Getting cold - need heat

[richard5933]

Pump looks similar to the Bosch pump mine had. Always seemed to do the job.

[Jon]

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.

[buswarrior]

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

[luvrbus]

You need to carry a few parts for those because they always stop working when you need one the most.
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

[eagle19952]

You need to carry a few parts for those because they always stop working when you need one the most.
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.

[TomC]

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

[windtrader]

@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.

[luvrbus]

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  

[thomasinnv]

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.

Sent from my SM-G930T using Tapatalk

[thomasinnv]

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.

Sent from my SM-G930T using Tapatalk

[Jon]

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.

[Geoff]

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.

[richard5933]

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.

[Geoff]

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.   

[opus]

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.