Understanding the system and rad issues

[DougieDJ]

Hi there 👋🏾

Hoping that someone might be able to take the time to help me understand our central heating system.

We recently moved in to a relatively new, 4-bed semi-detached house (2015), having come from a 2-bed flat. The new house has three floors, with a ground floor WC, first floor bathroom and second floor en-suite.

The flat had a combi boiler only; very straightforward to understand.

Here we have a tank, which is described as an indirect unvented water heater and "conventional" boiler.

I've got three issues - possibly connected:

1) in redecorating we had one of the radiators removed and drained. Whilst we were able to bleed it to get it filled again, this seems to have drained one of the second floor rads - I've tried bleeding them and one doesn't hiss with air or return water...any ideas?

2) the pressure gauge near the hot water tank was at around 1.5 bar after the radiator was replaced, but now seems to have dropped - I would assume I need to open the two valves in the attached picture near this small tank (no idea what this does)?

3) the pipes near the tank itself male hissing sounds intermittently - not sure if I should be worried?

Thanks

 

[Gasmk1]

you need to top up using those two valves open them allow to approx 1.5 bar bleed you r rads and repeat until all full pressure in system when cold should be 1 to 1.5 bar 1.5 is where the red pointer is

 

[DougieDJ]

you need to top up using those two valves open them allow to approx 1.5 bar bleed you r rads and repeat until all full pressure in system when cold should be 1 to 1.5 bar 1.5 is where the red pointer is

Thanks for the swift response - I'll give this a go.

In theory, should this deal with the second floor rads too? Being that they are above the hot water tank?

 

[Deleted member 120897]

In theory, should this deal with the second floor rads too? Being that they are above the hot water tank?

Yes, it fills with mains pressure not gravity.

 

[Ben-gee]

When you bled the lower rad, the water to fill it came from the second floor rads- you just moved around the water that was in the system.

When you use the black valves on the filling loop the water comes from the mains so you are adding water to the system, when you bleed the air out all will be fine - it may take a couple of goes .

 

[DougieDJ]

Thanks @Ben-gee and @Undertrained - bit delayed in my response, but I got it sorted (though, I reckon the system needs flushing now as some rads are cold at the bottom and hot at the top...)

When you bled the lower rad, the water to fill it came from the second floor rads- you just moved around the water that was in the system.

When you use the black valves on the filling loop the water comes from the mains so you are adding water to the system, when you bleed the air out all will be fine - it may take a couple of goes .