Grundfos circulation pump for heating is stuck

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Das Problem: Die Heizkörper bzw. die Fußbodenheizung oder das Warmwasser bleiben kalt, obwohl die Wärmequelle funktioniert.

Besonders wenn die Heizungs-Umwälzpumpe über den Sommer nicht in Betrieb war, kann es sein, dass der erste Start danach nicht klappt. Als Vorbeugung könntest du die Pumpe auch im Sommer einmal im Monat für ein paar Sekunden laufen lassen. Aber wenn du diese Anleitung liest, ist es dafür dieses Mal wohl schon zu spät. Das Problem kann aber auch ohne offensichtlichen Grund jederzeit auftreten.

Den ersten Versuch, den man dann üblicherweise macht, findet man auch an vielen anderen Stellen im Internet beschrieben, auch in mehreren Videos. Sollten diese Tipps nicht helfen, muss man die Pumpe trotzdem nicht gleich wegwerfen, sondern kann ihr mit dieser Anleitung noch eine zweite Chance geben. Besonders, wenn das Problem (so wie bei mir) an einem Sonntag-Morgen auftritt und man keine Ersatzpumpe kaufen kann, ohne einen Notdienst in Anspruch zu nehmen.

Die ersten 3 Schritte sind einfach. Ob du dir auch die restlichen Schritte zutraust, musst du selbst entscheiden. Ich habe diese Anleitung nach bestem Wissen und Gewissen geschrieben. Trotzdem lehne ich jede Verantwortung ab, falls bei dir beim Nachmachen etwas schiefgeht.

Bevor du loslegst prüfe bitte, ob es die Besitzverhältnisse und Vorschriften an deinem Wohnort überhaupt zulassen, dass du Arbeiten an der Heizungsanlage durchführst. In jedem Fall trägst du die Verantwortung.

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The problem: The radiators, underfloor heating or hot water remain cold even though the heat source is working.

Especially if the heating circulating pump was not in operation over the summer, it may be that the first start afterwards does not work. As a preventive measure, you could run the pump for a few seconds once a month, even in the summer. But if you're reading this guide, it's probably already too late for that this time. However, the problem can also appear at any time for no apparent reason.

The first attempt, which is then usually made, can also be found in many other places on the Internet, including in several videos. If these tips don't help, you don't have to throw the pump away right away, you can give it a second chance with these instructions. Especially when the problem (like mine) occurs on a Sunday morning and you can't buy a replacement pump without calling emergency services

The first 3 steps are easy. You have to decide for yourself whether you trust yourself to do the rest of the steps. I have written this manual to the best of my knowledge and belief. Nevertheless, I decline all responsibility if something goes wrong with your fix when copying.

Before you get started, please check whether the ownership situation and regulations at your place of residence allow you to carry out work on the heating system. In any case, you are responsible.

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crwdns2936071:01crwdne2936071:0 — Sound Test

Before beginning the following steps, make sure the pump is running. Because if it does work, then these instructions are not suitable for your problem. Only step 11 would still have to be checked.

crwdns2936071:02crwdne2936071:0 — Removal of the Bleed Screw

Open the pump's large bleed screw with a suitable, large slotted screwdriver. You can also use a coin if you don't have a large enough screwdriver.

crwdns2936071:03crwdne2936071:0 — Attempt to manually start the pump

Select a screwdriver that is sized and shaped to match the indentation in your pump. Insert the screwdriver into the opening exposed in the previous step.

crwdns2936071:04crwdne2936071:0 — Turn off the water supply to the pump

Shut off the water supply on both sides of the pump. If you are lucky, any necessary maintenance was already considered when the pump was installed. There might be a ball valve directly in each flange that connects the pump to the rest of the pipe network. All you have to do is turn its slot 90° with a screwdriver.

crwdns2936071:05crwdne2936071:0 — Electrical Connection Removal

Depending on the type of pump, it is connected with either one or two cables. If these are plug connections, then carefully loosen them. The plugs usually have a mechanical lock that you have to lift slightly with a small screwdriver beforehand.

crwdns2936071:06crwdne2936071:0 — Pump Removal

Make a note of the installation direction of the pump, i.e. the direction in which it pumps the water. You'll find an arrow in the middle of the pump, between the pipe connectors (red rectangle).

crwdns2936071:07crwdne2936071:0 — Pump Disassembly

Caution: If you continue now, you will probably void any warranty for your pump.

crwdns2936071:08crwdne2936071:0 — Cleaning of the Pump inside

I suspected a lime deposit and was able to successfully dissolve it with commercially available vinegar essence. In detail ...

crwdns2936071:09crwdne2936071:0 — Pump Reassembly

Before assembling, make sure that the gasket between the two housing parts is clean.

crwdns2936071:010crwdne2936071:0 — Pump Reinstall

Now put the pump back in its old place. Note the previously noted direction of conveyance. Don't forget to put the two gaskets (cleaned) between the flange and the pump.

crwdns2936071:011crwdne2936071:0 — Optional: Check capacitor

If your pump is equipped with a capacitor, you will usually find a corresponding inscription on the nameplate of the pump. In the example pictures, "3 µF" at the bottom right and "2.5 µF" at the center left.

crwdns2936071:012crwdne2936071:0 — Saving Energy

If everything is working again, you could now think about or even check if your heating can be set to be more energy-efficient without losing living comfort.

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