Hello Al, The electric hot water heater should be at the lowest position in your heating system. The tank I use is the same type that a lot of auto use that has its radiator lower than the engine. Call a remote fill tank that is place up even or a bit higher than the heater core in the passenger apartment.
The tank has a standard radiator pressure cap on it like it would on a high radiator has. No radiator cap is use on these low radiator systems. The tank has a outlet on the bottom that connects to a hose that is connected in line with the tank heater. A hose is then connected from the tank heater and connected directly to the input line to the heater core. The return line that comes out of the heater core is then connected to the hose connection that is place high on the tank. When filling the tank with fluid, fill the tank about only half full. Some of these remote fill tanks have a cold fill line and a hot fill line on them. The return fluid is only allow to drip into the tank. As the fluid heats up, the fluid will expand to the hot fill line and may even up to the top of the tank. This increases the pressure to the maximum relief pressure of the pressure cap, just like the one that is use on radiators. You can use a standard pressure cap, but you do not need a high pressure or high temperature one that goes over 180 F. If for some reason the temperature and pressure goes above the rating of the pressure cap, the cap will open and the pressure and fluid flows to a small overflow tank, like the ones in other cars. The over flow tank has a small hose that vents to the outside air. This is how the air in the system is remove. You fill the overflow tank about half full or to the fill line in the overflow tank. As the heater systems cools down, the fluid in the overflow tank will than be drawn up to the fill tank. You can first test this heater system without the overflow tank by adjusting the temperature and pressure by using different radiator caps. I first started out with a lower fluid temperature and a 15 psi pressure cap that will open at 180 F. degrees. Just attach a overflow line on the pressure cap on the fill tank directly to the outside air or let it drip into a catch can for this test. If you keep the fluid temperature below the rating of the pressure cap, then you may not need a over fluid, but still attach a pressure relief hose to the pressure cap anyway and down, just incase it blows, the fluid does not get on any equipment. Unlike a radiator cooling system to keep a engine at a certain temperature, we want to keep the heater fluid at a maximum set temperature. In a standard engine vehicle, you will notice none of the fluid lines are not insulated. It is best to insulated all these lines in a EV. I use the round A/C dense black foam hose lines on all the heater feed and return lines. I also cover the 3 inch diameter 18 inch long 1500 watt heater unit which is use diesel engines which has a adjustable plug in thermostat on one end and a option pump on the other. I can also preheat this unit with commercial power, by using a on the dash transfer switch, that can either select the on board 120 Vac 60 hz which is inverted from 110 vdc rotating inverter by the pilot shaft of the main motor. All last winter for some reason, I did not have to used my on board heater, I just use the outboard commercial power to preheat the passenger apartment to 80 F degrees, which only takes about 15 minutes before I leave. Roland ----- Original Message ----- From: Al via EV<mailto:[email protected]> To: Electric Vehicle Discussion List<mailto:[email protected]> Sent: Saturday, October 18, 2014 8:58 PM Subject: [EVDL] Heating system It's that time of year, time to get the heater installed in my EV. It consists of a 3kW tank heater, a 12V solar pump, piped to the OEM heater core. My problem? I can't figure out why it is so damn hard to get the air out of the system. The tank and the pump are down low, the heater core about 6 inches above. My first guess was that a simple vertical tube with a small bottle on the outlet of the core at the highest point should work. It would allow expansion and any air should find its way up and out. Doesn't work. The only thing I have done that even comes close to working is to have a small diameter bypass around the core that runs through a bottle. Even then, it takes a long time to get a fairly solid fluid flow. Am I missing something? Thanks, Al _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub<http://www.evdl.org/help/index.html#usub> http://lists.evdl.org/listinfo.cgi/ev-evdl.org<http://lists.evdl.org/listinfo.cgi/ev-evdl.org> For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA<http://groups.yahoo.com/group/NEDRA>) -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20141018/5e8ded1e/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
