pumping question - solar panels

mark schofield

thanks for the replies. both the panels and wrap-around tank-heat exchanger are aluminium with cpvc piping. this was a system marketed by Gruman in the mid 70s-eairly 80s. the only problem has been the recent failure of the origional Parker-Hannefin aluminium fittings to the cpvc (easily fixed after a trip to the plumbing sypply house). I've had to recharge a few times and have used a small pump as you suggest to pump the glycol in, and continue to circulate until the fluid comming back into the pail (after the check valve) has no bubbles. Then shut the outlet, preasurize it to 15 psi, close the inlet and done. My main concern was the height of the piping being lower than the HX loop inside, but from what you have said, it shouldn't pose a problem. Even for a system this old and inefficient I can get 80 gallons of 125 deg water on a sunny day (madison, ct.) which feeds my propane DHW tank. So I'd like to keep it going untill something really blows out. thanks again. mark s.

mark schofield

I recently reroofed my house after 25 years and removed the two Grumman solar panels. The solar system (for DHW) still works well but it’s about 20 years old and will fail sooner or later, probably soon after I push the panels back up, remount, replumb, fill, and charge. So I plan to plan to mount the panels close to the house on a frame on the ground until the system quits. The location will require that the inlets and outlets on the panels will be much closer to the height of the HX tank and pump in the cellar. Using the existing plumbing runs attached to the cellar ceiling, the inlet to the panels outside will now be a few feet below the piping while the outlet will be about 3 feet higher. The system has a bleed valve at the highest point outside, expansion tank and air vent inside, Grundfos UM25-18SUC pump, preasurized closed loop glycol year round (about 5 gallons) I kept the system at 15 psi when the panels were on the roof. Will “pumping down to the inlet “if possible cause any problems? The system was very easy to charge and remove the air when mounted on the roof 15 feet above the HX tank. But now it will be in an approximate level plane. It works well. No sense to loose it. But I’m getting too old to do this roofing stuff anymore.

Bob Gagnon plumbing and heating

air removal

should be no problem for the system you describe, but if your collectors are copper and the anti-freeze was properly maintained, they may last longer than you think. I put a spirovent to remove air on my solar loop and it works great. Thanks for staying with solar, Bob Gagnon

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hr

A good manual purge set up

is the key to getting a good air free system. Plenty of systems working without auto air purgers, just a coin vent at the high point.

A purge pump is a help to get the fluid in and air out. The location of the panels to the tank will not matter.

Webstone makes some valves that are near perfect for this. Or build your own with a ball valve and a couple boiler drains.

A small submersible sump pump in a 5 gallon bucket is a good way to pump the glycol in and purge the air out.

Rental shops have them if you don't own, or want to buy one.

hot rod



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