Using OTR heater blower and exchanger for normal heating.

[neoneddy]

The other thread on winters got me wondering.  Has anyone just plumbed a webasto heater into the normal coolant line and , or maybe easier, used a secondary heat exchanger in the same heater core compartment to get  that space warm and then to use the OTR blower to circulate warm air?  like a normal home forced air system? 

I left my returns intact and  recreated the original side vents along the sides. Seems like the simplest way.   I'd love an aquahot, but even a refurb unit / used unit is $3-4k .   

Other than insulating around the vents some , I think the real hurdle here is a seperate speed controller for that beast of a motor.   Which to be honest I wouldn't mind anyway when going don the road... just to dial the fan speed down sometimes.

So anyone even gone here?

[richard5933]

Might work when you're plugged in. That OTR HVAC fan draws lots of power, so I don't know that it would be efficient for use off batteries though. Our Webasto on our 4106 used some low-current 12v blowers to move air through the heat exchangers. We could have gone for days with our Webasto on 12v compared to maybe a few hours trying to power the big fans in the HVAC system.

You'd also have to find some way to isolate the engine from the system when you're camping, as the engine would be a huge heat sink that served to suck all the heat out of the system and send it out the back of the bus into the atmosphere.

Our Webasto did have a connection to the bus coolant loop. This was used only when we wanted to use the Webasto to pre-heat the bus engine. At all other times there were valves to keep the hot coolant where we wanted it, inside the Webasto loop serving the interior heat exchangers.

Another thought is that sometimes it's nice to have redundant systems. One day you might have a leak in the OTR system and have need to temporarily shut the valves bringing coolant forward from the engine bay. With the Webasto system you'd at least still be able to keep warm while driving.

[neoneddy]

Well mid post there above, I think I realized having a redundant system would be best. but still using the same blower.

I found a reasonably price webasto  (heater only for $500) , I was thinking.  What if I find a radiator or two to  put in the same heater bay.  So two systems for heat generation, but one for air circulation.

I've been trying to find out the amperage draw for the blower.   I'm thinking I could find a newer brushless motor or something that might be better on power.

[opus]

You found a Webasto for $500?

Personally, I would never isolate the engine, and I dont.

[neoneddy]

https://minneapolis.craigslist.org/hnp/for/d/webasto-thermo-top-w-diesel/6673883010.html

[opus]

You must be talking about heating a bay then?

[Lee Bradley]

https://minneapolis.craigslist.org/hnp/for/d/webasto-thermo-top-w-diesel/6673883010.html

Nice boiler I have one. Makes up to 17,000 btu. I use it to for floor hydoric and five toe kick heater does ok here in Pacific NW.

[richard5933]

Isn't that Webasto intended for pre-heating an engine? Will it produce enough BTUs to do much in the way of heating a bus to make it worth the effort?

The 2010 units like we had in the 4106 make about 45K, much more than the Thermo Top.

[Jeremy]

Isn't that Webasto intended for pre-heating an engine? Will it produce enough BTUs to do much in the way of heating a bus to make it worth the effort?

The 2010 units like we had in the 4106 make about 45K, much more than the Thermo Top.

Yes they are - I bought one for my bus and then sold it again and bought a much bigger Webasto instead when I realised that the Thermo Top was way too small for anything other than what it's designed for, which is preheating car engines. In fact ironically I now the same heater again because there's one on my diesel Range Rover. They come as OEM equipment on many different car models, which is why Ebay is full of them. I dare say they'd do a decent job of heating the interior of a VW microbus or something, but I think you'd be disappointed using them in anything bigger.

Jeremy

[buswarrior]

Yes, you can plumb. A big Webasto into the lines heading forward to the stock HVAC system.

Efficiencies aside, it works just like the coach does going down the road, including lots of fresh outside air.

My MC8 was a mobile classroom in its earlier life. A DBW 300 webasto in the middle bay, plumbed into the forward flow pipe. A little bypass wiring and a switch, and the coach blowers and the temp control all worked as designed.

Of coursen you need to have a healthy 24 volt power source to keep those big fans blowing, but it's cold out...

The engine and its cooling system provides a handy expansion tank function.

For the weekend busnut, you can "waste" a lot of heat before all the valves and hoops get paid for, in efforts to be efficient.

For a full timer, this system would NOT be easy on the wallet...

But, my coach would stay warm inside, at a high price, anywhere on this continent...

Many efficiency pursuits never pay for themselves, when busnuts and internet forums collide...

Happy coaching!
Buswarrior

[buswarrior]

And, all your 4 stroke highway coaches already come with a hydronic boiler as part of the original equipment...

Already bought and paid for, and plumbed in someplace...

Happy coaching!
Buswarrior

[Geoff]

I use a 45,000 BTU diesel Webasto, and it makes cozy heating when routed into the loop for the driver's heat.  The system includes the water heater, two box heaters, and the driver's heat.  All run by a wall thermostat.  If I want the engine pre-heated, I just turn on the loop to the engine.

[dtcerrato]

Our conversion maintained the OTR heating & ventilation system, we removed all the AC portion (dedicated 4 cyl gas engine, 84,000 btu Trane compressor & evaporator/condenser) The large heater core under floor is operational as is the dash heat. Original ducting is maintained with ducts going also into bottom compartments. We have 2000 watt heat coils mounted on the under floor heater core for stationary heat. When where not on shore power or running the genny the 34,000 btu LP furnace forced air is distributed by the original otr heating & ventilation ducting - there's redundancy there & options. The greatest thing about using the original ducting over interior space heaters which we also have as option is the warmth is "deeper" in the vehicle so when the furnace (or other options) are blowing through the original ducting - at the end of a heat cycle - the cabin stays warmer for a longer period of time before another cycle starts. Alaska was always on our minds even back in the 70s -80s when we were converting the ole' girl.

[eagle19952]

I dare say they'd do a decent job of heating the interior of a VW microbus or something, but I think you'd be disappointed using them in anything bigger.

Jeremy

Or a standalone recirc'd windshield defroster.

[neoneddy]

dtcerrato: can you go intomore detail on that? I'm at a crossroads here and very much like the idea of using the OTR ducting. Any photos of the propane system?