grundfos pump

Jorge

I don't think anything is stuck in the pump .It is very quiet when it is working. It seems like it just doesn't have enough power to start on low sometimes.

Jorge

Grundfos pump stuck

I have a hot water bb loop system in my home I just installed a Grundfos 1558 3speed pump that I have set to low speed. My problem is that every time the system cools off and then re starts the pump will not turn unless I turn the speed switch to medium then back to low. Anyone else Run in to this problem? I need low speed from the pump because on medium speed I get velocity noise.

kevin coppinger_4

is something..

stuck in there? kpc

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hot_rod

How do you know

it's not starting or spinning?

hot rod

st heat

voltage

did you check your voltage? once i fried 2 nrf 36 s and finally measured the voltage and found 170 volts on 1 leg from the power co.

Jorge

Sometimes it works sometimes it doesn't. I can't here the pump running. Used a screw driver as a stethoscope. Old mechanic's trick. When I switch the pump to medium speed I can here the pump running then when I switch it to low I can still here it running. It only gets stuck when it sits for awhile.

hot_rod

that circ

has a little "tickler" device that should prevent the rotor from sticking. Maybe a bad capacitor of capacitor wire? I know the capacitor tends to fall from the box with the cover off in some positions. I'd like to see a clip on it.

I wonder that it is spinning, very quietly. Really without a flow indicator it's sometimes hard to tell they are circulating.

Do you have one of those Grundfos "spin-dicators" It's a good wy to see the difference in rpms. I use mine all the time.

If you have a iso valve on the discharge slowly close it down. this will generally indicate if you in fact have flow. or a quick close- open, close- open will usually show some results

hot rod

Unknown

Spin-dicators

Be careful with these. They only prove a magnetic field in the winding (Viessmann uses them to prove power to solenoid valves with no spinning parts).

Jorge

If I take this pump apart is anything going to pop out at me or is it all contained in a cartridge. Also do I need a new gasket or oring?

kpc_3

self contained

if it a new pump you might not even need that...kpc

hot_rod

they do spin faster and slower

as you change speeds. a pretty good indicator of rotation. Fun to watch on a VS circ.

But you are corrct they will read a stuck rotor also.

hot rod

Unknown

Spinning Testers

Good morning Hot Rod...

I don't want to get into a "spinning match" with you (you are a very knowledgeable heationg expert, well respected in the industry) but the reason these devices run slower at different speeds because the magnetic field is slower (changed via the speed switch).

You can remove the rotor and they still spin.

Agreed they are a pretty good indication of a rotating rotor (99% of the time if there is a magnetic field the rotor is turning).

My point is the typical "don't assume in hydronics".

Chris M.

Is it possible there is too much head to overcome on startup? Was the circulator sized correctly when replaced? If not, the pump may need the second speed to get moving. My suggestion is to take an amp reading on L1 on start-up in low speed to see if the pump is in fact operating.

radioconnection_2

Clamp on ampmeter

Do you have a clamp-on AC amperage probe that you could use to see if the motor is drawing current when failed in the low speed condition? That would help isolate the problem to a stuck rotor, bad cap; or perhaps an intermittent switch contact.

Pete