Hello, I'm new to this forum and am asking this question because I found quite a bit of information about radiant floor heating in other posts here.
I'm converting a 4x4 ambulance into a winter camper for weekend ski trips in Colorado. I have a really good sleeping bag... but I would much rather have a really good heating system and use the sleeping bag as a back up. Single digit temps are common and I've experienced temps as low as -26F.
I also do not want to use propane, I want to keep this build strictly off grid solar. The electrical system I have is 800ah of LiFePo4 battery, with 480W of solar panel to recharge.
My plan is to use 3/8" pex tubing filled with propylene glycol in the floor and 1 wall. I will use a 12v 2.65gpm pump to circulate the fluid. The "boiler" is where it gets interesting. I plan to make an array of pex, and cover it with (10x) 5v heating pads controlled by a simple on/off switch. The 5v heating pads are the type found here, (sparkfun.com), and a few other places. Other than a fill valve that would be all the parts.
This is the part that I'm not sure of:
The idea is that since the system will be running at only one temperature (on or off only), I can use a fixed amount of eutectic fluid and not have to worry about over expansion. Therefore I wont need an expansion tank and relief valves, keeping the system closed.
Is this ok? Having the system closed like that with no expansion tank?
The pex tubing will be 1 continuous piece (one end connects to the fill valve, the fill valve connects to the pump, the pump connects to the other end of the pex), so the chance of a leak would be minimized. I imagine that it would take a long time to heat the system up, but the low voltage / amps of the total system will allow me to continuously run it off of battery power for over 3 days without sun (3 days without sun would be extremely rare in CO). So I can essentially just leave this system on all winter and my truck would always be warm. The whole system will use about 1/2 gallon of fluid, so the fluid would pass through the "boiler" 5 times per minute for heating, 20% of the fluid will be in the "boiler" being heated at any given time.
Thoughts and ideas would be appreciated. If it will safely work I may split it into 2 separate pex/pump systems that use the same 5v "boiler" array (one system for floor, 1 system for wall). I could also use a propylene glycol and water mix to reduce expansion, but i would be concerned if water would be able to evaporate from the system? I could also double the percentage of system fluid in the "boiler" to 40% if necessary.
I'm converting a 4x4 ambulance into a winter camper for weekend ski trips in Colorado. I have a really good sleeping bag... but I would much rather have a really good heating system and use the sleeping bag as a back up. Single digit temps are common and I've experienced temps as low as -26F.
I also do not want to use propane, I want to keep this build strictly off grid solar. The electrical system I have is 800ah of LiFePo4 battery, with 480W of solar panel to recharge.
My plan is to use 3/8" pex tubing filled with propylene glycol in the floor and 1 wall. I will use a 12v 2.65gpm pump to circulate the fluid. The "boiler" is where it gets interesting. I plan to make an array of pex, and cover it with (10x) 5v heating pads controlled by a simple on/off switch. The 5v heating pads are the type found here, (sparkfun.com), and a few other places. Other than a fill valve that would be all the parts.
This is the part that I'm not sure of:
The idea is that since the system will be running at only one temperature (on or off only), I can use a fixed amount of eutectic fluid and not have to worry about over expansion. Therefore I wont need an expansion tank and relief valves, keeping the system closed.
Is this ok? Having the system closed like that with no expansion tank?
The pex tubing will be 1 continuous piece (one end connects to the fill valve, the fill valve connects to the pump, the pump connects to the other end of the pex), so the chance of a leak would be minimized. I imagine that it would take a long time to heat the system up, but the low voltage / amps of the total system will allow me to continuously run it off of battery power for over 3 days without sun (3 days without sun would be extremely rare in CO). So I can essentially just leave this system on all winter and my truck would always be warm. The whole system will use about 1/2 gallon of fluid, so the fluid would pass through the "boiler" 5 times per minute for heating, 20% of the fluid will be in the "boiler" being heated at any given time.
Thoughts and ideas would be appreciated. If it will safely work I may split it into 2 separate pex/pump systems that use the same 5v "boiler" array (one system for floor, 1 system for wall). I could also use a propylene glycol and water mix to reduce expansion, but i would be concerned if water would be able to evaporate from the system? I could also double the percentage of system fluid in the "boiler" to 40% if necessary.