05-03-2016, 12:39 PM
If a modern boiler of any type, combi, or 'system', is to be fitted to an old system an acid flush is a necessity. A so called power flush is only a quicker way of cleaning out the debris, repeated washing through in both directions achieves the same result provided the debris is loosened by an acid soak first.
We used to leave it to soak at least overnight followed by repeated hot and cold fresh water flush until the water is crystal clear, as clear as what comes out of the tap!
We always acid flushed even new systems, new radiators are not clean inside and any metallic pipework will be contaminated.
I think you have done well not to be charged for the repair, many manufacturers would have charged you if there was any debris in the water.
The expansion vessel is charged with dry nitrogen, not air. Repressurising with compressed air does shorten the life. The working volume should not be less than 5% of the system total volume otherwise over pressure will result when the system is at maximum temperature.
Using an anti corrosion additive is mandatory, using a leak sealer is a bit suspect as it introduces contamination and will not seal worn radiator valves or lockshields. Systems that lose pressure regularly need attention, not just frequent topping up. With good quality valves and careful assembly there should be no leaks. We used to test to 5 bar.
I don't think there is a boiler manufacturer who will guarantee an open system with header tank on a sealed system boiler.
We used to leave it to soak at least overnight followed by repeated hot and cold fresh water flush until the water is crystal clear, as clear as what comes out of the tap!
We always acid flushed even new systems, new radiators are not clean inside and any metallic pipework will be contaminated.
I think you have done well not to be charged for the repair, many manufacturers would have charged you if there was any debris in the water.
The expansion vessel is charged with dry nitrogen, not air. Repressurising with compressed air does shorten the life. The working volume should not be less than 5% of the system total volume otherwise over pressure will result when the system is at maximum temperature.
Using an anti corrosion additive is mandatory, using a leak sealer is a bit suspect as it introduces contamination and will not seal worn radiator valves or lockshields. Systems that lose pressure regularly need attention, not just frequent topping up. With good quality valves and careful assembly there should be no leaks. We used to test to 5 bar.
I don't think there is a boiler manufacturer who will guarantee an open system with header tank on a sealed system boiler.
Boater Sam.
