vent with automatic fan

stowbilly

Member
In a 2011 3250TS 5th Wheel, I have an automatic vent with fan that comes on and off with rain. It is controlled by a wall thermostat but does not seem to have an actual temperature control. It comes on at all temp settings and never goes off unless it rains or if I slide the temp controller all the way to one end.. I cannot identify the brand on the unit. It looks like a Fantastic but I can't see the exact same model on their website.

Does anyone know what brand was supplied and if there are models that are operated by a wall thermostat but not really controlled by temp?
 

danemayer

Well-known member
Hi Stowbilly,

Welcome to the Heartland Owners Forum. You'll find a lot of useful information here along with a great bunch of people who are willing to share their knowledge and experience.

Here's the general instruction for Fantastic Fans controlled by thermostat. If it's 85 degrees inside the coach, when you set the thermostat to 75, the fan should run until the inside temp gets below 75. If yours doesn't do this, there might be a thermostat problem.

Set your interior temperature on the wall mounted thermostat between 60°F and
90°F. When interior ambient temperature is warmer than thermostat setting, the
dome opens automatically and the fan blade turns on to the pre-selected speed.
When the cabin cools below the thermostat setting, the dome closes and fan blade
turns off.
 

Ray LeTourneau

Senior Member - Past Moderator
stowbilly, remember, when operating the fan, it is exhausting the air from the inside of the rig. While not totally necessary, it's best to have a window or 2 open to allow fresh air into the coach.
Like Dan explained, it should work according to the t'stat setting. We usually just slide the t'stat to the right till we hear the lid motor opening the vent and leave it there.
 

JohnDar

Prolifically Gabby Member
In your post, you say that it comes on at all settings. Does that mean if you slide the temperature selector all the way to the left/OFF position, and then start sliding it to the right, that it immediately turns on again? If that's the case, then your thermostat is probably bad. The fan is trying to cool the volume of air to where the thermostat is mounted, so you can figure roughly half the volume of the trailer air space. As mentioned, opening a window helps to provide air flow, but the fan is going to run for a long time until it can cool that area. And, depending on the outside air temperature, it may never make it since all you're doing is pulling in more hot air. If you have a digital thermometer (or furnace/AC thermostat) near the fan thermostat, you can see what the effect of the fan is by watching the temperature drop.

Something else I recall about the analog thermostats is their margin of error (hysteresis?). It can be as much as 5 degrees plus or minus.
 

danemayer

Well-known member
If you have the Furnace/Air Conditioning thermostat next to the fan control thermostat, and it's the Dometic Single Zone Digital model, you can get the current temp at the thermostat. When the thermostat is set to OFF (nothing running), press either + or - key to display current temp.

Compare that to the setting for the fan thermostat.
 
Top