A rough guide to power or chemical flush diagnostics.
To Flush or not to flush that is the eternal flushing question.
A qualified and experienced (at least 5, maybe 10 years) should asses the system. Here’s our rouge guide;
All systems;
(Inhibitor levels must be maintained with any filters cleaned).
Boilers must be serviced.
Checks for systems;
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Colour of heating system water (use Fernox test tool, do not use first water drawn off)
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pH level of heating system water
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Are radiators reaching surface temperature use an infrared thermometer, not by hand. (If not power flush, check pump performance and size)
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Age of radiators and heat exchanger (unless stainless steel) and pipework. The older the ferrous parts of the system are the more likely a flush and power flush will be necessary.
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Sealed/open vented. Open vented system more likely to oxidise so treat same as an older system and consider sealing the system.
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Magnetic check, if a small powerful magnet sticks to copper pipe the pipes need to be replaced (a thorough power flush is a minimum but not a long-term solution).
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Age and condition of heating circulating pumps. Some pumps should be changed as an addition.
Failing of 1 or 2 chemical flush required.
Failing of 1 or 2 and 3 Power flush required.
Older components of the system, magnetic flier required.
Notes
pH under 6 or over 8 (invalidates some warranties e.g. Worcester Bosch)
Filters always recommended for older systems (not always space) and these improve efficiency.
Boiler service always recommended, an aluminium heat exchanger may need cleaning (some brands should be cleaned annual, always refer to manufacturers instructions).
Only settle for a chemical clean when the heating engineer is satisfied that all the radiators reach approximate design temperature, this indicates good circulation, however if some (usually in a house ground floor) radiators are found to not reach design temperature then it is likely that there are significant deposits of sludge/debris (iron and/or aluminium oxides) in your heating system, then the preferred cleaning method should be a power flush. Pumps and other related components must be checked.
Inhibitor labelling should be used (inside boiler panel, or under boiler?)
Fernox sample lab test kits are available cost + one hour labour.
Examples;
Example 1
Water clear
pH 6.5-7.5
All parts of system new, less than 10 years old
Radiators reaching the design surface temperature
no action required.
Example 2
Water dirty.
pH 6.5-7.5
All radiators getting hot.
Boiler and radiators less than 20 years old.
Chemical flush and filter.
Example 3
Water dirty
pH neutral
All radiators getting hot.
Radiators over 40 years old.
Chemical flush and replace radiators.
Example 4
Water dirty
pH 8 or over (or under 6)
All radiators getting hot.
Radiators over 40 years old.
Power flush + replace radiators, magnetic filter recommended.
Example 5
Water dirty
pH 8 or over (or under 6)
Radiators not getting hot throughout
Radiators 10 years old
Power flush + magnetic filter
Power flush procedure;
https://fernox.com/powerflushing/
https://fernox.com/wp-content/uploads/sites/3/2017/12/powerflushing_a_central_heating_system.pdf
Chemical Flush Procedure;
Commercial Flushing Procedure;
CULKIN PLUMBING AND HEATING LTD
Director JEFF CULKIN ACIPHE RP RHP
29B CHANDOS ROAD
WILLESDEN GREEN
LONDON
NW2 4LS
Gas Safe Reg no 305929
Company No. 07980305
VAT No. GB172932986
D-U-N-S Number: 21-827-8135
Primary Coverage;
NW1 Camden, Primrose Hill
NW2 Willesden Green Cricklewood, Childs Hill
NW3 Hampstead, Belsize
NW5 Kentish Town, Camden
NW6 West Hampstead, Kilburn, Queens Park
NW7 Mill HIll
NW8 St Johns Wood
NW10 Kensal Rise, Harlesden, Willesden
NW11 Golders Green Hampstead Garden Suburb
W9 Maida Vale
W10 North Kensington, Queens Park