Grundfos UPS 25-40 Circulation Pump Fails to Start After Summer, Only Hums

Question

Hello Today I turned on the central heating furnace and immediately noticed that there was no water flow in the radiators. I quickly figured out the reason for this. The circulation pump does not pump water. Throughout the summer, the stove operated in summer mode and only heated water for the...

Anonymous · Answer

Unscrew the pump bleed screw and try to start the impeller with a screwdriver. Maybe it got baked during the summer?

nikusert · Answer

Hello
Disassemble the pump, maybe the impeller is caught. Unscrew the screw at the back of the pump and try to move the impeller with a screwdriver, turn off the water before and after the pump if you have valves, because water may leak out.

TomD · Answer

Sorry to hijack this topic, but I had a similar problem. But now an additional one has appeared, which I caused myself. I have two Grundfos pumps that work with the fireplace. After the summer period, one of the pumps, the one behind the exchanger, did not work or worked too inefficiently to push water to the radiators. But not about that now. While checking the pumps, I found a short circuit on the second one. I simply inadvertently touched the cable from minus to plus, and the pump does not work. What could burn after such a short circuit? Capacitor or something in the engine?

Anonymous · Answer

The pump was not damaged by the short circuit. I would look for the fault in the controller, check the fuses.

kwantor · Answer

By short-circuiting the power supply, you damaged the controller or some protection - the fault lies there far beyond the pump ,. My friend beat me to it, so he`s deleting it.

TomD · Answer

I checked the fireplace controller and there is electricity at the output. The fuses are all OK. The pump receives electricity, so theoretically it should work.

Anonymous · Answer

How did you check that the current was coming? It`s best to connect a light bulb instead of the pump because neon indicators are misleading.

TomD · Answer

But where? As I wrote above, the pump receives electricity, so if the controller was damaged, it seems to me that there would be no power to the pump.

kwantor · Answer

What is this current? connect a test tube made of a 230V bulb, e.g. 60W.

TomD · Answer

Well, I checked it with an ordinary current tester. Added after 40 : Okay, since you say it will be better, I have to check it out.

Anonymous · Answer

What kind of sampler is this and how do you interpret the measurement results?

TomD · Answer

The most ordinary one for PLN 2 Interpretation, it shines or it doesn`t shine :) Okay, I`ll test it with a light bulb and then I`ll be sure if there is normal voltage there.

kwantor · Answer

There certainly isn`t. No neutral.

TomD · Answer

Thanks for the help. I checked the bulb and it didn`t actually light up. I replaced the fuse in the fireplace controller (luckily I had one) and now the pumps work. Unfortunately, there is still the same problem as the friend who started this topic, i.e. the pumps work, but they do not push water into the system.

Anonymous · Answer

Have you checked the filters?

TomD · Answer

Which filters do you mean? The ones on the installation pipes?

kwantor · Answer

You need to determine whether the rotors are spinning, if so, there is air in the system, or it is a matter of filters, as a colleague wrote, if there are any.

irus.m · Answer

Yesterday I had a breakdown in the UPS - the mechanical connection between the rotor and the pump axis was loose. The pump is turning, the impeller is standing. Check it out. Regards

TomD · Answer

It currently looks like this:

There is circulation everywhere, but it ends in the place marked in yellow, i.e. where there is (I don`t know if I`m calling it correctly) a one-way valve.
However, when I manually turn on the underfloor pump, the water immediately continues to flow, as if the underfloor pump was sucking in the water further.
Grundfos UPS 25-40 Circulation Pump Fails to Start After Summer, Only Hums

Grundfos UPS 25-40 Circulation Pump Fails to Start After Summer, Only Hums

Anonymous · Answer

This is a check valve. It`s possible that it got blocked somehow. Maybe try tapping it while the pump is running, maybe it will unlock? The filters are the ones on which you drew the arrows and there is number 2.

TomD · Answer

I guess that was it. I tapped the valve and it also went to the radiators. We`ll see what happens next, but it seems that everything should be OK. The only question is whether I shouldn`t replace this valve now to make sure it doesn`t get blocked again.

Anonymous · Answer

You can always replace it because there is no guarantee that the situation will not happen again. And in the summer, it is worth turning on the pump once a week, even for a minute, to get everything moving.

faloxx · Answer

Topic to be closed. The pump stopped after the summer season. It was enough to unscrew the cap, lightly move the screwdriver and go. Thank you all for your comments.

Grundfos UPS 25-40 Circulation Pump Fails to Start After Summer, Only Hums

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