Grundfos Pump Circulator not operating
Hello, My Grundfos pump circulator for the family room hot-water base-board heating system (zoned) does not operate. Could someone please kindly shed some light? Thank you in advance! Background Info: The ciruclator's model number is Grundfos UPS20-42F (I believe the newer replacement model is UP15-42F). When I turn up the thermostat in the family room and move across the temperature threshold, I hear a fairly audible click from the utility room right next to the family room. However, upon a close-up checking, the circulator did not seem to be operating (no vibration felt from the housing and no pumping noise). Both shut-offs on the circulation path were open and no heat was felt at the fin-tubes. Somebody on the web talked about a capacitor that can go bad. If that's the case, what is the function of this capacitor and where is it located? The circulator (pump) has a slotted circle on the top of the house. Looks like something that one can turn with a flat screw driver. What is the function of that? Other potentially useful info: The gas supply was shut off last winter (by the previous owner) and there probably had been a deep freeze in the pumbing system. As a result I have to replace a section of the fin-tube that had gone cracked. Could the deep freeze hurt the pump? The rest of the house has hydronic floor radiant heating and they are all still in good working condition. hsieh I'm not sure that the position your pump is mounted in is a good one. I don't think the shaft should be vertical. In any event, if you take the large screw out, carefully, I think you can rotate the motor shaft with an allen wrench. Be careful when taking it out because water may come out. I don't think it will gush out but if the pump is just stuck, that may be all you need to do. Then put the plug back in and see if it runs on it's own. If you can isolate the pump from the system with valves before you try taking the plug out, then you will be OK for sure. I doubt if a freeze damaged the pump and nothing else near it. More likely fresh water (a lot of it) has entered the system and caused a little rust to bind the pump. If it has a speed control dial on it, set it to high speed. (The one with 3 dots) Let us know how you make out. Ken Ken, Thank you for the suggestion. I'll try the allen-wrench-pump-blade-loosening procedure later tonight and see if it would solve the problem. I will report back. Regarding the point you made on pump mounting position (orientation), I'm afraid I found that one too from an online Grundfos manual. It suggests that the pump should be mounted with the shaft sitting horizontally; I take it that it means my pump should have been installed on a vertical section of the plumbing route. (Anyone knows why this is so important?) The contractor installed my system had obviously missed that manufacturer's requirement Hsieh With water lubricated, water cooled pumps, it is important thet no air can get trapped inside the motor cartridge. With yours mounted the way it is, air is trapped up there and causes corrosion even if it is a small amount and it also prevents adequate cooling by not having water surround the whole motor. You can turn the flanges and the pump 90 degrees and you will be OK. You do not need to mount it in a vertical pipe. Good luck. And don't be disappointed in your service tech. One in 20 read the manual. The other 19 learn the hard way. My only complaint is that we all pay higher prices for the products because the manufacturer has way too many warranty returns on perfectly good materials that are improperly installed and then returned for warranty. Ken Ken, I tried the allen wrench trick as you suggested last night. Everything went as you said. The blade rotor in the pump spinned all right with the allen wrench, although I noticed some looseness associated with the shaft/rotor (my allen wrench wobbled when I spinned the rotor with it) . Is this normal? After that I replaced the giant screw and turned on the thermostat. The pump did not run on its own . I also performed an independent investigation on the side of electrical supply. I open up a box (2x4x6) on the wall that the thermostat, the pump, and the house line apply to. I verified 115V power did go to the pump when the thermostat is turned on. Then I went to the box mounted on the pump and opened it up to inspect. I found an 8 microF capacitor in it (this might be the capacitor that I asked about in my base note) and a bunch of other wires. I did not go any further from there since I did not readily have a diagnostic plan for the pump control box on the housing. Any other suggestions would be welcome. Hsieh You did well. The capacitor is the one that was mentioned in another post. My suggestion is to replace the pump with a Taco 007. Follow the same rules and don't put the motor shaft in a vertical position. I hope you can tackle that project. Maybe you even have isolation valves nearby. Good Luck. Ken
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