Thread: Help wiring vent fan on our command trailer.

I am working on adding stuff to our command trailer. I know what I'm doing about lights,radios and batteries. My next project on the trailer is adding a vent fan through the roof. I am bidding on a RV/trailer retractable vent on Ebay that has a 12 volt fan. What I need help on is putting a thermostat on it so it doesn't run all the time. I'm looking for it to run when the inside temp gets above 80-90 degrees. I found this on Amazon, but the temp is higher than I want, but the price is right for me.


Amazon.com: Hayden Automotive 3653 Economy Adjustable Thermostatic Fan Control: Automotive


We had the trailer pulled out the other day, I opened it up after it sitting for a few hours, to try to work inside and it was completely unbearable. It was atleast 20 degrees hotter than outside(It was already hot anyway). This was expected condition, but it got me thinking of putting a small fan through the roof to at least try to keep it a little cooler. Even sitting inside the building it gets a little warmer, so I know this would help.


What would be the simplest, easiest thing to do? The way we have it wired, I have a battery in the tool box, with a trickle charger. The trailer is wired for 110 A/C with a plug outside where the generator is hooked up. When at the hall is plugged up to the building as there is a refrigerator inside with drinks and such.

Thanks for the help.

Jordan,TCFD

Have you thought about using a 110 Volt ventilator fan with an intake vent, powered on the 110V shoreline? Or a ceramic heater/fan in combination with air vents. (See Bradley County EMS vehicles for their use of ceramic heater.) That way, you could also heat the trailer in cold weather. Might also look at placing solar panels on top of the trailer to power a fan or charge the batteries.

Also, does the trailer have a white roof? The situation in the summer is a phenomenon known as "heat soaking" and when the vehicle is in the sunshine, the build up of heat exceeds the environmental temperature. Some colors will accumulate heat rapidly when in direct sunlight.

You may want to seek some advice from a HVAC professional concerning the cubic feet in the trailer and the kind of BTU factors you will need for the volume of air to be moved.

Good luck. Keep us posted on your solution.

Richard

Here is one for you to think about before you get too far into this project. One of my neighboring depts has a rescue truck that they use for a command vehicle. I was on top of their tanker the other day and looked across and saw an air conditioner on the roof of the rescue. It says "Colman" on the side of it. Someone picked up an AC unit out of a camper and mounted it on this truck. Low dollar but it works great!

Kevin

I might have to think about the heater situation, but give to you some more info, the trailer is only a 8 foot long trailer. I'm 6'3" tall and I can't quite stand up in it. The roof is standard galvanized sheet metal color. Might look at trying to cover it in white vinyl. This trailer is also our high angle rescue trailer, so it goes into the woods when needed. Couldn't quite have anything sticking out the sides or anything,like a AC unit. I'll get some pictures posted of what the trailer looks like.

Jordan,TCFD

You are already bidding on the 12v fan but just need a way to activate the fan when the temperature gets above a certain point?

What about a simple attic fan thermostat?

(One where the switch closes as the temperature rises.)

Thermostat, Attic Fan Control, 120 Volt - Line Voltage Thermostats - HVAC Controls - 3HJN6 : Grainger Industrial Supply

How about sticking a 12volt solar panel on the roof. That will power the fan through the day. Could also have it trickle charging a 12volt battery.

It sounds like you most likely use the trailer with one or more doors open since there is no AC. Might be easier to wire up one or two 12 volt fans on the wall and just put them on a switch. You could also use a heater/fan unit for this purpose so you would have heat when you need it. Usually these are ceramic heater / fan units used in RV's.

With a door open, you should be able to move a fair amount of air through the trailer and out the door in a short time when you activate the fans. This would also allow your personnel to have some air moving across them when working inside the trailer since it sounds like an AC unit isn't feasible.

Our command post is a retired Horton Ambulance. The vent fan in the ceiling really doesn't seem to do much as far as heat removal. Our CP is parked outside, and I can tell you the only thing that cools it down is the AC. I think RV type exhaust fans are more effective at removing humidity and smells than heat. The only way they will remove much heat is if they are able to draw air from outside through the trailer, such as a wall vent or door for cross-ventilation.

You might also check a local RV dealer for a reflective roof coating (usually white in color) that will reduce the temp when in the sun, or throw a white tarp over the top when heat is an issue. It's amazing how much heat will be reflected by a white surface.

Good luck with the project!

no wiring needed. but costs a lil more


solar fan from Northern Tool + Equipment

The problem is, the trailer sits inside like 99% of the time. We only had it pulled out because we needed the building for a fund raiser. Unless we're doing high angle training(which our certified trainer had to stop training due to SAR in South America,which has been going on for a few months), it does not get pulled out. That is why I wanted to hook it up to either 12 or 110 volts. With A/C power, it would just be the time between the station and the scene to when the generator could be hooked up.

We only have 2 fluorescent shop lights and a fridge in the trailer anyway, so it doesn't pull much compared to the generator power. We keep the trailer locked up when at the hall as only HAR personnel are the only one's allowed in the trailer. I'm mainly wanting the fan to be turned on when at the hall, when we're at a scene the side and rear doors will be open and won't really matter.

The solar panel idea is nice, but really overkill for this trailer.

We're put solar panels on trailers at work before for TDOT incident that carries brooms,oil dry, cones and anything else for a large accident or leaks. These were dual axle, 20 foot trailers.


I should be able to get some pictures of it tomorrow.

Jordan,TCFD

i misunderstood what you were trying to accomplish. Does the trailer have a vent? Without the ability to pull in some outside air, the exhaust fan isn't going to do much for you to remove heat. If it doesn't have one, you might want to consider putting a louvered vent down low so that cooler air from near the floor level will circulate through when the warmer air is exhausted out through the roof.

Any type of fan that is used for cooling, like in a computer case, or other application, relies on pulling air through the space to cool, it can't just suck the heat out of a closed space efficiently without some way to pull air in.

Hope that helps.

Originally Posted by Jordan,TCFD

I am working on adding stuff to our command trailer. I know what I'm doing about lights,radios and batteries. My next project on the trailer is adding a vent fan through the roof. I am bidding on a RV/trailer retractable vent on Ebay that has a 12 volt fan. What I need help on is putting a thermostat on it so it doesn't run all the time. I'm looking for it to run when the inside temp gets above 80-90 degrees. I found this on Amazon, but the temp is higher than I want, but the price is right for me.


Amazon.com: Hayden Automotive 3653 Economy Adjustable Thermostatic Fan Control: Automotive


We had the trailer pulled out the other day, I opened it up after it sitting for a few hours, to try to work inside and it was completely unbearable. It was atleast 20 degrees hotter than outside(It was already hot anyway). This was expected condition, but it got me thinking of putting a small fan through the roof to at least try to keep it a little cooler. Even sitting inside the building it gets a little warmer, so I know this would help.


What would be the simplest, easiest thing to do? The way we have it wired, I have a battery in the tool box, with a trickle charger. The trailer is wired for 110 A/C with a plug outside where the generator is hooked up. When at the hall is plugged up to the building as there is a refrigerator inside with drinks and such.

Thanks for the help.

Jordan,TCFD

like this?

McMaster-Carr

Originally Posted by Jordan,TCFD

My next project on the trailer is adding a vent fan through the roof. I am bidding on a RV/trailer retractable vent on Ebay that has a 12 volt fan. What I need help on is putting a thermostat on it so it doesn't run all the time. I'm looking for it to run when the inside temp gets above 80-90 degrees. I found this on Amazon, but the temp is higher than I want, but the price is right for me.

Jordan,

MaxxAir makes some aftermarket RV vent fans that are powerful enough to do what you need and include a thermostat. It is all 12vdc powered so you can run it off a battery in the trailer or on power from the tow vehicle.

Take a look at the MaxxFan series. Maxxair Vent Corporation It's probably what you need all in one package.

Yes, like that. When it comes to dealing with A/C stuff I'm kind of lost. I can work most 12 DC circuits with no problem.

Thank you.

Jordan.

Originally Posted by bill98579

like this?

McMaster-Carr

Originally Posted by MESDA6

i misunderstood what you were trying to accomplish. Does the trailer have a vent? Without the ability to pull in some outside air, the exhaust fan isn't going to do much for you to remove heat. If it doesn't have one, you might want to consider putting a louvered vent down low so that cooler air from near the floor level will circulate through when the warmer air is exhausted out through the roof.

Any type of fan that is used for cooling, like in a computer case, or other application, relies on pulling air through the space to cool, it can't just suck the heat out of a closed space efficiently without some way to pull air in.

Hope that helps.

This is what I am looking at putting in, a regular roof mount vent with fan. The link shows the fancy ones as well, but I just want a manual raise with a fan.

http://www.maxxair.com/images/storie...view_Thumb.jpg

Here are the pictures of our trailer.The antenna you see is for the VHF mobile and actually does very well. Only 1-3 watts reflect with over 40 watts out of the 45 watt TK-790. I am looking at adding a UHF(Ambulance is on UHF), and 800 for interop(If anyone has anything cheap,I might be interested), just in case. I don't have the LED's hooked up yet. They will be controlled by a Sho-Me flasher, as the front 2 are actually S/T/T lights(I had them, and I'm using them) and don't flash. I'm hooking the flashing LED's up on 1 switch, then a second switch will be hooked up to the marker lights of the trailer. The outside "step lights" were hooked to the marker lights, so I want to be able to run them when not hooked up to a vehicle. I'm also using this for vehicle identification when in the woods. For you technical people who see the problem, I'm using a rectifier diode to keep the trailer battery from back feeding to the vehicle.

The LED's are Code 3 LC LED's.

Originally Posted by Jordan,TCFD

This is what I am looking at putting in, a regular roof mount vent with fan. The link shows the fancy ones as well, but I just want a manual raise with a fan.

http://www.maxxair.com/images/storie...view_Thumb.jpg

This same fan is what is in the back of our Converted Ambulance Command Post. Same setup with a multi-speed fan and vent that has to be opened manually.

The main issue we have with the fan is that we need to be careful about which doors or windows are open on the CP in relation to our vehicle exhaust. The fan is powerful enough to pull exhaust fumes in from your tow vehicle or other equipment that is running nearby. You might want to consider installing a Carbon Monoxide Detector in the trailer if personnel could be working in there for an extended time with the fan running. We actually have a section of high temperature exhaust hose on board our CP so we can direct the vehicle exhaust away if we are going to be parked and running for long periods.

Nice looking trailer. Good luck with it!

Originally Posted by MESDA6

This same fan is what is in the back of our Converted Ambulance Command Post. Same setup with a multi-speed fan and vent that has to be opened manually.

The main issue we have with the fan is that we need to be careful about which doors or windows are open on the CP in relation to our vehicle exhaust. The fan is powerful enough to pull exhaust fumes in from your tow vehicle or other equipment that is running nearby. You might want to consider installing a Carbon Monoxide Detector in the trailer if personnel could be working in there for an extended time with the fan running. We actually have a section of high temperature exhaust hose on board our CP so we can direct the vehicle exhaust away if we are going to be parked and running for long periods.

Nice looking trailer. Good luck with it!

Ok... this whole thing needs reevaluated from the ground up. That trailer is not meant to be occupied.... it' a cargo trailer..... they used to lock POWs in metal boxes in the sun to get them to talk...... Sitting in there is going to require more than a vent fan. That thing needs a propperly installed RV AC unit in order to be used for incident command safely. If you plan to keep the tow vehicle running as a source of power you need to pipe the exhaust away from the IC area. They make shop pipes for this purpose. I would suggest getting with your local RV dealer and having them help you safely climate control this unit ASAP. You have two real threats to your own safety here.... heat an CO.

Originally Posted by JohnMarcson

Ok... this whole thing needs reevaluated from the ground up. That trailer is not meant to be occupied.... it' a cargo trailer..... they used to lock POWs in metal boxes in the sun to get them to talk...... Sitting in there is going to require more than a vent fan. That thing needs a propperly installed RV AC unit in order to be used for incident command safely. If you plan to keep the tow vehicle running as a source of power you need to pipe the exhaust away from the IC area. They make shop pipes for this purpose. I would suggest getting with your local RV dealer and having them help you safely climate control this unit ASAP. You have two real threats to your own safety here.... heat an CO.

John, in my response that you quoted, I wasn't certain that someone was actually sitting in the unit for long periods, but put that info in as a caution, knowing that the vent fan in our ex-ambulance will pull in those fumes, and we do use ours for hours at a time as a full command post and rehab unit. Even if no one is in this trailer to do more than grab equipment or make a radio call, it definitely needs a CO Detector as a precaution.