💡 Hot water cylinders work hardest alongside a heat pump — the cylinder stores the heat pump's output for domestic hot water, cutting fossil fuel use to near zero. SEAI grants of up to €1,600 available for hot water cylinders. Apply at seai.ie →
Heats from the top down — always have hot water even with partial charge
Mixergy's patented top-down heating technology addresses a fundamental problem with conventional cylinders: when a standard cylinder is 30% charged, you get only cold water — even though there are 63 litres of hot water at the top that can't reach the draw-off. Mixergy heats from the top down using an internal heat exchanger, meaning a 30%-charged 210L Mixergy cylinder gives you 63 litres of usable hot water. The Mixergy app monitors real-time charge level, integrates with time-of-use tariffs to heat at cheapest electricity periods, and pairs with heat pump schedules to optimise running costs. Full API and smart home integrations.
210L3m² HP coil10-yr warrantyStainless steelVentedSEAI: part of HP grant
⚙️ Specifications
Capacity
210 litres
Primary (HP) coil area
3 m²
Cylinder type
Vented (gravity-fed cold tank)
Inner material
Stainless steel (304)
Insulation thickness
75 mm
Standing heat loss
1.45 kWh/24h
Max primary temp
80°C
Immersion heaters
2 × 3 kW
Dimensions (H × Ø)
1520 × 545 mm
Weight (empty)
44 kg
Warranty
10 years
Made in Ireland
No
💰 Pricing & SEAI grant
Cylinder supply price
~€1,250
Plus installation labour ~€400–€700 · Total installed ~€1,800
💰 Covered by SEAI Heat Pump System Grant (3 Feb 2026)
The cylinder is included as part of your overall heat pump installation cost. The SEAI grant covers the total installed system cost — heat pump, cylinder, controls, pipework and labour — up to:
① Heat Pump Equipment Grant€6,500
② Central Heating Upgrade (inc. cylinder)€2,000
③ Renewable Heat Bonus (fossil fuel switch)€4,000
Maximum total grant€12,500
Apply at seai.ie — receive Letter of Offer before installation begins. BER assessment required (€200 SEAI grant). Homes built before 2007 need Technical Assessment (€200). Installer must be SEAI-registered.
Key highlights
🧠
Top-down heating — always usable hot water
Conventional cylinders heat from the bottom up. When the lower element switches off, the top might be hot but you can't reach it through the cold water below. Mixergy heats from the top — 30% charge means 30% of 210L = 63 litres of usable hot water at the tap
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Smart tariff integration
Connects to Irish time-of-use tariffs (Night Saver, Smart Export, Boost rates). Automatically heats at cheapest periods and avoids expensive peak hours — reducing the annual electricity cost of hot water by 20–35% compared to dumb cylinder operation
📱
Real-time charge monitoring
The Mixergy app shows the exact charge level as a percentage — the first cylinder to tell you not just the temperature but how much hot water you actually have available. Integrates with Home Assistant via official API for whole-home energy management
Installation note: Vented cylinders require a cold water storage tank (usually in the loft) feeding by gravity. If your home doesn't have a loft tank, discuss with your plumber whether a vented or unvented cylinder is more appropriate for your installation.
✅ What we like
Top-down heating — always have hot water even at 20–30% charge level
Smart tariff integration — heats at cheapest night rate or solar surplus automatically
Real-time charge level in the app — know exactly how much hot water you have
API integration with smart home systems (Home Assistant, IFTTT)
Stainless steel — hard water and coastal resistant
Reduces wasted energy — only heat what you need
⚠️ Worth knowing
Highest supply price of any cylinder in this directory (~€1,250)
10-year warranty — shorter than copper/stainless alternatives at 25 years
Requires Wi-Fi connectivity — dependent on internet for smart features
Smaller installer network in Ireland — fewer familiar with commissioning
Primary coil (3.0 m²) adequate but not the largest for heat pump use
🌡️ Compatible heat pump brands
The Smart Connected Cylinder 210L is compatible with all major air-to-water heat pump brands. See the Heat Pump Directory for full specifications, pricing and SEAI grant details on all 19 heat pumps available in Ireland.
❓ Questions about the Smart Connected Cylinder 210L
The Mixergy Smart Connected Cylinder 210L cylinder itself costs approximately ~€1,250. Installation (remove existing cylinder, connect to heat pump primary circuit, commission immersion backup) adds approximately €400–€700. Total installed cost: typically ~€1,800. This is usually included in the overall heat pump installation quote from your SEAI-registered installer — ask for the cylinder to be itemised on the quote so you can compare against other brands.
In most cases, no — your existing cylinder should be replaced as part of the heat pump installation. Standard cylinders have small primary coils (1.5–2.0 m²) designed for boiler temperatures of 70–80°C. Heat pumps deliver water at 45–55°C and need a much larger coil (typically 2.8–3.4 m²) to transfer adequate heat at the lower temperature. The Mixergy Smart Connected Cylinder 210L has a 3 m² primary coil — specifically sized for heat pump low-temperature operation. Using a standard cylinder with a heat pump results in slow reheat, inefficient operation, and higher running costs.
Yes — the cylinder cost is included within the SEAI Heat Pump System Grant (up to €12,500 for houses switching from fossil fuel heating, from 3 February 2026). The grant is applied to the total installed system cost including heat pump, cylinder, controls, pipework and labour — not as a separate per-component payment. Cylinders are not individually grant-funded as standalone items. A BER assessment is required before the grant can be drawn down, and all work must be carried out by a SEAI-registered contractor. The Mixergy Smart Connected Cylinder 210L's ~€1,250 cylinder cost contributes toward the Central Heating Upgrade element of the grant (up to €2,000).
A heat pump cylinder is typically set to 55–60°C to balance legionella risk with heat pump efficiency. Legionella bacteria cannot survive above 60°C. Most heat pump systems include a weekly legionella protection cycle where the immersion heater in the Mixergy Smart Connected Cylinder 210L raises the full cylinder to 60–70°C. Day-to-day, the heat pump heats the cylinder to the setpoint temperature (often 50–55°C) — a heat pump's COP drops significantly above 55°C. The Mixergy Smart Connected Cylinder 210L's max primary temperature of 80°C accommodates both routine heat pump operation and legionella protection cycles. Your installer will configure the legionella cycle as part of commissioning.
The Mixergy Smart Connected Cylinder 210L at 210L is suited to a typical 3–4 bedroom family home. A heat pump heats the cylinder slowly over 2–4 hours (compared to a boiler's rapid reheat) — so the system is usually programmed to heat the cylinder once or twice daily, storing enough hot water for the day's demand. General guideline: allow 40–50 litres per person per day. For a 4-person household with a heat pump: 160–200L minimum. Homes with high shower use or a bath should consider 200–250L.
For hard water areas (Dublin, Kildare, Meath, parts of Munster) and coastal locations within 10km of the sea, yes — stainless steel is worth the premium. Copper cylinders in high-hardness water areas frequently develop pinhole corrosion after 15–20 years. The Mixergy Smart Connected Cylinder 210L's stainless steel inner resists hard water pitting and coastal salt air corrosion. The cost premium over a comparable copper cylinder is typically €120–180 — which is easily offset by avoiding a cylinder replacement at €800–1,200 installed. For soft water areas (Connacht west coast, most of Donegal), copper is perfectly adequate and the saving is a reasonable decision.
The Mixergy Smart Connected Cylinder 210L reduces costs in two ways. First, its top-down heating technology means you only heat the hot water layer you need — a conventional cylinder heats from the bottom up, wasting energy on cold water before usable hot water reaches the top. Second, its smart tariff integration connects to Irish time-of-use electricity tariffs (Night Saver, Smart Export) and automatically schedules heating during the cheapest rate periods — typically avoiding peak hours (5pm–7pm at €0.42–0.50/kWh) and using night or solar-surplus rates (€0.09–0.18/kWh). Combined, these features can reduce annual hot water electricity cost by 20–35% compared to a standard cylinder on the same heat pump.
Heat transfer through a coil depends on temperature difference (ΔT), flow rate, and coil surface area. In a boiler system, ΔT is large (boiler at 75°C, cylinder at 55°C → ΔT = 20°C) — even a small coil transfers heat quickly. In a heat pump system, ΔT is small (HP at 50°C, cylinder at 45°C → ΔT = 5°C). With a small ΔT, you need a much larger coil surface area to transfer the same heat. The Mixergy Smart Connected Cylinder 210L's 3 m² primary coil compensates for the low temperature differential, allowing the heat pump to operate at lower, more efficient flow temperatures without sacrificing reheat time. Standard boiler cylinders typically have only 1.5–2.0 m² coils — using one with a heat pump results in slow reheat and the heat pump working harder and less efficiently.
A standard immersion heater sits at the bottom of a cylinder and heats the entire water volume from below — thermodynamically inefficient because you heat all the cold water before you get hot water at the top. Mixergy uses an internal coil that draws water from the top, heats it externally, and returns it to the top — maintaining a stratified hot layer at the top of the cylinder that grows downward as more heat is added. You can use hot water from the top at any charge level. The system also precisely measures the temperature gradient through the cylinder, calculating exact usable volume at any moment — this is what the percentage display in the app represents.
Yes — the Mixergy has a 3.0 m² primary heat exchanger coil that connects to any air-to-water heat pump. The heat pump heats the cylinder via the coil in the conventional way; the Mixergy's smart layer management then ensures you always have access to the hot layer at the top. The smart controls can also be programmed to align with the heat pump's heating schedule — heating the cylinder during the heat pump's most efficient operating window (e.g. mild afternoon temperatures) and using the top-down stratification to avoid unnecessary reheat cycles. The combination of heat pump efficiency + Mixergy stratification management delivers meaningful running cost reductions.
Get it installed
Find SEAI-registered heat pump installers for the Mixergy Smart Connected Cylinder 210L
Your installer will supply and install both the heat pump and the Mixergy cylinder as a complete SEAI-eligible system. Tell us what combination you need — we match you with up to 3 SEAI-registered installers in your area. Free and no obligation.
💧 Get heat pump + cylinder quotes
Up to 3 SEAI-registered installers in your area will contact you within 1 business day with system recommendations and pricing — including the Mixergy Smart Connected Cylinder 210L cylinder.
💶 Get quotes
3 local installers · 1 business day
💬 Get advice first
Free assessment · no obligation
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✅
Request sent!
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De Energy Hub
More power to youTM.
🏨 Built for hotels, guesthouses & hospitality
Turn your car park into a guest amenity — fully managed
Add EV charging as a guest service without the headache. Set your energy rate — Pure Energy from your solar or heat pump, Smart Energy balancing grid and renewables, or Boost Energy for maximum speed. Issue complimentary promo codes for guests on arrival. Eliminate first-come-first-served with advance booking — just like your meeting room.
☀️ Pure Energy🔄 Smart Energy🚀 Boost Energy
🎟️
Complimentary guest codes
Issue promo codes at reception — guests manage their own charging from check-in to check-out
📅
Book in advance
Guests reserve a charger before they arrive — no queuing, no reception involvement
⚡
Pure Energy badge
Guests see your charger runs on 100% renewable energy — a selling point for eco-conscious EV drivers
The Mixergy Smart Connected Cylinder 210L is designed to work with the following heat pumps, solar diverters and smart energy products from our Irish directories.
Solar diverters — use surplus solar for free hot water
This cylinder has an immersion heater — which means it can receive free hot water from surplus solar. A solar diverter intercepts solar surplus before it exports to the grid and redirects it straight to your immersion, typically providing 60–80% of annual hot water from the sun. Payback is usually under 18 months.
A 4kWp solar system generates approximately 3,600 kWh/year in Ireland. With a solar diverter redirecting surplus to this cylinder's immersion heater, you can cover 60–80% of annual hot water energy for free — on top of the heat pump doing the heavy lifting.
EV charger + home battery — run everything on solar
Your heat pump and this cylinder provide low-carbon heating and hot water. Add solar panels, a home battery and an EV charger and you can power your car, your heating and your hot water from the same roof — the combined SEAI grants available reach up to €14,600.
A hot water cylinder upgrade is often the first step in a wider home energy transformation. With a solar diverter filling your cylinder for free during the day, the next natural step is an EV — charged overnight on cheap night-rate electricity or from surplus solar. See all 205+ EVs in the EV Vehicle Directory.
💧 Solar hot water + EV: your whole home running on free energy
☀️ Solar diverter
Free hot water
surplus solar → cylinder
🚗 Smart EV charger
Free driving
surplus solar → your EV
💶 Combined saving
~€3,000/yr
hot water + fuel combined
A myenergi Eddi fills your cylinder with free solar. A myenergi Zappi in Eco+ mode fills your EV with whatever solar is left — both share generation data via the Hub so they never compete. View myenergi Eddi →
