Hot water radiator

[Viajante]

On Fiberglass RV there is a post about the possibility of using the hot water tank as a source for a radiator to heat the trailer. I'm interested in hearing opinions on this. Maybe RoninBC, Myron, Rubicon, and others can analyze this, just to mention a few of the modification enthusiasts.

My furnace works fine, but when camping in temps of 45 to 60 degrees it is nice to have a source of constant low level heat rather than the intermittent furnace or a somewhat noisy electric cube. I have used a cast iron pan on low heat during the day with fair results. Would a little radiator be better?

Thanks for any thoughts.

[rbryan4]

Using a hot water tank to heat water going into a radiator would mean making the system yourself, making it compact and practical enough for interior use, and using propane as a fuel source. If you have electrical hookups, I think a portable oil-filled electric radiator heater would make more sense. They put out alot of heat with a reasonable amount of electrical useage, are safe, and almost silent in operation. I know Delonghi makes some good ones.

The little convection space heaters are also great for heating a small space, and are very quiet if not silent.

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[Brian B-P]

A radiator circulating hot water from the fully vented water heater would certainly be safer than using a stove burner as a heat source; it would also (presumably) be better placed and better shaped for effective natural convection heating of the air.

It would require a circulating pump to be effective, drawing from the water heater output and returning to the water heater input; that's normal for the equivalent domestic heating systems, but a suitable pump in the required (small) size would not be common. The radiator is easier: there are various suitable units designed for automotive use (such as bus and truck interior heating from engine coolant).

I don't know how efficient the water heater is on propane; that could be calculated. On electrical power, it will be 100% less losses to the outside (it's somewhat exposed).

My only caution would be that I knew a guy who built an interesting alternative heating system for his house which incorporated a gas-fired water heater as the heat source, and he found that the water heater failed very prematurely because it was not up to the task of running so much. I don't know how fast RV water heaters burn themselves out if asked to run a lot.

If a quiet and continuous heat source is the only requirement, and shore power is available, a radiant electric heater might be a simpler and still effective choice. I have used 700-watt oil-filled radiant heaters for this purpose; they are heavy and bulky for their power (compared to a fan heater), so if you can find a mounting location one of the lower-power radiant panel-style, wall- (or cabinet-) mounted heaters might be more convenient.

[float5]

Quite a few people with RVs use the oil-filled radiators that Robert and Brian are mentioning and they like them.

Contriving your own alternative system is fraught with unknowns and unimagianable problems of which you might not even be aware. Best to go with what already works.

[Donna D.]

I love my Vornado Whole Room Heater (3 heat settings: 1500, 1125 and 750 watts). It's not silent, but not loud and the fan runs continuously so no hearing something powering up. It runs on a thermostat and when heat is required it pumps out heat, but no cycling on/off.

I know this isn't what you were asking about....

[rbryan4]

Originally Posted by Donna D.

I love my Vornado. It's not silent, but not loud and the fan runs continuously so no hearing something powering up. It runs on a thermostat and when heat is required it pumps out heat, but no cycling on/off.

They're very effective because they move the warm air around - so you get a much more even temperature throughout the trailer. Thing about a radiator, convection or ceramic heater is that it's red hot close to the heater but colder several feet away.

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[Brian B-P]

The original poster in FiberglassRV did find a suitable 12V circulating pump - presumably intended for either those automotive applications or for the few RV (typically Class A motorhome) applications which include a water heater built for this purpose - so that part is easier than I first thought:

[Brian B-P]

Another variation of this approach which could work well is in-floor radiant heat, with the heated water circulating in a layer added on top of the Escape subfloor and under the finish flooring. In this case, underfloor insulation seems particularly appropriate.

As with the fan heaters and radiators, there is an electric equivalent if on shore power.

[Brian B-P]

Originally Posted by Brian B-P

... the few RV (typically Class A motorhome) applications which include a water heater built for this purpose...

This is the best-known brand of these systems:
Aqua-Hot Products

I suppose one could fit an Aqua-Hot system in an Escape - although even their smallest 400LP would be hard to fit in - but even if home-brewing a system, a look at the setup in a motorhome at an RV dealership or belong to someone else at a campground might be worthwhile for inspiration. The installation and operation manuals might be informative, too.

[rubicon327]

What you describe could be done, but I'm not sure it is very practical. At least with my experience in commercial HVAC you need a heat exchanger to isolate any domestic water heating and space heating loops. This is so the domestic water does not become contaminated. Plus you have to find space to mount the radiator. If 120V electric is typically available then the options mentioned by others are worth considering. With my mini-split mod we just run the heat pump which is great for heating at moderate temps.

The Truma Combi is cool, but boy would that be an expensive and challenging retrofit. Probably best done at the factory and designed into a build.
www.truma.com/us/en/heating/combi-eco.php

[War Eagle]

Originally Posted by Donna D.

I love my Vornado Whole Room Heater (3 heat settings: 1500, 1125 and 750 watts). It's not silent, but not loud and the fan runs continuously so no hearing something powering up. It runs on a thermostat and when heat is required it pumps out heat, but no cycling on/off. I know this isn't what you were asking about....

Donna, If you don't mind sharing, which model of the Vornado Whole Room Heater do you have? There are several....

[float5]

And it is fraught with unimaginable problems, too, (when I pay attention to how my spelling comes out!)

And Donna may have the best thing going.

[StarvingHyena]

Originally Posted by Viajante

On Fiberglass RV there is a post about the possibility of using the hot water tank as a source for a radiator to heat the trailer. I'm interested in hearing opinions on this. Maybe RoninBC, Myron, Rubicon, and others can analyze this, just to mention a few of the modification enthusiasts.

My furnace works fine, but when camping in temps of 45 to 60 degrees it is nice to have a source of constant low level heat rather than the intermittent furnace or a somewhat noisy electric cube. I have used a cast iron pan on low heat during the day with fair results. Would a little radiator be better?

Thanks for any thoughts.

At one time, I wanted heat up in the bow of my boat and played with the ide of setting up a hot water system to do that. Look up a company called Webasto. If you go to their site and click on "cooling water heaters" you will find and interesting unit. It is designed for continious use, unlike a trailer hot water heater. Webastco builds quality gear and this heater is pretty small in size but runs on diesel. I don't know about the cost. I'd start looking there.

www.webastco.com

I have been using a DeLonghi oil filled radiator type heater ... model TRN0812T. Its about 20" long X 16" high X 6" thick.... about $75. I like this type of heater cause it doesn't get hot enough to start a fire. It fits nicely under my table and I'll install an outlet there that draws power from my power port so my inverter doesn't have to run to power the heater. Will mean heat only available when I'm plugged into 110.

Tom

[arniesea]

Originally Posted by rubicon327

What you describe could be done, but I'm not sure it is very practical. At least with my experience in commercial HVAC you need a heat exchanger to isolate any domestic water heating and space heating loops. This is so the domestic water does not become contaminated.

Not necessarily. I installed a potable radiant heat system in my sister's new home that uses an on-demand, high efficiency hot water heater for both the radiant floor and domestic hot water. The trick is that the source water flows through the radiant floor tubing before going to the heater, then the domestic taps. It is an open system rather than a closed system so the water throughout is always fresh. Also all the components are potable water safe.

You can read more here: http://www.radiantec.com

However, I would not want to try it in a trailer since when boondocking one is limited to the fresh water tank. The open system requires a constant source of fresh water.

[Mike Lewis]

I have three of the DeLonghi heaters at home; I even use one to keep my trailer from freezing in the winter. But I never thought about bringing one with me due to their size. Maybe I should rethink this, as the electric space heaters I've used when I've had hookups are so noisy that I've given up on them and just used the trailer's propane heater all the time. If there were an electric oil heater small enough to fit into one of the floor-level storage compartments, that would be ideal.

[StarvingHyena]

The one I listed isn't that big .... but it isn 't light either.
Eventually I'll make a bracket and fasten it to the rear wall under the table. There is 1/2" ply there.

However, a folded map rack and laptop computer rack are competing for the same space. Not sure at this time who will win. I'm putti g my trailer on a diet .... the oil filled heater at about 20 lbs might stay home. Its also a matter of weight and balance.

Tom

[Donna D.]

Originally Posted by War Eagle

Donna, If you don't mind sharing, which model of the Vornado Whole Room Heater do you have? There are several....

Vornado AVH2 Whole Room Heater with Auto Climate Control
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[cpaharley2008]

In all 3 Escapes I have installed the Broan wall heater, made for bathrooms, variable heat output and very quiet. Installed in the dinette wall, there is a thermostat, the heat runs along the floor. Eliminates cords and their possible fire hazards.
In addition, those contemplating the use of an on demand water heater, they are very noisy. I had them in both of my Lance trailers, they come on every time you turn on the hot water spigot and run long after you turn the water off. The Suburban is much quieter and less obtrusive.

[rubicon327]

Originally Posted by arniesea

Not necessarily. I installed a potable radiant heat system in my sister's new home that uses an on-demand, high efficiency hot water heater for both the radiant floor and domestic hot water. The trick is that the source water flows through the radiant floor tubing before going to the heater, then the domestic taps. It is an open system rather than a closed system so the water throughout is always fresh. Also all the components are potable water safe.

You can read more here: http://www.radiantec.com

However, I would not want to try it in a trailer since when boondocking one is limited to the fresh water tank. The open system requires a constant source of fresh water.

Arnie: This is interesting and highly dependent on what local codes may allow. I am more familiar with commercial systems. Radiantec has some fine print about the open system and they also offer a closed system with a heat exchanger as I described. Codes notwithstanding, the challenge I see with the open system design is that when there is any demand for hot water (showers, sinks, washer, etc.) you are no longer heating your house because the cold fresh water has to flow through the radiant loop. They do this because you cannot have your radiant loop ever sit stagnant too long (i.e. summer). Most areas will naturally have domestic city water that is very cold in the winter and quite warm in the summer. This is obviously the opposite of what you would want. I suppose that if the potable demand is low enough, and the recovery of the hot water heater high enough, then maybe this is not a real issue in a well insulated home that can tolerate space temperature fluctuation.

Back to some relevance to the original post, your point of all components being potable water safe is well taken. This is easier when it is a radiant loop with tubing. If someone did try to add a heating element such as a radiator to a domestic water loop without isolation from the potable side they would be well advised for it to have stainless steel construction and confirm all other system components are appropriate.

[arniesea]

Originally Posted by rubicon327

Arnie: I suppose that if the potable demand is low enough, and the recovery of the hot water heater high enough, then maybe this is not a real issue in a well insulated home that can tolerate space temperature fluctuation.

I agree, an open system is not applicable in many situations. In this case it works because the primary purpose is supplemental overnight heating when the primary source is a "Vermont Castings" wood burning stove in a temperate climate. The radiant heat will come on during times when potable water use is low. (night time and when the home is vacant.) The home is also modest in size so that is also a factor.

And again, I would never put such a system in a trailer. But I thought you might find the information interesting.