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Introduction
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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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.
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If you're familiar with the usual, low operating noise of the pump and it has now become a very low, low-pitched hum or no noise at all, then the pump rotor may be stuck. The hum is consistent with (e.g. 50 or 60 Hz) and clearly not regular running noise.
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Caution: The pump may be hot. Please check before you touch the pump with your ear. It is safer, for example, to hold a screwdriver with one end against the bleed screw of the pump (red arrow) and with the other end against your ear. This way you can listen to the pump like a doctor with a stethoscope.
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If you can't identify a running noise (or if you're not sure), then you've come to the right place.
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Note: With some pump types, the vent screw (marked red in the picture) is covered by an additional housing. I don't own such a pump so I can't offer a solution for it. It may be possible to easily remove this additional housing.
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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.
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Warning: Some water will run out. Hold some sort of catch container under the pump.
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The face of the rotor shaft is now visible. Depending on the type of pump, there is a notch, either in the form of a slot or a cross.
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If you are unsure if the pump is running, carefully insert a screwdriver (e.g. 5mm slot) into the hole and be prepared that it will start to turn by itself if the pump is running. In this case, the instructions end here. Reinstall the bleed screw. Ensure that there is no water dripping .
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If the pump runs slowly and does not react to the change of the power levels with an audible change in speed, you could finally go to step 11.
Super Dankeschön hat nach Sommerpause heute die Pumpe für Warmwasserbereitung wieder in Gang gebracht die Anleitung :-). Nachdem ich die Entlüftungskappe abgemacht hatte und mit dem Schraubenzieher kurz in die Kerbe gefahren bin ist die Pumpe auf einmal gestartet. Bin super erfreut darüber
Gerne!
Schön, dass es geklappt hat!
Franz -
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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.
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Try turning the pump rotor using the screwdriver. If that works, turn on the pump. Does it start on its own? Good, problem solved.
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If it doesn't start on its own, give it a little jump-start by quickly turning the screwdriver in the direction indicated by the arrows on the case and "starting" the pump.
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Michael B wrote to me: There is a notch on his circulation pump. Insert the screwdriver into this notch and then hit it with a small hammer in the direction of rotation (indicated on the pump) so that the flywheel starts to move.
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Does the pump now run? Then the problem is solved. Reinstall the bleed screw and check that no water is dripping out. Ready.
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Otherwise, if the pump is still not working:
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Did the rotor turn easily during startup? Continue to step 11
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If it was difficult or even impossible to turn the rotor, continue with the next step.
Danke für die Erklärung. Diese sollte noch vervollständigt werden. Bei meiner Grundfos Umwälzpumpe sieht man eine Kerbe. In diese Kerbe muss man den Schraubenzieher einsetzen und dann in Laufrichtung (auf der Pumpe angezeigt) mit einem kleinen Hammer schlagen, so dass sich das Schwungrad in Bewegung setzt. Läuft die Pumpe, merkt man dies auch weil die rotierende Kerbe am Schraubenzieher ein Geräusch macht.
Hallo Michael B,
danke für den Hinweis. Ich habe ihn soeben eingetragen.
Falls möglich: Bitte auch um ein Foto, dann füge ich es ebenfalls hinzu.
Viele Grüße
Franz
Franz -
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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.
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Otherwise you will have to look for suitable shut-off options in your facility.
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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.
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If the electrical wiring is permanently connected to the pump, then the usual safety precautions necessary for all electrical work must be taken. Switch off all poles and all sides, etc., check that there is no voltage!''
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Warning: if you are not familiar with these things and unsure on how to proceed please stop your work at this point. Otherwise you would endanger your own safety and maybe other people too! Before continuing into an area that could cause harm, ask someone who has the relevant specialist training for help.
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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).
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Now open the screw connection on one side of the pump a little. There will be water coming out so use a catch container (bucket etc,) to capture that.
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If the water leakage does not subside after a very short time and stops completely, then you have probably not completely shut off the water supply. Should that happen, retighten the fitting immediately.
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Open the screw connection on the second side of the pump.
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Remove the pump. Be sure to keep the gaskets you find on both sides.
Für die Reparatur der festen Pumpenwelle ist es nicht nötig, die Pumpe komplett auszubauen.
Meiner Meinung nach kann Schritt 6 entfallen.
Entscheidend ist Schritt 7, mit dem das Pumpenlaufrad zugänglich wird.Ja, danke für den Hinweis. Ich habe nicht bedacht, dass die Pumpe nicht überall so eng verbaut ist wie bei uns.
Franz -
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Caution: If you continue now, you will probably void any warranty for your pump.
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Loosen the four assembly screws with a suitable Allen wrench
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Now pull the two housing parts apart. Make a note of the original position of the two parts in relation to each other so that you can put them back together exactly the same way later. If you were to assemble them incorrectly, e.g. rotated by 90° or 180°, you would probably have problems installing them in your system.
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The pump impeller should now be visible. Try to turn it carefully. If this works fine and easily after a few changes of direction, you can put everything back together and skip to the last step.
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However, if the impeller (as in my case) is completely stuck and cannot be turned at all, then the next step is carried out.
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I suspected a lime deposit and was able to successfully dissolve it with commercially available vinegar essence. In detail ...
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Place the pump, impeller down, on a small plastic container, such as a small bucket.
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Pour a few drops of vinegar essence into the opening marked with the arrow until the essence drips out at the bottom. If you don't have vinegar essence at hand, you can also use normal salad vinegar. The process just takes longer.
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Note the safety instructions on the essence bottle. If nothing is written there, use rubber gloves and safety goggles. If you have accidentally worked without gloves, rinse your hands with clear water to be on the safe side.
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Wait 15 to 30 minutes
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Then try to spin the wheel. If it still doesn't turn or doesn't turn easily, repeat the above process. My pump was fine after three repeats.
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Now let water run through the pump - even through the opening marked by the arrow, to flush out any acid residue. You can dispose of the now heavily diluted acetic acid down the drain without hesitation. It is in principle a food and is now certainly much weaker than your salad dressing.
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Before assembling, make sure that the gasket between the two housing parts is clean.
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Put the two housing parts back together. Pay attention to the alignment of the two parts to each other as noted earlier.
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Insert the four Allen screws and tighten them "crosswise" evenly (i.e.: top left, bottom right, bottom left, top right) - only tighten slightly at first and then tighten completely in a second round
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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.
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Reinstall the bleed screw and tighten it.
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Open the first water shutoff a little. Be ready to snap it back on immediately in case you didn't mount the pump properly or tightly. If necessary, tighten the screw connections.
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Now open any other shut-offs that you previously closed. Check for any leaks.
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Reconnect the electrical connections
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Time for a test run!
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If there is an automatic bleed valve somewhere above the pump, the job is done. Otherwise, you'll probably need to bleed the radiators now.
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Check the water pressure in your system according to the specifications of your system.
Falls das Problem öfter auftritt, kann es auch daran liegen, dass der Motorkondensator (im schwarzen Kästchen an der Pumpe) zu wenig Kapazität hat. Meine Grundfos-Pumpe hat z.B. einen Kondensator mit 2uF Nennwert (lt. Aufdruck). Ausbau und Messung mit einem DMM ergaben aber nur noch einen Wert von 0,7uF (nach 20 Jahren Betrieb).
Nachdem ich den Kondensator ersetzt hatte, lief die Pumpe wieder zuverlässig - und sie brummte auch nicht mehr so laut wie vorher.
Bevor man also die ganze Pumpe ersetzt: Erstmal den Kondensator durchmessen :-)
Der neue Motorkondensator hat mich ca. 6€ (incl. Versand) gekostet. Eine neue Pumpe ist viel teurer.
Allerdings kann es sich trotzdem lohnen, eine neue, intelligntere Pumpe einzubauen, denn die spart auf Dauer sehr viel Strom.
Vielen Dank für den Hinweis. Leider weiß ich nicht, wie man solche Kommentare hier in iFixit auffälliger gestalten kann. (Mir ist er leider erst heute aufgefallen, nachdem ich schon Schritt 11 dazu geschrieben hatte.)
Franz -
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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.
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If the pump runs very slowly and hardly delivers any water, then it is worth checking the condenser. Likewise, if the pump does not respond to the power stage changeover with an audible change in speed. Or if it does not run at all, although the pump impeller can be turned easily.
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Please perform this step only if you have the appropriate electrical engineering expertise. Otherwise, ask someone for help. See step 5.
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Switch off all the poles and all the circuits. Check that no voltage is present.
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Disconnect the capacitor and measure its capacitance. If it is much lower than the value printed on the capacitor and on the nameplate, then this could be a reason for the behavior described above. I once found a capacitor that had only 66% of the printed capacity. Capacitor replaced - pump fine.
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See also Ralf Müller's comment under step 10.
Hello, very helpful article. Followup question on the capacitor testing- using the multimeter I select the continuity symbol and touch probes to leads on capacitor. The multimeter displays "OL", regardless if I have the probes touching the capacitor leads or not. Assuming that means the capacitor is bad? Can I replace it (8u 180v) with an 8u 250v or 450v one? Any way to know if this is a "start' capacitor or "Run" capacitor? Or does that matter? The motor operates with the capacitor disconnected, but I have to manually start it. Thanks again for the helpful insight !
Hello Cris,
"OL" does not necessarily mean, that your capacitor is bad.
But your test result "motor runs after starting it manually" probably does.
Some multimeters are able to measure capacitors directly, some are not. If you do not see a capacitor symbol on your multimeter's mode/range selector, then probably not. Please check the manual of your multimeter to find out.
Alternatively you can use a method, that works with any multimeter ... if you have a low voltage AC power source at hand, e.g. a 12 V transformer, some types of halogen desk lamps, etc.:
a) Set your multimeter to "AC voltage" and measure the transformer's output voltage. Note it. Example: 12.1 V
b) Then set your multimeter to "AC current", connect one lead of the capacitor to the power source and the other one to the multimeter. Connect the 2nd probe to the other lead of the power source. Double check your circuit before switching on. Note the measured current. Example: 11.4 mA
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Franz -
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c) Divide the voltage value of step a by the current value of step b. Example: X = 12.1 / 0.0114 = 1061 Ω
d) The capacity reactance X of a capacitor C can be calculated using this formula:
X = 1 / ( 2 π f C ) [Ω] where f is the frequency of your power supply: 50 Hz or 60 Hz, depending on where you live
Solving this for C: C = 1 / ( 2 π f X ) [F]
Example for countries with 50 Hz: C = 1÷(2×π×50×1061) = 0,0000030 F = 3 µF
Example for countries with 60 Hz: C = 1÷(2×π×60×1061) = 0,0000025 F = 2.5 µF
Replace the above values with your measured values.
Aged capacitors tend to lose a part of their capacity. Your 8 µF capacitor might have degraded to 5 µF or less. In that case you should replace it.
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Franz -
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Regarding your 2nd question:
Yes, you can replace the capacitor with a capacitor for higher voltage. That value tells you the maximum voltage, that this capacitor can stand. Any voltage equal to or higher than the voltage value of the original capacitor is ok.
AFAIK there is no difference between start and run capacitors.
Best regards
Franz
Franz -
-------- Summary:
Das Wichtigste nochmal in Deutsch:
Manche Multimeter können die Kapazität eines Kondensators direkt messen, andere nicht. Bitte in der Bedienungsanleitung nachsehen.
Alternative Methode, die mit allen Multimetern funktioniert, wenn man eine Wechsel-Kleinspannungsquelle zur Hand hat, z.B. einen 12V-Transformator oder manche Arten von Halogen-Schreibtischlampen mit Metall-Teleskopauszug, etc.:
a) Wechselspannung messen
b) Test-Stromkreis aufbauen: Spannungsquelle -> Kondensator. 2. Kondensatoranschluß -> Meßgerät. Meßgerät -> 2. Anschluss der Spannungsquelle. Wechselstrom messen.
c) Messwert a durch Messwert b dividieren.
d) Kapazität daraus berechnen: C = 1 / ( 2 π f X ) [F]
Zur 2. Frage:
Ja, man kann als Ersatz einen Kondensator verwenden, der mindestens die gleiche oder eine höhere zulässige Spannung aufgedruckt hat.
Franz -
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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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For example: Is your circulation pump constantly running at high power 24 hours a day and therefore consuming an unnecessary amount of electricity? Or does the heating control system ensure that it only runs when necessary and also controls the pump's output depending on the heating situation?
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Is the heating control system unable to do this? Then the installation of a so-called high-efficiency pump, which automatically adapts to the heat demand, could greatly reduce electricity consumption.
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There are many articles on energy-saving topics on the Internet. These lines are only intended as an invitation to do your own research.
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For pumps without slide valves upstream and downstream of the pump, the water of the entire heating circuit must be drained. The heating circuit must then be refilled and vented if necessary. After 24 hours, check again whether everything is tight and bleed again.
For pumps without slide valves upstream and downstream of the pump, the water of the entire heating circuit must be drained. The heating circuit must then be refilled and vented if necessary. After 24 hours, check again whether everything is tight and bleed again.
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19 Guide Comments
Danke habe mit eurer Anleitung
Meine Pumpe wieder zum Laufen gebracht
Mit freundlichen Grüßen
Dierk aus dem Schwabenland
Hallo Dierk,
danke für deine Rückmeldung!
Es freut mich, dass es geklappt hat.
Viele Grüße aus Niederösterreich
Franz
Franz -
Alles gut beschrieben soweit, nur musste ich noch etwas weiter gehen, um meine Pumpe wieder in Gang zu bringen... Die Pumpe in meiner Solaranlage war zusätzlich auch noch mit altem, verbranntem Glykol verschmutzt, das ist ähnlich zäh wie Teer. Das einzige, was da noch hilft, ist Farbentferner /terpentin, danach lief die Pumpe besser als jemals zuvor... Keine Angst, etwas kaputt zu machen, meine lief eh nicht mehr, danach aber wie ne eins. Brennspiritus reicht nicht, hab ich probiert. Einweichen, durchspülen, fertig. Kondensator checken, meiner war ca 10 jahre alt lieferte nur noch 0,9 statt 2,5 NV... Nach Reinigung und Austausch läuft alles wie am ersten Tag, die Pumpe hält sicher noch viele Jahre.... Hoffe ich zumindest...
Hallo North70,
danke für die Ergänzung!
Viele Grüße
Franz
Franz -
Tolle Anleitung! Schritt 11 (Austausch des Anlaufkondensators) behob das Problem, Umwälzpumpe läuft nun seit paar Wochen störungsfrei. Der alte Kondensator hatte nur noch 13 Prozent seiner ursprünglichen Kapazität (2 µF).
Danke! Es freut mich, dass die Pumpe wieder funktioniert.
Viele Grüße
Franz
Franz -
Hi Peter, kannst du mir den Typ des Kondensator nennen. Ich denke ich werde das gleiche Problem haben.
Nachdem der nicht die Welt kostet würde ich den gleich vorab vor der Demontage der Pumpe besorgen.
Viele Grüße
Andreas
Andreas -
Thank you so much for taking the time to write this guide 🙏
You are very welcome! I am glad that you liked it.
Franz -
Danke für die gute Anleitung. Es könnte vlt. noch dazu erwähnt werden, dass man sich bei einem Austausch auf eine sg. Hocheffizienz-Pumpe auch vieles an Energiekosten sparen kann (bis zu -80%).
Danke für den Hinweis. Ich habe es soeben ergänzt.
(Weil ich leider keine eigene Erfahrung mit Hocheffizienz-Pumpen beisteuern kann, habe ich auf die Nennung einer exakten Prozentzahl verzichtet. Die findet man dann ohnehin in den diversen Artikeln im Internet.)
Franz -
Danke!!!
Wir sind in unsere Ferienwohnung und froren uns den A.... ab. Der eine Ölradiator, den wir für alle Fälle haben, hat in Sufe III die Sicherung immer wieder rausfliegen lassen und nur für's Schlafzimmer ausgereicht.
Dank dieser Anleitung hier läuft nun die Umwälzpumpe wieder und die Wohnung wird gleich bestimmt muckelig warm. Mehrfach die Pumpe mit dem Schraubendreher "angesschubst" und nun läuft sie.
Tolle Schritt-für-Schritt-Anleitung!
Gruß,
Anselm
p.s.: ich habe mich extra nur für's Bedanken angemeldet. Aber vielleicht kann ich hier in Zukunft ja auch mal etwas beitragen.
Hallo Anselm,
es freut mich, dass es funktioniert hat und euer Urlaub damit vielleicht noch ein wenig schöner wurde. Danke für die nette Rückmeldung! Die Anmeldung nur für's Bedanken finde ich besonders toll.
Viele Grüße
Franz
Franz -
Meine Pumpe macht im stündlichen Abstand knatternde Geräusche ca. 20 Minuten lang.
Was könnte das wohl für eine Ursache haben?
Hallo Mennochris,
ich könnte mir vorstellen, dass ein Stück vom Laufrad abgebrochen ist. Aus der Ferne kann ich allerdings nur raten.
Darum schalte bitte mal die Pumpe ab und versuche wie in Schritt 2+3, ob sich der Pumpenrotor leicht und ohne Geräusch drehen läßt.
Die 20 Minuten Knattern und danach 40 Minuten Ruhe könnten dadurch zustande kommen, dass die Heizungssteuerung die Pumpe jede Stunde 40 Minuten lang abschaltet, weil im Moment vielleicht nicht so viel Wärme gebraucht wird.
Franz -
Vielen Dank für diese super Beschreibung, unsere Pumpe ist wieder am laufen. By the way - Der Heizungstechniker meinte, unsere Pumpe ist defekt und ersatzlos aus dem Programm gestrichen, also komplett neue Gastherme :-( Irgendwann vielleicht mal, aber jetzt noch nicht ;-)
:-D
Das erinnert mich ein wenig an ein Lied von Reinhard Mey: "Ich bin Klempner von Beruf". Da scherzt er, dass es für das 3 Tage alte Gerät schon längst keine Ersatzteile mehr gibt.
Es freut mich, dass neben der Pumpe auch gleich die ganze Gastherme "gerettet" wurde. Das nenn' ich nachhaltig!
Franz -
