Radiators slow heating down stairs

bazlers

Hi all hope ye can help.
I had a burst pipe underground between burner andhouse.
That was repaired, system filled up again all good. The only thing is now all heat goes up stairs. I turned off all radiators then and turned on the radiators down stairs one by one. They heated up but when i turn on the radiators upstairs they seem to take nearly all the heat and the radiators down stairs are left nearly cold.
Pressure in system is 1.5 bar. I have now swapped out circulation pump to rule this out.
I dont believe its the automatic valve for down stairs as i opened it manually and can feel and hear it opening.
Its a sealed system with a top up valve if pressure drops.
There is a small red expansion tank in hot press too.
All ideas welcome

Nanoc

I have similar issue, been told I need a power flush with of get rid of silt and grime etc but mine are hot at the top of the radiators cold at bottom, other are hopping off the walls

bazlers

Maybe. Just all seems to have happened very suddenly. Why all 3 the same down stairs. Has me drove demented.

John.G

bazlers wrote: »

Hi all hope ye can help.
I had a burst pipe underground between burner andhouse.
That was repaired, system filled up again all good. The only thing is now all heat goes up stairs. I turned off all radiators then and turned on the radiators down stairs one by one. They heated up but when i turn on the radiators upstairs they seem to take nearly all the heat and the radiators down stairs are left nearly cold.
Pressure in system is 1.5 bar. I have now swapped out circulation pump to rule this out.
I dont believe its the automatic valve for down stairs as i opened it manually and can feel and hear it opening.
Its a sealed system with a top up valve if pressure drops.
There is a small red expansion tank in hot press too.
All ideas welcome

What is the make/exact model of your new pump and what mode/setting is it on.?

bazlers

Dab evosta 2. Its not the pump. The pump went about a month ago and was changed. I changed it it again incase it ran dry with burst pipe. I have it on level 2.
I have tried it on level 3 but still the same.

Vinnyda

Sounds like you opened all the valves at the radiators fully open again after repairing the leak. The system is usually balanced, some valves have to be barely opened to encourage flow to radiators in the ground floor. Try closing one valve on each upstairs radiator halfway and see if the downstairs radiators heat up. Some radiators may only need to be opened a half turn and that is enough to get them to warm

bazlers

Vinnyda wrote: »

Sounds like you opened all the valves at the radiators fully open again after repairing the leak. The system is usually balanced, some valves have to be barely opened to encourage flow to radiators in the ground floor. Try closing one valve on each upstairs radiator halfway and see if the downstairs radiators heat up. Some radiators may only need to be opened a half turn and that is enough to get them to warm

Thats the way i have it at present to keep a bit of heat in the rads down stairs. If im open one one anymore than half a turn upstairs it will get roasting hot.
Its only a 3 bedroom semi in an estate. No big long runs.

bazlers

There is a small red expansion tank fitted on system. Could that effect heating down stairs or is it just to regulate pressure when water heats up.
I mean do i need to put air in this after leak or anything?

John.G

If the pressure is still 1.5 bar then you should be fine, it should rise up to ~ 2 bar with a hot system, if it doesn't move then it may be blocked as you certainly need to top up any system after draining but upstairs should be the first affected, normally.
Give the pressure gauge a tap of a spanner at its base in case its just sticking, also if it doesn't change pressure on heat up then definitely a problem there.
If it has lost its air pressure then the pressure should shoot up when the system heats up and lift the PRV at 3 bar or 2.5 bar if a Grant oil condensing boiler.

John.G

bazlers wrote: »

Dab evosta 2. Its not the pump. The pump went about a month ago and was changed. I changed it it again incase it ran dry with burst pipe. I have it on level 2.
I have tried it on level 3 but still the same.

Friend of mine installed a new "smart" circ pump recently and was getting circulation problems after a few weeks, eventually found the pump had a lot of magnetic type build up on the rotor and impeller, cleaned it off and problem disappeared.

Unlikely to be your problem but if you isolate the pump valves and carefully remove the pump head after undoing the securing studs you will quickly see if any build up,