Saunier Duval Thema MiConnect 31-CS/1-C boiler

Condensing boiler · New equipmentSaunier Duval Thema MiConnect 31-CS/1-C

New boilerSaunier Duval Condensing boilers

Saunier Duval Thema MiConnect 31-CS/1-C boiler

VAT includedIn stock

The Thema MiConnect 31-CS/1-C offers 3.4-25.0 kW of heating at 80/60 °C with natural gas and 31.0 kW nominal for domestic hot water. It retains the 344 mm deep body of the Thema 26, with wired MiSet and greater sanitary capacity: D30 of 14.8 l/min and indicated limiter of 10 l/min. With wired MiSet. Installation not included. VAT and mainland shipping included.

Heating power (80/60 °C, G20): 3.4-25.0 kW
Specific flow rate for domestic hot water (ΔT 30 K): 14.8 l/min
Dimensions (height x width x depth): 740 x 418 x 344 mm

Condensing boiler

The model, at a glance

Saunier Duval Thema MiConnect 31 with wired MiSet: 3.4-25.0 kW in heating G20, DHW D30 of 14.8 l/min and 344 mm deep.

Heating power (80/60 °C, G20): 3.4-25.0 kW
Specific flow rate for domestic hot water (ΔT 30 K): 14.8 l/min
Dimensions (height x width x depth): 740 x 418 x 344 mm

Read the full description and what it includes.

The Saunier Duval Thema MiConnect 31-CS/1-C combines 3.4-25.0 kW of heating at 80/60 °C with 31.0 kW nominal for domestic hot water using natural gas. At 50/30 °C, it delivers 3.9-27.3 kW of useful output. Compared to the Thema 26, it increases the power and the domestic hot water flow without enlarging the body, a useful difference for comparing heating demand, domestic hot water usage, and space separately.

The specific domestic hot water flow rate reaches 14.8 l/min at ΔT 30 K; the manual distinguishes this test from its limiter of 10 l/min. AquaFast Warm Start prepares the service and SmartShower maintains the DHW mode during brief pauses in a shower. None of these functions equate to a storage tank: simultaneous demand must be assessed with pressure, inlet temperature, mixers, and actual settings.

The reference 125125143 corresponds to MiSet wired, with MiGo Link as an option for connection via application. It is not the MiSet Radio set nor does it include other mounting accessories. Its primary heat exchanger is made of stainless steel. The unit is labeled A for heating and domestic hot water, with an XL profile and 47 dB of acoustic power; a different system label requires the specific combination that justifies it.

Its dimensions of 740 x 418 x 344 mm and a weight of 32.4 kg without water or packaging must be checked along with the clearances: 50 mm on the sides, 160 mm below, and 500 mm for front access. The gas variant also matters: at 80/60 °C, the minimum changes from 3.4 kW in G20 to 8.0 kW in G31. In electricity, the total maximum published is 105 W, different from 77 W in heating and 83 W in domestic hot water. The choice must consider all these conditions, not just the number 31.

What is included in the purchase?

With MiSet wired. Installation not included.

Price including VAT and shipping to mainland Spain. Installation, adaptations, and commissioning are valued separately.

Consult the manufacturer's PDFs ↓

Guide

What to check before installing this boiler

The choice of equipment does not replace the inspection of the installation by a qualified professional.

Confirm the model and commercial reference, the type of gas, and the supply configuration in the manufacturer's documentation.
Ask a qualified installer to assess the heating and domestic hot water demand; compare measured flow rates at the same temperature difference.
Check dimensions, connections, flue gas evacuation, condensate drainage, and controls compatible with the existing installation.
Confirm the included accessories and the delivery time before scheduling the installation. The online purchase of the equipment does not include installation or commissioning.

Technical data

Technical data of Saunier Duval Thema MiConnect 31-CS/1-C

Brand: Saunier Duval
Model: Saunier Duval Thema MiConnect 31-CS/1-C boiler
Status: New
Supply scope: With MiSet wired. Installation not included.
Shipping: Included in mainland Spain. Please confirm the deadline.
Commercial reference: 125125143

Specifications and dimensions of the model

Compare each magnitude under its testing conditions: heating, domestic hot water, efficiency, and dimensions.

Useful heating output (80/60 °C, G20): 3.4-25.0 kW
Heating
Useful heating output (50/30 °C, G20): 3.9-27.3 kW
Heating
Useful heating power with propane (80/60 °C, G31): 8.0-24.8 kW
Heating
Useful heating power with propane (50/30 °C, G31): 8.9-26.7 kW
Heating
Heating temperature adjustment: 15-80 °C
Heating
Maximum heating pressure: 3 bar
Heating
Heating expansion vessel: 8 l; it is not a domestic hot water storage.
Heating
Nominal power of domestic hot water (G20): 31.0 kW
Hot water
Specific flow rate DHW D (ΔT 30 K, EN 13203-1): 14.8 l/min
Hot water
Minimum flow rate of domestic hot water: 1.5 l/min
Hot water
Domestic hot water flow limiter: 10 l/min
Hot water
Permissible service pressure of domestic hot water: 0.3-10 bar
Hot water
Required connection pressure for domestic hot water: 0.7 bar
Hot water
Adjustment of domestic hot water temperature: 35-60 °C
Hot water
Preparation of domestic hot water: AquaFast Warm Start and SmartShower
Hot water
Primary heat exchanger: Stainless steel
Construction
Control of the offered reference: MiSet wiring
Regulation
Connection with application: Optional MiGo Link for this MiSet set
Regulation
Dimensions (height x width x depth): 740 x 418 x 344 mm
Dimensions and installation
Weight without packaging or water: 32.4 kg
Dimensions and installation
Minimum lateral distance: 50 mm per side
Dimensions and installation
Minimum lower distance: 160 mm
Dimensions and installation
Front access space: 500 mm
Dimensions and installation
Upper space with duct 60/100: 165 or 248 mm, according to the installation plan
Dimensions and installation
Heating energy class of the appliance: A
Efficiency and sound
Energy class of domestic hot water: A
Efficiency and sound
Sanitary profile: XL
Efficiency and sound
Acoustic power: 47 dB
Efficiency and sound
Seasonal ErP efficiency: 94 %
Efficiency and sound
Electrical supply: 230 V, 50 Hz
Electricity
Maximum electrical consumption in heating: 77 W
Electricity
Maximum electrical consumption in domestic hot water: 83 W
Electricity
Maximum power consumption: 105 W
Electricity
Standby power consumption: 2 W
Electricity
Degree of protection: IPX5D
Electricity

Manufacturer's sources

PDF and documentation of the model

Original documents, unmodified. Refer to the installation plan and the conditions of each data point before selecting the equipment.

The gallery sheets are summaries of Uniclima based on these documents. The external volume diagram does not represent connections, accessories, or service distances.

Frequently Asked Questions

Frequently asked questions: condensing boilers 125125143

Can the Thema MiConnect 31 heat a house of 180 m²?

As an example of calculation, 180 m² with a supposed loss of 80 W/m² require 14.4 kW. The model offers 3.4-25.0 kW at 80/60 °C with natural gas, so that hypothetical load falls within the range. This is not a certification for 180 m²: climate, height, insulation, and emitters can change the requirement. If an area only requires 3 kW, it falls below the minimum. The installer must verify the total load and the active zones; the 31 kW corresponds to domestic hot water, not to the maximum heating power under those conditions.

Does the Thema MiConnect 31 allow for two simultaneous showers of 8 l/min?

The combined demand would be 16 l/min. Its specific flow rate is 14.8 l/min at ΔT 30 K and the indicated domestic hot water limiter is 10 l/min: those two showers cannot be guaranteed. It is also not enough to simply add two low-consumption showers and compare only with the test flow rate, because the limiter, mixing, pressure, and temperature of the cold water are involved. Compared to the Thema 26, the sanitary capacity increases, but it does not include a storage reserve to cover peak consumption.

Does it have a storage tank or are the 8 liters a reserve for showers?

The 8 liters are from the heating expansion vessel, not from a domestic hot water tank. This Thema produces DHW on demand. AquaFast Warm Start reduces preparation time, and SmartShower maintains the sanitary mode during brief interruptions, without increasing the continuous flow or adding a water reserve. For a home with several frequent showers at the same time, it is advisable to compare a storage solution sized according to usable liters and recovery, not just the XL label.

Does it take up more space than the Thema MiConnect 26 and fit in the same cabinet?

The body retains the dimensions of 740 x 418 x 344 mm of the Thema 26, but weighs 32.4 kg without water or packaging compared to 29.6 kg. The installation requires 50 mm of clearance on each side, 160 mm below, and 500 mm of front access. With a 60/100 duct, the upper distance is 165 or 248 mm depending on the plan. Sharing external measurements does not guarantee that the flue, support, or connections can be reused without reviewing the installation.

What does reference 125125143 include and how does it differ from MiSet Radio?

The reference 125125143 identifies the version with wired MiSet. MiSet Radio corresponds to a different line: sharing 31-CS/1 does not validate the same regulation set. The connection with the mobile device requires the appropriate MiGo Link solution, which is optional for this offer with MiSet. A WiFi accessory, flue, or installation is not assumed to be included unless expressly stated in the supply. The unit has class A for heating and domestic hot water; a higher class system requires its specific combination of controls.

Why is the minimum power important when comparing natural gas and propane?

At 80/60 °C, this model starts at 3.4 kW with natural gas G20 and 8.0 kW with propane G31; the maximums are 25.0 and 24.8 kW respectively. In propane, an area that requires 5 kW would fall below the minimum and could experience more starts and stops. Therefore, the G20 range should not be transferred to a home using propane. The version and commissioning must be verified by a qualified professional. The maximum electrical consumption of 105 W does not represent the heating power.

Does the price include installation and shipping?

Includes VAT and shipping to mainland Spain. Installation and adaptations are valued separately. With MiSet wired. Installation not included.