With thanks to members here who posted How To narratives and advice, I have completed Winterizing my motorhome as best I could; however there is one aspect I am not completely satisfied with: Evidently my older Shur-flow fresh water pump is simply not up to the task of pressurizing the hot water lines once the hot water tank is filled.(Note: I did not notice that there was no tank by-pass prior to starting the winterization project.) Consequently, all I get out of all three hot water faucets is air and no water. Cold water side is fine and I have manually filled the traps and lines to grey water tank.

Now, a theory I have developed is that there may be no real harm in this as, if all there is in those lines is air, they won't freeze, but I'd like to hear thoughts and comments on this anomaly, and why the pump simply won't fill the hot water side of the system. Would a newer, higher output Shur Flow be a good idea? (My pump is, after all, 36 years old!)

Tags: C, Class, Winterize

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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///

Had I thought to check during clement weather, I would have installed a hot water tank bypass valve, in which case, in all likelihood, this problem would have been averted. By the time I surrendered to the inevitability of Winterizing, it was too late (and too cold) to install the bypass system.
Yes, I thought of that, but I have put over 10 gallons in (no bypass) and I do not think the hot water tank is more tha about 7 gal. I checked for leaks and found none.

Thanks very much for the reply.

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.

if the tank has 1/2" nipples that the lines hook to, one could simply disconnect the lines and join them with a 1/2" nipple, effectively bypassing the 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.

Im froma fairly mild climate too Matthew. I think the volumn of air pumped by the diphram would not be sufficient to get all the water out. Several in here have extreme winters and have touted the benefits of the strongest antifreeze and very thorough winterizing regimen which i am inclined to agree with after hearing their points. Having put over 10 gallons in, I believe he has a 10'gallon WH or his coach is angled so he cant get all the antifreeze out of the fresh water tank. The cheap route wouls be the nipple i discussed earlier....just drain the antifreeze out of the WH into a bucket first and screen it and reuse it. Then do the nipple for the bypass...

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.

Wow...that was quite a system you had...never seen one that complete. I was aware that the pump would lift up to 6 feet to prime they claim...at least in their prime..hehe.. But i had no idea they would actually pressure up a tank...like an accumulator tank! Thats news to me. Inthe repair industry I have seen them in some state of decline...usually failing to even prime..

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.




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