Building&Living – Issue 04/2009

This season, heating is a hot topic. TÜV SÜD warns heating system owners not to top up their systems with ordinary drinking water – this can end in a ruined heating boiler. A further article in this winter issue of Building&Living examines ways of protecting outdoor flooring from the ravages of frost and snow. And our checklist for winter reminds house owners what to look for in winter. Finally, we present some guidelines about selecting indoor staircases.

Topics

• Drinking water can ruin heating boilers Page 2
• Helping outdoor floorings to survive the winter Page 4
• Checklist for house owners throughout the year – Part 4 Page 5
• The right staircase – step by step Page 6

Drinking water can ruin heating boilers

There's water … and there's water. This simple truism becomes critical when your heating system needs to be topped up with water. In extreme cases, blithely using drinking water may ruin your boiler. TÜV SÜD's experts offer background information and practical tips.

The material: Today's heating systems are manufactured using materials of increasingly high quality – and low thickness. If heating systems are topped up using household drinking water which has a high percentage of lime (calcium carbonate), deposits may form at exposed points of radiator components – in direct contact with the heat source – and may generate such extreme thermal stress that the boiler develops cracks. A leaking boiler may ensue. This danger is particularly prevalent in all heating systems of low-energy design installed at the time of or after introduction of the German Energy Saving Ordinance (EnEV) of 2002: oil or gas boilers, condensing technology or conventional combustion, heat pumps of all kinds driven by heating water or even plate heat exchangers. Another combination to avoid is water with excessive potassium levels plus heat exchangers made of aluminium or aluminium alloys. Here the water may also chemically attack the material.

Water quality: The current state of the art is the VDI 2035 guideline, "Prevention of damage in water heating installations". While it initially applies to heating systems with an output of over 50 kW, many manufacturers also stipulate water quality in line with VDI 2035 as an operating condition for lower-output systems, or state even stricter conditions. If the heating system needs to be topped up with water, it is always wise to read the operating manual and consult the maintenance company.

Required water volume: When pressure drops in the heating system, it must be topped up with water. The pressure loss is generally shown by a manometer. TÜV SÜD advise that a heating system operating normally in a detached house loses one to two litres of heating water per year through evaporation at seals and screw fittings. If more water is lost, there is generally a technical cause – perhaps a leaking pipe connection. To avoid the problems described above in topping up the system with hard water, it is best to ask a specialist to check both system pressure and heating water quality during the annual maintenance. After checking the system for leaks, suitable water (VDI 2035!), if necessary with chemical additives, should be used to top up the system. To prevent corrosion, heating water should be strongly alkaline, with a ph value of over 8.5, and as lime-free as possible. By way of comparison, drinking water is neutral, with a pH value of around 7, and contains an average of 0.2 grams of lime per litre.

Helping outdoor floorings to survive the winter

Rain, snow or ice - wet weather and cold may make life tough for outdoor floorings. The experts at TÜV SÜD list some aspects to watch out for with concrete or natural-stone slabs or tiles on balcony or patio, and provide advice on action to take.

Against the grain: Road salt should not be used to combat ice and snow on external stairs, balconies or terraces. The salt may damage the material, and can also ruin its appearance. In addition, salt can cause or accelerate corrosion of steel and reinforced concrete components.

All covered up: A full blanket of snow is normally no problem for concrete, paving, natural stone and tiles. However, check that there is no build-up of water at balcony or patio doors, warns TÜV SÜD.

Dirty work: Where patio or balcony drainage is effected by a drainpipe or drain grooves, care should be taken to avoid blockages by dirt or moss that cause water build-up; in extreme cases, this may cause water to enter the apartment. If natural-stone or concrete slabs are laid on chippings, check every five years or so that this base is still in good order and that dust, dirt or earth from flowerpots has not impaired its function: if the water uptake of the chippings has been reduced, the next downpour may cause a build-up of water. In addition, drains and emergency overflows on patios or balconies with closed railings must be prevented from clogging or blocking.

Wet problems: Where tiles are glued to screed, excessive water may become a problem if it penetrates through to the screed; frost damage may be the result.

Checklist for house owners throughout the year – Part 4

Ice, snow, cold: the experts at TÜV SÜD present a brief checklist of action for house owners in the current season.

Outdoor water sources: Have all outdoor water sources been frostproofed? Then they're ready for winter!

Roofs: Are house and garage roofs and balconies able to withstand the weight of winter snowfalls? Find out the snow load calculated for your region by asking the planner / architect of your house or enquiring at your local council building authority. In addition, balconies and patios should regularly be cleared of snow to prevent water from seeping through the (balcony) door.

Roof underside: Have icicles formed on the underside of the roof? This may be an indication of physical defects in construction. If in doubt, consult a specialist company and have the roof inspected.

Indoor climate conditions: Correct heating and airing is critical in creating healthy indoor climate conditions. The best way of combating mould is dryness, achieved by airing rooms sensibly. Airing with windows fully open enables indoor air to be exchanged in the shortest possible time without cooling walls. To keep humidity under control at all times, a hygrometer is useful. As a rule of thumb, humidity in new buildings should not exceed 50 per cent. In older buildings problems may arise when windows are replaced with newer airtight models. When outside temperatures fall below zero, indoor humidity should not exceed 45 per cent; otherwise mould may form at weak points in the construction known as "cold bridges".

Step by step to the perfect staircase

Stairs are not only essential from a practical viewpoint, but also influence the style of a house or flat. To ensure that indoor stairs continue to please over the long term, they must be safe and robust. TÜV SÜD presents some tips for planning your stairs.

Type: A spiral or newel staircase saves space and is thus particularly suitable for subsequent installation – perhaps as part of a loft conversion. A classic full wooden staircase along a wall provides an enhanced feeling of security for older people thanks to the additional support they have from the wall.

Width: A staircase that is wide enough is not only convenient to use, but is also a practical transport route. The minimum width of the staircase must be determined on the basis of the DIN 18065 standard. Depending on the general conditions, it may be from 80 to 100 centimetres.

Riser height: The pitch ratio of a flight of stairs – the ratio of rise height to tread depth – is essential to create a feeling of security. TÜV SÜD's building engineering experts recommend a pitch ratio of 17 to 29 centimetres. This figure is used to calculate the number of steps required, depending on floor height. All steps must be at equal distance – a point to consider particularly when selecting the floor covering on top of and below the steps – such as tiles or parquet.

Balustrade: If the steps need to be childproof, the balustrade does the job. According to building regulations, a balustrade must be at least 90 centimetres high, and the distance between the individual vertical risers or stair supports must not exceed twelve centimetres, to ensure that children cannot slip through. Indoor stairs for apartments are still permitted to have horizontal banisters or railings; however, these could be seen by children as an ideal adventure playground and represent quite a risk in this respect. This aspect should be considered by the installer of the stairs when deciding on the final design. Iron or steel elements with sharp edges should never be used.

Handrail: Handrails – where possible installed on both sides of a staircase – give children and older people additional security. The minimum width of the stairs must be calculated between the handrails. The new edition of the DIN 18065 standard (currently in draft form) contains detailed descriptions of handrail requirements. TÜV SÜD's tip: simply ask your specialist.