Zilmet Boiler Plate Heat Exchanger 14 Plates – 17B1901426, 148 mm | ECA Confeo, Ferroli Divatop, Viessmann Vitopend, Ariston Uno, Biasi, Fondital Compatible

Zilmet 17B1901426 (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 central heating circuit without mixing the two. It has 14 plates; the distance between the fixing pins is 148 mm and the body length is 190 mm. The plates are AISI 316L stainless steel, joined by copper brazing — it has no removable gasket or spare plates and is replaced as a complete unit when it fails. Made in Italy.

It is listed in manufacturer catalogs under codes Viessmann 7825534 and 7856964, Ariston 995945, Ideal 173544, Biasi BI1001101, Fondital 6SCAMPIA01 and Ferroli / ECA / Lamborghini 04558260. In the field it is searched for as the Viessmann Vitopend plate heat exchanger, ECA Confeo heat exchanger, Ferroli Divatop plate heat exchanger and Ariston Uno heat exchanger.

When Should the Plate Heat Exchanger Be Replaced?

• Hot water runs hot and cold alternately. This is the first and most common sign of plate channels narrowed by limescale.
• Hot water from the tap arrives late or does not heat up at all. When the central heating side works normally but only the domestic water does not heat, this is the distinguishing test that links the fault to the heat exchanger.
• The water flow is weak. A drop in flow while there is pressure in the system shows that the channels are blocked.
• The boiler locks out quickly in domestic hot water mode. When water cannot pass through the heat exchanger, the outlet temperature rises suddenly and the appliance goes into a high temperature fault.
• Radiators cool down when hot water is turned on, or conversely, radiators heat up while hot water is being drawn.
• System pressure rises by itself. With this symptom the plate is perforated and mains water is leaking into the heating circuit; chemical cleaning will not solve it, the heat exchanger must be replaced.

For light scaling, chemical cleaning may work; if the deposits are old or the plate is perforated, replacement is required.

Technical Specifications

• Brand: Zilmet — made in Italy
• Manufacturer Code: 17B1901426 · Model: ZB 190
• Number of Plates: 14
• Distance Between Fixing Pins: 148 mm
• Distance Between Hole Centers: 154 mm (40 mm transverse)
• Body Dimensions: 190 × 77 mm · pack thickness approx. 39 mm
• Weight: approx. 0.82 kg
• Plate Material: AISI 316L stainless steel · copper brazed
• Maximum Working Pressure: Primary circuit 3 bar · Secondary circuit 8 bar
• Operating Temperature: −10 … +120 °C
• Fluid Group: Group 2
• Approval: WRAS No. 1904702

Compatibility Table

A heat exchanger of this size is used in the brands and models below. To avoid ordering the wrong part, verify the brand/model of your appliance; if you are not sure, ask for confirmation using the code on the removed part.

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

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

Choosing the Right Heat Exchanger

Plate heat exchangers can look the same but differ in size. The same 190 mm body is produced with connection spacings of 142, 148, 154, 160 and 166 mm and with 10–20 plates. Before ordering, compare the removed part at three points:

• Number of plates: The copper strips counted from the side — 14 on this product.
• Distance between pin centers: The center-to-center distance of the copper tube ends at both ends — 148 mm.
• 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.

Installation Notes

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