Cold downstairs radiators

Auti

Hello. Upstairs radiators get warm/hot - downstairs radiators stay cold! Boiler works 17yrs old, room thermostat calls for heat but upstairs sauna downstairs fridge. Am attempting to get someone to come and give idea (new TRV’s very likely as over 30 yrs old and sticking) - worrying about expense so wondered if anyone had any ideas so I can ask. Thank you

FreeBear

Can you hear the water circulating ?

If not, it could be the pump at fault.

Auti

FreeBear - can hear the pump in the airing cupboard with water passing through sound. System has water cylinder and expansion tank in the loft. Have turned all the trv’s to highest setting and thermostat to 30 degrees and after a while managed to get all but one radiator downstairs warm/hot - could feel copper pipe going to the cold radiator getting warm but just not getting into radiator. Waited a while but not getting through so turned the thermostat back to 18 and upstairs was so hot put the upstairs trv’s to 3 (from full on 5). When thermostat called for heat later on was back to hot upstairs stone cold downstairs (hot upstairs to the level I set trv to). 

ThisIsWeird

If you close the upstairs TRVs down to, say, 1 - effectively off - do they cool down? And do the downstairs ones now heat up?

ThisIsWeird

Is there only a single wall thermostat in the house? 
Did your heating work fine last year? 

[Deleted User]

Hi.

have you checked the TRVs on cold rads, maybe stuck closed if shut off since heating last used? LOOK.

Have you bled the offending rads?

Auti

Yes upstairs rads cool down when heating on and trv’s set to 0. No, downstairs do not heat up.

only single wall thermostat in hall. Yes all was fine last year.

have checked TRV’s on rads pin moves. Rads bled. 

Thank you

ThisIsWeird

Auti said:

Yes upstairs rads cool down when heating on and trv’s set to 0. No, downstairs do not heat up.

only single wall thermostat in hall. Yes all was fine last year.

have checked TRV’s on rads pin moves. Rads bled. 

Thank you

Cool. If the pins are moving freely, then it's extremely unlikely that the valve internals are seized. 
Q just to confirm this aspect - when you press the pins down, and then release them, do they make an obvious firm 'thunk' as they bottom out, and then spring back instantly when released? Are they smooth in travel? If yes, yes and yes, they'll almost certainly be completely fine.
And the TRV heads - do they turn smoothly when fitted? Importantly, do they feel much  easier - almost loose - to turn from numbers around 3 upwards, and become progressively more firm to turn from ~3 down to frost? Good.
Ok, leave the TRV head off one of the cold rads for the time being while we check it further.
I guess this leaves two remaining options. The first is that the other valve - the lockshield (l/s) - has an 'issue'. This could be that someone has tweaked them too closed for some reason - have you had any work carried out on your rad system over the past year? Or possibly it has a coating of sludge built up around it that's enough to seal off the flow - the gap in these valves tend to be small.
And the other main option is that you have a significant pipe blockage in one of the main pipes supplying the ground floor...
For the first possibility, choose a completely cold rad from which you've removed the TRV head. Now pull off the white plastic cap from the l/s valve. (If it has a screw in the top, remove this first).
You should see a brass spindle with a 'flat' or 'square' top. Get a small piece of paper and tape, and stick a 'flag' on that spindle, pointing straight outwards - this is so that you can determine how much you turn this spindle, and you can return it to the same position.
Ok, get a nice fitting spanner - pliers will do, I guess. First, turn the spindle clockwise as you look down. This will close the valve. Ok, count how many turns, and part turns, this talks, and write it down. Tell us this figure. Does it turn freely and smoothly? And stop very obviously when it bottoms out?
Now open (anti) it a good half-dozen turns, so's there's no question it's comfortably open.
Turn on the heating. Does the rad heat up?
If not, close the upstairs TRVs again. Does it heat up now?

Q - do you have a magnetic filter fitted? If so, when was that last checked?