Mixergy Smart Hot Water Cylinder Installation in Cornwall

Conventional hot water cylinders heat from the bottom up: a thermostat at the bottom of the tank measures temperature, and the heating element (immersion or coil) heats the entire tank to the setpoint. The result is that you wait for the whole 200L tank to reach 60°C before you can draw hot water at temperature. Mixergy turns this on its head: their patented top-down heating element heats only the top portion of the tank first — typically the top 30L within 10–15 minutes — meaning you can start drawing hot water far sooner.

The cylinder then progressively heats more of the tank as needed. Combined with Mixergy's machine-learning usage prediction (which learns when you typically take showers and runs the bath), the system heats only the water you'll actually use, when you'll need it. The reduction in standing losses (cylinder heat loss to the surrounding cupboard) is significant: typically 20–30% less than a conventional cylinder of equivalent size. For Cornish customers paying for hot water via electricity (heat pump or direct immersion), this saves £80–£150/year.

The biggest single improvement Mixergy makes is to heat pump system performance. Conventional heat pump installations use a coil-equipped indirect cylinder where the heat pump heats the entire 200L+ cylinder volume to 50–55°C, then waits an hour for the next heating cycle. The heat pump runs at high flow temperature (around 55°C) to achieve cylinder temperature, sacrificing efficiency.

With a Mixergy paired to a heat pump, the cylinder uses the same coil but the smart controls heat only the volume of water predicted to be needed. The heat pump runs at lower flow temperatures more often, and the cylinder achieves usable hot water temperature with smaller heat inputs. Real-world Cornish data from CCS-monitored installations shows SCOP improvements of 0.3–0.5 versus conventional cylinders — meaningful both for running costs and for the heat pump's overall efficiency claim during the BUS grant submission process.

Mixergy is built for solar PV diversion. The cylinder includes a built-in CT clamp interface that connects to your meter tails — when surplus solar generation is detected, Mixergy diverts that energy to the immersion heater, storing it as hot water. This is essentially the same function as a myenergi Eddi diverter, but built directly into the cylinder.

For households on smart electricity tariffs (Octopus Cosy, Flux or Agile), Mixergy schedules immersion heating during the cheapest tariff windows — typically overnight on Cosy, or whichever 30-minute Agile window is cheapest. The system trades off cheap electricity prices against predicted hot water demand to minimise total cost. This typically delivers £100–£200/year of additional savings for tariff-aware Cornish households on top of the standard efficiency benefits.

The Mixergy app gives full control: target temperature, holiday mode, scheduled heating, solar/tariff prioritisation, and live state-of-charge (Mixergy displays cylinder content as a percentage of usable hot water, like a fuel gauge). For households with variable patterns — holiday lets, second homes, B&Bs (common across Cornwall) — the app's remote control means you can heat the cylinder on the day guests arrive without leaving it on for weeks.

Remote diagnostics also benefit installers: CCS can log into your Mixergy remotely (with permission) to diagnose issues without a site visit. Most service issues are resolved over the phone or via firmware updates pushed remotely.

Mixergy installation requires G3 unvented hot water qualification (CCS engineers carry this) and follows the same general process as any premium unvented cylinder: tundish discharge to safe location, pressure-reducing valve on incoming mains, expansion vessel sized to cylinder capacity, and Building Regulations Part G3 notification. Most installations take 1 day for a direct-feed Mixergy or 1–2 days for an indirect heat-pump-compatible Mixergy.

For older Cornish properties with low mains water pressure (common in rural areas, particularly West Cornwall), we may need to install a small whole-house pressure pump alongside the Mixergy to ensure adequate flow rates. CCS quotes this at survey if needed. See our heat pump installation page for more on integrated heat pump + Mixergy specifications.

Typical fully installed pricing (May 2026):

• Mixergy 150L Direct (electric, no heat pump) — from £1,650
• Mixergy 210L Indirect (heat pump compatible) — from £2,250
• Mixergy 300L Indirect (high demand) — from £2,650
• Upgrade premium when paired with new heat pump install — typically £400–£600 over standard cylinder

All prices include 0% VAT (when installed alongside qualifying renewable technology — heat pump or solar PV), G3 commissioning, expansion vessel and discharge plumbing, app setup, and Building Regulations Part G3 notification. Standalone Mixergy installations not paired with renewables are subject to standard 20% VAT. See finance options.