Heater modification

[silverbullet]

Has anyone ever successfully modified a watercooled heater unit to full-flow operation? In other words, no water valve but with an (extra?) internal flap and/or ducting to blend hot/cold air for instant temperature control.
Thinking that it might be a worthwhile investigation?

[StuM]

Are you saying have hot water always flowing through the matrix, but either blow cold air from outside or cold air heated (or mixture of the two) based on a flap in the ducting?

[ghost123uk]

Not sure what the advantage might be (in view of the work involved) as these heaters "come on" in only a few seconds after operating the control (well mine does anyway )

I have wondered why, even on these older vehicles, there is no thermostatic control of cabin temperature.
This would be relativity easy to fit with a tiny bit of electronics and a servo controlled water valve.

[silverbullet]

Are you saying have hot water always flowing through the matrix, but either blow cold air from outside or cold air heated (or mixture of the two) based on a flap in the ducting?

Yes, which is how a lot of Japanese vehicles did it (Subaru springs to mind...) the heater mixes cold and heated air to deliver to the cabin. No waiting for the matrix to cool down or heat up, so the heater responds almost instantly to control changes.

I have wondered why, even on these older vehicles, there is no thermostatic control of cabin temperature.
This would be relativity easy to fit with a tiny bit of electronics and a servo controlled water valve.

Like most modern cars. They all have electric pumps for the heater matrix too, for faster engine warm up (no bypass circuit to speak of)

[StuM]

One thing that came to mind here is that the hoses up to the matrix emit a fair amount of heat themselves - so even with no blower you might get unwanted heat during the summer?

[ghost123uk]

I wondered how much heat is lost by a 60mph icy wind blowing along 10 feet of heater feed pipe under the van.
When I mentioned lagging those pipes on here a while ago most thought it not worth it

[silverbullet]

Very much worth it in cold climates I'd have thought but since the heater hoses are routed alongside/between the coolant pipes what's heating what?

I agree about the observation about radiant heat in hot weather, since I'm always cold in the workshop at this time of year it hadn't occurred to me! Aluminized space blanket/bubble wrap for the heater box then...maybe not such a good idea after all

[Aidan]

surely it would slow down engine warm up because of the size of the system and the volume of fluid with the engine at the front,
I was taught back in the day (1980) to let the engine warm up and not put heater on for first 5 mins untill temp gauge had stated to move up and to wear hat and gloves and coat and not expect the car to be a sauna when the outside temp is zero, but these modern combined systems with the aircon/dryer in the system in a front engined car works fine, though the scooby isn't quick to come up to temperature ime but now every one seems to leave the car running for 10 mins on the drive first then get in and turn heater on and have warmth
the difference in the cooling systems/car heaters is a problem for changing the engines across from the subaru to the T25