Heat: Diesel Hydronic or Diesel Air???

[JDOnTheGo]

For background, my build thread is: http://www.skoolie.net/forums/f32/mi...-a-17040.html]

I know its summer and most folks are not thinking about heaters. However; winter is not far off and I have not yet done anything about house warmth. So, I had better start thinking about it…

I was initially thinking of building a diesel hydronic system. I like the diesel hydronic approach as I have plenty of diesel, it creates warm water for the house, could warm the engine (when desired), and when operating, the engine provides warm coolant to warm the house. However; the thought of buying and installing the additional components of this system (heat exchangers, fans, tubing, coolant pump, connectors, coolant, etc.), running all that plumbing, and getting it to work right is less exciting. Without much scrounging, it seems like it would be fairly easy to spend $1,000 just on the heat exchangers. I'm not sure yet if it is a positive or negative but the coach already has engine coolant lines running the full length so they could likely to tapped into and used. As soon as I remove the bus air conditioning condensers, I have a perfect spot for a diesel heater and generator (vented to the outside).

Then I got to thinking about the diesel air heaters (that heat air instead of coolant/anti-freeze). It seems that two of the diesel air heaters would be less total work and easily creates a two-zone system. I would need to run diesel fuel lines and DC power. Installation would be in the bus basement (dumping the exhaust outside) and two-three air ducts. Seems VERY simple!

I should note that I am not positive that either a 12Kw diesel hydronic heater or two 5Kw diesel air heaters are sufficient for my needs - but I think so. In theory, a poorly insulated house matching the coach's interior size requires 44k BTU (13Kw) to achieve a 50 degree temperature increase. I always winter in semi-warm locations where overnight lows are occasionally around freezing and day time highs in the 50's. I tend to keep house temp at about 60 degrees but am happy with 50 degrees overnight (no women to please, ever). 12Kw is approximately 41k BTU, 10Kw is approximately 34k BTU. So, I think either of these two options are sufficient - but perhaps marginally so. Adding a third diesel air heater at a later date would be easy, adding another diesel hydronic heater - less easy, I think.

I have been watching the hydronic threads and searched the forums for info (and did find some).

What am I missing? Do you have positive or negative experience with either approach? Am I over/under estimating the complexity of something?

[PNW_Steve]

Regardless of fuel source I always lean towards a radiant heater versus a forced air heater.

I don't know the science behind it but I am, hands down, more comfortable in a space with radiant heat and have found that I can be comfortable with a lower thermostat setting. Standing on a warm floor just seems to make me more comfortable.

I also think that the ability to preheat your engine with the hydronic heater is an advantage. Lastly, you have the ability to use the engine heat when you are driving.

Now for the diesel force air heaters: The install will be cheaper, simpler and.......... I can't think of any other advantages.

BTW: I am still on the prowl for a used hydronic boiler if anyone out there is removing one from their bus.

[turf]

floor tube heat all the way. - says the guy with the diesel air heater


diesel air heat is ok. outside the bus, it sounds like a jet engine. so that's a bit embarrassing, but if its running, you probably aren't spending time outside.

high altitude starting can be impossible. the big downside for me is distribution. plan ahead for ducts, retrofitting them is tough. i have one big air heater and the back half of my bus is toasty warm and the front, not so much.

cost being equal, i'd go hydronic in floor heat.

[JDOnTheGo]

Thanks for the input guys! Keep it coming!

One quick update; if I go hydronic, it will not be in-floor. No room and too late for that. It will be via coolant-to-air heat exchangers.

[joeblack5]

Used an eberspacher air heater in my vanHool bus in Amsterdam. pretty noisy but the advantage is that it is fast. We used it in the morning before coming out of bed and before the wood fire kicked in when we were coming home.

later j

[2kool4skool]

Our 26' shorty has a Planar 44D and it's perfect for the size. One outlet and the unit is under the stairs, taking up no room inside.

[JDOnTheGo]

Thanks again for all the input - it is helpful!

I said that in-floor hydronic was out. Thinking about it some more, it is a possibility for the bathroom/bedroom. The living/kitchen area floor is done so it would not be easy to put there. However; it is not impossible either. That said, I am becoming a bit of a "vertical space freak". The internal ceiling height started out at 78", it now down to 76" and I don't have a ceiling yet. I'm short enough that this doesn't matter too much but it does feel a bit "compressed" - I want to avoid that as much as possible.

For those of you that have used the diesel air heaters. Is the sound they produce similar or worse than a typical RV propane furnace (which also sounds like a jet engine from the outside)? I've heard these heaters run on youtube videos and they don't seem any worse but it is hard to tell. I am a bit of a noise-nazi so this is a significant factor for me.

Laying in bed thinking about it - maybe a hybrid approach is the way to go. Some in-floor hydronic where it is "easy", hydronic coolant-to-air heat exchanger(s) where that is easy, and a diesel air heater where that is easy??? I suppose the worst part of that would be getting it to all work together from a thermostat/temp control perspective. Anything is possible, right?!?!