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Gravity fed open system, having to constantly bleed top floor radiators

I have a gravity fed system for radiators with boiler in downstairs kitchen. Two tanks in loft. One for radiators and one for hot water I've been told. I have a copper cylinder tank on top floor.

Plumber replaced copper cylinder tank recently as it leaked. He said I would have to bleed radiators but its been a month and I have to bleed radiators only on top floor every week. when turn heating on I can hear lots of air in system till settles down. Could I have a leak or is it something else ?

IF I have a leak within walls, can they pressure test to locate ?

I changed the pump setting from 3 to 2 last night and the system sounded like there was less air in it when I turned on this morning. Do hope its not a leak. The problem coincides with having a new cylinder fitted 4 weeks ago

3 Answers from MyBuilder Plumbers

Best Answer

Sounds like you have a lot of oxidation within the system if you are bleeding UPPER radiators more often than normal.
When bleeding an upper radiator you won't find SILT or any evidence of dirt " UP THERE"in the system.. this would be found at the mid lower parts.
With these type of "gravity systems" where the tank in the loft is open to atmosphere and primaries over time create dirt and silt if there are no inhibitors and or cleaners adding to the system.
When or if a boiler is "compatible" to have the system "SEALED" this is to eliminate the TANK in the loft feeding the radiators in your system and keeping water in COPPER CYLINDER HOT adding additional expansions onto the system with AAV (auto air vents) or thumb venting👍 at high level making it run much longer cleaner clearer and more efficient.
Hope this helps


Answered 23rd Jan 2019

Could be a number of things;

Curculation pump
Rust inside heating system
Leak on your heating pipework
Incorrectly installed hot water cylinder
Etc etc.

These are just a few that spring to mind. The list of what can cause these issues is quite extensive


Answered 22nd Jan 2019

its certainly possible that you may have a leak somewhere. how old is the original installation?

also when bleeding the radiators, what's the state of the water?
clear or sludge?

when you call for heating there will be a pump that switches on. generally located in airing cupboard with hot water heater. If the pump is modern you will find it has a 3 speed setting. this can be adjusted. It could be that it is pumping over into the header tank in the loft, therefore taking out any water to the upstairs radiators.
I would recommend bleeding the radiators with the heating off. check the speed setting on pump and if its on 3, turn to 2 (most likely). If its on 2, turn to 1.
this should make a difference.

hope this helps

Scott Freeman


Answered 22nd Jan 2019

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