Downstairs rads are not hot.

[Dpg91]

I think I know the answer, but I hope there is an easy fix. Moved into an old Victorian house and haven't had the heating on. All the upstairs rooms are nice and warm. However, downstairs is struggling.

Radiator one: Lock shield side is hot, 15mm pipe running under the rad is hot. TRV side and rad are warm at best

Radiator two: Lockshield and TRV side out of the wall, and the radiator are warm at best. (I've isolated this one only, and it still won't get past warm.)

Radiator 3: Same as one.

I've also installed a new towel rail, which gets super hot, super quickly.

Boiler is a Baxi Combi, and I replaced the knackered Fernox TF1 with a Spirotech MB3, which wastes cleanish water,

 

[terryplumb]

If you close down every radiator except one of the problem rads ,by their TRV, does problem rad then heat fully ?

 

[Dpg91]

If you close down every radiator except one of the problem rads ,by their TRV, does problem rad then heat fully ?

Unfortunately, nothing. I've blocked everything off via TRV and lock shield and nothing.

 

[terryplumb]

Are the upstairs and downstairs radiators on different zones ( thermostat for each floor ) ?
If not ,there are restrictions to either the pipework to the problem rads ,or within the radiators themselves . Their valves may be an issue ,but that's less likely.
Also check the pump is circulating .

 

[terryplumb]

Deleted ,duplicate post.

 

[gigz]

Take the head off the trv, spray the pin with WD40 and use some grips to push/pull the pin out.

 

[Justin Passing]

Radiator one: Lock shield side is hot, 15mm pipe running under the rad is hot.

Do you mean you have a pipe running between the valves? If so it's a "One Pipe" system. Much grief, eg modern TRVs don't work properly and a modern boiler can object.

How old is the boiler? Could be you have convection circulation and little or nothing more.
Pump could be blocked, have a worn impeller, loose impeller.
System could be blocked of course. Your new towel rail is a dead short if both valves are wide open, which will stop most systems, especially if it's near the boiler/pump.
Does HW work ok? Does it go hot-cold-hot-cold?

Was the TF1 sludged up?
When the boiler's on and you have nothing getting hot, ie you shut the OK rads, is the return to the boiler as hot as the flow?