Radiator - No Heating Upstairs; Plenty on Ground Floor

Paris18

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Boiler: Greenstar Combi 30CDi.
Boiler at Ground Floor (Kitchen)
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BACKGROUND:

I have just moved in around the end of winter.

##[A]##
I noticed when newly moved in, that all the upstairs radiators are kind of 'no power'.

So, I 'kind of' did a test, as below (didn't have much time as busy with moving in and stuff...)

[i] Switched off all the Ground Floor radiators, then I found the upstairs radiator is kind of difficult to get heat.

[ii] I had to have the radiator in the kitchen turned on, and only by doing this I will have better heating upstairs. That means I will be wasting gas at night.

##[B]##
The radiators on the Ground Floor are all not very well at providing heating (apart from the one in the kitchen, which is closest to the boiler).

Through some internet research, I thought there may be some issues (e.g. a blockage somewhere / sludge / air / ....)

#####################################

STORY:

So, coming to summer, I thought it was time do to see if I could do a bit of DIY. Try to learn something, why not?

By researching and following lots of YouTube, I have done :
1) Switched off the boiler, then, drained the system
2) Took off all (Ground Floor and Upstairs) radiators, flush them with water in the garden,
3) Have all the TRV and Lockshield valves replaced with new ones.

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Now,
All 3 radiators on the Ground Floor get hot very quickly, and very hot, can feel the heat from 1m distance. Issue ##[B]## resolved.
All radiator upstairs - not hot, not even warm. Legs (pipe) are cold. Issue ##[A]## still there.

I found, there are 3 no 22mm pipes, each running to a floor. (The 4th one is for the hot water - have it tested already)

I noticed the pipes running upstairs, didn't get hot.
Even after switching on the boiler for 30 minutes, it is slightly warm (I am guessing it is because of the heat transfer from Ground Floor's pipe).

[a] air in the radiator, bleed it already
[b] pressure on the boiler, the reading is 1.5 Bar. It also went to nearly 2 bar when the boiler was on, then dropped back to 1.5 (I guess no issue here?).
[c] The Expansion Vessel is ok (1 Bar).

NOTE 1:
In order to check what might be the issue, I switched off the TRV on all the Ground Floor's radiators.
Then, upstairs only 3 or 4 radiators all with both TRV and Lockshield valve turned on.
Then, start the heating.
I noticed that the temperature (I can see it on the boiler) rises very quickly within 10/20/30 seconds.
Then, when it reached around (didn't really record the exact number) 60 or 70, the boiler burner light went off, and the temperature continued to rise to 90+. That is kind of telling me (my own logic), as there is no flow within the Ground Floor's pipe, the hot water isn't or CANNOT reach upstairs either (hence, the heat has no place to go, then, once the temperature has reached 60ish the burner switched off.) So, I kind of concluded that there's an issue with ???? .... why the heat in the pipe cannot go upstairs.... pressure was okay (1.5 Bar).

Could anyone help me or even just me a guess / idea, please?
Thank you so much, anything would help.

Jamie Hall

This is hot water? My first question would be were all the upstairs radiators bled for air? If not, it is likely that they are air locked -- air is trapped in them.

Steamhead

Either that or the system is low on water.

Ironman

Or, the static fill pressure is too low.

What’s the pressure on the boiler gauge?

Steamhead

@Paris18 , time to call a pro. Where are you located? We might know someone........