Answer first
Ask for the cylinder as a separate line within the whole-system quote: make and model, usable volume, heat-pump coil, standing loss, immersion arrangement, controls, installation, pipe insulation and disposal of the old vessel.
Home Energy Scotland includes a required replacement hot-water cylinder among eligible heat-pump costs under the current grant-and-loan terms. That does not mean every cylinder must be replaced or that every optional upgrade is funded.
The cylinder supply and installation should be visible in the quote
View sourceHot-water design is coordinated with heat-pump capacity and controls
View sourceA required replacement cylinder is listed in current Scottish funding terms
View sourceHave FLO price the right cylinder within the complete system
Share the property, postcode, current heating and the cost question you want answered. FLO will explain what can be estimated now and what needs a survey before a figure is reliable.
The vessel price is only one part
A cylinder installation can require new primary pipework, motorised valves, sensors, immersion wiring, tundish and discharge route, condensate work, controls integration and changes to cupboards or access.
Removing an old cylinder or converting from a combi boiler adds labour. A difficult loft, narrow stair or confined cupboard may change the specification and installation method.
Size for people and recovery
The correct volume depends on occupants, baths, showers, peak use and the temperature at which water is stored and mixed. Oversizing increases space and standing losses; undersizing creates avoidable shortages.
A heat-pump-compatible coil needs enough heat-transfer area at lower primary temperatures. The designer should check recovery alongside space-heating demand, not simply match the old cylinder volume.
Check whether the existing cylinder can stay
Some modern cylinders may be usable if their coil, insulation, controls, pressure arrangement and condition suit the proposed system. Others will recover too slowly or cannot accept the required sensors and controls.
A label photograph and model data help at enquiry stage, but the survey should inspect connections, access, discharge and available space. Retaining equipment should be an evidenced design choice, not an assumption.
Compare like-for-like cylinder quotes
Record capacity, heat-loss rating, warranty, coil specification, included valves, immersion, controls and all labour. Confirm whether cupboard alterations and old-vessel disposal are included.
The cylinder should appear on the schematic and commissioning documents. The handover must explain hot-water schedules, boost use and any hygiene cycle so the household does not undo the efficiency work.
What to read next
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Questions people also ask
Can I keep my existing hot-water cylinder?+
Sometimes. Its coil, insulation, capacity, controls, condition and pressure arrangement must suit the proposed heat pump.
Does a cylinder need an immersion heater?+
Many designs include one for backup or hygiene functions; its intended control and normal use should be explained.
Is a bigger cylinder always better?+
No. Size should reflect demand, recovery and available space while limiting unnecessary standing loss.
Evidence used for this answer
Figures are explained in context and links go to the independent source. Prices, tariffs, scheme rules and standards can change, so check the source again before making a financial or technical decision.
- MCS heat-pump design standardTechnical requirements for heat loss, equipment selection, domestic hot water and system design.
- MCS domestic heat-pump guideConsumer guidance covering design, installation, controls, handover and maintenance.
- Home Energy Scotland Grant and Loan: terms and eligible costsCurrent Scottish grant and loan limits, eligible heat-pump costs, application conditions and rural uplift rules.
- Energy Systems Catapult: home surveys and installation reportEvidence from 742 installations, including radiators, cylinders, survey constraints and typical installation duration.