Ibaiondo CMF expansion vessel without feet, red, with threaded bottom connection
Ibaiondo CMF expansion vessel with feet, red, vertical model
Ibaiondo CMF expansion vessel without feet, red, with threaded bottom connection
Ibaiondo CMF expansion vessel with feet, red, vertical model
Ibaiondo

Ibaiondo CMF fixed-membrane expansion vessel for heating and cooling systems

Capacity
€31,71
/
Shipping calculated at checkout.
  • 4 in stock
  • Backordered, shipping soon

At Q-TECH, we apply the same clear rules for everyone: the law protects you, and when applied correctly, it protects us as well. By processing your purchase, you accept our General Terms and Conditions of Sale. If you are purchasing as a consumer (B2C), nothing stated herein limits the rights granted to you by mandatory law (RDL 1/2007, TRLGDCU): the 3-year legal warranty of conformity and the right of withdrawal under the terms and with the exceptions legally provided, which are detailed below. References to "B2B" apply only to businesses and professionals.

Your guarantees

  • Rights intact: 14 days of withdrawal from receipt for most products—subject to the legal exceptions you will see below, such as goods made to your specifications—and a 3-year legal warranty of conformity, under the terms of the TRLGDCU.
  • Conformity with the description: we guarantee that the equipment will correspond to the published technical description and what one could reasonably expect from it (arts. 115 et seq. TRLGDCU). Images and videos are for guidance only: the manufacturer may supply a more recent revision of the product or introduce minor aesthetic, packaging, or firmware changes, without this constituting a lack of conformity as long as the described characteristics and performance are maintained.
  • Traceability that also protects you: we document the condition, serial number, and seal of each piece of equipment upon shipment, and we video-record the opening of returns; this is your proof of the condition in which the goods were delivered.

Responsible use and your part

  • If you are thinking of returning it, keep it as you received it: without installing or activating it, with its seals, accessories, and packaging intact. This is how to ensure a full refund, without deductions.
  • Handling that exceeds inspection reduces value: handling the equipment beyond what is necessary to verify its nature and operation may result in a real, assessed, and case-by-case justified deduction (art. 108.2 TRLGDCU), never a fixed percentage. In particular: activating or registering the serial number, linking it to a manufacturer's account or app, circulating water through hydraulic equipment, unsealing probes, or installing software or consumables. Initial inspection of the product does not lead to a deduction.
  • The same item must be returned: withdrawal requires returning the supplied unit. Different equipment, or equipment with prior use, age, or wear prior to purchase, does not constitute a valid withdrawal.
  • Installation and cybersecurity, shared responsibility: this is technical hardware; you are responsible for correct installation, credentials, patches, and backups, while we deliver a compliant product. Q-TECH is not liable for damages resulting from poor installation, incorrect configuration, or omission of patches by the customer or third parties (in B2C, without prejudice to the legal warranty and liability for intent or negligence, arts. 86 and 130 TRLGDCU).
  • Delivery of bulky goods: delivery is made to the curb. B2C: transport risk is ours until physical delivery (art. 66 ter); we recommend noting visible damages on the delivery note and notifying us of breakages within 24-48 hours with photographs to activate the insurance. B2B: inspection and notation on the delivery note are mandatory; hidden damages must be reported within 24 hours (art. 366 CCom). Unjustified rejection or incorrect shipping information will entail the actual outbound and return costs (approx. €85-550 for heavy machinery).

Made to your measure (Advanced Pre-Assembly)

  • If your order includes equipment, racks, hydraulic assemblies, or technical rooms made or configured according to your specifications (permanent joints, custom cuts or wiring, parameterization, pressure testing), these are custom goods without the right of withdrawal from the conclusion of the contract (art. 103.c TRLGDCU; CJEU Case C-529/19), which is informed before purchasing and documented in the signed Order Note. A test you request without permanent modification retains your right of withdrawal, with only the actual loss of value caused by that test being deducted. Would you prefer to receive it tested, configured, and ready to connect, without assuming these risks? Contract our Advanced Pre-Assembly or the prior technical audit.

If you are purchasing as a business or professional (B2B)

  • The transaction is governed by the Commercial Code: firm sale, without the right of withdrawal; notification of defects within 4 days (apparent) / 30 days (hidden), arts. 336 and 342. Q-TECH acts as a distributor and excludes indirect damages, loss of profit, and data loss, limited to the price of the equipment, without prejudice to the manufacturer's commercial warranty.

Product warnings v1.0 · June 2026. Information summary; the complete and binding conditions are those published at q-tech.es.

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Fixed-membrane expansion vessel that absorbs water expansion in heating and cooling circuits

The Ibaiondo CMF expansion vessel keeps the pressure of your closed circuit stable when the water heats up and expands. Ibaiondo manufactures it in Spain in 14 capacities, from 8 to 500 litres. At Q-Tech we fit it into your pre-assembled plant room, connected and tested with the rest of the circuit before it reaches the site.

Summary

TypeClosed fixed-membrane expansion vessel
Brand and modelIbaiondo CMF and CMF-P
UseClosed heating and cooling circuits
Capacities8, 12, 18, 25, 35, 50, 80, 100, 140, 200, 250, 300, 400 and 500 litres
Maximum working pressure5 bar up to 35 litres, 4 bar for 50 litres and 6 bar from 80 to 500 litres
Compatible withClosed-circuit water; the membrane is not suitable for drinking water
Manufacturer's warranty3 years
Q-Tech installationConnection and adjustment by an on-site hourly Expert Technician

What is the Ibaiondo CMF?

The Ibaiondo CMF is a fixed-membrane expansion vessel for closed heating and cooling circuits that absorbs the expansion of the water. A membrane separates the water from a pre-charged air chamber. It connects to the circuit through a single male thread.

What problem does it solve?

The water in your system takes up more volume when it heats up. In a closed circuit that volume has nowhere to go and the pressure rises. Ibaiondo explains that the excess water enters the vessel and compresses the air chamber. That way the pressure stays below the setting of the safety valve. When the circuit cools down, the air returns the water to the system.

The capacity is calculated for each system. Ibaiondo states that authorised personnel must calculate the volume, using standard UNE 100155 or UNE-EN 12828. Its manual also requires the safety valve to be set below the maximum allowable pressure of the Ibaiondo CMF you choose.

Technical data

ApplicationClosed heating and cooling systems
MembraneNon-replaceable, to EN 13831, not suitable for drinking water
Body materialSteel
FinishRed epoxy paint, RAL 3000
Factory pre-charge1.5 bar, air
Maximum system temperature100 °C
Working temperature−10 °C to +70 °C
Water connectionMale thread R ¾" from 8 to 50 litres and R 1" from 80 to 500 litres; zinc-plated up to 35 litres
Test pressure7.5 bar on models without feet from 8 to 35 litres
StandardsManufactured in accordance with the Pressure Equipment Directive 2014/68/EU
Made inSpain

Models and data by variant

ModelCapacityMaximum pressureDiameterHeightConnectionWeightMountingReference
8 CMF8 litres5 bar200 mm340 mmR ¾"2.5 kgWithout feet02008343
12 CMF12 litres5 bar270 mm310 mmR ¾"3.2 kgWithout feet02012343
18 CMF18 litres5 bar270 mm415 mmR ¾"4 kgWithout feet02018343
25 CMF25 litres5 bar320 mm430 mmR ¾"4.5 kgWithout feet02025343
35 CMF35 litres5 bar360 mm475 mmR ¾"7 kgWithout feet02035343
50 CMF-P50 litres4 bar360 mm630 mmR ¾"7.5 kgWith feet02050343
80 CMF80 litres6 bar485 mm570 mmR 1"16 kgWith feet04080351
100 CMF100 litres6 bar485 mm650 mmR 1"18 kgWith feet04100351
140 CMF140 litres6 bar485 mm935 mmR 1"24 kgWith feet04140351
200 CMF200 litres6 bar600 mm860 mmR 1"36 kgWith feet04200351
250 CMF250 litres6 bar600 mm1,095 mmR 1"44 kgWith feet04250351
300 CMF300 litres6 bar600 mm1,240 mmR 1"49 kgWith feet04300351
400 CMF400 litres6 bar600 mm1,480 mmR 1"56 kgWith feet04400351
500 CMF500 litres6 bar750 mm1,445 mmR 1"63 kgWith feet04500351

Compatibility and limits

  • The Ibaiondo CMF works only in closed heating and cooling circuits.
  • The membrane is not suitable for drinking water: it is not used for domestic hot water.
  • The maximum pressure depends on the model: 5 bar from 8 to 35 litres, 4 bar for the 50 CMF-P and 6 bar from 80 to 500 litres.
  • Ibaiondo recommends adding an intermediate vessel when the heating return exceeds 70 °C.
  • Ibaiondo's manual requires it to be installed indoors, protected from the weather, with the air valve and the label accessible.
  • The safety valve of the circuit is set below the maximum pressure of the vessel.

When this product is not the right choice

ProductWhen to choose itMembraneMaximum pressureFactory pre-charge
Ibaiondo CMRYour circuit is domestic hot waterSuitable for drinking water8 or 10 bar, depending on the model3 bar
Ibaiondo SMFYour circuit is solar thermalWithstands peaks of 130 °C for one hour8 or 10 bar, depending on the model2.5 bar
Ibaiondo AMRYou need a pressure tank for a booster pump setReplaceable and suitable for drinking water8 or 10 bar, depending on the model1.5 bar

Frequently asked questions

Which Ibaiondo CMF model do I need?

It depends on the water volume, temperatures and pressures of your circuit. Ibaiondo publishes a volume calculator for heating (in Spanish) and asks for the calculation to be checked by authorised personnel.

What is the delivery time?

It is in stock at our warehouse. If no units are left when you order, we order it urgently and tell you the updated delivery time.

Can the Ibaiondo CMF be used for domestic hot water?

No. Its membrane is not suitable for drinking water. For domestic hot water, Ibaiondo makes the CMR expansion vessel.

Can the membrane be replaced?

No. The membrane of the Ibaiondo CMF is fixed. If it is damaged, the whole vessel is replaced.

What air pressure does it arrive with?

1.5 bar. That is the factory pre-charge; check Ibaiondo's manual before changing it.

Can I install it myself?

That is not what the manufacturer indicates. Ibaiondo asks for it to be installed by professional installers or authorised technical personnel.

Q-Tech installation and support

A well-chosen expansion vessel only does its job if it is properly connected and its air pressure is set for your circuit. Q-Tech delivers it inside a pre-assembled plant room: assembled, wired and tested in our workshop, arriving at your site ready to connect. You book it with the Expert Technician workshop pre-assembly service.

If your system already exists, an on-site hourly Expert Technician connects the Ibaiondo CMF and checks its pressure. For selection questions you have the remote technical call. See the whole range in Ibaiondo expansion vessels or write to us on WhatsApp or through contact.

Documentation

Availability and lead times: this item is in stock at our warehouse. Occasionally, depending on the time of year, the stock update may contain an error. If no units are available when you place your order, we will order it urgently and inform you immediately of the updated delivery time.

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