Vaillant thermal insulation for PHE C 720-170 plate heat exchanger

Vaillant thermal insulation for plate heat exchanger PHE C 720-170

This thermal insulation is an original Vaillant accessory intended exclusively for the plate heat exchanger PHE C 720-170 (exchanger order number 0020137074). The insulating cover is shaped precisely to the dimensions of the exchanger body (421 × 532 × 636 mm, connection height K 479 mm) including cutouts for the side connections of both the primary and secondary circuits, and fulfills three key functions: safety (prevents accidental contact of the operator with the hot surface of the exchanger), energy-saving (reduces heat losses by radiation and convection to the surroundings of the technical room) and anti-condensation (limits the formation of condensate on the exchanger surface during operation with lower temperatures of the secondary medium, e.g. when connected to a heat pump circuit).

According to the official Vaillant installation manual for the PHE S/PHE C series, there is an explicit safety warning: „Wärmetauscher kann im Betrieb sehr heiß werden – Verbrennungsgefahr“ (the exchanger can get very hot during operation – risk of burns). This insulation is precisely the recommended solution for eliminating this risk in real boiler room operation without the need for additional protective measures or restricted access to the area.

Parameters of the protected exchanger PHE C 720-170

Overview of the entire Vaillant PHE series (official manufacturer's technical data)

Plate material: stainless steel. Operating temperature (material range of plates): -196 °C to +200 °C. The PHE S model has a threaded connection 1 1/4", the PHE C models have a flanged connection. Source: Vaillant installation manual „Externer Plattenwärmetauscher PHE S, PHE C“, document 0020196730_00.

Construction of the insulating cover

The cover is made of closed-cell thermal insulation foam with a black surface, resistant to the usual temperatures of boiler room operation. The construction is designed as a detachable, shaped enclosure that follows the angular body of the PHE C 720-170 exchanger and leaves free access to the side connections of both the primary and secondary circuits, as well as to venting and draining fittings, if included in the assembly. Thanks to the split construction, the cover can also be fitted subsequently on an already assembled and connected exchanger, without the need to dismantle the piping.

Installation of the insulating cover

1. Before fitting the insulation, it is recommended to complete the installation and leak testing of all exchanger connections.
2. The cover is fitted onto the exchanger body in its individual parts so that the cutouts align exactly with the side connections of the primary and secondary circuits.
3. The parts of the cover are joined together (depending on the design: clips, velcro or overlap with a fastener) so that no gaps arise through which heat could escape or contact with the hot surface underneath the cover could occur.
4. Before putting the system into operation, it is recommended to visually check that the cover does not interfere with the space needed for operating the shut-off valves, venting or any future measurement interventions.

Service, cleaning and care

If signs of limescale or dirt build-up appear (typical with hard or contaminated water), the exchanger is cleaned as follows: the system is taken out of operation, the exchanger is drained and removed. Only agents suitable for stainless steel and copper are used for cleaning – unsuitable cleaning agents can irreparably damage the exchanger. Flushing with the cleaning solution takes place in the reverse direction to the normal flow, then the exchanger is flushed with clean water, reassembled, and it is recommended to check the water hardness before restarting. In the case of high water hardness, treatment of the heating water is recommended according to the documentation of the other components of the system – atria.sk offers, in the category chemical and physical water treatment, e.g. corrosion inhibitors and cleaning agents from the SENTINEL and ULTIMA lines, which extend the service life of the exchanger and the entire boiler room.

In case of temporary shutdown (repair, service, longer outage), it is recommended to completely drain and clean the exchanger, to avoid damage from frost, aggressive media or biological fouling. In the case of permanent decommissioning, the primary circuit is closed first, then the secondary circuit, followed by draining and disassembly.

Compatibility and related accessories

The PHE C 720-170 exchanger belongs to the PHE C series, which is always installed together with the supplied floor bracket with height-adjustable feet. When completing the assembly, we also recommend adding the following original accessories from the same category on atria.sk:

• Connecting pipe DN100 (code 0020107887) – a flanged connecting piece for PHE C models above 360 kW, into which, besides the main supply/return, additional fittings can also be connected (venting, draining, thermometer, pressure gauge).
• Insulation of the connecting pipe (code 0020248930) – a thermal cover for the aforementioned connecting piece, for complete insulation of the entire assembly, including the pipe connections, not just the exchanger body itself.

Typical application scenario

A district heating plant or a large industrial complex with a cascade near the upper limit of the series (720 kW) represents the most demanding application of the entire PHE range. Given the scale of the equipment and the number of technical personnel in such a plant room, thorough insulation of all hot components, including the largest exchanger in the series, is a standard part of the operational safety documentation. At this scale of equipment, consistent insulation of every single component is part of standard operational practice, not just an optional extra.

Why an improvised solution is not a good choice

In practice, we sometimes come across a makeshift solution, where the installation company simply wraps the hot exchanger with mineral wool and secures it with tape or wire. Such a solution is problematic for several reasons: mineral wool absorbs moisture from the surroundings and loses its insulating properties, does not precisely follow the shape of the exchanger (gaps arise with heat loss and risk of contact), and during service interventions it usually has to be completely discarded and replaced with new material. The original, shape-adapted Vaillant cover, on the other hand, retains its shape and insulating properties over the long term, can be repeatedly removed and refitted without loss of functionality, and its appearance matches the professional level of the rest of the boiler room equipment.

Energy and operational benefits of insulation

An uninsulated metal surface of a large-area plate heat exchanger represents a permanent source of heat losses during operation, through radiation and convection into the surrounding plant room space. In models with higher output (and thus also a larger surface area of the body, as is the case with the PHE C 720-170 model), this effect is more pronounced than in small domestic appliances. Covering the body with suitable thermal insulation is one of the simple and low-cost measures with which these losses can be noticeably reduced without interfering with the functional part of the system – similar to how distribution pipes or fittings in the same boiler room are also commonly insulated. Together with the other accessories (e.g. insulation of the connecting pipe), this creates a comprehensively insulated assembly, which reduces the total heat losses of the plant room and contributes to a more stable and predictable operating temperature in the given space.

Why choose the original Vaillant insulation for PHE C 720-170

• Exact shape match with the PHE C 720-170 exchanger – no additional adjustments or custom trimming, unlike universal insulation from the general market.
• Increased operational safety in accordance with the manufacturer's explicit recommendation in the installation manual.
• Reduced heat losses and thus a slight improvement in the real efficiency of boiler room operation.
• Detachable construction does not hinder normal servicing or occasional inspection of the exchanger.
• Long-term stability of shape and function compared to improvised solutions made of mineral wool or other materials.
• The PHE C 720-170 model is the top of the series and is used in the most demanding operations – district heating plants, large industrial complexes and energy centers – with boiler room output up to 720 kW.

When ordering, we always recommend verifying the match of the exchanger order number 0020137074 with the model stated on this page (PHE C 720-170), as the individual covers of the PHE C series are not interchangeable with each other and differ not only in outer dimensions, but also in the exact placement of the cutouts for the side connections and the floor bracket, if applicable. In case of any uncertainty in selecting the correct part, we recommend contacting the atria.sk customer support or directly the designer of the given heating system.

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