PIGLETJOHN - boiler making strange noise

[superstar84]

Please help! I’ve got a vaillant ecotec combi boiler

came down this morning to fault code f75 and no pressure so I topped up the pressure and we now have hot water & heating

ever since the boiler is making a kind of whirling noise, I’ve got a video I can show?

You need to @PigletJohn

AFAIK boilers only contain 3 types of moving parts. Fans, pumps and valves.

If you get pressure loss in the CH loop then it is likely the pump has to work harder. My guess is that the loss of pressure has caused a marginally operating pump to move closer to its failure point and that is why it is now making a noise.

Does your system still make the noise when you turn off the CH and just run the hot water ? I don't think the hot water uses a pump in a combi system, so if the noise disappears but the water is still hot it does imply it is the CH loop pump, as the fan will still be running as gas is burnt to heat the hot water.

You need to find out why your system lost pressure. For example did it lose it overnight, or has it been losing it gradually over time ? Because as well as possibly having a damaged pump you might also have a CH loop leak. It's also possible that the pump itself is leaking inside the boiler.

Keep an eye on the pressure and see what happens. If it rapidly goes down to zero again then you clearly have some sort of leak as well as a possible pump problem.

The pressure was absolutely fine yesterday, I was looking at it as we need a new thermostat so was getting the model number etc

it still makes the noise when we use hot water

its settled down now randomly but I think I’ll get it serviced asap and hope it doesn’t need a new boiler

Maybe it is the fan then.

Fans do tend to be one of the first components to wear out. Anything that moves wears out faster. I use them in products and they are normally rated to about 20000 or 40000 hours of operation. Not that much if they are on a lot. As well as the fan bearings, they also have a habit of shaking themselves loose from mountings, which can make them noisy.

Hopefully you can get the boiler looked at/serviced and thermostat done at the same time.

I would still be worried why the pressure suddenly plummeted. I would check the whole CH loop carefully for leaks.

I don't know what the noise is. If it is the fan, it should start when there is demand for HW or CH, just before the boiler fires up. It should then run continuously all the time the boiler is firing, though the note may vary, and stop a few seconds after the boiler stops firing.

If it is the circulation pump, it should start immediately there is demand. It will usually run on for a period after the boiler stops firing, to cool the boiler down. You might feel a slight vibration in the pipes while it is running.

Both of these are replaceable parts.