Vaillant thermal insulation for PHE S 120-70 plate heat exchanger

Vaillant thermal insulation for plate heat exchanger PHE S 120-70

This thermal insulation is an original Vaillant accessory intended exclusively for the plate heat exchanger PHE S 120-70 (heat exchanger order number 0020137069). The insulation cover is shaped precisely to the dimensions of the heat exchanger body (281 × 335 × 73 mm (height × width × thickness)) including cutouts for the side connections of both the primary and secondary circuits, and serves three key functions: a safety function (prevents accidental contact by the operator with the hot surface of the heat exchanger), an energy-saving function (reduces heat loss by radiation and convection into the surrounding plant room), and an anti-condensation function (limits the formation of condensate on the surface of the heat exchanger during operation with lower secondary medium temperatures, e.g. when connected to a heat pump circuit).

According to the official Vaillant installation manual for the PHE S/PHE C range, there is an explicit safety warning: „Wärmetauscher kann im Betrieb sehr heiß werden – Verbrennungsgefahr“ (the heat exchanger can become 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 heat exchanger PHE S 120-70

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

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

Construction of the insulation cover

The cover is made of closed-cell thermal insulation foam with a black surface, resistant to common boiler room operating temperatures. The construction is designed as a removable, shaped enclosure that follows the angular body of the PHE S 120-70 heat exchanger and leaves free access to the side connections of both the primary and secondary circuits, as well as to venting and drain fittings, if included in the assembly. Thanks to its split construction, the cover can also be fitted subsequently onto an already assembled and connected heat exchanger, without the need to dismantle the piping.

Installation of the insulation cover

1. Before fitting the insulation, it is recommended to complete the installation and pressure test all heat exchanger connections for leaks.
2. The cover is fitted onto the heat exchanger body in its individual parts so that the cutouts precisely align with the side connections of the primary and secondary circuits.
3. The cover parts are joined together (depending on the version, using clips, hook-and-loop fastener, or an overlap with a locking feature) so that no gaps are created 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 obstruct the space required for operating the shut-off valves, venting, or any future measurement interventions.

Service, cleaning and maintenance

If signs of limescale or dirt build-up appear (typical with hard or contaminated water), the heat exchanger is cleaned as follows: the system is taken out of operation, the heat exchanger is drained and removed. For cleaning, use only agents suitable for stainless steel and copper – unsuitable cleaning agents can permanently damage the heat exchanger. Flushing with the cleaning solution is carried out against the normal flow direction, after which the heat exchanger is rinsed with clean water, reinstalled, and before restarting it is recommended to check the water hardness. In case of high water hardness, treatment of the heating water is recommended according to the documentation of the other system components – atria.sk offers, in the chemical and physical water treatment category, e.g. corrosion inhibitors and cleaning agents from the SENTINEL and ULTIMA ranges, which extend the service life of the heat exchanger and the entire boiler room.

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

Compatibility and related accessories

The PHE S 120-70 model connects directly via a threaded 1 1/4" connection without the need for a flanged connection part. If copper piping is used in the project, we recommend adding a connection adapter for a 35 mm copper pipe (code 0020248931), available separately in this category on atria.sk.

Typical application scenario

A typical example is an apartment building with 20 to 40 residential units, where the owners' association operates its own building boiler room with two smaller wall-mounted condensing boilers connected in a cascade. The boiler room space is usually small, often located in the basement or a plant room, accessible not only to the maintenance technician but occasionally also to members of the association's committee during meter readings or routine visual inspections. In such an environment, this compact insulation is an important, though often overlooked, safety feature – it prevents accidental contact with the hot stainless-steel heat exchanger body without the boiler room operator necessarily being aware of it as a risk.

Why an improvised solution is not a good choice

In practice, we occasionally encounter a makeshift solution where the installation company simply wraps the hot heat exchanger in mineral wool and secures it with tape or wire. This solution is problematic for several reasons: mineral wool absorbs moisture from the surroundings and loses its insulating properties, does not accurately follow the shape of the heat exchanger (creating gaps with heat loss and risk of contact), and during service interventions it usually has to be completely discarded and replaced with new material. An 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 standard 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 constant source of heat loss through radiation and convection into the surrounding plant room space during operation. For higher-output models (and thus also larger surface areas of the body, as is the case with the PHE S 120-70 model), this effect is more pronounced than with small domestic units. Covering the body with suitable thermal insulation is one of the simple and low-cost measures that can noticeably reduce these losses without interfering with the functional part of the system – similarly to how distribution pipes and fittings in the same boiler room are commonly insulated. Combined with other accessories (e.g. insulation of the connecting piping), a comprehensively insulated assembly is created, which reduces the overall heat loss 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 the PHE S 120-70

• Precise shape match with the PHE S 120-70 heat exchanger – no additional modifications or custom trimming required, unlike generic insulation available on the general market.
• Increased operational safety in accordance with the manufacturer's explicit recommendation in the installation manual.
• Reduced heat loss and thus also a slight improvement in the real efficiency of boiler room operation.
• Removable construction does not hinder routine servicing or occasional inspection of the heat exchanger.
• Long-term stability of shape and function compared to improvised solutions made of mineral wool or other materials.
• The PHE S 120-70 model is used mainly in smaller apartment buildings and smaller commercial facilities with a cascade output of up to 120 kW, where the plant room is often accessed by less trained building management staff – this is precisely where thermal insulation has the greatest practical safety significance.

When ordering, we always recommend verifying that the heat exchanger order number 0020137069 matches the model stated on this page (PHE S 120-70), as individual covers of the PHE C range are not interchangeable with one another and differ not only in their outer dimensions but also in the exact placement of the cutouts for the side connections and any floor bracket. If you are unsure about selecting the correct part, we recommend contacting atria.sk customer support or directly consulting the designer of the given heating system.

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