Water heater/central heating sounds like a jet plane?

[King Herald]

When the central heating is on, which is all day, and the water heating comes on for its morning and evening hour, it sounds like a jet plane is doing maneouvers above the house. It is not really loud, but a continually changing roaring whooshing fly-by sound. It never used to do it, so I'm not sure why it started this last winter.



The system is am ancient gas boiler in the garage, and water tank in the landing airing cupboard, so its not a combi. Rads are bled, system seems to work okay otherwise.

[Ferg]

Sounds like air in the system. Slowing the pump is sometimes the best way to get it out. Often the pump moves the water too fast for the air's bouyancy to take it up the vent.

[King Herald]

Ferg said:

Sounds like air in the system. Slowing the pump is sometimes the best way to get it out. Often the pump moves the water too fast for the air's bouyancy to take it up the vent.

How do you slow the pump though?

Also, sometimes the system comes on for less than a minute sometimes, which seems odd as it surely doesn't have time to change the room temp enough to click it off at the thermostat.

[robinhood21]

If you have a look at the pump there should be a switch of some sort to turn the pump speed up/down.


In the picture there is a wheel at the bottom of pump for doing so.

[Dogwatch]

It's not the room 'stat which is causing the boiler to cut in and out, it is the 'stat in the boiler which measures the temperature of the water cycling through it. The pump is on continuously when the room/tank 'stat is calling for heat but if the circulating water isn't cooled enough this stops it turning into steam.
Perhaps the system needs a good flush through.

[King Herald]

Dogwatch said:

It's not the room 'stat which is causing the boiler to cut in and out, it is the 'stat in the boiler which measures the temperature of the water cycling through it. The pump is on continuously when the room/tank 'stat is calling for heat but if the circulating water isn't cooled enough this stops it turning into steam.
Perhaps the system needs a good flush through.

We had a problem a few months back when something went wrong and the heating would not turn off at all, house got up to 29c. The engineer came out and adjusted things, something to do with the freeze 'stat in the garage, and also fitted a new starter sparker thing in the boiler, so maybe he fiddled with some setting for temps.

Winter is over now, so I'll probably not hear it again until later in the year.