Baseboard heat or other radiant heat with no fan using espar for heat source.

[javajoe79]

Seems that people mostly use a small radiator with a fan to heat their campers when the heat source is hydronic. My camper is rather small and I am thinking that baseboard heater pipes would work well enough and require no fan. I could install them along the edge of the floor in my camper. That would be about 15 feet of tubing. Or even double stack them for 30 feet. That or I had another idea to use an old intercooler for a turbo engine with no fan. I feel like placing the intercooler facing up would create a convection current and naturally draw cooler air from below it and heat the entire camper. This would also be a more compact and cheaper option with less plumbing.

 

[fluffyprinceton]

Great idea but it didn't work for me. I had 25" of 3/4 copper tubing coiled into a spiral - it was in a box containing the control manifold, 5gal heater tank with 4 computer fans blowing out virtually silently. Heat is a webasto 17000 btu coolant heater. Idea was for silent heat - the silent part was a great success but the heat produced was a bad match for the capacity of the webasto, it would run, heat the system then shut off for 20 or more minutes while the heat slowly distributed into the camper. I changed it to 10x14 radiator type heat exchanger. That works very well - still, I'd need another of the same size with fans to effectively pull all the heat the webasto is capable of putting out. Floor radiant is IMO the best solution for utilizing the available heat produced if you want quiet even heat - I have both - the air heater reacts faster. Only downside to the floor radiant is the sound of the pump circulating the floor circuit. If I did it again I'd go to the trouble of putting the pump outside the camper. It's not loud by any definition but when camping in the silent vastness back of beyond it's annoying...In practice over night I run just two of the fans to keep the cabin around 45-50 degF.

Maybe if your baseboard was the finned type & ran full length it might work (IMO not very well but certainly enough to keep the cabin comfortable for sleeping) it would be an interesting experiment but I think you need fans or an awful lot of passive surface area (that you'd have to find a place for...) to warm up the cabin fast enough to be useful ...Moe

http://www.ebay.com/itm/14x10-Water-to-Air-Heat-Exchanger-1-Copper-ports/301598238254?_trksid=p2045573.c100505.m3226&_trkparms=aid%3D555014%26algo%3DPL.DEFAULT%26ao%3D1%26asc%3D38530%26meid%3Dcaa831981f664538ba260cb400ff46d9%26pid%3D100505%26rk%3D1%26rkt%3D1%26

 

[javajoe79]

Great response! thank you. I was thinking finned 3/4" baseboard tubing.. http://www.slantfin.com/wp-content/uploads/2015/11/Bare-Elements-Ratings-107.pdf

According to that chart it's 578btu/hr per foot that 17,340 with 30 ft. The dimensions of that stuff makes me think that I don't have room for all that. I may just do the intercooler plan and add fans if I have to.

 

[nick disjunkt]

I have 2 radiators, a towel rail and a calorifier on my Webasto Thermo 50 and it doesn't have enough area to use all of the heat from the Webasto. It also doesn't heat the camper enough when outside temps are really low. At some point in the future I'm going to try and retrofit a fan matrix heater somewhere.

 

[fluffyprinceton]

I have 2 radiators, a towel rail and a calorifier on my Webasto Thermo 50 and it doesn't have enough area to use all of the heat from the Webasto. It also doesn't heat the camper enough when outside temps are really low. At some point in the future I'm going to try and retrofit a fan matrix heater somewhere.

Without adding floor radiant (ah...that's a project...) I think a fan matrix heater is only practical cost & space effective way to extract all that Webasto heat. I've got 4 fans @33.5 cfm (134 cfm total) sucking through a 10x14 radiator. A "typical" marine type hydronic heater - a Red DotR290 rated @ 20,000btu blows 220 cfm. My system is adequate to at least 10degF (lowest I've camped in) but as I mentioned I'd like add another fan/radiator to speed the morning warm up. The Red Dot has 3 speeds & isn't too loud...

Basically - when I built my system I underestimated the Webasto output & over estimated the heat extraction ability of my passive systems. In a do-over I'd double my floor radiant, put in a RedDot and use my existing (very quiet!) fan/radiator as my "hold this temp" heater. Moe

 

[Coachgeo]

Floor radiant..... a potential easy way to do this is a false floor with the tubes attached to surface of real floor underneath. Something like a nice looking lattice floor the dirt can fall into and disappear till you get the hankering to tilt up the sections of floor and vacuum it all out.:wings:

 

[javajoe79]

For me I have a hard time figuring out what I need to shed all the heat that the Espar provides. Maybe I should consider in floor heat to go with the radiator? I guess for a cold night, I don't want the Espar short cycling but I also don't want it too hot. My camper is fairly small. I've been discussing this with an hvac friend of mine and he was suggesting zone valves with thermostatic control that could bleed off hot coolant into the engine circuit as a heat sink to prevent short cycling the Espar.

 

[fluffyprinceton]

I'd put radiant floor heat at the top of cold weather camping must haves. The whole purpose of having a big camper was to have something comfortable enough to enjoy waiting out bad weather. The experience with my Alaskan was in very cold weather the floor would roughly be at the outside temp and no matter how much warm air I blew around the cold would radiate off the floor & make it pretty much necessary to sit up off the floor. With the floor @ 110deg the comfort level is great & I can work inside without fighting the cold.

I solved the short cycle issue by having a 5 gal insulated tank in the system - the webasto runs & heats the tank up then the circuits bleed off the heat so the heater comes on every 30 minutes at most - much less when just heating for sleeping. Moe

 

[loonwheeler]

I solved the short cycle issue by having a 5 gal insulated tank in the system - the webasto runs & heats the tank up then the circuits bleed off the heat so the heater comes on every 30 minutes at most - much less when just heating for sleeping.

Exactly. The spec sheets for most hydronic heaters will list the minimum system volume required to reduce or eliminate short cycling. Usually adding in the calorifier in the same loop as the matrix heaters will do just as Moe mentions. Not only that, the calorifier also provides the obvious benefits of on board hot water.

 

[javajoe79]

Well I've got a whale marine hot water heater. Was planning on that being first in series with the radiator then in floor heat. I don't think I'll have a problem getting the recommended system volume

 

[javajoe79]

A calorifier is the same as a hot water heater correct? Seems like once the calorifier was fully heat soaked it would no longer prevent short cycling.

 

[jwiereng]

Water volume

Adding a calorfier adds volume to the hydronic system.

Larger volumes will result in longer cycle times. Energy is initially stored in the water and released over time to the cabin. More water holds more energy and takes more time to release enough energy to decrease its temp below the cut in temperature set point of the heater. For faster reaction time, mixing valves could be used to prioritize components allowing the calorifier or any other heat storage to only accept energy after the cabin loops have been sufficiently warmed.

Do the espar heaters have adjustable cut in and cut out temperature set points? Setting these points as wide as possible would also allow for longer cycle times.

 

[javajoe79]

No the espar heats to a certain temp, then cycles to low and then shuts off if the temp keeps rising. I am beginning to realize why people have such complex systems now. You have to have enough volume and radiators or towel racks or in floor heat to shed the heat made by the espar or it will short cycle. I guess I just have to build my system and see how it does with my camper. I feel like it will be too hot unless it's very cold out. So I will have to find a way to shed the excess heat from the system if I have a short cycling problem.

 

[dwh]

How about two loops? One to insert heat into the calorifier, and another to extract it.

 

[fluffyprinceton]

I feel like it will be too hot unless it's very cold out.

Not a problem - they come with thermostats - not sure why you see an issue?

My adding a 5 gal tank to my system was just to increase the volume of the hot water to allow a long (quiet) time between the webasto coming on. The tank & manifold & most of the plumbing are in/under cabinets that are connected in such a way that air flows in one end & out through the radiator/fan. So there is no wasted heat - it's all contained within the camper envelope (except the webasto & inlet/outlet hose). The bed is above the tank...The point is there can be a number of ways to enhance the passive, unpowered or low powered extraction of heat from the system - which was the central question of your first post. Moe