hydronic heating

[dirtdr]

I read an article here (i think) about a fella who installed a hydronic heating ststem in his TT. I can't seem to find it anywhere.

I am looking into installing a hydronic system to heat the underbelly tanks of my fifth wheel. I don't know if it is possible or not, but am looking into it.

What I am thinking is to run a low current draw water pump and a circuit of water pipe from the hot water heater ( either existing 10 gal heater or new 6 gal stand alone auxillary unit) through the enclosed underbelly much like an in-floor system in a stick house.

A few ??? i have are:
1) is there water heaters available with variable temp thermostats to limit how hot the output water is?
2) can a standard RV water pump safely pump hot water? how hot is too hot?
3) are there other options for 12v dc (preferred) or 120v LOW CURRENT DRAW water pumps

The rig that i want to do this to already has a forced air heat duct going to the underbelly, and i made it through last winter with everything OK, but as some of you may have seen from my other posts, I am one for overkill. I have decided to keep this trailer for a long time so i want to make it as fool proof as possible to survive many canadian winters.

Any suggestions are welcome, just note that i am without shore power most of the time, so any high current 120v heaters are out of the question. I have propane to burn in abundance.

thanks

 

[Tom]

Is this the prior topic you were looking for? He installed it on a boat.

 

[dirtdr]

thanks tom, although not the topic i was thinking of, still just as interesting. thanks

 

[baadpuppy]

here are a few links I've gathered in my "hydronics information" collection so far:

http://www.solarhaven.org/HPArticle.htm

http://www.solarhaven.org/Hydronic.htm

http://www.radiantheating.com/

http://www.houseneeds.com/shop/HeatingProducts/WaterHeating/AquaStar1/AquaStar125.htm#125bl

http://gmcmotorhomeinfo.com/hydronic.html

http://www.ki7xh.com/campheat.htm

http://www.warmzone.com/hydronic-radiant-floor-heat.asp

http://www.aimradiantheating.com/

http://www.bgmsupply.com/

http://www.pexsupply.com/

http://oee.nrcan.gc.ca/publications/infosource/pub/home/Heating_With_Gas_Section3.cfm

Note, some of these are people trying to sell things, some are people who have done hydronic installs in RVs, some just talk about hydronics in general.

I've been doing a lot of research into this lately.  In fact, I'm planning to go completely hydronic in my motorhome when I rebuild it.

There isn't a lot of information out there on hydronics for RVs.  Much of what is out there for mobile homes and even stick built houses still applies though.  One of those links is a place that sells 5/8" board aluminum clad with grooves for PEX that can be installed under regular flooring.  One of the links shows how to use a regular car heater core and a very low current fan and pump to heat a space with forced air.

One other advantage of hydronics that is often overlooked is that water/glycol also makes a good cooling system.  By use of a chiller (essentially a refrigerator or A/C unit that transfers the heat out of the liquid instead of out of the air), you can cool a space as easily as heating it.

There are still a lot of unknowns for me.  But I'm still researching.

Finding a LPG powered heat source isn't as easy as finding diesel powered.  Although it turns out the espar has a few models that will run off of gasoline as well, which is likely what I'll go with.  There was a swedish company that made a really nice unit that used LPG, but I have no idea where you would find one to purchase here.

Anyway, I hope some of this was helpful for you and/or others.

jim

 

[dirtdr]

wow. great help. the first link you posted was the one i was thinking of.

the hartel dc brushless pump is just what i was looking for.

i will let you know how I make out.

 

[Tom]

Looks like I was confusing hydronic heating with a HydroHot diesel heater. Reading some of those linked articles, I now understand what you're trying to do.

 

[dirtdr]

yes, and after reading some myself, i believe i should call it 'radiant' heating as hydronic refers to using heater cores and fans... which i may do as well.

From what i have seen so far i should be able to utilize my existing hot water heater, a circulating pump, thermostat, and a couple of check valves.

sounds so simple

 

[Tom]

Be sure to take photos as you progress with the project and post them here with a description of what you did. This could be very useful for others in the future. TIA.

 

[dirtdr]

yea, i keep meaning to take pics and such, but i have a hard enough time finding my tools, never mind the camera. i will try tho.

the more i read baadpuppy's links, the more i want to do a complete in- floor system in the entire 5er. my slide-outs may pose a problem, tho.

 

[baadpuppy]

I'm glad the links are proving useful.

The more research I do on this, the more I want to go ahead and put radiant in my floor, walls, and ceiling.  I've also been considering adding a few low power fans with heater cores in strategic locations.  Sometimes you want that warm spot.  And with my motorhome being a blank slate, this should be quite doable.

dirtdr, I've read all about your electrical system and I hope to apply some of what you did there to my motorhome.  Good luck with your hydronic/radiant heating. 

jim

 

[baadpuppy]

This weekend I ran across a book I had picked up during a library's weeding process called "technician's guide to HVAC systems".  This book goes into a lot of good information about heating and cooling, including some calculations you can do to determine how much you need and/or how you can improve what you have.  It also has chapters on hydronic and radiant heat as well as water chilled cooling systems.

Needless to say, I'm spending a fair amount of time poring over it.  This is just what I need to figure out my heating/cooling system design.

Anyway, if you check your local library, you might find this book or one similar to it that could be quite helpful.

jim

 

[Jackliz]

Jim,
My Bluebird Wanderlodge has a hydronic heating system that originally was fired by LP. The previous owner had it converted to a Webasto, diesel-fired system. The LP unit was called Primus and I have been told that it uses a lot of propane. The Wanderlodge forums on Yahoo have good threads on hydronic heat but the Webasto web page has a lot of GOOD information. We have the Webasto Bluebird schoolbus system.  Hope this helps.

Regards,
Liz Pearce
Running our hydronic heat system in 20 degree Buena Vista, CO    ;D

 

[baadpuppy]

Liz,

From what I've been able to determine in my research, the Primus system is no longer available.  Probably because it was a fuel hog as you said.

The webasto has a good reputation from what I've found.  I see that it is often installed in diesel motorhomes.

The espar was mentioned in another thread here on the forum, and it turns out to have a smaller footprint in the vehicle than any of the webasto systems (at least, that I've seen so far), and they have a couple of gasoline models available.  That would keep me from having to add a second fuel tank just for the heating system... assuming I could find space for such a tank.  ;D  The only gasoline models are the smaller ones though... to get more BTUs I would have to go diesel for an espar.

Still, I'm far from any decision point.

One of the links I listed earlier mentioned a company in sweden I think that had a hybrid propane/AC heating system.  I suspect that would be good for many people.

I bet you're quite comfortable with your hydronic heat.  Is yours the radiant floor type or the forced air heat exchanger type, or a hybrid of the two?  I've been leaning most strongly towards the hybrid type.

When I was growing up, we had an old house with hot water baseboard heat, and it was very comfortable year round.  And there was virtually unlimited hot water.  ;D

jim

 

[ArdraF]

Jim,

The October 2007 issue of Family Motor Coaching magazine (the FMCA magazine) has an article that might interest you titled "Servicing the Aqua-Hot Diesel Burner"  (pp. 114, 116-118).  It has six photos as well as a "full-coach" diagram of how an Aqua Hot system works.  The Aqua Hot system is similar to Wabasto.

ArdraF