Requirements for the heating water

Suitable heat transfer medium

In order to avoid corrosion, compliance with VDI 2035 Part 1/2005 (Correction 12/2006) and VDI 2035 Sheet 2 from 1998 and 2009 is strongly recommended.

Cast iron radiators in particular with their product-specific characteristics (sealing points) require a suitable heat transfer medium for reliable operation. The same applies to other sectional radiators, flanges and pumps. The requirements for the heating water are specified in more detail here.

Water quality:

According to VDI 2035 Sheet 1, there are no special requirements for systems up to 50 KW (with the exception of circulating water heaters and electrically heated systems). From 51 KW, the sum of the alkaline earths and the total hardness is limited to a maximum. This may result in a softening of the water.

Under VDI 2035, possible leaks from sealing points are traced back to partially or fully softened water. Leakages first become noticeable through the formation of a salt crust. Later, water can escape and signs of corrosion in the sealing area can occur.

The structure of the seals used has a swelling effect. It is possible for the carrier medium to diffuse through the seal. First, the water (carrier medium) evaporates on the surface. This enables the water content to be enriched at the edge of the seal.

With partially or fully softened water, sodium bicarbonate is initially present instead of calcium bicarbonate. At the edge of the seal, this can be converted into easily soluble and strongly alkaline sodium carbonate. This carbonate can decompose the organic components of the seals and the sealing material by hydrolysis. This significantly increases the water permeability of the sealants. This leads to further leaks.

We therefore recommend using fully demineralised water. Failure to comply will void the warranty in the event of leaks.

Water glycol mixture:

The diffusion performance of the seals is significantly increased by reducing the surface tension of the glycol mixture. Slight leaks are thus clearly evident.

Chemical oxygen reduction:

Chemical oxygen reduction depends on several factors. (Concentration of oxygen content, concentration of reducing agent, PH content and temperature.

Therefore, the suitability and dosage of the agent must be determined by experts. Toxicological and physical-chemical properties must be observed.

Especially when using salt-like oxygen scavengers, there can be problems with increased leakage of the sealing points (VDI 2035) through the heating water, as well as crust formation and corrosion as a result.

Inhibitors:

The purpose of corrosion inhibitors is to prevent possible oxygen corrosion. It is noteworthy that if the anodic inhibitor is not dosed enough or there is local access obstruction, increased corrosion can occur in the unprotected anodic area.

One type of inhibitors are film-forming amines. Some of these amines have a dispersing (separating) effect and can loosen existing deposits. Film-forming amines generally do not get along well with phosphates and can impair their functions. This can result in failure of elastomer materials, resinous releases or decomposition and oxidation. This can also attack seals or deposits can form in boilers or radiators.

Assembly of the seals:

With all flat gaskets, attention must be paid to their assembly. Only properly installed seals prevent their structural changes and leaks.

The seals are 1.5 mm thick.

The tightening torque of GURATEC cast radiator seals (nipple points) is specified as at least 320 Nm.

Summary:

From an output of 51 KW, special demands are placed on the water (system medium). Since the interaction of different systems causes chemical, biochemical, toxicological and physical reactions, expert and professional water treatment is essential. This can only be guaranteed by specialist companies / specialists.

Cast iron radiators, like other sectional radiators, flanges or screwed pump connections, are fitted with flat gaskets. If the composition of the heating water being treated is incorrect or if the system conditions are incorrectly interpreted, they can lead to corrosion.

Cast iron radiators from GURATEC have a below average leakage and corrosion rate. Incorrect water treatment can cause leaks and corrosion. These are not factory defects and are not subject to the usual manufacturer's warranty.

When used correctly, cast iron radiators are historically proven to last more than 100 years.

GURATEC generally prescribes oxygen-free water according to VDI 2035 for the operation of cast iron radiators. If other system components (e.g. boiler, etc.) or the described excess output make it necessary to treat the system water, the responsibility for the treatment and the resulting system safety falls under the guarantee of the system operator or the responsible specialist company. The large number of chemical / physical events and counter-reactions in processing plants cannot be estimated by the manufacturer during production.

These can only be assessed on site and system-specifically by experts.

If there are leaks in several sectional radiators, flanges, screwed pump connections, hemp points, valves or fittings in a large system, then the logical conclusion should first be to check the chemical compatibility of the additives in the water and their effects on the system.

Source: www.gussradiatoren.info