Help - boiler issue

[jackfoley]

Hello,

I have not been using the central heating for a few days.

When I use the hot water I can hear a "swoshh" sound in the first radiator after the boiler and it gets a bit warm. This does not sound right.

What could it be?

Thanks

 

[superdupergasman]

Could just be the boiler getting rid of the excess heat from itself after its finished its demand cycle.

The radiator may need bleeding and once done the system refilled afterwards if you have a sealed system.

 

[jackfoley]

Could it be a stuck diverted valve?

 

[ChrisR]

Yes but it doesn't even need to be stuck. It's designed to stay in the position it was last used. If that was CH only, then the boiler and pump will start in that position. The valve closes in a couple of seconds but slow enough for a swoosh. Not enough to get warm though.

A ch diverter valve doesn't get rid of excess heat to the rads at the end of the HW cycle unless it's in a combi.
It could be that the DV is "letting by" slightly.