Aqua-Hot 250P: RV Heating and Hot Water

 Originally Published in Trailer Life Magazine and RV.com

Aqua-Hot 250P: RV Heating and Hot Water

"Travel trailer and fifth-wheel owners can tap into continuous hot water and quiet, even heating with the new Aqua-Hot 250P"

The smiles you see on the faces of families coming out of those big diesel motorhomes on cool autumn mornings in the campground have a lot to do with the good night’s rest and hot showers everyone enjoyed.

Long a staple in half-million-dollar-and-up mobile residences, hydronic heating systems now are available for all RVers. Hydronic systems supply an unlimited amount of hot water and quiet, evenly distributed moist-air heating throughout the interior.

Throughout its history, beginning in 1984, Aqua-Hot has focused on making heating units for the motorhome market. The good news for owners of travel trailers and fifth-wheels is that Aqua-Hot recently introduced a smaller LP-gas- and electric-powered system that can be installed in towable RVs.

Hydronic systems work much like radiant heaters in cars. An antifreeze-based fluid circulates through the system and maintains a temperature of 190 degrees Fahrenheit for heating. When warmth is needed, up to five heat exchangers come on to deliver a moist, even heat without drying the air. For domestic hot water, water flows through the boiler unit and maintains a 120-degree temperature.

John Carrillo spent nine years at Aqua-Hot as a production worker, service technician and technical adviser before leaving in 2008 to start Heat My RV and do business as an independent hydronic-heating specialist. With his office located across from Aqua-Hot’s headquarters in Frederick, Colorado, Carrillo has been a go-to guy for Aqua-Hot repairs and installations. An RVer himself, Carrillo travels to Arizona and California in January and February to service RV heating systems at events and rallies, including the giant Quartzsite, Arizona, show.

When Carrillo offered to give us an inside look at the installation of the new Aqua-Hot 250P in his Grand Design Imagine travel trailer, we took him up on it.

PREPARATION AND INSTALLATION

For the installation, the drawers and cabinet facing covering the Imagine’s original forced-air furnace were pulled out. From there, the original LP-gas furnace was quickly removed.
The 250P measures about 12 by 13 by 22 inches and weighs 84 pounds. Surprisingly, it fit perfectly where the old furnace sat. There are many options concerning where to place the unit, including the front storage compartment, but with cargo space always at a premium, using the old furnace bay was a no-brainer.

Once the hole in the flooring of the trailer for the unit’s exhaust manifold was cut, the technician spliced into the potable water lines and connected them to the new system, which are on top for ease of installation. A reservoir mounted on the wall above the system will make it easy to top off the heating system antifreeze fluid through the exterior-access panel. An exhaust pipe was dropped down with an elbow, sending the heat from the unit out the side. Because the system runs on propane or electricity, no smell or smoke is discharged.

The most labor-intensive part of the installation required dropping the underpinning beneath the trailer to run the plastic piping for the antifreeze and electrical wiring to operate the heat exchangers. Runs were made to each of the five heat exchangers, which consist of a combination of the two-fan, 8,200-Btu Cozy units and the smaller single-fan, 4,000-Btu Whisper units.

At the rear of the trailer, the existing water heater was pulled out, and one of the heat exchangers was mounted in its place. That left additional storage space, and Carrillo plans to have a detachable door fabricated to cover the opening.

After mounting the heat exchanger in the water-heater opening, a vent passage to heat the primary living space was cut. Additional exchangers were placed beneath the kitchen island, in the primary living area, and inside the bathroom to heat it and the bedroom. One heat exchanger was mounted in the front storage bay to keep it and the entry point for the water systems warm. A direct connection was established from the heat exchangers to the vents, plus the existing ductwork, to move heat throughout the trailer.

After the plastic pipe and heat connections were made, 6 gallons of propylene-glycol antifreeze solution were used to fill the system. Aqua-Hot recommends making a 50-50 mix, which can change depending on the brand of antifreeze used. The connection for the electrical element was then completed. The LP-gas and electric-element switches were mounted next to the existing thermostat using the wires from the original switches.
The furnace wires were connected to the LP-gas switch and the water-heater wires to the electric-element switch.