Hydronic vs. Non-Hydronic Heating. (Air & Water)


The question: Given the realities that most modern diesels are light years better than vintage trucks in regards to cold-temp starting and running, I'm wondering if anyone has specific advantages or disadvantages of hydronic vs non-hydronic type systems?

We are currently faced with a decision between utilizing a hydronic-type air and water heating system (which for the record is the style we are familiar with from other vehicles) or using a non-hydronic diesel heating system. Aka: the choice between Webasto Hydronic Thermo Pro vs Webasto Dual Top Evo

Obviously, if you have an older truck that isn't particularly a fan of the cold, or you are looking to explore in some true corner-case cold environments where engine preheating is a true necessity, then the choice is clear. But for a modern truck that doesn't need the preheating capability, I'm wondering if there are advantages of one system over the other? Clearly, Hydronic is more expensive - looking for justification for that.

System Simplicity? Maintenance? Dealing with Cold Weather (outside of the engine preheat argument)? Efficiency?

Thanks in advance for insights and opinions.


Is outside
Go air, easy install. Palcement where you can easily take out to do yearly cleanout of carbon buildup. Enough heat where youll be keeping your vent open some.


Tea pot tester
Do you want hot water?

Also Eberspacher tell me a hydronic has to be outside your living space,their air heater can be inside, air in- and outlets suitably ducted for both of course..

Air ducts will be bigger than a water pipe, so how easily can you get the heated air/water from the heater to where you want it? Too far and the air will have cooled too much perhaps?


Thanks. (And yes on the water per the OP).

Mezmo, because our frame of reference is from a hydronic heat-exchanger for water, we never had to keep water hot somewhere. As a result, we didn't have boilers or hot water tanks and such. Is there a higher maintenance process for the Air that includes those types of things?

I do like the prospect of easy access for cleaning/maintenance so thanks for that.


I chose hydronic for a few reasons besides engine preheat. I wanted hot water from it also, I will be attempting a fanless heating system to cut down on power draw and noise, I would also like a floor heat circuit.


Anyone that has side-by-side experience with the two types (or better yet the two models listed above) that can speak to Adv/Dis?


We run hydronic. Pros: free engine heat for water tank and cabin when running, no fan/blower noise, no short cycling, engine preheat(I don't care how new your vehicle is, at -20C it is an instant start and reduces engine wear).
Cons: heavy radiators required, wall space for radiators required.


Thanks Joe! This is helpful. When you say "No Short Cycling" do you mean the (annoying) turning on/off for brief moments that an air system might need to keep a boiler hot or something similar?

The "free" hot water when the engine is running was something we truly enjoyed about our hydronic. Example: You pull in somewhere late and turn the truck off and still have reasonably hot water to wash your face or something before turning in.

If you think of anything else, post it up.
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with that set up (diesel or LP coolant heater / engine heated coolant ) keep in mind hydronic radiator and hoses etc. ... must be compatible with the type of coolant your engine requires.


Hydronic heaters are designed to heat engine coolant directly, there is no requirement for water to water heat exchangers.