Downstairs radiators all cold, upstairs all normal & hot

We have a gas boiler Ideal W200 (Stelrad Ideal) which was fitted by previous owners over 10ys+ ago. On Wednesday we had a new fuse box fitted and my husband mounted the timer control unit for the boileron the wall as it was hangign free (v old fashoined dial type). On Thursday we noticed all the rads downstairs not working but upstairs were normal, and hot water was normal. Timer is coming on and off as set. The boiler is firing up no problem and the pump is vibrating and hot. All pipes from boiler and pump are hot however the pipes travel from boiler overhead through a sealed arch where on the opposite accessible side are cold - I understand this feeds all the downstairs radiators. if we peep inside the arch (over the rsj) we can see what appears to be a valve midway on the pipe, however this is not of the motorised kind....before we start having to knock down walls to access a mystery motorised pump (not fitted by us and with no apparant access point) could this manual valve be the problem (it is brass looking T shape) if so how do we adjust this? Could the pump not be functioning properly despite appearances?

I have tried the following: bleeding all rads (one rad had a bit of air and one/two with slightly black water but runny, others were clear running water), turning red balance wheels, switching down radiator therms up and upstairs to minimum. All to no resolution.
Also wondered if the hot water cylinder was heating upstairs rads by gravity and tried to test this by switching off central heating and only having water on - the effect was most upstairs radiators became cooler but not cold (left for 2 hrs) however 2 remained quite hot.

I'd really appriciate any advice.

This could be a pump problem, however this

We can see what appears to be a valve however this is not of the motorised kind....before we start having to knock down walls to access a mystery motorised pump (notn fitted by us and with no apparant access point) could this manual valve be the problem (it is brass looking T shape

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intrigues me.

We are not - as you will have gathered- experts, so I am unsure if this is a valve. It is not easy to see as it is inside the overhead arch and we have to stand in a utility cupboard (where boier is) on a chair and look through 'tunnel' where rsj supports archway and houses pipes.
I'm hoping it is the pump as this will be easier to sort.
Do I need a corgi plumber to fit a new pump (if it is this) or not? We are trying to sell our house too - so really bad timing!
Thanks for any replies.
Rachel

thought these pics might help[/img]

Do I need a corgi plumber to fit a new pump (if it is this) or not?

Click to expand...

yer dont have to have a dog licence to change a pump

pic would be nice oh and take one of the valve aswell

might be an anti gravity valve but my crystal balls bust

err do both them pumps work ??

The one on the left of the boiler seems to be vibrating etc but the one on the right of the boiler next to the three way is warm but not seeming as busy as the other. My v clever husband has painted it - so v hard to see any arrows etc for turning - thereis a button underneath with min/max but I'm not sure if this should be turned or pushed etc. Also we only found this second pump and threeway join when we cleared the cupboard out this morn.
When looking at the piping it seems that it has a pipe from upstairs to it then it joins to the boiler - runs through this (?) to the vibrating pump which seems to feed the majority of pipes.
To complicate matters -ha- my brother mentioned we probably have 3 pumps - but we don't know where that one is... oh dear what a mess.

thanks Rachel