Mon–Sun, 8:30am–5:30pminfo@harrisonejonesheating.co.uk 07523 7382850151 384 5908 HomeAboutServices Areas ReviewsContact Us07523 738285Get a Free Quote New Boilers Fully Fitted from £1,299 with Immediate Installation and a FREE Gas Safety Certificate HomeBoiler SupplierSystem Boiler InstallationBoilers # System Boiler Installation in Liverpool: Stored Hot Water for Bigger Homes For homes with more than one bathroom in regular use, a system boiler and unvented cylinder keep mains-pressure hot water flowing to every outlet at once, sized properly to how your household actually lives. Get a Free Quote07523 738285 Gas Safe registered no. 576059 · fixed written price before any work starts Gas Safe registered Registration no. 576059 · licence no. 3715984 Fixed written prices Agreed before work starts, no hourly rates Boilers from £1,299 Fully fitted, immediate installation available FREE Gas Safety Certificate With every new boiler installation Open 7 days Mon–Sun, 8:30am–5:30pm Overview ## What This Service Is, and Who It Is For ### What it is A system boiler heats the central heating circuit directly and separately stores hot water in an unvented cylinder, fed from the mains at mains pressure rather than gravity. Unlike a combi, hot water is drawn from the cylinder's stored capacity rather than generated instantly, which means two or more outlets can run at full pressure simultaneously without the flow dropping at either one, provided the cylinder is sized correctly for the household. ### Who it is for Larger households, particularly homes with two or more bathrooms used at similar times of day, families with teenagers on similar morning routines, and homes on a mains water supply with flow rate too limited to satisfy a combi's instantaneous demand. Also a common choice where a homeowner values having a genuine reserve of hot water rather than relying on the boiler keeping pace in real time. ### When you need it System boiler installation suits new-build extensions with an additional bathroom being added, renovations where an airing cupboard or utility space can accommodate a cylinder, and replacements of ageing gravity-fed systems where converting to unvented mains-pressure storage is a clear upgrade in performance. ### Why it needs a registered engineer The physics is straightforward: a combi has to heat water fast enough to keep pace with demand in real time, which caps how much it can deliver to more than one outlet at once. A system boiler with a properly sized cylinder has already done the heating in advance and simply delivers stored water at mains pressure, so two showers and a bath tap can run together without a noticeable drop, which a combi cannot replicate regardless of its rated output. Related services - New Boiler - Combi Boiler Installation - Central Heating Installation - Boiler Installation - Heating System Upgrades Areas we cover - Liverpool - Knowsley - Prescot - Halton - St HelensTowns we cover West Derby, Belle Vale & Netherley, Clock Face & Sutton Manor, Tarbock Green, Hough Green, Huyton, Kirkby, Halewood, Whiston, Rainhill, Eccleston Park, Newton-le-Willows, Widnes, Runcorn, Woolton, Allerton, Childwall, Wavertree, Garston, Speke, Crosby, Bootle, Aintree, Maghull, Birkenhead Speak to an engineer Mon–Sun, 8:30am–5:30pm 07523 738285Get a Free Quote The cost of leaving it ## What Happens If This Gets Left The most common regret with hot water systems in larger households is discovering the hard way, mid-shower, that the boiler installed was never designed for how many people actually use the house at once. ### Risks and escalating costs - Fitting a combi into a household that regularly needs two or three hot outlets running together leads to constant frustration that no amount of servicing or adjustment will fix, because it is a design mismatch rather than a fault. - An undersized unvented cylinder runs out of stored hot water at exactly the times demand peaks, typically weekday mornings, which defeats much of the point of choosing a system boiler in the first place. - Skipping proper commissioning and safety testing on an unvented cylinder is a genuine safety issue, since these cylinders are pressurised and rely on correctly functioning expansion vessels and safety valves. - Poor zoning and control design on a larger system means you end up heating the whole house to run a shower in one bathroom, which costs more than it needs to across a heating season. - Choosing a cylinder based on tank size alone, without checking recovery rate and the boiler's ability to reheat it promptly, leaves you with plenty of stored water but a slow refill once it is used. ### Mistakes we are called out to fix - Sizing the cylinder purely by counting bedrooms rather than by realistic simultaneous demand and the times of day it actually occurs. - Choosing an unvented cylinder installer who is not qualified specifically for unvented hot water systems, which is a distinct competency from general boiler installation. - Placing the cylinder somewhere with poor access for future servicing of the expansion vessel, pressure relief valve and other safety components. - Ignoring pipe sizing between the cylinder and the outlets, which can bottleneck flow even when the cylinder itself is generously sized. - Not zoning the heating circuit separately from the hot water demand, which limits control flexibility in a larger property with different rooms in use at different times. Our process ## How We Carry Out the Work, Step by Step - 1 ### Step 1: Household demand assessment We look at bathroom count, typical routines and peak simultaneous demand, not just bedroom count, to establish the cylinder capacity and boiler output the household genuinely needs. - 2 ### Step 2: Cylinder sizing and location We size the unvented cylinder against realistic peak demand and recovery time, and agree a location with proper access for future servicing of its safety components. - 3 ### Step 3: Written specification and fixed price Boiler make and output, cylinder size and brand, pipework and zoning plan, controls, and the total price, all agreed in writing before work starts. - 4 ### Step 4: Installation and unvented commissioning The system boiler and cylinder are fitted, pipework is sized and installed to carry the design flow rate, and the unvented cylinder is commissioned to building regulations, including testing the expansion vessel and safety valves. - 5 ### Step 5: Zoning, controls and handover Heating and hot water are set up as independent zones with appropriate thermostats, we test flow at every outlet under simultaneous demand, and hand over the Benchmark record and a free Gas Safety Certificate. What you get ## The Difference It Makes ### Multiple outlets, full pressure, at once Stored hot water at mains pressure means two showers and a bath tap can genuinely run together without a noticeable drop, unlike a combi under the same demand. ### Cylinder sized to your household, not guessed Capacity and recovery rate are based on realistic peak demand for your family's routine, so the tank keeps up with mornings rather than running dry. ### Independent heating and hot water zoning Proper zoning lets you heat rooms and run hot water on separate schedules, useful in larger homes with rooms in different use through the day. ### Unvented systems commissioned to regulations Expansion vessel, pressure relief and safety components tested and commissioned correctly, which matters because these cylinders operate under pressure. ### One fixed written price Boiler, cylinder, pipework, zoning and controls are all itemised and priced before work starts, whatever the scope of the job. ### Free Gas Safety Certificate included Every new system boiler installation comes with a free Gas Safety Certificate as part of the handover. In detail ## System Boilers and Unvented Cylinders in Detail System boilers earn their keep in exactly the household situation a combi struggles with: multiple bathrooms in genuine simultaneous use. Where a combi has to generate hot water fast enough in real time to satisfy every open tap at once, a system boiler has already done the heavy lifting in advance, storing hot water in an unvented cylinder ready to be drawn off at mains pressure the moment it is needed. The practical result in a larger Merseyside family home, a four or five bedroom semi or detached property with an en-suite and a family bathroom both in use on a school morning, is that showers stay strong regardless of what else is running. Cylinder sizing is the part most likely to be got wrong by anyone pricing on assumptions rather than measurement. A cylinder is specified by its litre capacity and, just as importantly, by its recovery time, how quickly the boiler can reheat it once drawn down. A generously sized cylinder paired with a boiler that cannot reheat it promptly still leaves a household waiting for hot water to return after a busy morning. We size both together against your household's actual routine, not a rule of thumb based on bedroom count alone. Unvented cylinders operate at mains pressure and are sealed rather than vented to a header tank, which is what gives the strong, even flow at every outlet, but it also means they rely on correctly functioning safety components: an expansion vessel to absorb the pressure change as water heats, a temperature and pressure relief valve, and an expansion relief valve, all of which need to be commissioned correctly and are subject to building regulations requirements. This is a distinct qualification from general boiler installation, and it is worth confirming any installer working on an unvented system is specifically competent to do so. Zoning is where a system boiler installation in a larger property really pays off day to day. Splitting the heating circuit into zones, upstairs and downstairs, or by wing of the house, and controlling hot water independently of space heating, means you are not warming rooms nobody is using just to get a hot shower, and you are not waiting for the whole system to fire up for one radiator. In a five-bedroom house this control granularity makes a genuinely noticeable difference to running costs across a heating season. ### Residential and commercial properties System boiler and unvented cylinder installations are most common in larger detached and semi-detached homes across Liverpool, Knowsley, Halton and St Helens, though they also suit smaller properties with a genuinely limited mains flow rate that would otherwise struggle with a combi. We will confirm which approach suits your specific property and household during the survey. ### Variations of this service - New system boiler with unvented cylinder For larger homes upgrading from a combi or from an old gravity-fed system, sized against real household demand for strong simultaneous hot water flow. - Cylinder replacement on an existing system boiler Where the boiler is sound but the cylinder is old, corroded or undersized for current household demand, replaced with a correctly sized unvented cylinder. - Gravity-fed to unvented conversion Replacing an old vented cylinder and its header tank with a modern unvented cylinder for stronger flow at every outlet and reclaimed loft space. - Multi-zone controls upgrade Adding or improving heating and hot water zoning on an existing system boiler installation to give better control in a larger property. ### Materials, parts and equipment - Vaillant, Worcester Bosch, Baxi, Heatline and Main system boilers - Unvented hot water cylinders sized to household demand - Expansion vessels, pressure and temperature relief valves commissioned to building regulations - Copper and press-fit pipework sized for simultaneous outlet demand - Zone valves and multi-zone thermostat controls - Magnetic system filter and central heating inhibitor Questions ## System Boiler Installation: Frequently Asked Questions How much does a system boiler installation cost in Liverpool?It depends on boiler output, cylinder size and whether pipework and zoning need upgrading alongside it. We price each property individually and confirm the full itemised cost in writing before any work starts. How is a system boiler different from a combi?A system boiler heats the central heating circuit and stores hot water separately in an unvented cylinder at mains pressure, so multiple outlets can run at once without the flow dropping. A combi heats water instantly on demand with no storage, which limits how many outlets it can serve simultaneously. What size cylinder do I need?It depends on your household's realistic peak demand, not just the number of bedrooms. We assess your routine, the number of bathrooms used at similar times, and the boiler's recovery rate before recommending a cylinder size. Are unvented cylinders safe?Yes, when installed and commissioned correctly to building regulations, including a working expansion vessel and pressure and temperature relief valves. This is why unvented cylinder work needs to be carried out by someone specifically qualified for it, which we are. Where does the cylinder go?Typically an airing cupboard, utility room or loft space with good access, which we agree with you during the survey. We also consider access for future servicing of the cylinder's safety components when choosing the location. Can I run two showers at once with a system boiler?Yes, provided the cylinder and pipework are sized for that level of simultaneous demand, which is exactly what we design for in larger households with more than one bathroom in regular use. How long does a system boiler installation take?A straightforward installation with an existing suitable cylinder location is often completed within a couple of days. Conversions from an old gravity-fed system or new pipework runs take longer, and we confirm the expected timescale in the written quote. Do you install system boilers across all of Merseyside?Yes, across Liverpool, Knowsley, Halton and St Helens, including Huyton, Prescot, Widnes, Runcorn, Crosby, Woolton and Newton-le-Willows. We answer the phone seven days a week, 8:30am to 5:30pm, and we tell you the same day whether we can get to you. Still not sure? Send us the details or ring 07523 738285. Your next step ## Get Your Fixed Price in Writing Send us the details and we'll come back with a clear price, or ring now if you're without heating or hot water. - Gas Safe registered no. 576059 · licence no. 3715984 - 25 Bardley Cres, Tarbock Green, Liverpool L35 1RJ - 07523 738285 · 0151 384 5908 - info@harrisonejonesheating.co.uk - Mon–Sun, 8:30am–5:30pmCall 07523 738285 ### Request your free fixed price Takes under a minute. No pushy sales visit, no obligation. Or call us direct on 07523 738285 · 0151 384 5908 Gas Safe registered heating and boiler engineers serving Liverpool, Knowsley, Halton, St Helens and the wider Merseyside area. 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