle19952 on December 15, 2017, 07:17:24 PM
A webasto is not a system that i consider a reliable heat source.
Disagree, I use mine constantly. However, if you arent a master at maintaining things, look somewhere else. You have to stay on top of these or else they get expensive to fix.
Quote from: opus on December 16, 2017, 09:57:04 AM
Disagree, I use mine constantly. However, if you arent a master at maintaining things, look somewhere else. You have to stay on top of these or else they get expensive to fix.
They are expensive for parts the board for 1 was over 400 bucks and the coil was 500 bucks 24v on a 12v system is not all that good ???
OK. rephrase. There are better options.
What are those options. I have had heat pumps, propane furnaces, electric heaters etc. but hands down Webasto is the most efficient, can heat the engine also, and over the last 13 years has been reliable.
Hard to beat so I am curious as to what you think might be a better choice.
Quote from: Jon on December 16, 2017, 12:45:35 PM
What are those options. I have had heat pumps, propane furnaces, electric heaters etc. but hands down Webasto is the most efficient, can heat the engine also, and over the last 13 years has been reliable.
Hard to beat so I am curious as to what you think might be a better choice.
The propane furnace in our current coach is one option, but I'd hesitate to call it a better choice. I'd exchange it for the Webasto in a heartbeat. Webasto used a fuel already on board, was more powerful, and it had the ability to preheat the bus engine and generator. With our current setup I've got to figure out how to plug in the engine block heater before taking off for the day. This means running the generator, but of course it will be just as cold and difficult to start as the bus engine. The Webasto was plumbed to both the bus engine and the generator, so if the inside of the coach was being heated by the Webasto a flip of a switch and the generator and bus engine could be warmed up. Nothing about the propane furnace even comes close to that.
As a side note, yesterday I did verify that the generator will start with an outside temp of just 25F. The glow plugs work, but it did take more than a couple of attempts to get the Perkins to fire up. Our old coach with the Webasto was much easier.
I stand by my suggestion to contact Lloyd De Gerald. Your unit appears to be mounted in a way that makes access very easy, so you should be able to break it open and do some simple troubleshooting with him on the phone.
I had the Primus (propane fired) system in a Eagle I liked it much better than the diesel fired Webasto (Aqua/Hot) had all the functions like demand hot water and engine warming.Used less propane than the Aqua Hot used in diesel.The Primus was so quite,didn't smoke or stink either and very little maintenance in the 10 years I owned it.LOL Webasto's sound like helicopters at 3 am
Bruce my Webasto does it all ,pre heat engine and yes the heat from the engine will keep you warm when driving saving you 2 heat sources but when it's really cold out I have found that if you use both systems ( engine , Webasto ) there is lots of heat and as of yet no large repair bills
because I store the coach in the garage I have a magnetic cat electric heater to pre heat the engine when its cold rather then run the diesel boiler inside the garage
I had a pro heat diesel system on the M C I and it did the same thing
dave
I solved the stink problem and quieted some of the sound by putting a stack on the exhaust . now the stink goes up above the roof but yes it makes noise out side when running but nice and warm inside
dave
I installed A Webasto in my RTS .15 years ago. Does it all like above. I.got to quit trying to type, road is too bumpy. No, I'm not driving. Oh.mine is in an enclosed sound. Box
Thanks for the tips. Lloyd has a webpage http://lloyddegerald.com/ (http://lloyddegerald.com/)
NorCal wimp here - today 60 but too windy. Heading to the bus tomorrow and will give it a go. I think the posted diagrams are not accurate as built, so I'll validate them too.
If it acts odd or cranky, I'll give Lloyd a call on Monday to walk me through it.
Was not aware it is good to turn it on regularly to keep things working well.
Thanks
Don
Was not aware it is good to turn it on regularly to keep things working well.
Thanks
Don
[/quote]
That is what I like about my on demand hot water it fires every time you turn the hot water on,it was getting a little annoying though so I install a electric heater for storage where it doesn't come on if plugged in or I can make hot water from the engine will driving.Caution watch the exhaust it gets very hot like 500+ degrees
Quote from: Jon on December 16, 2017, 12:45:35 PM
What are those options. I have had heat pumps, propane furnaces, electric heaters etc. but hands down Webasto is the most efficient, can heat the engine also, and over the last 13 years has been reliable.
Hard to beat so I am curious as to what you think might be a better choice.
it wouldn't matter what i thought.
Quote from: windtrader on December 16, 2017, 04:06:25 PM
Was not aware it is good to turn it on regularly to keep things working well.
Thanks
Don
Actually, the Webasto not having been run in many years also took out our generator on that coach for a while. Happened when I pulled the Webasto to send it for repairs. There was a lot of bad/stale diesel in the lines to the Webasto. The generator apparently drank through the same straw as the Webasto, and removing the Webasto from the loop allowed the bad fuel to find its way to the generator. There was enough of it to clog up the generator's fuel filter and cause it to not run.
Lesson learned - don't let equipment sit idle without either periodically running it or properly preparing it for storage.
Quote from: sledhead on December 16, 2017, 02:49:59 PMBruce my Webasto does it all ,pre heat engine and yes the heat from the engine will keep you warm when driving saving you 2 heat sources but when it's really cold out I have found that if you use both systems ( engine , Webasto ) there is lots of heat and as of yet no large repair bills because I store the coach in the garage I have a magnetic cat electric heater to pre heat the engine when its cold rather then run the diesel boiler inside the garage
I had a pro heat diesel system on the M C I and it did the same thing
dave
Thanks, Dave. We used Webasto systems in super-cold spec Land Rovers from our Special Vehicles operations and also also military vehicles and found them reliable and useful. I appreciate your info, it sounds like you've got a great system going for you.
I too have a webasto for cabin heat and engine preheat. We also have heat pumps for electric, and propane brick heaters. Since installing the webasto system I haven't even fired up the propane. Webasto is just so much nicer, and warms the floor too. I have a loop that runs the full length of the bus down the center. Takes the chill off the floor on those brisk mornings.
To the op, for the first time you fire it up, have someone stay next to the webasto to monitor it until it completes it's first cycle and shuts off. You are listening for signs that the coolant is beginning to boil. If you miss a valve somewhere or the stir pump isn't working it will start overheating. If you shut it down quickly enough you won't have to replace the overheat thermostat. (Newer ones are resettible, older ones not)
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Did your DL have the factory unit installed already back on drivers side rear corner, mine had 1 there that I removed lol I didn't need 2 of those sucking fuel.I think John and Steve rigged it up to boon dock in the Arctic I removed 6 heat ex-changers and still have 6 left in a 5 zone system plus the drivers heater is tied in to the system
Quote from: Jon on December 16, 2017, 04:59:33 AM
I would have to disagree. Like any other device a Webasto needs maintenance. From the experience of hundreds if not thousands of conversions with a Webasto or Espar or Hurricane system these diesel powered heat exchangers are reliable and fuel efficient. All of them however require exercising on a regular basis because the most likely trouble spot is the nozzle that gets plugged from the waxy substances in fuel if not used routinely.
There are other items that may occasionally need attention such as cleaning the electronic "eye" or making sure the points for the igniter are set correctly but generally speaking Webasto and other similar heaters are pretty reliable.
What Jon said. FWIW my favourite truck shop told me he could fix Webastos in his sleep but, although he owned some, he didn't have any idea of how to work on my Proheat. They're mechanical devices so they don't tolerate neglect. I'll echo the advice to be aware of where your exhaust is pointed. Mine would burn a 10 inch hole in the grass. The Proheat was never quiet but once I got it sorted out it was dead reliable and its a pretty simple machine - change the filter once in a while and clean the combustion chamber was pretty well all it asked of me. Anyone who says they are unreliable hasn't taken the time to understand them.
Quote from: luvrbus on December 17, 2017, 08:01:53 AM
Did your DL have the factory unit installed already back on drivers side rear corner, mine had 1 there that I removed lol I didn't need 2 of those sucking fuel.I think John and Steve rigged it up to boon dock in the Arctic I removed 6 heat ex-changers and still have 6 left in a 5 zone system plus the drivers heater is tied in to the system
Mine has the factory 2020 in the engine compartment. I replumbed the system into heat and preheat zones so as not to dump heat outside when just warming the inside. I have 4 heat exchangers and the floor loop. You can make it as warm as you want inside.
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Went to the coach today.
Opened the heater bay, made sure all the valves were open, then went inside, turned up all the thermostats, flipped the switch to burner, noticed the green light, then went back to the bay. Heard the pump going and in just a few more seconds, hear the woosh of the Webasto firing up and the exhaust belching out hot air.
After a minute, the supply side pipes were warming up nicely, went back in the coach and felt nice warm air coming out of all the registers. Wohoo!
After some time, the coach seemed nice and toasty and the burner turned off. Was not certain what triggered it to stop but assuming a thermostat was triggered. I did not check all the radiators in the bays so not sure what was going on there this time around. Two of the bay heaters are thin finned pipes running underneath the fresh water, gray and black tanks. Going to be hard to figure out how warm they are getting. The one in the open bay is easy to check.
Spent time following pipes around and updated the heater system schematic. None of the ones I had was accurate but one was close and with some updates it is really close. Did not look for the expansion tank mounted in the coach so could not verify the routing of the piping.
Also, did not chase the piping into the engine bay to confirm how that is working. The diagrams show a pump on that circuit but what I see seems really small for a pump but maybe it doesn't need much volume to the engine block. Check out second link. The "pump" is the black vertical round barrel shaped thing in the upper left of the image.
All in all, a very happy busnut today. Seems to be working super.
https://www.dropbox.com/s/k0yzg3lrvaz147t/Coach%20heating%20schematic%20as%20built.jpg?dl=0 (https://www.dropbox.com/s/k0yzg3lrvaz147t/Coach%20heating%20schematic%20as%20built.jpg?dl=0)
https://www.dropbox.com/s/q23ebqur3pk6mxe/Coach%20heating%20bay2.jpg?dl=0 (https://www.dropbox.com/s/q23ebqur3pk6mxe/Coach%20heating%20bay2.jpg?dl=0)
Pump looks similar to the Bosch pump mine had. Always seemed to do the job.
Generally speaking (all installations are different) when the Webasto is functioning correctly the circulating coolant will be limited to 160 degrees, at which point the burner will shut off. I can't remember the temp when the burner kicks back on but once the system reaches temp the burner is going to cycle.
Also, depending on the engine operating temperature, once everything is up to the normal range the Webasto will not fire, but all other functions will operate as long as the engine loop is open. In cold temps I can use the Webasto when driving instead of the coach over the road heat and AC and because my normal engine operating temp is 195-205 my Webasto burner does not fire.
Excellent thread, and great news on your functionality!
The troubles busnuts have with diesel fired coolant boilers are self-inflicted.
As noted earlier, they are maintenance dependant. All who own one need to read and understand the maintenance requirements. Cleaning the soot from the sensor eye that detects the flame at least annually smooths out that common problem.
The other area is system design flaws. These things need minimum FLOW specs met. The boiler has to be able to shed the heat it is making. This manifests itself as burner short cycling, when the coach interior is not reaching set temps. The boiler is reaching the 160, but it can't be carried away fast enough. Downsized piping somewhere, mistakenly using flow controls designed into zones for temperature control. Some of these issues won't show themselves except under certain operating conditions.
These coolant boilers also come in various strengths. The BTU rating for the unit, and then the size of nozzle installed in the burner.
Money saving tip: get your replacement nozzles from a regular heating supply house, the branded ones are horribly marked up.
Happy coaching!
Buswarrior
You need to carry a few parts for those because they always stop working when you need one the most. :o
They are not cheap to run when fuel prices increase figure 5 gals a day on average in cold climates a few gals more a day if you have grand kids in and out and taking showers.
Then add generator time and fuel it gets up there in a hurry
Quote from: luvrbus on December 18, 2017, 05:40:09 AM
You need to carry a few parts for those because they always stop working when you need one the most. :o
They are not cheap to run when fuel prices increase figure 5 gals a day on average in cold climates a few gals more a day if you have grand kids in and out and taking showers.
Then add generator time and fuel it gets up there in a hurry
i can meet most of my needs per day on 5 gallons of diesel...and get more than heat.
all my needs are met by Edison. :)
The most reliable engine heating system is the electric block heater-that is basically a heating coil that you screw into a specific place in the engine block. I have one on my 3406B Caterpillar. It was plugged into my on board generator. Whenever the generator (gasoline 6.5 Onan Emerald III commercial) was running, the 1500 watt block heater was on to give the generator a load. Because of this, my first generator lasted 12,000 hours. Also, I had Arctic Fox loops in my water tank and my primary fuel tank. At night, I'd crack open the ball valve and had a 120v boiler pump that pumped the coolant through the loops to keep from freezing. It was so reliable, in 800,000 miles of driving over 10 years, never had a problem with it. I don't think you can say that with a Webasto. Good Luck, TomC
@Richard
When I get free time I'll put a volt meter on that pump and flip the engine heat exchanger switch in the coach to confirm that is what is connected. Also, try to get some make/model info off it; could not see anything visible on first glance.
Jon - The coach was toasty but the thermostats were all cranked to max. I could find no reference to a high heat shutdown circuit in the docs. What might have triggered the shutdown is one of the t-stats got to temp and triggered the burner shutdown. Since the system has not been balanced, heat was not evenly distributed to all the heaters.
Clifford - The DBW300 is rated 100K Btu and consumes 3.3 pints/hour. I guess if it were running full tilt you better make sure you got fuel in the tank. Then again, what busnut is watching the fuel gauge or cost of fuel. There is a small electric block heater but swapping for a full sized electric space heater to get "free" heat while on shore power. LOL
BW - There is a LOT to properly engineering a good water heating system. Everything I read is reflected in the build. Pipe sizing, runs, flow control valves, pump volumes, etc. Like I said earlier, I'm pretty sure one of the tstats triggered off due to system not being balanced. Will do that next time around.
I need to go check again but I think the motor has an electric block heater too. If so, then the heat exchanger is primary there to use heated engine coolant to drive the water heaters. Guess it can go both ways.
If it is a 100 btu Webasto it going to short cycle lol pay no attention to hourly burn check it in cold weather after 24 hours,they make a inline a electric heater for the Webasto check around I see them used all the time for sale ,my system has the electric backup
Quote from: luvrbus on December 18, 2017, 04:17:30 PM
If it is a 100 btu Webasto it going to short cycle lol pay no attention to hourly burn check it in cold weather after 24 hours,they make a inline a electric heater for the Webasto check around I see them used all the time for sale ,my system has the electric backup
I have a 6 gallon boiler tank with dual 2000 watt elements. On electric only it will keep the inside comfy down to about 35 outside temps, then you better switch on the diesel. The extra 6 gallons in the tank keeps the webasto from having to run as often and keeps it from short cycling when it does come on.
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Fyi if you are running a 2020 or a 300 and your system is small enough capacity that it is causing extreme short cycling, you can put a smaller nozzle in the burner. I have been running a 0.4 in my 2020 for over a year now with very good results.
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On most Webasto units (also used as the boilers in Aquahot) there is a control module that is mounted on the unit. That control module regulates the burner by measuring the coolant temp. The control module has a specific sequence of events that must take place before fuel delivery and ignition, the burn cycle and shut down of the burn cycle. When the Webasto is on-line typically the circulation pump runs 100% of the time and the control unit regulates the burner to maintain hot (160 degree) coolant that is circulating based on the valve positions, such as to the engine, HW tank or coach interior.
The thermostats inside the coach regulate the heat exchanger fans. The two system controls are separate and unrelated. The coach interior can have one thermostat or several depending on how the converter set up the coach, and generally all the thermostats control is fan operation.
Since there are an almost infinite number of ways Webasto systems can be installed and controlled an owner just has to go through the pain of following the plumbing, valves, thermostats, etc on his coach to make heads or tails of it.
I am trying to sift through all these posts and I am puzzled. I have a 2010 Webasto that puts out 45,000 btu's. It "short cycles" if I am heating the engine AND interior. If I am just heating the interior the cycle time is longer apart thus saving fuel. A 1500 watt block heater only puts out 5,100 btu's. That is barely enough to heat the engine, much less the interior. I have a 2500 watt in-line 120v coolant heater that keeps the interior from freezing, but I haven't tried to double it up and heat the engine also. That is what the Webasto is for.
The electric engine block heater is not designed to heat the interior of the coach. Will probably not be able to even touch that in cold weather, even if you have circulating pumps running to keep the coolant running through the heat exchange units.
If the Webasto is short cycling when the engine loop is on I'd suggest making sure the pump in that loop is working and make sure that all the valves are open.
On ours when heating the interior, the burner only fired when the thermostat called for heat. The main circulating pump and the unit's blower kicked on first. When they were both running the control box on the Webasto would fire the burner. It would burn until the water in the main loop got to the preset temp, and the burner would fire on/off as needed to keep the water at temp. Once the water in the loop reach the proper temp, the blower which brought warm air into the coach would turn on. When the temp inside the coach was at the temp on the thermostat the burner would shut down, but the blower on the unit and the water circulating pump would keep going until the main boiler got below the temp set for cool down. The interior blower would shut down immediately when the temp at the thermostat was reached. One of the goals I had was to minimize the 12v draw while using the Webasto, so only the required parts would run at any given time.
When the outside temp is not too cold it would only take a few minutes for the coach interior to hit the thermostat temp. If you've got poor insulation it could drop again quickly, causing the Webasto to cycle on and off more frequently. When the outside temp is colder you'll get longer run times.
When pre-heating the engine on our the burner would fire until the coolant in the loop was to the preset temp. If the volume of water is small or if the temp is not that cold it will only take a short time to bring the temp up and the burner will shut down. It will of course start up again as soon as the water temp drops. On ours, when the engine pre-heat was turned on the smaller Bosch pump was always running as was the main circulating pump. When we ran the preheat only, the whole thing ran just like the hot water heating system in a house - the only temp control was the one that tried to keep the coolant at the proper temp at all times.
51,000 BTUs is a lot of heat if your outside temps are not too low, so it wouldn't surprise me if the burner only runs a short time on each cycle.
Hope this helps. I know that your unit is probably set up differently (as they all are) but hopefully knowing how the logic on ours functioned will help you figure out yours.
Richard, I think the interior thermostat only controls the heater fans. The Webasto should be independently controlled by an off on switch that cycles based on coolant temperature. There is nothing wrong with my system, I was just wondering about what everyone else posted that doesn't ring true. ???
Generally you have 2 options for temperature control for the Webasto itself. The Temperature Control Thermostat comes in 167 degree or 158 degree versions. There is also a Temperature limiter that is set for 203 degrees. Then if things really go sideways and you manage to get to 280 degrees, the over heat fuse blows and you get to spend $100+ for a new one.
Quote from: opus on December 19, 2017, 08:03:26 PM
Generally you have 2 options for temperature control for the Webasto itself. The Temperature Control Thermostat comes in 167 degree or 158 degree versions. There is also a Temperature limiter that is set for 203 degrees. Then if things really go sideways and you manage to get to 280 degrees, the over heat fuse blows and you get to spend $100+ for a new one.
I blew so many overheat fuses due to air locks I installed a 205f N.C. engine overheat switch in the output hose of the Webasto. Now I run the circulating pumps before turning on the Webasto until I can hear that all the air has been purged.
In the on-hand Webasto documents, nothing provided on the internal workings of the heater. The complete repair manual is available online. I'm sure the answers lie there.
Usually it is great having documentation supplied with the conversion. Sometimes too much documentation is confusing. Finally, after reconciling the different versions of the design and the actual inspection (pictures) of the as built coach heating system, the following diagram reflects the best take of how it actually is plumbed up.
'
https://www.dropbox.com/s/wx0ujdcvsxwwlbk/Coach%20heat%20As%20built.png?dl=0 (https://www.dropbox.com/s/wx0ujdcvsxwwlbk/Coach%20heat%20As%20built.png?dl=0)
Update:
Reviewed the factory service manual. Following are references to the control aspects of the heater. There is a control unit that manage the heater through the attached sensors. It seems the magic number for heater shutdown is 167, what was mentioned earlier.
From the service manual
For control and monitoring, the heater includes:
– a control unit
– an overheat fuse (non-reset)
– a temperature limiter
– a temperature control thermostat
test switch/ timer
- test control thermostat on heater Normal operating range
- approx. 75 °C (167 °F) or higher
open (no heat required)
- approx. 68 °C (155 °F) or lower
closed (heat required)
Since the heater operates in the 68 °C
(155 °F) to 75 °C (167 °F) On to Off / Off to On
range, and the vehicle engine may be hot [e.g.
coolant above 75 °C (167 °F)], the heater will
not start until the coolant temperature is below
68 °C (155 °F). THIS IS NORMAL and does not
indicate a problem.
Quote from: Geoff on December 19, 2017, 07:56:44 PM
Richard, I think the interior thermostat only controls the heater fans. The Webasto should be independently controlled by an off on switch that cycles based on coolant temperature. There is nothing wrong with my system, I was just wondering about what everyone else posted that doesn't ring true. ???
Like I said, they are all installed differently. On ours when the temp setting on the thermostat was met the control box on the Webasto had the power cut and it went into a controlled shut down procedure. Only if the engine pre-heat was turn on did the thermostat act like yours.
But, if your system is installed in a way that the thermostat only controls the fans your Webasto will certainly cycle on/off quite often when the interior fans are not running. There will be nothing to dump the heat from the loop. If your high & low temp settings on the coolant loop are close together you can expect an even shorter on/off cycle. It won't take very much firing of the Webasto to bring the coolant temp in the loop to the upper limit.
If you ever plan to dry camp and run the Webasto just on 12v this setup will drain your batteries pretty quickly. Not sure if there are changes on your system that can be made to reduce power consumption. Not sure if you need or want to make the changes. That's up to you.
Also, if you get air locks in the system between running the unit then you might have a leak somewhere or may not have fully purged the air from the many places it can be trapped. On ours, once I got the air purged from the system I did not encounter any additional air locks. This did require me to burp a few of the lines and the move them around to encourage air to go to the bleed point.
Thanks for the advice, Richard. However, I have had my Webasto for over 15 years and I know exactly how it operates. I do my own maintenance and repairs and it works exactly like it should. I don't have any problems anymore. Again, thank you for your help!!
Every aquahot/hydrohot or hurricane packaged system operates the same way as far as what the thermostats do. The main diesel switch turns on the system, control thermostat is mounted on the burner unit or the tank and controls the burner according to coolant temp, wall thermostat controls zone pump and fan. Having the wall thermostat control the burner operation is not optimal system design and no manufacturer of packaged systems will build it as such. The only reasonable exception imho would be a home built system with a single heat zone and no buffer tank.
Having said that, everyone has their own ideas and opinions. Your bus, your way.
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