stupid question time, do you have the pump pulling from a full jug of antifreeze? Sounds to me like the hot water tank is not full enough to move water, just air
the hot water tank should be drained and isolated before you put the rv antifreeze through the system thats they way i do mine and it works for me good luck chuck///
If the pump works on the cold side, it's working. I agree that the tank's probably not full enough for water to come out the "hot" side. There is no added resistance from a full (or empty) water heater tank for the pump to overcome, since the pump doesn't care one way or the other if it's a 1'2" line or a storage tank.
My Hall has drains for the storage tank and the water heater - along with the remnants of an automatic winterizing system that was missing in action when I bought it 4 years ago. I've been lucky so far and gotten by with pumping the delivery lines dry and leaving both of the drain lines open. I also leave both drains open on the holding tanks. The point is that most all of the water pumps in service these days are the diaphragm type that will pump air, as well as water, without damaging anything. If the taps are all opened and the system pumped until nothing but air is coming out, the chances of anything other than a couple minor deposits of water being left to freeze are unlikely. Because water causes damage to plumbing systems by expanding while freezing, the absence of a "closed" system (all the taps open) should prevent any problems, since the little water in there is free to expand and thaw without restriction. At least this is how it's worked for me, even though it seldom gets below 20 deg F here and I also leave an oil-filled electric heater on low 24/7.
Yes. This is why I installed a mini pressure tank. Because quite a bit of pressure can build up in them that last several seconds, the DC pump acts just like a municipal system, albeit briefly, which allows something like a purge. Still, there's no substitute for draining and antifreeze sometimes. The equipment originally installed in my RV had a antifreeze tank, small pump and several solenoid valves that would automatically protect all the lines, tanks and fittings. It must have failed at some point, cuz most of the bits are gone.
After digging around through 40 years of manuals and receipts I found that it was made by "Cascade Winterizing Systems" of Bend, Oregon. It has two positions: winterize and bypass, and says that it protects to -60 deg F and has a Limited Lifetime Warranty! Geeze. I wonder if they'll fix it for free? Too bad it was installed in 1973 and nobody seems to know what happened to them. ;-) From the rather poor illustration in the manual, it looks like the pump might have been something like a Procon positive displacement rubber impeller type. As long as they don't stick to the pump body, those impellers will indeed create good pressure.
Rats. I take it all back! The pump in the illustration is actually supposed to be some kind of motorized valve actuator, not a water pump. Like I said, bad drawing. On the other hand, the original pump was a P.A.R, with a cogged belt drive; same kind used in yachts and Airstreams. It would definitely do the job. However, after discovering that it was far less expensive to just replace the pump with a Shurflo than it was to get a few parts for the damned thing, that's what I did. The original was really LOUD and the water came in pulses.