The Mixergy X Indirect Slimline is a stainless steel unvented cylinder heated via an internal primary coil from a gas, oil or LPG boiler, built into a narrower 475mm case for restricted cylinder cupboards and loft hatches. It shares the same 2.0 Controller and WiFi connectivity as the standard-case Indirect model.
Spanning 120 to 210 litres across four SKUs, the slimline case uses the same stratified thermocline smart charging to deliver minimum reheat times of just 11 minutes from the boiler coil, despite the reduced diameter.
Please Note: Current Lead Times
Mixergy cylinders typically ship on a 3 to 6 week lead time, depending on model and quantity ordered. Please call us to check current availability before confirming an installation date.
Important: Unvented Installation Requirement
This is an unvented cylinder. Installation must be carried out by a G3-competent operative and commissioned per the manufacturer's Installation & Servicing instructions. Incoming mains pressure must be less than 10 bar and at least 1 bar, with a minimum flow rate of 10 L/min. Unvented cylinders must never be used with a solid fuel heat source.
Slimline 475mm Case
Purpose-built for restricted cylinder cupboards or loft hatches, trading additional height for a narrower footprint versus the 550mm standard case.
Boiler-Fed with Immersion Backup
Heated primarily via the internal coil from a gas, oil or LPG boiler, with the 3kW immersion heater available as backup or for smart-tariff top-ups.
Stratified Smart Charging
Thermocline sensors mean the controller only heats the volume of water required from the boiler coil, giving minimum reheat times as fast as 11 minutes.
Full App Control & Monitoring
The bundled WiFi dongle connects to the Mixergy app for remote boost, live charge-state monitoring, and voice control via Google Assistant or Amazon Alexa.
Coil Output for Every Size
Coil ratings from 17.8kW to 19.9kW across the range support fast boiler-fed reheats even at the taller 210L capacity.
Safety-Certified Components
Factory-fitted monobloc cold water inlet control group, T&P relief valve (7 bar/90°C), and expansion vessel charged to 3 bar.
Controller & Electrical
| Controller generation |
2.0 Controller |
| Immersion heater rating |
3kW, 230–240V~ |
| Immersion heater specification |
EN 60335-2-73, 356mm Incoloy |
| Electrical supply |
16A, dedicated MCB-protected circuit |
| Thermostat safety cut-out |
80°C |
| Adjustable temperature range (digital) |
50–65°C |
| Connectivity |
WiFi dongle (supplied) or hardwired Ethernet |
Unvented Safety Components
| Max. supply pressure to PRV |
10 bar |
| Operating pressure |
3 bar |
| Expansion vessel charge pressure |
3 bar |
| Expansion relief valve setting |
6 bar |
| T&P relief valve setting (pressure) |
7 bar |
| T&P relief valve setting (temperature) |
90°C |
| Coil max. working pressure |
3.5 bar |
Construction
| Cylinder material |
Stainless steel |
| Insulation type |
CFC/HCFC-free polyurethane foam |
| Insulation thickness |
50mm |
| Connection size/type |
22mm compression |
| Coil max. working pressure |
3.5 bar |
| Diverter valve (>70°C boilers) |
Honeywell V4043H1056 2-port, or equivalent |
Model Range
| Model Code |
Capacity |
ErP |
Height |
Coil Rating |
Weight Full |
Min Reheat |
| MX-120-IND-475 |
120L |
B |
1247mm |
17.8kW |
146.6kg |
11 mins |
| MX-150-IND-475 |
150L |
C |
1518mm |
18.3kW |
180.4kg |
11 mins |
| MX-180-IND-475 |
180L |
C |
1790mm |
19.4kW |
214.8kg |
11 mins |
| MX-210-IND-475 |
210L |
C |
1962mm |
19.9kW |
247kg |
11 mins |
Please Note: Indirect Installations Over 70°C
Where the boiler or primary heat source is capable of exceeding 70°C, the supplied 2-port diverter valve (Honeywell V4043H1056 or equivalent) must be fitted, per the manufacturer's Installation & Servicing instructions.
What is the difference between the slimline and standard case?
Both share the same controller, coil configuration principle, insulation and connections. The slimline case is 475mm diameter but taller at equivalent capacity; the standard case is 550mm diameter.
Does the Mixergy X Indirect need an internet connection to work?
No — the cylinder heats and operates normally without WiFi. An internet connection unlocks app features such as remote control, smart tariff scheduling, and usage monitoring for the immersion backup.
Can the Mixergy X Indirect Slimline be used with a heat pump instead of a boiler?
Yes. The controller supports a heat pump heat source setting in place of a boiler, and cylinders have dedicated heat pump-ready ports.
What certification does the installer need?
Installation must be carried out by a competent operative who has completed a recognised unvented hot water systems course, with commissioning recorded per Building Regulations (G3) requirements.
What is included in the box?
Each cylinder ships with the monobloc cold water inlet control group, expansion vessel with mounting bracket, factory-fitted immersion heater(s), WiFi dongle, Ethernet cable, gauge, and user guide.
How long is the lead time and how do I check stock?
Lead times typically run 3 to 6 weeks depending on model and order quantity. Please call us to confirm current stock and expected delivery before booking an installation.
