{"product_id":"honeywell-home-stored-hot-water-kit-for-evohome-atf500dhw-cylinder-control-accessory","title":"Honeywell Home evohome Stored Hot Water Kit ATF500DHW — CS92A BDR91 Cylinder Thermostat Wireless Zone Valve Control Vented Unvented","description":"\u003cdiv style=\"font-size:16px;font-family:Arial,Helvetica,sans-serif;color:#1a1a1a;max-width:900px;margin:0 auto;line-height:1.6;\"\u003e\n\n  \u003c!-- ── INTRO ─────────────────────────────────────────────────────── --\u003e\n  \u003cp style=\"margin:0 0 18px;\"\u003e\n    The \u003cstrong\u003eHoneywell Home evohome Stored Hot Water Kit (ATF500DHW)\u003c\/strong\u003e is the dedicated accessory that adds \u003cstrong\u003efull stored hot water control to any evohome system\u003c\/strong\u003e — enabling the evohome controller to manage, schedule, monitor, and remotely override the hot water cylinder alongside the heating zones it already controls. Compatible with both \u003cstrong\u003evented and unvented indirect cylinders\u003c\/strong\u003e. The kit contains a \u003cstrong\u003eCS92A wireless battery-operated cylinder thermostat\u003c\/strong\u003e (with transceiver), a \u003cstrong\u003eBDR91 wireless relay box\u003c\/strong\u003e to switch a 2-port zone valve or 3-port diverter valve, a \u003cstrong\u003eT8674B strap-on sensor\u003c\/strong\u003e for vented cylinders, and a \u003cstrong\u003eF420079510 insertion sensor\u003c\/strong\u003e for unvented cylinders. Once bound, the \u003cstrong\u003eevohome controller displays the live hot water temperature\u003c\/strong\u003e on its main screen, allows schedule viewing and instant override, and hot water can be controlled remotely via the \u003cstrong\u003eTotal Connect Comfort app\u003c\/strong\u003e (iOS and Android). Battery life on the CS92A is typically \u003cstrong\u003eat least 2 years\u003c\/strong\u003e on 2× AA alkaline cells. This kit is an \u003cstrong\u003eadd-on accessory\u003c\/strong\u003e — an existing evohome controller is required.\n  \u003c\/p\u003e\n\n  \u003c!-- ── AMBER COMPATIBILITY CALLOUT ──────────────────────────────── --\u003e\n  \u003cdiv style=\"border-left:4px solid #e67e22;background:#fef9f0;padding:10px 16px;margin-bottom:14px;border-radius:0 6px 6px 0;\"\u003e\n    \u003cstrong style=\"color:#b7580a;\"\u003e⚠ Requires an Existing evohome Controller\u003c\/strong\u003e — This kit does \u003cstrong\u003enot include an evohome controller or touchscreen\u003c\/strong\u003e. It is an accessory that adds hot water control to an \u003cstrong\u003eexisting evohome installation\u003c\/strong\u003e. The evohome ATP921R2143 Thermostat Pack (or equivalent) must already be installed and operating. This kit cannot function as a standalone hot water controller.\n  \u003c\/div\u003e\n\n  \u003c!-- ── TEAL CYLINDER CALLOUT ────────────────────────────────────── --\u003e\n  \u003cdiv style=\"border-left:4px solid #008377CF;background:#e6f4f3;padding:10px 16px;margin-bottom:22px;border-radius:0 6px 6px 0;\"\u003e\n    \u003cstrong style=\"color:#005c54;\"\u003eℹ Not for Combi Boilers — Stored Cylinder Systems Only\u003c\/strong\u003e\u003cbr\u003e\n    This kit controls \u003cstrong\u003estored hot water cylinders\u003c\/strong\u003e — it is designed for properties with a \u003cstrong\u003esystem boiler or heat-only (regular) boiler\u003c\/strong\u003e that heats an indirect hot water cylinder via a zone valve or diverter valve. It is \u003cstrong\u003enot suitable for combi boilers\u003c\/strong\u003e, which produce hot water on demand without a storage cylinder. If you are unsure whether your system has a stored cylinder, check the airing cupboard — if there is an insulated hot water tank connected to the boiler via pipework, this kit applies. Combi boiler users do not need hot water control accessories.\n  \u003c\/div\u003e\n\n  \u003c!-- ── STAT STRIP ─────────────────────────────────────────────────── --\u003e\n  \u003cdiv style=\"display:flex;flex-wrap:wrap;gap:10px;margin-bottom:20px;\"\u003e\n    \u003cdiv style=\"flex:1;min-width:90px;background:#008377CF;color:#fff;border-radius:6px;padding:11px 8px;text-align:center;\"\u003e\n\u003cdiv style=\"font-size:15px;font-weight:700;\"\u003eVented \u0026amp; Unvented\u003c\/div\u003e\n\u003cdiv style=\"font-size:12px;margin-top:3px;\"\u003eBoth cylinder types\u003c\/div\u003e\n\u003c\/div\u003e\n    \u003cdiv style=\"flex:1;min-width:90px;background:#008377CF;color:#fff;border-radius:6px;padding:11px 8px;text-align:center;\"\u003e\n\u003cdiv style=\"font-size:15px;font-weight:700;\"\u003eCS92A + BDR91\u003c\/div\u003e\n\u003cdiv style=\"font-size:12px;margin-top:3px;\"\u003eFull wireless kit\u003c\/div\u003e\n\u003c\/div\u003e\n    \u003cdiv style=\"flex:1;min-width:90px;background:#008377CF;color:#fff;border-radius:6px;padding:11px 8px;text-align:center;\"\u003e\n\u003cdiv style=\"font-size:15px;font-weight:700;\"\u003eApp Control\u003c\/div\u003e\n\u003cdiv style=\"font-size:12px;margin-top:3px;\"\u003eTotal Connect Comfort\u003c\/div\u003e\n\u003c\/div\u003e\n    \u003cdiv style=\"flex:1;min-width:90px;background:#008377CF;color:#fff;border-radius:6px;padding:11px 8px;text-align:center;\"\u003e\n\u003cdiv style=\"font-size:15px;font-weight:700;\"\u003e2+ Years\u003c\/div\u003e\n\u003cdiv style=\"font-size:12px;margin-top:3px;\"\u003eBattery life (CS92A)\u003c\/div\u003e\n\u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003c!-- ── FEATURES ──────────────────────────────────────────────────── --\u003e\n  \u003cdiv style=\"background:#008377CF;color:#fff;font-weight:600;font-size:15px;padding:10px 16px;border-radius:6px 6px 0 0;\"\u003eFeatures \u0026amp; Benefits\u003c\/div\u003e\n  \u003cdiv style=\"display:grid;grid-template-columns:repeat(auto-fill,minmax(255px,1fr));gap:12px;background:#e6f4f3;padding:14px;border-radius:0 0 6px 6px;margin-bottom:22px;\"\u003e\n\n    \u003cdiv style=\"background:#f0faf9;border:1px solid #c8e6e3;border-radius:6px;padding:13px;\"\u003e\n      \u003cdiv style=\"font-weight:700;color:#008377CF;margin-bottom:5px;\"\u003e✔ CS92A Wireless Cylinder Thermostat — No Extra Wiring\u003c\/div\u003e\n      \u003cdiv style=\"font-size:14px;\"\u003eThe \u003cstrong\u003eCS92A\u003c\/strong\u003e is a wireless, battery-operated cylinder thermostat that communicates with the evohome controller by radio — \u003cstrong\u003eno additional wiring between the cylinder and the evohome system is needed\u003c\/strong\u003e. It mounts directly to the cylinder or pipework using the supplied sensor, and once bound to the evohome controller, it transmits live cylinder temperature readings to the controller screen. The CS92A is powered by \u003cstrong\u003e2× AA alkaline batteries\u003c\/strong\u003e with a typical life of at least 2 years, making it entirely independent of any cable run to the airing cupboard. This is a significant advantage over wired cylinder thermostats in properties where running a new cable from the cylinder to the programmer or wiring centre would be disruptive.\u003c\/div\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv style=\"background:#f0faf9;border:1px solid #c8e6e3;border-radius:6px;padding:13px;\"\u003e\n      \u003cdiv style=\"font-weight:700;color:#008377CF;margin-bottom:5px;\"\u003e✔ BDR91 Wireless Relay Box — Zone Valve Control\u003c\/div\u003e\n      \u003cdiv style=\"font-size:14px;\"\u003eThe \u003cstrong\u003eBDR91 wireless relay box\u003c\/strong\u003e receives switching commands from the evohome controller by radio and operates the \u003cstrong\u003ehot water zone valve or diverter valve\u003c\/strong\u003e — the same way it switches heating zone valves in the rest of the evohome system. The relay box is wired to the zone valve's motor wires (the same connection a conventional programmer would use) and requires only a mains supply. For S-plan systems (separate zone valves for heating and hot water), the BDR91 switches the hot water zone valve independently. For Y-plan systems (a single 3-port diverter), the BDR91 provides the demand signal that calls for hot water via the diverter's mid-position.\u003c\/div\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv style=\"background:#f0faf9;border:1px solid #c8e6e3;border-radius:6px;padding:13px;\"\u003e\n      \u003cdiv style=\"font-weight:700;color:#008377CF;margin-bottom:5px;\"\u003e✔ Both Vented \u0026amp; Unvented Sensors Included\u003c\/div\u003e\n      \u003cdiv style=\"font-size:14px;\"\u003eThe kit includes \u003cstrong\u003etwo temperature sensors\u003c\/strong\u003e for both cylinder types: the \u003cstrong\u003eT8674B strap-on surface sensor\u003c\/strong\u003e is attached to the outside of the cylinder body and is used with \u003cstrong\u003evented (gravity-fed \/ open-vented) indirect cylinders\u003c\/strong\u003e where access to an immersion heater pocket is not available. The \u003cstrong\u003eF420079510 insertion sensor\u003c\/strong\u003e inserts into the thermostat pocket on \u003cstrong\u003eunvented (mains-pressure) cylinders\u003c\/strong\u003e for a more accurate in-cylinder temperature reading. Having both sensors in the box means the kit is compatible with virtually any stored cylinder installation without needing to order additional parts.\u003c\/div\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv style=\"background:#f0faf9;border:1px solid #c8e6e3;border-radius:6px;padding:13px;\"\u003e\n      \u003cdiv style=\"font-weight:700;color:#008377CF;margin-bottom:5px;\"\u003e✔ Live Cylinder Temperature on the evohome Screen\u003c\/div\u003e\n      \u003cdiv style=\"font-size:14px;\"\u003eOnce bound, the \u003cstrong\u003eevohome controller's main screen displays the actual live temperature\u003c\/strong\u003e of the stored hot water alongside the heating zone temperatures. This gives the homeowner a single dashboard showing the state of both heating and hot water from one location — no need to check a separate cylinder thermostat dial or programmer. The screen also shows the \u003cstrong\u003ehot water schedule\u003c\/strong\u003e (the times when hot water heating is active) and allows the schedule to be \u003cstrong\u003eoverridden instantly\u003c\/strong\u003e with a single tap — boosting the hot water for an unexpected bath or guest without reprogramming the schedule.\u003c\/div\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv style=\"background:#f0faf9;border:1px solid #c8e6e3;border-radius:6px;padding:13px;\"\u003e\n      \u003cdiv style=\"font-weight:700;color:#008377CF;margin-bottom:5px;\"\u003e✔ Remote Control via Total Connect Comfort App\u003c\/div\u003e\n      \u003cdiv style=\"font-size:14px;\"\u003eVia the \u003cstrong\u003eHoneywell Home Total Connect Comfort app\u003c\/strong\u003e (iOS and Android, free), the hot water can be \u003cstrong\u003emonitored and controlled remotely\u003c\/strong\u003e from anywhere with an internet connection — the same app used to control the evohome heating zones. Check whether the hot water is on, boost it before returning home, cancel the afternoon cycle if plans change, or view the hot water temperature from the office. The evohome system also integrates with \u003cstrong\u003eAmazon Alexa, Google Home, and Apple HomeKit\u003c\/strong\u003e for voice control via the wider evohome ecosystem.\u003c\/div\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv style=\"background:#f0faf9;border:1px solid #c8e6e3;border-radius:6px;padding:13px;\"\u003e\n      \u003cdiv style=\"font-weight:700;color:#008377CF;margin-bottom:5px;\"\u003e✔ Time and Temperature Scheduling — LED Status Indicators\u003c\/div\u003e\n      \u003cdiv style=\"font-size:14px;\"\u003eThe hot water schedule is programmed on the evohome controller using the same interface as the heating zones — set the \u003cstrong\u003etimes and target temperatures\u003c\/strong\u003e for hot water heating across the day, with the system heating the cylinder to the set point temperature at the scheduled times and holding it there. The BDR91 relay box features \u003cstrong\u003eclear LED status indicators\u003c\/strong\u003e showing whether the relay is energised (hot water called) or at rest, making commissioning checks and fault finding straightforward without needing to refer to the controller screen or app.\u003c\/div\u003e\n    \u003c\/div\u003e\n\n  \u003c\/div\u003e\n\n  \u003c!-- ── WHAT'S IN THE BOX ───────────────────────────────────────── --\u003e\n  \u003cdiv style=\"background:#008377CF;color:#fff;font-weight:600;font-size:15px;padding:10px 16px;border-radius:6px 6px 0 0;\"\u003eWhat's in the Box — ATF500DHW\u003c\/div\u003e\n  \u003ctable style=\"width:100%;border-collapse:collapse;margin-bottom:22px;font-size:14px;\"\u003e\n    \u003ctbody\u003e\n      \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;width:40%;border-bottom:1px solid #c8e6e3;\"\u003eCS92A\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003eWireless battery-operated cylinder thermostat with transceiver — 2× AA alkaline (typical 2+ year life)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;border-bottom:1px solid #c8e6e3;\"\u003eBDR91\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003eWireless relay box — controls 2-port zone valve or 3-port diverter valve (mains wired)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;border-bottom:1px solid #c8e6e3;\"\u003eT8674B\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003eStrap-on surface sensor — for vented indirect cylinders\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;border-bottom:1px solid #c8e6e3;\"\u003eF420079510\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003eInsertion sensor — for unvented cylinders (inserts into thermostat pocket)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;\"\u003eDocumentation\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;\"\u003eInstallation guide (including wiring diagrams for S-plan and Y-plan)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003c!-- ── SPEC TABLE ─────────────────────────────────────────────────── --\u003e\n  \u003cdiv style=\"background:#008377CF;color:#fff;font-weight:600;font-size:15px;padding:10px 16px;border-radius:6px 6px 0 0;\"\u003eTechnical Specifications — ATF500DHW\u003c\/div\u003e\n  \u003ctable style=\"width:100%;border-collapse:collapse;margin-bottom:22px;font-size:14px;\"\u003e\n    \u003ctbody\u003e\n      \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;width:44%;border-bottom:1px solid #c8e6e3;\"\u003eManufacturer \/ MPN\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003eHoneywell Home (by Resideo) — \u003cstrong\u003eATF500DHW\u003c\/strong\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;border-bottom:1px solid #c8e6e3;\"\u003eGTIN\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003e5025121382274\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;border-bottom:1px solid #c8e6e3;\"\u003eCompatible System\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003eHoneywell Home evohome (requires existing evohome controller)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;border-bottom:1px solid #c8e6e3;\"\u003eCylinder Compatibility\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003eVented (gravity-fed) indirect · Unvented (mains-pressure) indirect\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;border-bottom:1px solid #c8e6e3;\"\u003eValve Compatibility\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003e2-port zone valve (S-plan) · 3-port diverter valve (Y-plan)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;border-bottom:1px solid #c8e6e3;\"\u003eCommunication\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003eWireless RF (evohome ecosystem protocol)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;border-bottom:1px solid #c8e6e3;\"\u003eCS92A Power\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003e2× AA alkaline batteries — typical life 2+ years\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;border-bottom:1px solid #c8e6e3;\"\u003eBDR91 Power\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003e230V AC mains (wired to zone valve circuit)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;border-bottom:1px solid #c8e6e3;\"\u003eApp Control\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003eTotal Connect Comfort (iOS \u0026amp; Android) · Alexa · Google Home · Apple HomeKit\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;border-bottom:1px solid #c8e6e3;\"\u003eBDR91 LED Indicators\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003eYes — relay status, time and temperature set display\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;border-bottom:1px solid #c8e6e3;\"\u003eWeight (inc. packaging)\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;border-bottom:1px solid #c8e6e3;\"\u003e0.662 kg\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 14px;font-weight:600;\"\u003eWarranty\u003c\/td\u003e\n\u003ctd style=\"padding:9px 14px;\"\u003e1 year — Honeywell Home manufacturer's warranty\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003c!-- ── FAQ ────────────────────────────────────────────────────────── --\u003e\n  \u003cdiv style=\"background:#008377CF;color:#fff;font-weight:600;font-size:15px;padding:10px 16px;border-radius:6px 6px 0 0;\"\u003eFrequently Asked Questions\u003c\/div\u003e\n  \u003cdiv style=\"border:1px solid #c8e6e3;border-top:none;border-radius:0 0 6px 6px;margin-bottom:8px;\"\u003e\n\n    \u003cdetails style=\"border-bottom:1px solid #c8e6e3;\"\u003e\n      \u003csummary style=\"padding:13px 16px;cursor:pointer;font-weight:600;background:#f0faf9;\"\u003eDo I need this kit if I have a combi boiler?\u003c\/summary\u003e\n      \u003cdiv style=\"padding:11px 16px;font-size:14px;\"\u003e\n\u003cstrong\u003eNo\u003c\/strong\u003e — combi boilers heat water on demand and have no stored cylinder to control. This kit is for properties with a \u003cstrong\u003esystem boiler or regular (heat-only) boiler\u003c\/strong\u003e that feeds an indirect hot water cylinder. If you have a combi boiler, the evohome system controls your central heating zones but there is nothing to add for hot water — it operates automatically whenever a hot tap is opened. Only purchase this kit if your property has a hot water cylinder in an airing cupboard or plant room.\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails style=\"border-bottom:1px solid #c8e6e3;\"\u003e\n      \u003csummary style=\"padding:13px 16px;cursor:pointer;font-weight:600;background:#fff;\"\u003eCan I control the immersion heater with this kit?\u003c\/summary\u003e\n      \u003cdiv style=\"padding:11px 16px;font-size:14px;\"\u003eThe ATF500DHW controls the \u003cstrong\u003ezone valve or diverter valve\u003c\/strong\u003e that routes boiler-heated water to the cylinder — it does not directly switch an immersion heater. The CS92A cylinder thermostat monitors temperature and signals the BDR91 relay, which in turn controls the valve. For direct immersion heater control, a separate dedicated immersion heater controller or timer would be needed. However, many properties use the immersion heater purely as a backup — if the cylinder is already zone-valve-controlled via the ATF500DHW, the immersion can be left on its standard thermostat as a safety fallback without requiring additional evohome integration.\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails style=\"border-bottom:1px solid #c8e6e3;\"\u003e\n      \u003csummary style=\"padding:13px 16px;cursor:pointer;font-weight:600;background:#f0faf9;\"\u003eWhat is the difference between S-plan and Y-plan, and does this kit work with both?\u003c\/summary\u003e\n      \u003cdiv style=\"padding:11px 16px;font-size:14px;\"\u003eYes — the ATF500DHW works with both. \u003cstrong\u003eS-plan\u003c\/strong\u003e systems use separate 2-port motorised zone valves for the heating circuit and the hot water circuit — the BDR91 in this kit switches the hot water zone valve. \u003cstrong\u003eY-plan\u003c\/strong\u003e systems use a single 3-port mid-position diverter valve that routes flow to heating only, hot water only, or both simultaneously — the BDR91 provides the hot water demand signal to the diverter valve's mid-position terminal. The installation guide included in the box contains specific wiring diagrams for both S-plan and Y-plan configurations. If you are unsure which plan your system uses, an installer can identify it from the valve fitted to the pipework near the boiler.\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails style=\"border-bottom:1px solid #c8e6e3;\"\u003e\n      \u003csummary style=\"padding:13px 16px;cursor:pointer;font-weight:600;background:#fff;\"\u003eDo I need to keep my existing programmer or wiring centre?\u003c\/summary\u003e\n      \u003cdiv style=\"padding:11px 16px;font-size:14px;\"\u003eWhen the ATF500DHW is fully installed and controlling hot water via the BDR91, the \u003cstrong\u003ehot water channels on an existing programmer are bypassed\u003c\/strong\u003e — the BDR91 takes over the switching function for the hot water zone valve. You can remove or bypass the programmer's hot water output, or leave the programmer in place with its hot water output permanently enabled (which passes control back to the BDR91 and CS92A). The evohome system and BDR91 become the new hot water controller. Your existing wiring centre (if fitted) typically remains in place as it provides the switching connections for the zone valves, pump, and boiler — the BDR91 replaces the demand signal input, not the wiring centre itself.\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary style=\"padding:13px 16px;cursor:pointer;font-weight:600;background:#f0faf9;\"\u003eWhere should I mount the CS92A and BDR91 — are there placement restrictions?\u003c\/summary\u003e\n      \u003cdiv style=\"padding:11px 16px;font-size:14px;\"\u003eThe \u003cstrong\u003eCS92A cylinder thermostat\u003c\/strong\u003e should be mounted on the cylinder body or pipework adjacent to the cylinder, where it can receive the temperature signal from the selected sensor. Keep it away from direct heat sources and ensure it has clear RF line-of-sight (or minimal interference) to the evohome controller or a BDR91 used as a relay. The \u003cstrong\u003eBDR91\u003c\/strong\u003e should be mounted near the zone valve it controls, close to the wiring connections. Critically: do \u003cstrong\u003enot mount the CS92A close to any BDR91\u003c\/strong\u003e — the relay box generates RF interference that can disrupt the thermostat's transmission. Maintain at least 30cm separation between the CS92A and any BDR91 unit. Similarly, keep both units away from other RF sources, metal enclosures, and large electrical loads where possible.\u003c\/div\u003e\n    \u003c\/details\u003e\n\n  \u003c\/div\u003e\n\n\u003c\/div\u003e","brand":"Honeywell","offers":[{"title":"Default Title","offer_id":62799405744477,"sku":"ATF500DHW-R","price":133.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0958\/2051\/3629\/files\/HoneywellHomeStoredHotWaterKitForEvohomeATF500DHW.webp?v=1764921029","url":"https:\/\/qualityheating.co.uk\/products\/honeywell-home-stored-hot-water-kit-for-evohome-atf500dhw-cylinder-control-accessory","provider":"AIZO Quality Heating","version":"1.0","type":"link"}