Any experience with Laing ecocirc® solar pumps?

[Mikey]

I have a March 809 pump controlling circulation through the solar panel (open-loop system). It's driven by a PV panel - no sun, no circulation -- and has worked well for just over 4 years, but started getting intermittent recently. On inspection, the brushes were down to nubs and the entire motor body was filled with brush dust. No problem, right? Just replace the brushes. Wrong. March claims they're not replaceable and don't offer them as parts, but several vendors claim they've got them, for only about $30 per brush. Either way, I'm looking for another solution.

Enter ITT, with something called the Laing ecocirc® D5 Solar pump. It's a spherical motor pump (a new thing for me) intended for direct connection to PV panels, with microprocessor controlled optimization of pump output as a function of PV panel output. They claim "maximum performance at any given insolation." On paper, it looks great. I've got one coming and will report back on it, but has anybody already blazed that trail?

[Mikey]

Last year, while waiting for my new pump to arrive, I cleaned the old motor thoroughly and reinstalled it. I recently found out on another forum that March does have brushes available, at $26 or $66 each, depending on the brand of motor, but since I had already purchased a replacement, I passed. The cleaned-up motor worked fine until a couple of weeks ago, when it died again. Same problem, motor full of carbon, but this time the brushes had truly worn out, and the commutator was damaged enough that it was unusable.

So, I replaced the March pump with the Laing. The March came with male pipe threads, the Laing with female, of course, so some minor plumbing was required, but the Laing is in and running. I haven't got any instrumentation in the system to give me numbers, but the new pump appears to be much more effective than the old -- i.e., the manufacturer's claim cited above seems to be true. The downside is it's dead quiet, compared with the whirring of the old pump. We used to like hearing the pump running (barely audible in the kitchen), a pleasant reminder that we're making free hot water.

There's another pump out there from Ivan Labs called the El Sid (Static-Impeller Driven) that looks very much as though the pump body is the same one as is used in the March 809 series. The El Sid motor (they call it the "driver") is available separately, and I'll bet it would be a bolt-up replacement for the March motor.

[Gary Swart]

No experience with that type of Laing pump, but I have been using a Laing recirculating pump for several years, running it 24/7, and it has absolutely had zero problems. It appears to be an excellent brand.

[Mikey]

I'm happier by the day. I had some initial problems in that it looked as though the pump wasn't working, but now I know it was just too quiet. When I first plugged it in to the PV panel, it didn't appear to start up at all, so I used a lab 12V power supply, and got the same result, quickly unplugging it in case it was frying itself internally or something. The supplied documentation was skimpy, so the old RTFM advice wasn't helpful. I wrote the vendor I bought it from, but they were clueless and unhelpful, so I went to the horse's mouth. The Laing/ITT website has lots more information, including the fact that the motor spends a short time analyzing the power it sees, and adjusting the pump position for best startup onder low-power conditions. I then got out my mechanic's stethoscope and listened carefully as I plugged it in to the PV panel again, and sure enough, there was a click... click... click... kind of noise which eventually turned into a whirring-motor kind of noise as the sun broke through the morning clouds.

Bottom line -- it requires much less sunlight to run than the old pump did. I'm wondering now if it might be circulating water when it shouldn't be -- i.e., are there times when there's enough sunlight to run the pump, but not enough to raise the temperature of the water? Time for some instrumentation and maybe a controller of some kind.

[Mikey]

After 10 1/2 months, I can say the Laing pump is a roaring success. In fact, maybe too much so. Even early in the year, the water in the storage tank seems much hotter than I've ever seen it. It may be purely subjective, especially since I've already gone through late summer with the new pump and didn't notice anything unusual. But I think once again I've got to find a way to reduce the efficiency of the solar collector to get the temperature down. It's over 160° now. I'm thinking some kind of hurricane-proof shutter arrangement. Where is Rube Goldberg when you need him?