Dash Heater: Shutting off/switching Heat from vents while driving

[Rickf1985]

 I know that my engine heater lines also heat my hot water tank and I have a separate heater core under the rear bed with a blower for rear heat while driving. My issue is that I get a lot of heat out of the heat registers on the floor while driving. Is there a heat transfer from the heater lines to the coach heater also? If so how do I turn it off? I have not found any valves. I could just add valves and shut off the entire rear hose set but I like the hot water exchange. Saves propane!

Rick

[DaveVA78Chieftain]

Not sure if you have a cable operated heater control valve or not.  Winnebago provided all the dash heater/AC components.   Most installations are based on an MOPAR design though

Do you have push button:


or like this:


or dial controls?

Push button model: 
The top slide bar operates a water supply control valve in heater hose via a cable.  Might be rusted up.  Usually in engine area.
The push buttons use a vacuum control (rear of panel) to operate flapper valves in the heater assembly.  The felt/spounge seals may have deterioated allowing engine heat to enter from VENT mode.
Dave

[Rickf1985]

I have the slide control but it is Chevy based. The slide does work because it shuts off the heat at the front  heater and defrost. Well, defrost is all that works because something is up with the push buttons that control the vent selection. I haven't gotten into that yet. See that Mark, or Dave, you changed the title and this time you were a bit too quick! :)rotflmao The dash control IS working. The hoses that go to the back tee of before the controls for the heater controls. They basically come right from the water pump and the manifold and go straight back to the coach. That means they are hot all the time. I figure I could valve off the heater under the bed and that would eliminate that but that has it's own blower and vent setup and is totally independent from the coach heater. I also know the lines got to the hot water tank and transfer heat to that so when you get to your destination you have hot water without running the hot water heater. What I do not know is if there is some sort of connection between those hot water lines and the coach heater. That is where I am getting heat from, the coach heater floor registers.

Rick

[DaveVA78Chieftain]

The furnace registers?  Unless sombody modified something, you forgot to turn the thermostat off, or there is a problem in the furnace circuit, the furnace should not be lit.

Dave

[M & J]

He's not talking about his furnace Dave. Reread his opening post again.
I'm thinking instead of a flow control for the water, theres a fan control somewhere.

[Rickf1985]

There is a fan control on the dash but it is off and it only controls the heater under the bed that has its own outlet vent. It does not go into the registers. Unfortunately none of the diagrams I can find show any of this stuff. I didn't know about the hot water transfer until I drove it and found my water was hot.


I also want to mention that the hot air coming out of the registers is not forced air, no fan. Just hot air rising up. For now I am closing the registers but if there is heat in the plenum then the floor will be hot and that will not help the A/C any. I only have one A/C unit so I have to eliminate any excess heat wherever I find it.

[M & J]

I have another question Rick: Have you traced the plumbing lines from the engine - water heater - aux heater? Is it looped or is there a manifold that splits the coolant?
Cutting in a valve to stop the hot water to the aux heater under the bed is easy if it's not looped. If it is then you can cut in a bypass valve like the one used (later version) on the GM P30 chassis for the dash heater. Dave knows what it looks like and can post a pic I'm sure. It is also described in the GM  P30 service manual as an addendum to later chassis with the GM part number. I don't have my manual handy or I"d post it up for you.

[Stripe]

I have that same heater system and I haven't had any heat transfer from the lines to the registers. Then again the layout could be significantly different where maybe yours does.  I would take a look up underneath your chassis and see if maybe spraying on some expanding foam insulation onto the lines would help alleviate the heat transfer problem..

[Rickf1985]

This weekend I am going to move it to the driveway of the abandoned house across the street from me, that has a really nice perfectly flat concrete driveway. Too bad the house is falling down. I can crawl under it and do some serious looking at the lines and also the frame that I was talking about in another thread.

[DaveVA78Chieftain]

1989 Winnebago has a underbelly.  Is it possible hot engine air is getting funneled through that area allowing the vent ducts to get heated?

Dave

[Stripe]

Watch out for the Whites Bog ghost... woogie, woogie, woogie...

But what Dave says could be a cause for said heat...

[Rickf1985]

Dave could very well be on the right track and I will check that if I can get that far under there this weekend. You do realize I live less than a mile from Whites Bogs don't you. Am I going to see more black helicopters than usual over my house now?

[Stripe]

Umm... 

[M & J]

Remember the Oath Stripe.........

Just dunt tell him its the ones you cant see thats concerning.

[Stripe]

Hehe, Indeed....

[Rickf1985]

I am familiar with that oath, Got reminders for 30 years.