washing machine pump motor

So like a smaller version of a central heating circulation pump, magneticc oupling through a membrane. At least washing m/c get used through the summer , so nver a chance to seize up

Well, I've seen magnetic-coupled pumps. These have a totally standard induction motor turning a magnet outside the housing, and a magnet turning the impeller inside.

This is different - there is only one magnet, and the stator poles outside. So, it is a 2-pole permanent magnet synchronous motor. The only trick is to make sure the thing starts every time power is applied.

Jon

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I have used TACO and Grundfos sealed hydonic circulator pumps - our present system uses two TACO systems and one Bell & Gossett 1/4-horse as it is a s ummer-winter system that makes domestic hot water as well. The TACO pumps h ave one (1) moving part installed as a cartridge, and behave as does any ot her AC induction motor designed without brushes. There is no 'magnetic coup ling' in the true sense of the word, as there is only that single moving pa rt. I would agree on the 'synchronous' description as the impetus has to co mes from somewhere.

The Bell and Gossett, on the other hand has the standard induction motor us ing a spring-coupling to a separate pump housing with a sealed bearing. Muc h larger, much heavier, and much more powerful. That is what moves the appr oximately 110 gallons (400 liters) of water through the 34 radiators on a 2

-pipe system, that includes just under 450 feet (146 meters) of pipe in tot al. The house was built in 1890, and substantially expanded in 1928, when t he hydronic system was first installed. It is a 2-pipe, 3-zone system desig ned for gravity supply and return, with a single circulator not added until the 1950s. We converted from oil to gas and added the indirect water heate r, that conversion requiring the two additional circulators. But the first Grundfos pump I installed about 38 years ago is still going strong. And my first TACO pump (27 years) is equally good, so far. I have rebuilt our B&G twice - the first time just the coupling - the second time, the support bea rings and coupling. I should have done the support bearings the first time. That, now, has 8 years on it, but is dated 1978 as the original install-da te.

Peter Wieck Melrose Park, PA

Have you looked for a replacement motor? I had some motor fail on a Kenmore washer and the local appliance dealer had the part.

George H.

Yes, I ordered a replacement part through Amazon.

Ugh, yet another story. The replacement pump has a thermoplastic pump housing, while the original seemed like it was a thermoset. The pump leaked where the two parts were joined with a raidal O-ring seal. Removing the housing, it was visibly non-circular! So, I had to take the old housing and O-ring and put them on the new pump. It is now back in operation, but I'm not so happy about their crummy parts and the number of times I had to disassemble the thing to make it right.

Jon

I should have done the support bearings the first time. That, now, has 8 years on it, but is dated 1978 as the original install-date.

A problem with synchronous motors, is they can start backwards unless there is a "kicker" mechanism

Greetings Jon, Thanks for the motor update. I have been thinking about that motor and why they would use it and it must be because shaded pole motors are so inefficient. Eric

Right, it has to be fairly efficient as there is no fan. Since the rotor is in a sealed plastic housing, there is no external shaft to connect a fan to. That's probably why they cycle the pump on and off during drain/spin cycles.

I guess the permanent magnet rotor is way more efficient than an induction rotor, too. The only tricky part is assuring the motor starts every time you apply power.

Jon