Chemical Sweeping - DeDietrich GT 224 Installation And Service Manual

4. Maintenance

Chemical sweeping

A. General principle
Boilers are traidtionally swept mechanically. There are now chemical
sweeping methods which facilitate this maintenance work.
A chemical reagent is applied to the boiler's heating surfaces.
After application, the reaction is completed by igniting the burner. The
initial deposits are neutralised and pyrolised. The remaining pulverent
residues are easy to remove by sweeping or vacuum cleaning.
B. The products
The product must be suitable for boilers with a cast iron body. Various
manufacturers offer products in the form of a concentrated liquid or
aerosol.
The aerosols are packaged in 0.5 to 1 l spray cans for treating domestic
boilers. Refer to the instructions supplied with the product.
The liquid products are available in 1 to 50 l containers. These
concentrated liquids are diluted before application with a spray.
Sprays exist in various forms suitable for their intended use:
- Low capacity (2 or 3 l) spray with built-in reservoir for small boilers and
moderate frequency. Manual pressurisation of the reservoir.
- 5 l spray with separate reservoir, nozzle and connecting tube. The
nozzles enable easy application at the back of the combustion
chamber. Manual pressurisation of the reservoir.
- Motor-assisted pressurisation spray with reservoir, nozzle and
connecting tube. These sprays are intended for intensive use.
C. Operational mode
The operating mode mentioned corresponds to standard user
situations. Refer to the manufacturer's instructions for specific advice on
the product used.
Application
- Depending on the product, the boiler must be cold or heated. Refer to
the instructions supplied with the product.
- Direct application to the heating surfaces with aerosol sprays.
- The concentrates are diluted in the proportions 1/5 to 1/20 (depending
on the product and the condition of the boiler).
- Application with the spray is done in the upper part of the boiler and
on the walls of the combustion chamber. Surfaces are dampened but
not washed. It is not necesaary to use the spray to get between the
heating surfaces.
- A volume of one litre of solution is generally used for 1 m
surface (domestic boiler), i.e. 0.05 to 0.2 l of concentrate.
D. Ignition
The burner is ignited after allowing the product time to penetrate for 2 to
5 min. Refer to the instructions supplied with the product.
22
2
of heating
GT 220 - GT 2200
8800N065
8800N063
22/01/09 - 300008281-001-E