Zilmet Combi Boiler Plate Heat Exchanger 18 Plates – 17B1901826, 148 mm, 28 kW | Compatible with Fondital Tahiti, Flores, Pictor, Aries Dual

Zilmet 17B1901826 (manufacturer model name ZB 190) is a brazed plate heat exchanger that heats the domestic hot water flowing from the tap with the hot water of the boiler's central heating circuit without mixing the two. It has 18 plates; the distance between the fixing pins is 148 mm and the body length is 190 mm. The plates are AISI 316L stainless steel and the joints are copper brazed — it has no removable gasket or spare plates, and it is replaced as a complete unit when it fails. Made in Italy.

In manufacturer catalogs it is listed under the code Fondital 6SCAMPIA02 and is used in the 28 kW class combi boilers of Fondital / Nova Florida. In the field it is searched for as a combi boiler plate heat exchanger, an 18-plate heat exchanger or a 148 mm heat exchanger.

Why 18 Plates Matters: 24 kW or 28 kW?

The same 190 mm body and the same 148 mm pin spacing are produced with different numbers of plates. The number of plates determines the heat transfer surface and therefore the domestic hot water flow rate. Fondital's own spare parts list states the distinction clearly:

• 14 plates → 24 kW class combi boiler (Fondital code 6SCAMPIA01)
• 18 plates → 28 kW class combi boiler (Fondital code 6SCAMPIA02) — this product

Both fit the same seat, because the pin spacing is 148 mm on both. That is why they are easy to mix up: if a 14-plate unit is fitted to a 28 kW appliance, the boiler runs but the hot water flow rate drops and water at the desired temperature cannot be obtained from the tap. Count the plates of the removed part or check the kW rating of the appliance.

Technical Specifications

• Brand: Zilmet — made in Italy
• Manufacturer Code: 17B1901826 · Model: ZB 190
• Number of Plates: 18
• Capacity Class: 28 kW combi boiler
• Distance Between Fixing Pins: 148 mm
• Distance Between Hole Centers: 154 mm (40 mm transverse)
• Body Dimensions: 190 × 76 mm · pack thickness approx. 48–50 mm
• Weight: approx. 1 kg
• Plate Material: AISI 316L stainless steel · copper brazed
• Maximum Operating Pressure: Primary circuit 3 bar · Secondary circuit 8 bar
• Operating Temperature: −10 … +120 °C
• Fluid Group: Group 2
• Approval: WRAS No. 1904702

Compatibility Table

For an appliance not on the list: this heat exchanger has the 148 mm pin spacing + 18 plates dimensions. The same size may also be used in the 28 kW models of other brands — this size is asked about for ECA Confeo, Proteus and old Serena bodies. In this case compare dimensions with the removed part before ordering; do not order based on the brand name alone.

Choosing the Right Heat Exchanger

Plate heat exchangers can look the same yet differ in size. Compare the removed part at three points:

• Number of plates: The copper strips counted when viewed from the side — 18 on this product.
• Distance between pin centers: The center-to-center distance of the copper tube ends at the two ends — 148 mm. The same body is also produced in 142, 154, 160 and 166 mm sizes.
• Port layout: At each end there is one copper tube end (male) and one female port; all four connections are on the same face.

If you are not sure, send us the brand/model of the appliance or the code on the removed part.

When Should the Plate Heat Exchanger Be Replaced?

• Hot water comes hot one moment and cold the next. This is the first and most common symptom of plate channels narrowed by scale.
• Hot water arrives late at the tap or does not heat up at all. Only the domestic hot water failing to heat while the heating side works normally is the distinguishing test that links the fault to the heat exchanger.
• The water flows weakly. A drop in flow rate while there is pressure in the system indicates that the channels are blocked.
• The boiler locks out quickly in hot water mode. When water cannot pass through the heat exchanger, the outlet temperature rises suddenly and the appliance goes into overheat fault.
• The radiators cool down when hot water is turned on, or conversely, the radiators heat up while hot water is being drawn.
• The system pressure rises by itself. With this symptom, a plate is perforated and mains water is leaking into the heating circuit; chemical cleaning will not solve it, the heat exchanger must be replaced.

With light scaling, chemical cleaning may help; if the deposits are old or a plate is perforated, replacement is required.

Installation Notes

• Before replacement, the boiler's gas and electricity are shut off, and the domestic hot water and heating circuits are drained.
• The heat exchanger is bolted to the hydraulic group; during removal the port seals (O-rings) are also renewed — an old seal leaks when reused.
• The flow direction is important. The primary (heating) and secondary (domestic hot water) directions are shown by arrows on the manufacturer's label; a heat exchanger connected the wrong way round loses capacity.
• The screws are tightened crosswise and gradually; overtightening strains the plate pack.
• After installation the circuit is vented through the air vent and the system pressure is checked.
• In areas with heavy scale load, a filter or softening at the domestic water inlet is considered to extend the life of the new heat exchanger.