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ism minerals 10-31-2021 09:05 AM

Heating zones for front and back heaters
I plan on using the webasto heater and the front and rear heating coils as a heating source for the bus. The idea is to put two 3 way valves in line and create a closed loop for just heating the bus (with an expansion tank) or flick a switch to also heat the motor as originally designed, bypassing the small closed loop expansion tank. My question is for those that have done anything like this: Did you use one zone or two for this ( ie control the front and back heater independently)? If you used only one zone where there any issues with running the webasto on a single heating coil?

cadillackid 10-31-2021 01:01 PM

let the water circulate through both coils.. set up an electric valve set on your engine heating loops.. you can close one valve and leave the other open under the hood.. have no circulation to the engine but have expansion to / from the expansion tank already in the bus.. my DEV bus is built this way.. when my keys are off one of my 2 heater valves remains Open.. the one that is on the "suction" side of my auxilliary pumps (the webasto pumps).. the other valve is closed. when I drive the bus both of my valves follow the settings from the cab.. (if i want heat then both valves open. if i want heat off both valves close.)..

my bus is built with parallel flow heating.. meaning that i have a supply and return and each heater core has a valve that can open or close..except the rear heater it is always circulating when my main valves are open.. the main lines are 1 inch. my rear heater is 5/8 so it creates a pressure differential to push the water into any open heater core along the way... this way I can have selectable heat when driving for my A/C units which double as heaters..

the fact one heater valve stays open all the time when the bus is Off means that as my system heats and cools it expands and contracts normally using the already-present expansion system for coolant.. if i do want to heat the engine then I can command both valves under the hood open and the webasto heats the interior loops and the engine..

ism minerals 11-04-2021 10:44 AM

cadillackid thank you for the reply, seems very logical to leave the one valve open and allow the engine's expansion tank to work. Less valves overall. How well does the webasto heater work in your application? Did you keep the original fans on the heating coils? I may also run some sort of baseboard heat to reduce energy consumption while not running instead of using the front heater.

cadillackid 11-04-2021 12:10 PM

I installed a Jegs heater in my rear as the read underseat heaters are noisy and dont move a lot of heat.. in the front I have my original fans.. well I completely disassembled the units.. replaced a leaking heater core with a new one and new motors as they were old and yucky.. i wanted my bus to have its original feel up front .. my mid heater is a new system that is A/C, and heat and it has a good blower...

the 12kw coolant heater does OK but the 16kw is much better and keeps the bus much warmer in below 15f temperatures... when its that cold i run 3 blowers. the 12kw heater couldnt keep up in those temperatures.. my bus is all original ceilings, walls, windows and doors and none deleted..

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