Cold rads downstairs, is it still a faulty pump?

[beadalbum]

Hi,
I have a Worcester Bosch Gas Combi (24Si?) that is 6 or 7 years old.
I turned on the central heating and the rads downstairs wouldn't heat up. I joined the NPower CH scheme, a guy came to do a service, but we wont be covered untill its working. He said possibly pump or dirt in the pipes.
I have fitted a new Grundfos 15-60 pump and removed all downstairs rads and flushed them through with the hose (water was a bit grey) and flushed them again whilst connected to the pipe work with one end with a hose on.
When i was flushing i had the boiler running, with the mains cold water feed running too and hot water came through, when i connect the rad back to the system and the level was topped up, its still only the upstairs rads that get hot.
I have drained the system completely and refilled - no change
I have closed all upstairs - no change, downstairs still cold
I have closed all upstairs and all but the one nearest to the boiler - still doesnt warm up.

The Grudfos pump i bought has IP44 (not sure what that is) and so does the original Bosch/Grudfos
They are both 15 - 60
The original 3 speeds of the Bosch pump are 45 -75 -95, the new one is 50 - 60 70, would that make a difference, should i buy a bosch one?

If anyone has any ideas and can help, that will be great

Thank you for taking the time to read this.

Richard.

 

[Agile]

I am sure the pump is not your problem.

If some rads are working then there must be a blockage somewhere.

Where is the question!

Tony

 

[beadalbum]

Thanks for a quick reply Tony,

The question is, what else do i do, or what do i need to check.

How do i clear a blockage, is there a sequence/procedure to follow.

All upstairs are really hot and downstairs are stone cold.

Thanks

Richard

 

[twgas]

try looking in the pipework at the boiler, I've had several of these boilers getting blocked at the iso valves.

 

[adegknooors]

run c/heating and shut off rads that are working.if ok open same rads but only 50 percent

 

[misterdubya]

Downstairs is not Zoned is it?

 

[beadalbum]

In answer to these questions -

"try looking in the pipework at the boiler, I've had several of these boilers getting blocked at the iso valves.
Mick."

What is an iso valve?


"run c/heating and shut off rads that are working.if ok open same rads but only 50 percent"

Tried this and even with only one of the non working rads open, it still stayed cold

"Downstairs is not Zoned is it?"

Dont think so, but how do you know/check

 

[adegknooors]

when you filled back up did you fill all down stairs, first if not .you may have made the air lock.