Infloor heating questions

[scootermcscoot]

We just bought a shuttle bus and it looks like it uses the engine coolant to provide heat for passenger area via two heaters that blow air across the heated pipes. What I'm wondering is if we can remove the heaters and use/replace the piping to create an infloor heating zone?

In the summer we'd isolate the heating loop and just run the fluid back through the engine to cool it.

Or is there a problem with this idea that I haven't considered that someone can enlighten me about?

[BowserJournal]

I had never given that a thought when we removed ours. That is s great idea. Hopefully someone has done it and will respond.

[Drop out]

Maybe I'm paranoid but if I did a radiant heat system in a bus I would isolate the in floor plumbing with a water to water heat exchanger so I could cut out and drain the floor if it ever started to leak.

I would also use a wood or propane burning stove/boiler instead of engine heat so I can heat while parked.

The tricky part will be designing a stove/boiler that burns efficiently and a water jacket or coil to efficiently transfer heat from the exhaust gas to the water.

[Mark_In_MA]

I think there would be too much "cross contamination" of heat. If you just ran the system directly in a loop with the radiator, then you'd have heat only while the bus was running, and the engine was warm.

If you put in a heater on the coolant system, then you're trying to heat the floor AND the radiator, and whatever coolant is in the engine. (A waste of energy when parked.)

It might be possible to install a water-water heat exchanger between the two systems, but then the floor will only get as warm as the engine coolant. If you had a dedicated heater on the flooring side, once the water in the floor got hot enough, it would start to do its thing through the heat exchanger again. . .and heat the engine coolant of the hot engine.

It might be doable, with the correct assortment of valves and fixtures, but in the end, I wouldn't do it. If it leaked, flooring soaked in engine coolant doesn't sound fun. The radiant heat sounds fine, but I would make it its own system.

[somewhereinusa]

I just started a thread about how I built my heating system.

http://www.skoolie.net/forums/f51/hy...tml#post226299

[Drop out]

That system looks very nice but doing a little math it seems like it took 3 gallons of diesel to heat your RV every day.

That is probably cheaper than some systems but I'm really cheap so I think I want something that can run on busted up pallets, discarded furniture, scrap lumber, etc.

Unfortunately the companies that could make a nice system to do that are too expensive for a cheapskate like me.

[PNW_Steve]

3 gallons of diesel in one day? That equate to 417,000 Btu's.

What kind of climate are you in that calls for that kind of heat?

[somewhereinusa]

I may have misremembered the mpg difference. It doesn't use anywhere near that much

[scootermcscoot]

Originally Posted by Mark_In_MA

I think there would be too much "cross contamination" of heat. If you just ran the system directly in a loop with the radiator, then you'd have heat only while the bus was running, and the engine was warm.

If you put in a heater on the coolant system, then you're trying to heat the floor AND the radiator, and whatever coolant is in the engine. (A waste of energy when parked.)

It might be possible to install a water-water heat exchanger between the two systems, but then the floor will only get as warm as the engine coolant. If you had a dedicated heater on the flooring side, once the water in the floor got hot enough, it would start to do its thing through the heat exchanger again. . .and heat the engine coolant of the hot engine.

It might be doable, with the correct assortment of valves and fixtures, but in the end, I wouldn't do it. If it leaked, flooring soaked in engine coolant doesn't sound fun. The radiant heat sounds fine, but I would make it its own system.

All good points but I'm a little unclear as to understanding them so spologies if I've misunderstood

Not sure what you mean by cross contamination of heat, the in floor heating is about extracting the heat from the engine coolant. Also the idea is to use the infloor heating in the winter to really only heat the bus when its travelling. When its parked we'd be using a woodstove for heat.

Also not sure what you mean about "putting a heater on the coolant system". The current heaters already run off the coolant system, we're just using the floor as a heatsink for the heat generated by, and transferred away from the engine.

As for the risk of leaks, I think it's minimal as even if the loop was 100ft it would be done with no joins other than at the isolation switches which would remain under the bus and outside of the living space. Even an isolated in floor heating circuit should have some kind of antifreeze in it negating the benefit of having it separate.

[scootermcscoot]

Originally Posted by Drop out

Maybe I'm paranoid but if I did a radiant heat system in a bus I would isolate the in floor plumbing with a water to water heat exchanger so I could cut out and drain the floor if it ever started to leak.

I would also use a wood or propane burning stove/boiler instead of engine heat so I can heat while parked.

The tricky part will be designing a stove/boiler that burns efficiently and a water jacket or coil to efficiently transfer heat from the exhaust gas to the water.

A 100ft loop could be done from a single run of pex with no joins which is, in my experience at least, where the majority of plumbing installations fail. There would be isolators outside of the living space so I could easily drain from those in the event of a problem.

We plan to use this setup to supplement the heating of the bus when travelling and burning a woodstive to heat when parked. As the bus is so small, I think pretty much any woodstove will generate ample heat to keep everything toasty without the need to heat the floor at the same time.

And after all we're still just adapting a system that was already in place, if the manufacturers though using the engine coolant system to heat the bus was a good idea it can't be too crazy can it?

[Drop out]

Water damage is one of the worst things that can happen to a home and Schoolie conversions often have all the walls and bathroom built on top of a fairly contiguous floor so if anything goes wrong with the floor, it's like you almost have to start over.

That makes me really scared of water in the floor and much more scared of ethylene glycol (with water) in the floor.

Also if your engine overheats because all of your coolant dumped out and water damaged your floor, you have two really big problems. That seems like too much risk for something you will only use while on the road during winter.

I might try radiant for wood fired heat but my ultimate plan is to have a drop down bed over the cab and a dividing wall to make the cab a guest bedroom when parked and a smaller space to heat/air condition while on the road.