lifespan of a GRUNDFOS Circulater

rt_2

I posted this same post under the category of Solar but I thought it would get a larger exposure if I posted it here. Here's my situation.
I use a Grundfos circulator for my solar EVAC system. I've been using it for about 8 or 9 years now. Any idea what the lifespan of one of these pumps would be. The reason I ask is we are headed to FL for the winter again. In the past, I use to cover the array with a tarp so it did not run while we're gone. Last year, I ended up installing a heat exchanger in the loop so I can take advantage of the hot solar heated glycol and dump the heat in the basement. We had a fairly mild winter last year but I did burn only 1/2 of the fuel oil used to heat my house compared to previous years. So I believe it's working.
I'm afraid of the pump possible failing while I'm gone and end up with a mess. I'm thinking over the life of this pump, it probably has run on average 8 hours a day for the last 8 or 9 years. Am I running on borrowed time?

This is the circulator:
https://www.amazon.com/Grundfos-UPS15-58FRC-3-Speed-Circulator-59896343/dp/B003XEYLU0

hot_rod

Have you checked the glycol.. When glycol is overheated from stagnation or no load condition the inhibitors break down and the ph starts dropping.

Check and see what the ph of the fluid is from the tech sheet, Some may run 10- 11 ph, when new once it drops into the 8's then 7's, time to flush and clean and refill.

If the ph has dropped it indicate the system has been over-heating.

I would only use the very best, high temperature, HD solar fluids.

You were able to find an ultra high temperature from Tyfocor when evac tubes were popular a few years back.

I heard rumors that the high temperature fluids may not have been FDA approved?
http://www.tyfo.de/uploads/TI/Ti_TYFOCOR-HTL_gb.pdf

I have seen those pumps go 20- 25 years. it all depends on how often it cycles on and off, and the condition of the fluid.

Some of the nice digital solar controllers will log pump run time and on/ off cycles with the additional data logger attached. That would give you an ideal of how often it actually cycles.

These same controllers have evac tube settings and I would also run that pump in variable speed mode to eliminate some cycling or short cycling.

How many tubes do you have? , you can determine how much energy it is actually contributing with the model of the collector, mounting orientation, and your location.

Performance and output data is all listed at www.solar-rating. If it is a small array it might be better to just take them off line while you are gone, as opposed to over heating them day after day with low or no load conditions.

Solid_Fuel_Man

Could you pipe in a second redundant pump and controlled in with your solar controller? Some have a pump A and pump B so if it sees stagnation it will switch and latch to the opposite pump, otherwise it can just lead/lag themail two pumps. I do this in wood boiler installs, and it is standard practice in all commercial applications where pump failure is not an option.

For a drain back application you may need a three way zone valve due to the lack of check valves in drain back.

Taylor