Application of plastics in the heating industry

7 December 2022

Overview of covered topics

Plastics have a wide range of applications in various industries, and one of the less obvious ones is the heating industry, which has been increasingly opting for plastic products. In this article, we will introduce you to the applications of plastics in this market and what to consider during the design phase.

When thinking about storing hot fluids and pressure vessels, we typically envision large containers made of metal or consider ceramic materials. However, other construction materials can also be used to make covers for heating boilers.

Plastics – properties

Various types of plastics from which products can be made have several advantages over products made of metal. When taken in their liquid form, they can be thermoformed to inflate the plastic sheet, allowing them to take on various shapes. Such constructions can be very lightweight. Importantly, during thermoforming, the polymer’s atomic chains become biaxially oriented, making them significantly stronger than the parent polymer. Another advantage is cost-effectiveness, as the equipment is even up to 10 times cheaper than in other technologies (e.g., injection molding).

Covers for heating boilers made of plastics

Thanks to advancing manufacturing technologies, plastics can also be used in demanding conditions where devices in the heating industry operate. We collaborate with many leading companies in this market, allowing us to manufacture even complex shapes of covers made from polymer materials and provide a diverse set of properties. We perform mass production of covers for buffer tanks. In the next part of the article, we will show what to consider when designing covers.

What do we need for the valuation of a heating boiler cover (buffer tank cover) made of plastic?

The most crucial pieces of information for such projects are the dimensions of the diameter and height of the cover.

A technical drawing or 3D model of the cover is essential. It’s crucial for customers to provide technical drawings or 3D models as it helps us understand their concept and requirements.

Usage conditions – if the covers will be used outdoors, it will be necessary to add a UV stabilizer (a factor that protects the product from harmful UV radiation).

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What technology is used to make the covers, and what material is used?

The covers are made using the thermoforming technology. The most commonly chosen plastic material for producing covers is ABS regrind. This material is known for its high strength and scratch resistance, qualities that only a few plastics possess. The ideal thickness for an ABS sheet, balancing quality and cost, is 2 mm. This thickness ensures that the cover does not deform easily. Additionally, the fine texture of the ABS surface makes it more resistant to scratches.

What molds are needed for the production of covers, and what is the lead time for their production?

To minimize the initial costs for molds, we recommend clients use wooden molds coated with a composite. The cost of such constructions depends on the diameter and typically falls in the range of 1000 to 2000 PLN. Additionally, creating such a mold doesn’t take long – it’s about 2-3 weeks, with most of the time dedicated to ensuring the composite dries properly on the finished wooden mold. Among the many advantages of this construction, it’s essential to be aware of one significant drawback – there is a visible line around the circumference of the cover. With usage and heating of the mold, this line fades, but for some clients, it may be unacceptable. In such cases, we offer resin or aluminum molds, which are more expensive but eliminate this aesthetic drawback.

What happens if the diameter of the prototype cover is not suitable?

If the diameter is too large, there’s no problem in reducing it without the need for significant mold adjustments and returning to the previous dimensions. We need a few days to improve the mold and produce new prototypes, which are then sent to the client for approval. The process of reducing the diameter is free of charge.

If the diameter is too small, unfortunately, it’s an unfavorable situation. Increasing the diameter is also possible without the need for a new mold, but there are several potential risks. Firstly, there is a risk of weakening the mold. Another aspect is the risk of visible joint lines (inserts) during the forming process. Additionally, increasing the diameter incurs additional costs.

Is it possible to create holes on the surface of the cover?

Yes, it is possible to create multiple holes on the surface of the cover. These openings are made during post-production, which is referred to as machining. The cover is initially removed from the mold without any holes, and then it is sent to dedicated machining stations where specialists cut the necessary openings according to the technical documentation using a plotter. For large-volume orders, we use pre-made templates to automate the finishing machining process. It is also possible to produce covers without any openings if required.

Characteristics of covers produced by Plastipol.

  • High rigidity of the cover with relatively low weight.
  • Presence of embossments – they are necessary as they increase the strength of the structure, and additionally, the detail is easier to remove from the mold.
  • High aesthetic quality of the surface – most of the covers we produce have a textured finish, but it’s also possible to make them smooth.
  • Low implementation costs– cost of mold production range from 1,000 to 2,000 PLN, depending on the diameter, which is a very low cost compared to technologies like injection molding, where mold prices start at several tens of thousands of PLN.
  • Short implementation time – the standard time for creating a mold is approximately 2-3 weeks.
  • Use of secondary material – for most of the lids we produce, we use regrind for several reasons: firstly, it is a material that has already been used once, which helps reduce waste, which is especially important in the context of global warming. Secondly, it is a material that is lower in cost compared to the original, while its properties remain very similar.
  • Aesthetic product surface – thanks to the applied molet texture (very fine “sand”), we can achieve a scratch-resistant cover without any additional coatings.
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What should be taken into consideration when using a boiler cover?

While metal covers are susceptible to corrosion, plastic materials can also undergo changes due to weather conditions and the natural environment. They are most commonly exposed to UV radiation, which over the course of several years of use can lead to product brittleness. To counteract sunlight and other forms of radiation, covers made of polymers used outdoors are often painted black or reinforced with UV stabilizers. This color absorbs radiation effectively, protecting the material beneath it. Black color works well for disguising the aging effect of the material (yellowing of the detail). It’s also important to pay attention to the height of the cover. If the cover is taller than the market standard (approximately 15-30 mm in height), consider increasing the material thickness to 3 mm to maintain product rigidity and durability.


The heating industry is rapidly expanding, and it is increasingly turning to plastic components. Advantages such as the lightweight nature of the parts, low cost of mass production, and corrosion resistance are crucial in product solutions within this industry. The current economic crisis only accelerates the adoption of plastic solutions in the heating and energy sector. The applications of plastics in the heating industry are growing steadily.

Plastic everyday objects in various forms have long ceased to surprise us. Its applications are virtually limitless (even in the production of optical devices). However, with the right technologies, polymers can also be an excellent choice in the industrial sector. Plastics are becoming an increasingly attractive alternative, and lower production costs do not necessarily mean weaker properties.

If you need advice on the use of plastics in the heating industry, please contact us through the contact form or directly at our email address –

Adam Bernacki

Adam Bernacki

Technical director at Plastipol Poland. Popularizer of knowledge about plastics processing. Industry experience gained through education at Scandinavian polytechnics, work in global corporations in the plastics industry, and by managing technical issues in a Polish company. Specialist in plastics batch and mass production technologies. Author of articles and industry texts for clients in various industry sectors. Training Advisor.