Several responses here: First, I've been told not to use more than 30 lbs of air pressure when blowing out the lines. Second, my dealer told me to take the water filter out before blowing the lines or inserting antifreeze. You can't blow the water that is inside the filter itself, and he's had cases of residual water draining down into the canister, causing it to crack under freezing conditions. Third, I believe in overkill; I blow out the lines and also run RV antifreeze through the system. You're right; the Forest river manual is totally useless. I don't know why they even bother to call it a "Manual." I live in Wisconsin where the temperature can stay below freezing for weeks at a time. This is the procedure I use:
1. Open the low point and fresh water tank drains and let them run until empty. Then close 'em up.
2. Drain the hot water heater and close the valves so that RV antifreeze can't get into the water heater. Inspect the anode for possible replacement, then leave it out until Spring.
3. Open the water filter canister, empty it, remove the filter, screw the canister back on.
4. Run the water pump by opening the hot/cold faucets, shower heads, toilet flushers until no more water comes out of the lines.
5. Screw the air compressor plug into the city water opening and blow out the lines using 30 lbs. of pressure. Do this by opening faucets, toilet flush valve, inside and outside shower faucets, one at a time until no more water comes out.
6.Put 2 or 3 gallons (amount depends upon the size of your rig) of RV antifreeze into the water tank and pump it through the system, again opening one faucet at a time, holding the toilet flush open until you see pink in the bowl, etc. Make sure you closed the valves to the water heater so that the antifreeze can't get in there, unless you want to buy a new one. If you have a winterizing kit attached to your water pump, you can eliminate pouring antifreeze into the fresh water tank. Just close the valve on the line from the water tank to the water pump and draw the antifreeze right out of the bottles with the winterizing kit tube already attached to the pump for this purpose. Just open the valve to that tube, and stick the tube directly into the antifreeze jug and run the pump using the same procedure as above.
7. Pour antifreeze into the P traps, black and grey waste tanks. You did already dump them before doing any of this, right?!
8. Sit down, have a beer, and congratulate yourself on a job well done!