i had a play with the eberspacher water heater in my motorhome yesterday as my calorifier (hot water cylinder) arrived at last, and i found out just what a bugger of a job it is to get all the air out of a closed loop system,
how i plumbed it was.... boiler hot water output goes up through the floor, it went to the top connection of the coil in the tank, i put a T piece connector on that join, and ran a pipe to a car's expansion tank raised above the level of the coil in the tank, output from the calorifier coil goes down through the floor to the input of the circulation pump, output of the pump goes straight accross to the boiler.
Filled the system slowly through the expansion tank, turned the pump on manualy and tried all i could to burp the system, wouldent have it, disconnected the expansion tank and left the tee piece in place pointing up, dribbled water in there with the pump running untill it overflowed, re-connected the tank,
still lots of air in the system,
tried the same with the pump not running, same result.
i got the system working by using a bucket, splitting the pipe between the output of the boiler and input of the calorifier coil, filled it with water and let the pump suck the water down, wouldent at first, wont self prime it seems... air lock at the pump, so i ran the hose pipe at full pressure down the suction line and that got the water flowing,
Then for about 5 minutes it was burping air bubbles out of the feed line with the pump running.
I gather i'll need to put an air bleeder at a low point on the system, but was wondering if these automatic air bleeders/seperators would work in this situation? or do they have to be above the water line like what the expansion tank is supposed to do, or do i need to run the system with the output of the boiler coing into a tank, and suction line taking water out of that all the time?
Or any other solutions,
I was only running about 3 meters of pipe and what ever length the coil in the calorifier is in this experement, when i get the radiators i'll have about 20 meters of pipe and 3 rads, maybe that'll help as each rad will have an air bleeder on it, but i still need to get the air out of the pump to start with.