It’s really noisy when it comes on. There’s no hammering and the radiators are bled. It’s just noisy.
Gah, accidentally hit Post…
Anyway, it’s a gas-fired central heating system with radiators on two floors. The header tank has a decent amount of water in it and there’s an anti-corrosion fluid in there too.
Le bump.
I’m unlikely to be able to help you myself, but I think you’re more likely to get useful responses if you include more detail. For instance, what’s the nature of the noise? All you’ve shared is that it’s not hammering. Does it come from the radiators? The furnace? How long does it go on after the furnace kicks on? What does it sound like to you?
For what it’s worth, which I know is not much, I have an oil-fired furnace and hot water radiators. The only noises I ever notice are the muted sound of the furnace burning in the basement, and occasional ticking from the radiators from expansion.
I really don’t know how to describe it, which I suppose is half the problem.
The noise seems to be connected to the motor of the central heating pump, not the gas boiler, but I’m not sure, because it quietens down after a short while while still pushing hot water around the radiators.
The blower motor or its cage could be loose. I’m not an HVAC technician, but do support for it and that’s a pretty common problem.
Is your pressure low? So when the pump first starts it is cavitating?
How do I tell?