Radiant Floor Heating

oldog12 · 08-11-2006, 03:14 AM

New to this bus renovation/conversion stuff and I was thinking of installing radinat ofloor heating.... Has anyone done so and does it heat adequately? I was contemplating using the engine cooling system, and some sort of engine heater set-up for when the engine isn't running. Am I out in left field, or should I just get a dedicated water heater for the job. One thing worries me; if I spring a leak.... I loose heat and/or the engine.

lapeer20m · 08-11-2006, 07:34 AM

I'm definately going to run pex tubing in the floor of my next bus.

When the bus is running, engine coolant is the obvious choice for heating. Not only is there ton's of heat, but it's free when you're driving.

As for being parked...I utilize an old fuel oil boiler in my skoolie for heating the jacuzzi. In the new conversion, i plan to use a boiler to also heat the tubing in the floor when the bus is parked.

Talk to the local heating and cooling shop and see if you can't find a used boiler for free or cheap. I got mine for free....well, i actually got 3 for free but needed that many to get enough parts to end up with one that actually worked. The good news is that fuel oil is diesel fuel, so you can plumb the boiler directly into your fuel tank. Mine is a good sized boiler, and it uses a maximum of 1 gph of diesel, but it only takes about 45 minutes to heat 400 gallons of water (or whatever the jacuzzi holds) from 55 degrees to 105 degrees.

You could always buy a diesel furnace for a bus, but they are pricey and from what i've read are a little bit unreliable, and i'm not sure about their heat output either. It takes a lot of heat to keep a skoolie warm in the wintertime.

the_experience03 · 08-11-2006, 11:15 PM

You really should insulate under the pex. Even when they pour concrete floors with pex they insulate under them (I used to install them). As for heating it...I would keep the circuit seperate from the engine coolant for any number of reasons. However, a flat plate heat exchanger could be used to harness the engine heat while still allowing you to use a boiler and Taco pump for heating it while stopped.

How many more BTU's do you need to harness before you can just ditch the radiator entirely, Jason?

lapeer20m · 08-12-2006, 09:04 AM

Quote:

Originally Posted by the_experience03

You really should insulate under the pex. Even when they pour concrete floors with pex they insulate under them (I used to install them). As for heating it...I would keep the circuit seperate from the engine coolant for any number of reasons. However, a flat plate heat exchanger could be used to harness the engine heat while still allowing you to use a boiler and Taco pump for heating it while stopped.

How many more BTU's do you need to harness before you can just ditch the radiator entirely, Jason?

thanks for the info. Good point about keeping the coolant separate.

I never have to worry about my engine overheating with my aux. engine cooler AKA: The Jacuzzi

the_experience03 · 08-13-2006, 07:38 PM

The really nice thing about the insulation is that they make pex staples that go into it to keep your tubing in place until you do whatever it is you're going to do over it (like pouring concrete). The tool allows you to stand up and just walk. Very cool and very rentable from any pex dealer.

Here are some specs on my heat exchanger I'm going to use for my WVO which measures approx. 8"x5"x4" or so.

Water to water

50,000 BTU output (about the same as an underseat heater)
Input: 5.08 gpm@180*
Output: 1gpm@40* to 140* rise

So....you can get water from almost freezing to 140 degrees using a very minimal flow from your coolant. Flow more coolant (like the 60gpm our water pumps are capable of) and you can REALLY heat a large volume of water rapidly.

If you can't tell, I'm in love with high turbulance couterflow plate heaters.

Ryan Grimm · 08-21-2006, 10:46 AM

I love radiant floor heating, I've helped a few friends install it.
Tried to talk them into a K'ang (Korean underfloor heating, like a Roman hypocaust), but they wouldn't go for it.....
Stapling the PEX down and floating a thin layer of lightweight concrete is the way to go. The concrete slows down temp swings, and radiates the heat longer in cold weather.
Another benefit from the concrete floor is it stays cooler underfoot in the summer, at least in a 'fixed' home.......

Definitely insulate UNDER the PEX, you may lose a bit of headroom tho.

captainkf · 08-23-2006, 11:56 PM

I heard from a guy at work who helped a friend instal radiant heating in a conversion. The problem was he forgot to test the system for leaks before finishing the bus. Needless to say he has 500 feet of pex in the floor that safely moves, well, nothing. -Richard

oldog12 · 08-24-2006, 12:28 AM

So this guy who helped his friend.... What did he use for a circulation pump and what heat sourse did he use? Did he put in an expansion tank?

captainkf · 08-24-2006, 02:05 PM

The circulation pump was a normal sureflow 12v pump. For a heat source he used his 10 gallon propane water heater with a tee coming off. One to the floor, the other to the shower/sinks. This is the system I will use if I do another bus with more headroom. However this will not be for a very long time. -Richard

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