💡 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 →
Heatrae Sadia Megaflo Eco Solar Plus 210L — Ireland 2026
Mains-pressure hot water — dual coil for heat pump + solar thermal
The Megaflo Eco Solar Plus is the premium unvented heat pump cylinder — delivering mains-pressure hot water to every tap and shower in the home with no need for a cold water tank in the loft. Its dual-coil design accommodates both a heat pump primary coil and a solar thermal secondary coil — making it the correct specification for homes installing air-to-water heat pump alongside solar thermal collectors. The stainless steel inner has the same 25-year warranty as the Megaflo copper range. G3-certified installation is required by law for all unvented cylinders in Ireland.
210L2.8m² HP coil25-yr warrantyStainless steelUnvented☀️ Solar thermal coil included⚠️ G3 certified install requiredSEAI: part of HP grant
⚙️ Specifications
Capacity
210 litres
Primary (HP) coil area
2.8 m²
Secondary (solar) coil area
1.8 m²
Cylinder type
Unvented (mains pressure — G3 required)
Inner material
Stainless steel (304)
Insulation thickness
55 mm
Standing heat loss
1.64 kWh/24h
Max primary temp
85°C
Immersion heaters
2 × 3 kW
Dimensions (H × Ø)
1700 × 545 mm
Weight (empty)
58 kg
Warranty
25 years
Made in Ireland
No
💰 Pricing & SEAI grant
Cylinder supply price
~€1,100
Plus installation labour ~€400–€700 · Total installed ~€1,650
💰 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
🚿
Mains pressure — no pump needed
In a vented system, shower pressure depends on the height of the cold water tank above the shower head — often poor in bungalows and flat-roof properties. An unvented cylinder connects directly to the mains and delivers full mains pressure to every tap and shower — the same experience as a combi boiler but with a heat pump
☀️
Dual coil — heat pump + solar thermal
The lower coil connects solar thermal collectors; the upper coil connects the heat pump. Solar thermal heats the lower half of the cylinder; the heat pump tops up to the setpoint. Both renewable sources contributing free hot water in one cylinder
🛁
No loft tank — clean new build install
Without a cold water storage tank in the loft, new builds have simpler plumbing, no loft freeze risk in winter, and typically lower insurance risk. An unvented cylinder is now the default specification in A-rated Irish new builds
🏠 Suitable for
New buildPremium retrofitMains pressure hot waterSolar thermal + heat pumpG3-certified installation
⚠️ G3 Certified Installation Required: Unvented cylinders must be installed by a plumber with G3 unvented hot water certification. Installation also requires pressure reducing valve, expansion vessel, temperature and pressure relief valve, and correctly specified tundish discharge pipe. Always ask your plumber for evidence of G3 certification before agreeing to an unvented installation. Do not ask a standard plumber without G3 qualification to install an unvented cylinder.
✅ What we like
Mains pressure hot water — no gravity tank, full pressure at all taps and showers
Dual coil — connects both heat pump primary and solar thermal secondary in one unit
Stainless steel inner — 25-year warranty, hard water resistant
No loft cold water tank required — cleaner installation in new builds
Megaflo brand — the most recognised unvented brand with Irish installers
⚠️ Worth knowing
Requires G3-certified installation — a qualified plumber with unvented hot water certification
Requires pressure reducing valve, expansion vessel, and relief valves (included or installer-supplied)
Higher supply price (~€1,100 vs ~€650 for vented equivalent)
55mm insulation — thinner than vented alternatives, higher standing heat loss (1.64 kWh/24h)
If the heat pump coil (2.8 m²) is on the small side for lower-temperature HP operation
🌡️ Compatible heat pump brands
The Megaflo Eco Solar Plus 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.
The secondary coil on this cylinder is designed for solar thermal (flat plate or evacuated tube) collectors. The SEAI Solar Water Heating Grant (up to €1,200 for evacuated tube systems) may also apply to the solar thermal component. Always verify current eligibility at seai.ie.
❓ Questions about the Megaflo Eco Solar Plus 210L
The Heatrae Sadia Megaflo Eco Solar Plus 210L cylinder itself costs approximately ~€1,100. Installation (remove existing cylinder, connect to heat pump primary circuit, commission immersion backup) adds approximately €400–€700. Total installed cost: typically ~€1,650. 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 Heatrae Sadia Megaflo Eco Solar Plus 210L has a 2.8 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 Heatrae Sadia Megaflo Eco Solar Plus 210L's ~€1,100 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 Heatrae Sadia Megaflo Eco Solar Plus 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 Heatrae Sadia Megaflo Eco Solar Plus 210L's max primary temperature of 85°C accommodates both routine heat pump operation and legionella protection cycles. Your installer will configure the legionella cycle as part of commissioning.
The Heatrae Sadia Megaflo Eco Solar Plus 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 Heatrae Sadia Megaflo Eco Solar Plus 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.
No — the Heatrae Sadia Megaflo Eco Solar Plus 210L's upper primary coil can operate solely with a heat pump; the lower solar secondary coil (1.8 m²) is optional. You can install the cylinder now with just the heat pump and add solar thermal collectors later — the secondary coil is ready and waiting. When you do add solar thermal: the lower coil preheats the bottom of the cylinder using free solar energy; the heat pump tops up to your setpoint. On a good Irish solar day from April to September, solar thermal covers 60–70% of daily hot water — the heat pump handles the rest. The additional capital cost of solar thermal panels (€2,000–3,500 installed) needs to be weighed against savings for your household size.
G3 refers to Part G3 of the Irish/UK Building Regulations, which governs unvented (mains pressure) hot water systems. The Heatrae Sadia Megaflo Eco Solar Plus 210L is an unvented cylinder — it connects directly to the mains cold water supply and operates under mains pressure. G3 requires that the installing plumber holds a specific qualification in unvented hot water systems (available through CITB, City & Guilds or equivalent Irish plumbing bodies). Unvented cylinders contain large volumes of pressurised hot water — if the pressure relief valves or expansion vessel fail without correct installation, serious injury can result. Always ask for evidence of G3 qualification before agreeing to an unvented installation. Most RECI-registered plumbers in Ireland hold G3 qualifications.
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 Heatrae Sadia Megaflo Eco Solar Plus 210L's 2.8 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.
G3 refers to Document G3 of the UK/Irish Building Regulations, which governs the installation of unvented (mains pressure) hot water systems. Unvented cylinders operate under mains pressure and contain large volumes of scalding water — if pressure relief valves or expansion vessels fail, they can cause serious injury. The G3 requirement means the installing plumber must have a qualification specifically in unvented hot water systems (available through CITB, City & Guilds, or equivalent) and must comply with the manufacturer's installation requirements, including specific valve types and safety tundish configurations. In Ireland, most RECI-registered plumbers hold G3 qualifications. Always ask your plumber for evidence of their G3 certification before agreeing to an unvented installation.
In general, unvented (mains pressure) cylinders are preferred for new builds and major retrofits because they eliminate the cold water storage tank, deliver better shower pressure, and result in simpler overall plumbing. However, they have higher installation cost, require G3-certified installation, and need additional safety components (expansion vessel, PRV, tundish). For straightforward heat pump retrofits in homes with existing vented systems, replacing a vented cylinder with another vented cylinder is often the simpler and more cost-effective option — particularly when the existing cold water tank is in good condition. Discuss both options with your plumber as part of the heat pump system design.
Get it installed
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Your installer will supply and install both the heat pump and the Heatrae Sadia 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.
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De Energy Hub
More power to youTM.
💼 Built for employer-provided EV charging
Employee EV charging — bookable, tracked, BIK-compliant
Employers installing heat pumps and EV chargers can manage employee charging through De Energy Hub. Set energy rates from your renewable system — Pure Energy reduces costs and carbon reporting. Issue staff promo codes for free or subsidised charging. Automated check-in and check-out tracks every session for payroll or BIK reporting.
☀️ Pure Energy🔄 Smart Energy🚀 Boost Energy
📊
Per-session usage reporting
Full log of kWh delivered, duration and user — ready for payroll or benefits-in-kind accounting
🏷️
Staff promo codes
Issue codes for free or discounted employee charging — set usage limits and expiry dates
🔔
Overstay reminders
Automated notifications when session time is nearly up — free the charger for the next employee
The Heatrae Sadia Megaflo Eco Solar Plus 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 both a heat pump primary coil and a solar thermal secondary coil. If you have solar PV panels rather than solar thermal collectors, a solar diverter redirects surplus solar electricity directly to the immersion heater in this cylinder — giving you free hot water from your solar panels without any plumbing changes.
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 →
