{"product_id":"wisualarm-mains-powered-heat-alarm-grade-d2-class-a1-54-65-c-9v-battery-backup-wired-interconnect","title":"Wisualarm Mains Powered Heat Alarm | Grade D2 | Class A1 54–65°C | 9V Battery Backup | Wired Interconnect","description":"\u003cstyle\u003e\n  .wu-desc * { box-sizing: border-box; }\n  .wu-desc { font-family: inherit; color: inherit; line-height: 1.7; font-size: 16px; }\n  .wu-desc p, .wu-desc li, .wu-desc td, .wu-desc th { font-size: 16px !important; line-height: 1.7; }\n  .wu-desc h2 { font-size: 22px !important; font-weight: 700; color: #1a1a2e; border-bottom: 2px solid #c0392b; padding-bottom: 6px; margin: 2rem 0 1rem; line-height: 1.3; }\n  .wu-desc h3 { font-size: 17px !important; font-weight: 700; color: #1a1a2e; margin: 1.2rem 0 0.4rem; line-height: 1.4; }\n  .wu-desc p { margin: 0 0 1rem; }\n  .wu-desc ul { padding-left: 1.5rem; margin: 0 0 1rem; }\n  .wu-desc ul li { margin-bottom: 0.5rem; }\n\n  .wu-intro-box { background: #fef5f5; border-left: 4px solid #c0392b; padding: 1.1rem 1.4rem; border-radius: 0 6px 6px 0; margin-bottom: 1.5rem; }\n  .wu-intro-box p { margin: 0 !important; }\n\n  .wu-badge { display: inline-block; background: #c0392b; color: #fff; font-size: 13px !important; font-weight: 700; border-radius: 4px; padding: 2px 10px; margin-right: 6px; margin-bottom: 4px; vertical-align: middle; }\n  .wu-badge.dark { background: #1a1a2e; }\n  .wu-badge.grey { background: #555; }\n  .wu-badge.green { background: #1a7a3c; }\n  .wu-badge.orange { background: #d35400; }\n  .wu-badge.teal { background: #117a65; }\n\n  .wu-stat-bar { background: #1a1a2e; color: #fff; border-radius: 8px; padding: 1.1rem 1.4rem; margin: 1.2rem 0; display: flex; flex-wrap: wrap; gap: 1.5rem; align-items: center; justify-content: space-around; }\n  .wu-stat { text-align: center; }\n  .wu-stat .num { font-size: 24px !important; font-weight: 800; color: #ff6b6b; line-height: 1; }\n  .wu-stat .lbl { font-size: 12px !important; color: #aab; margin-top: 2px; }\n\n  .wu-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(230px, 1fr)); gap: 0.85rem; margin-bottom: 1.2rem; }\n  .wu-card { background: #fef5f5; border: 1px solid #f5c0c0; border-radius: 6px; padding: 1rem 1.1rem; line-height: 1.6; }\n  .wu-card strong { display: block; color: #1a1a2e; margin-bottom: 0.35rem; font-size: 16px !important; }\n\n  .wu-led-box { background: #f0f4ff; border: 1px solid #aab8d8; border-radius: 8px; padding: 1.1rem 1.4rem; margin: 1.2rem 0; }\n  .wu-led-box p { margin: 0 0 0.6rem !important; font-weight: 700; color: #1a1a2e; }\n  .wu-led-box table { width: 100%; border-collapse: collapse; }\n  .wu-led-box td { padding: 0.5rem 0.8rem; border-bottom: 1px solid #ccd4e8; font-size: 15px !important; vertical-align: top; }\n  .wu-led-box tr:last-child td { border-bottom: none; }\n  .wu-led-box td:first-child { width: 55%; font-weight: 600; color: #1a1a2e; }\n\n  .wu-reg-box { background: #fff8e6; border: 1px solid #f0d080; border-radius: 6px; padding: 1rem 1.3rem; margin: 1.2rem 0; }\n  .wu-reg-box p { margin: 0 0 0.6rem !important; color: #5a4a00; }\n  .wu-reg-box p:last-child { margin: 0 !important; }\n\n  .wu-use-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: 0.7rem; margin-bottom: 1.2rem; }\n  .wu-use-card { background: #fff; border: 1px solid #e8d8d8; border-radius: 6px; padding: 0.85rem 1rem; text-align: center; font-size: 15px !important; line-height: 1.5; }\n  .wu-use-card .ico { font-size: 28px !important; display: block; margin-bottom: 0.3rem; }\n  .wu-use-card strong { display: block; font-size: 15px !important; color: #1a1a2e; margin-bottom: 0.2rem; }\n  .wu-use-card.yes { border-color: #82e0aa; background: #eafaf1; }\n  .wu-use-card.no { border-color: #f5b7b1; background: #fef5f5; }\n\n  .wu-variant-table { width: 100%; border-collapse: collapse; margin-bottom: 1.2rem; }\n  .wu-variant-table th { background: #1a1a2e; color: #fff !important; padding: 0.65rem 0.9rem; font-size: 14px !important; text-align: left; }\n  .wu-variant-table td { padding: 0.55rem 0.9rem; border-bottom: 1px solid #e8d8d8; font-size: 14px !important; vertical-align: top; }\n  .wu-variant-table tr:nth-child(even) td { background: #fef5f5; }\n  .wu-variant-table td:first-child { font-weight: 600; color: #111; width: 30%; }\n\n  .wu-spec-table { width: 100%; border-collapse: collapse; margin-bottom: 1.5rem; }\n  .wu-spec-table th { background: #1a1a2e; color: #fff !important; text-align: left; padding: 0.7rem 1rem; font-weight: 700; font-size: 16px !important; }\n  .wu-spec-table td { padding: 0.6rem 1rem; border-bottom: 1px solid #e8d8d8; vertical-align: top; font-size: 16px !important; }\n  .wu-spec-table tr:nth-child(even) td { background: #fef5f5; }\n  .wu-spec-table td:first-child { font-weight: 600; color: #111; width: 44%; }\n  .wu-spec-table .section-head td { background: #c0392b !important; color: #fff !important; font-weight: 700 !important; font-size: 14px !important; text-transform: uppercase; letter-spacing: 0.05em; }\n\n  .wu-faq-item { border-bottom: 1px solid #e8d8d8; padding: 1rem 0; }\n  .wu-faq-item:last-child { border-bottom: none; }\n  .wu-faq-item p { margin: 0.4rem 0 0 !important; }\n\n  .wu-infobox { background: #fef5f5; border: 1px solid #f5c0c0; border-radius: 6px; padding: 1rem 1.2rem; margin-top: 1.5rem; font-size: 16px !important; line-height: 1.6; }\n\n  @media (max-width: 600px) {\n    .wu-grid { grid-template-columns: 1fr 1fr; }\n    .wu-stat-bar { justify-content: center; }\n    .wu-use-grid { grid-template-columns: 1fr 1fr; }\n  }\n\u003c\/style\u003e\n\n\u003cdiv class=\"wu-desc\"\u003e\n\n  \u003cdiv class=\"wu-intro-box\"\u003e\n    \u003cp\u003e\n      \u003cspan class=\"wu-badge\"\u003eGrade D2\u003c\/span\u003e\n      \u003cspan class=\"wu-badge dark\"\u003eClass A1 Heat Detection\u003c\/span\u003e\n      \u003cspan class=\"wu-badge orange\"\u003e54°C – 65°C Fixed Temp\u003c\/span\u003e\n    \u003c\/p\u003e\n    \u003cp style=\"margin-top:0.75rem !important;\"\u003eThe \u003cstrong\u003eWisualarm DHI-HY-HT5MB\u003c\/strong\u003e is a mains-powered Class A1 fixed-temperature heat alarm certified to BS 5446-2:2003, designed for rooms where a smoke alarm would cause persistent false activations — principally kitchens, garages, utility rooms and loft spaces. It draws its primary power from a permanent 230V mains connection and includes a \u003cstrong\u003ereplaceable 9V alkaline battery\u003c\/strong\u003e as standby backup, classifying it as a \u003cstrong\u003eGrade D2\u003c\/strong\u003e device under BS 5839-6. A high-precision thermistor triggers the alarm when the ambient temperature reaches 54°C–65°C. The 85dB sounder sounds continuously until reset. The unit interconnects by wire with up to 24 other Wisualarm mains-powered smoke and heat alarms, and can optionally join the WisuLink wireless mesh by adding the \u003cstrong\u003eDHI-HY-MRF50-R8 wireless module\u003c\/strong\u003e — enabling a hybrid system that links wired and wireless devices.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"wu-stat-bar\"\u003e\n    \u003cdiv class=\"wu-stat\"\u003e\n\u003cdiv class=\"num\"\u003eGrade D2\u003c\/div\u003e\n\u003cdiv class=\"lbl\"\u003eBS 5839-6\u003c\/div\u003e\n\u003c\/div\u003e\n    \u003cdiv class=\"wu-stat\"\u003e\n\u003cdiv class=\"num\"\u003eClass A1\u003c\/div\u003e\n\u003cdiv class=\"lbl\"\u003eFixed Temperature\u003c\/div\u003e\n\u003c\/div\u003e\n    \u003cdiv class=\"wu-stat\"\u003e\n\u003cdiv class=\"num\"\u003e54–65°C\u003c\/div\u003e\n\u003cdiv class=\"lbl\"\u003eAlarm Threshold\u003c\/div\u003e\n\u003c\/div\u003e\n    \u003cdiv class=\"wu-stat\"\u003e\n\u003cdiv class=\"num\"\u003e85dB\u003c\/div\u003e\n\u003cdiv class=\"lbl\"\u003eAlarm @ 3m\u003c\/div\u003e\n\u003c\/div\u003e\n    \u003cdiv class=\"wu-stat\"\u003e\n\u003cdiv class=\"num\"\u003e24\u003c\/div\u003e\n\u003cdiv class=\"lbl\"\u003eMax Wired Devices\u003c\/div\u003e\n\u003c\/div\u003e\n    \u003cdiv class=\"wu-stat\"\u003e\n\u003cdiv class=\"num\"\u003e148.6mm\u003c\/div\u003e\n\u003cdiv class=\"lbl\"\u003eDiameter\u003c\/div\u003e\n\u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003ch2\u003eKey Features\u003c\/h2\u003e\n  \u003cdiv class=\"wu-grid\"\u003e\n    \u003cdiv class=\"wu-card\"\u003e\n\u003cstrong\u003e🌡️ Class A1 Fixed Temperature Detection — 54°C to 65°C\u003c\/strong\u003eThe high-precision thermistor continuously monitors ambient temperature and triggers the alarm once it rises into the 54°C–65°C range. This Class A1 fixed-temperature response is the standard recommended for domestic heat alarms in BS 5839-6, making the unit suitable for kitchens (where cooking steam and fumes would trigger a smoke alarm) as well as garages, utility rooms and attics where dust or humidity create smoke detector nuisance conditions.\u003c\/div\u003e\n    \u003cdiv class=\"wu-card\"\u003e\n\u003cstrong\u003e🔌 Mains Powered + Replaceable 9V Battery Backup (Grade D2)\u003c\/strong\u003ePrimary power is drawn from a 230V AC mains supply via a direct wired connection — the alarm is always active as long as mains power is present. The replaceable 9V alkaline battery backup provides continued protection during power cuts. When the battery needs replacing, a low battery backup fault signal alerts the occupant (yellow LED flashing once per minute, audible beep). This mains + user-replaceable battery configuration is classified as \u003cstrong\u003eGrade D2\u003c\/strong\u003e under BS 5839-6. Grade D2 is the typical specification for mains-wired alarm systems in domestic properties in England, Scotland and Wales.\u003c\/div\u003e\n    \u003cdiv class=\"wu-card\"\u003e\n\u003cstrong\u003e🔗 Wired Interconnection — Up to 24 Devices\u003c\/strong\u003eConnects by wire to up to 24 other Wisualarm mains-powered alarm devices. When any one alarm triggers, all interconnected units sound simultaneously — ensuring occupants throughout a multi-room or multi-floor property are alerted even if the hazard is in an unoccupied area. The wired interconnect is compatible with all Wisualarm mains-powered smoke and heat alarms. No additional hardware is required for wired interconnection — it is built into the base unit.\u003c\/div\u003e\n    \u003cdiv class=\"wu-card\"\u003e\n\u003cstrong\u003e📡 Optional WisuLink Wireless Module for Hybrid Systems\u003c\/strong\u003eBy adding the separately available \u003cstrong\u003eDHI-HY-MRF50-R8\u003c\/strong\u003e wireless interconnect module, the HT5MB can join the WisuLink 868 MHz wireless mesh. This creates a hybrid system combining hardwired and wireless devices — for example, mains alarms in the kitchen and living areas wired together, with battery-powered WisuLink alarms in bedrooms communicating wirelessly. All devices in both the wired and wireless parts of the network sound together when any alarm triggers. Adding the optional Wisualarm Internet Gateway (DHI-HY-GW01A) then enables smartphone push notifications.\u003c\/div\u003e\n    \u003cdiv class=\"wu-card\"\u003e\n\u003cstrong\u003e🔊 85dB Continuous Sounder\u003c\/strong\u003eOnce triggered, the built-in sounder emits a continuous 85dB(A) alarm until the alarm is manually reset or the temperature drops below the threshold. 85dB(A) at 3 metres meets the BS 5446-2:2003 minimum output requirement and is sufficient to wake sleeping occupants and be heard throughout a typical domestic property.\u003c\/div\u003e\n    \u003cdiv class=\"wu-card\"\u003e\n\u003cstrong\u003e📺 IR Remote Silence — Unique Wisualarm Feature\u003c\/strong\u003eIn addition to the central test\/silence push button, the alarm can be silenced by pointing any standard infrared TV remote control at the unit. This is a distinctive feature of the Wisualarm mains range and is particularly useful in kitchens or high-ceiling utility rooms where the alarm may be out of easy reach, allowing occupants to silence a nuisance activation from ground level without needing to reach up to the alarm.\u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003ch2\u003eLED Status Indicators\u003c\/h2\u003e\n  \u003cdiv class=\"wu-led-box\"\u003e\n    \u003cp\u003eThree LEDs provide continuous status feedback:\u003c\/p\u003e\n    \u003ctable\u003e\n      \u003ctr\u003e\n        \u003ctd\u003e🟢 Green — steady on\u003c\/td\u003e\n        \u003ctd\u003eStandby, mains power confirmed and alarm operational\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003e🔴 Red — flashes once per second\u003c\/td\u003e\n        \u003ctd\u003eAlarm state — temperature threshold exceeded\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003e🟡 Yellow — flashes twice per minute\u003c\/td\u003e\n        \u003ctd\u003eSensor fault — replace alarm unit\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003e🟡 Yellow — flashes once per minute\u003c\/td\u003e\n        \u003ctd\u003eLow battery backup — 9V battery needs replacing. Green LED should remain lit (mains still present); if green is off, mains power has also been lost — check wiring, fuses or circuit breakers.\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/table\u003e\n  \u003c\/div\u003e\n\n  \u003ch2\u003eWhere to Use a Heat Alarm\u003c\/h2\u003e\n  \u003cp\u003eHeat alarms detect the rise in air temperature caused by fire rather than smoke particles. They are significantly less sensitive than smoke alarms to steam, cooking fumes, dust and humidity — which makes them the right choice in environments where smoke alarms would alarm repeatedly without a real fire:\u003c\/p\u003e\n  \u003cdiv class=\"wu-use-grid\"\u003e\n    \u003cdiv class=\"wu-use-card yes\"\u003e\n\u003cspan class=\"ico\"\u003e🍳\u003c\/span\u003e\u003cstrong\u003eKitchen ✓\u003c\/strong\u003eRecommended by BS 5839-6 in place of a smoke alarm. Cooking generates steam and aerosols that trigger smoke alarms; a heat alarm avoids nuisance alarms while providing real protection.\u003c\/div\u003e\n    \u003cdiv class=\"wu-use-card yes\"\u003e\n\u003cspan class=\"ico\"\u003e🚗\u003c\/span\u003e\u003cstrong\u003eGarage ✓\u003c\/strong\u003eVehicle exhaust and fumes can trigger smoke alarms. A heat alarm provides protection without false alarms from normal garage activities.\u003c\/div\u003e\n    \u003cdiv class=\"wu-use-card yes\"\u003e\n\u003cspan class=\"ico\"\u003e🧺\u003c\/span\u003e\u003cstrong\u003eUtility Room ✓\u003c\/strong\u003eDust from tumble dryers, steam from washing machines and boilers all create smoke alarm false alarm conditions. Heat alarms are well suited here.\u003c\/div\u003e\n    \u003cdiv class=\"wu-use-card yes\"\u003e\n\u003cspan class=\"ico\"\u003e🏚️\u003c\/span\u003e\u003cstrong\u003eLoft \/ Attic ✓\u003c\/strong\u003eAccumulated dust and temperature fluctuations make smoke alarms unreliable in loft spaces. A heat alarm provides appropriate fire detection without false activations.\u003c\/div\u003e\n    \u003cdiv class=\"wu-use-card no\"\u003e\n\u003cspan class=\"ico\"\u003e🛏️\u003c\/span\u003e\u003cstrong\u003eBedroom ✗\u003c\/strong\u003eA smoke alarm is required in sleeping areas. Heat alarms respond too late to smouldering fires — use an optical or multi-sensor smoke alarm in bedrooms.\u003c\/div\u003e\n    \u003cdiv class=\"wu-use-card no\"\u003e\n\u003cspan class=\"ico\"\u003e🚪\u003c\/span\u003e\u003cstrong\u003eHallway \/ Landing ✗\u003c\/strong\u003eSmoke alarms are the correct choice here. These are primary escape routes; early smoke detection is essential. Use an interlinked smoke alarm.\u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"wu-reg-box\"\u003e\n    \u003cp\u003e📋 \u003cstrong\u003eUK Regulatory Context — Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022 (England):\u003c\/strong\u003e Landlords must install a smoke alarm on every storey used as living accommodation. The statutory guidance specifically recommends a heat alarm (rather than smoke alarm) in kitchens with cooking appliances to avoid false activations. This alarm, certified to BS 5446-2:2003 and classified Grade D2, meets the technical requirements for compliance in England and Wales.\u003c\/p\u003e\n    \u003cp\u003e📋 \u003cstrong\u003eScotland — Housing (Scotland) Act 2006 \u0026amp; Fire (Scotland) Act 2005:\u003c\/strong\u003e Scottish regulations require interlinked alarms throughout all rooms used for living accommodation. In kitchens, a heat alarm is specified (not smoke). The HT5MB's wired interconnect capability — and its ability to join a wireless mesh via the optional WisuLink module — makes it suitable for Scottish compliance installations. Note: Scottish regulations specify that all alarms must be interlinked; confirm the full system design meets the relevant Scottish guidance before installation.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n  \u003ch2\u003eHT5MA vs HT5MB — Which Mains Heat Alarm?\u003c\/h2\u003e\n  \u003ctable class=\"wu-variant-table\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth\u003eFeature\u003c\/th\u003e\n        \u003cth\u003eDHI-HY-HT5MA\u003c\/th\u003e\n        \u003cth\u003eDHI-HY-HT5MB ★\u003cbr\u003e\u003csmall\u003eThis product\u003c\/small\u003e\n\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003ctd\u003ePrimary power\u003c\/td\u003e\n\u003ctd\u003e230V AC mains\u003c\/td\u003e\n\u003ctd\u003e230V AC mains\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eStandby battery backup\u003c\/td\u003e\n\u003ctd\u003e10-year sealed rechargeable lithium (built-in, non-replaceable)\u003c\/td\u003e\n\u003ctd\u003e9V alkaline (replaceable by user)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eBS 5839-6 Grade\u003c\/td\u003e\n\u003ctd\u003eGrade D1\u003c\/td\u003e\n\u003ctd\u003eGrade D2\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eBattery maintenance\u003c\/td\u003e\n\u003ctd\u003eNone — sealed lithium lasts life of alarm\u003c\/td\u003e\n\u003ctd\u003eReplace 9V battery periodically (every 1–3 years typical)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eDetection class\u003c\/td\u003e\n\u003ctd\u003eClass A1 (54°C–65°C)\u003c\/td\u003e\n\u003ctd\u003eClass A1 (54°C–65°C)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eAlarm output\u003c\/td\u003e\n\u003ctd\u003e85dB(A)\u003c\/td\u003e\n\u003ctd\u003e85dB(A)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eWired interconnect\u003c\/td\u003e\n\u003ctd\u003e✓ Up to 24 devices\u003c\/td\u003e\n\u003ctd\u003e✓ Up to 24 devices\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eWireless (built-in)\u003c\/td\u003e\n\u003ctd\u003e✓ WisuLink built-in\u003c\/td\u003e\n\u003ctd\u003e✗ Optional module only (DHI-HY-MRF50-R8)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eBS standard\u003c\/td\u003e\n\u003ctd\u003eBS 5446-2:2003\u003c\/td\u003e\n\u003ctd\u003eBS 5446-2:2003\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eBest for\u003c\/td\u003e\n\u003ctd\u003eInstallations specifying Grade D1; preference for maintenance-free sealed backup — typically new-build or refurb where no ongoing battery replacement is desired\u003c\/td\u003e\n\u003ctd\u003eInstallations specifying Grade D2; wired-primary systems where user-replaceable battery backup is specified or preferred; lower upfront cost\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n  \u003cp\u003eFor most domestic UK installations either Grade D1 or D2 meets the regulatory requirement — check your specific project specification or the applicable building regulations guidance. Grade D1 is increasingly specified in new-build because it eliminates battery replacement obligations. Grade D2 remains widely used in rental properties and retrofit installations.\u003c\/p\u003e\n\n  \u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n  \u003ctable class=\"wu-spec-table\"\u003e\n    \u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eSpecification\u003c\/th\u003e\n\u003cth\u003eDetail\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr class=\"section-head\"\u003e\u003ctd colspan=\"2\"\u003eProduct Identity\u003c\/td\u003e\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eModel number\u003c\/td\u003e\n\u003ctd\u003eDHI-HY-HT5MB\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eBrand\u003c\/td\u003e\n\u003ctd\u003eWisualarm (by Dahua)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eGrade (BS 5839-6)\u003c\/td\u003e\n\u003ctd\u003eGrade D2\u003c\/td\u003e\n\u003c\/tr\u003e\n\n      \u003ctr class=\"section-head\"\u003e\u003ctd colspan=\"2\"\u003eDetection\u003c\/td\u003e\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eSensor type\u003c\/td\u003e\n\u003ctd\u003eHigh-precision thermistor\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eDetection class\u003c\/td\u003e\n\u003ctd\u003eClass A1 — fixed temperature\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eAlarm temperature range\u003c\/td\u003e\n\u003ctd\u003e54°C to 65°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\n      \u003ctr class=\"section-head\"\u003e\u003ctd colspan=\"2\"\u003ePower\u003c\/td\u003e\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003ePrimary supply\u003c\/td\u003e\n\u003ctd\u003e230V AC mains (hardwired)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eStandby battery\u003c\/td\u003e\n\u003ctd\u003e9V alkaline — user replaceable\u003c\/td\u003e\n\u003c\/tr\u003e\n\n      \u003ctr class=\"section-head\"\u003e\u003ctd colspan=\"2\"\u003eAlarm Output\u003c\/td\u003e\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eAlarm volume\u003c\/td\u003e\n\u003ctd\u003e85dB(A) at 3 metres\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eAlarm mode\u003c\/td\u003e\n\u003ctd\u003eContinuous until reset\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eVisual alarm\u003c\/td\u003e\n\u003ctd\u003eRed LED flashes once per second\u003c\/td\u003e\n\u003c\/tr\u003e\n\n      \u003ctr class=\"section-head\"\u003e\u003ctd colspan=\"2\"\u003eIndicators\u003c\/td\u003e\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eGreen LED\u003c\/td\u003e\n\u003ctd\u003eSteady on — mains power present, operational\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eRed LED\u003c\/td\u003e\n\u003ctd\u003eFlashes 1\/sec — alarm state\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eYellow LED\u003c\/td\u003e\n\u003ctd\u003eFlashes 2\/min — sensor fault; flashes 1\/min — low battery backup\u003c\/td\u003e\n\u003c\/tr\u003e\n\n      \u003ctr class=\"section-head\"\u003e\u003ctd colspan=\"2\"\u003eControls\u003c\/td\u003e\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eTest \/ Silence button\u003c\/td\u003e\n\u003ctd\u003eCentral push button — combined test and silence\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eIR remote silence\u003c\/td\u003e\n\u003ctd\u003eSupported — any standard IR remote control\u003c\/td\u003e\n\u003c\/tr\u003e\n\n      \u003ctr class=\"section-head\"\u003e\u003ctd colspan=\"2\"\u003eInterconnection\u003c\/td\u003e\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eWired interconnect\u003c\/td\u003e\n\u003ctd\u003eYes — up to 24 compatible devices\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eWireless interconnect\u003c\/td\u003e\n\u003ctd\u003eOptional — requires DHI-HY-MRF50-R8 module (sold separately)\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eApp connectivity\u003c\/td\u003e\n\u003ctd\u003eOptional — requires wireless module + DHI-HY-GW01A Gateway\u003c\/td\u003e\n\u003c\/tr\u003e\n\n      \u003ctr class=\"section-head\"\u003e\u003ctd colspan=\"2\"\u003ePhysical\u003c\/td\u003e\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eDimensions\u003c\/td\u003e\n\u003ctd\u003eØ148.60mm × 68.44mm deep\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e310g\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eMounting\u003c\/td\u003e\n\u003ctd\u003eCeiling mount\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eColour\u003c\/td\u003e\n\u003ctd\u003eWhite\u003c\/td\u003e\n\u003c\/tr\u003e\n\n      \u003ctr class=\"section-head\"\u003e\u003ctd colspan=\"2\"\u003eCertifications \u0026amp; Standards\u003c\/td\u003e\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eHeat alarm standard\u003c\/td\u003e\n\u003ctd\u003eBS 5446-2:2003\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eCertifications\u003c\/td\u003e\n\u003ctd\u003eCE, UKCA\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch2\u003eFAQs\u003c\/h2\u003e\n  \u003cdiv class=\"wu-faq-item\"\u003e\n    \u003ch3\u003eWhy choose a heat alarm for my kitchen rather than a smoke alarm?\u003c\/h3\u003e\n    \u003cp\u003eKitchens produce steam, cooking fumes and aerosols that smoke alarms cannot reliably distinguish from smoke. The result is persistent nuisance activations — the most common reason people remove or disable their smoke alarm, leaving the property unprotected. BS 5839-6 and the statutory guidance for the Smoke and Carbon Monoxide Alarm Regulations 2022 specifically recommend a heat alarm in rooms with cooking appliances for this reason. A heat alarm detects the dramatic rise in air temperature caused by an actual fire rather than reacting to airborne particles, providing reliable protection without the nuisance alarm problem.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"wu-faq-item\"\u003e\n    \u003ch3\u003eWhat does Grade D2 mean?\u003c\/h3\u003e\n    \u003cp\u003eBS 5839-6 defines fire alarm system grades for domestic properties. Grade D2 means mains-powered detectors with an integral standby power supply consisting of a \u003cstrong\u003euser-replaceable battery\u003c\/strong\u003e. This is the grade of this unit — it runs on 230V mains and includes a replaceable 9V battery for backup during power cuts. Grade D1 (like the HT5MA) is the same but with a sealed, non-replaceable lithium backup battery. Both grades are widely accepted under current UK regulations; the choice between them is typically set by the specifying designer, building regulations guidance or client preference.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"wu-faq-item\"\u003e\n    \u003ch3\u003eDoes this alarm require an electrician to install?\u003c\/h3\u003e\n    \u003cp\u003eYes. The HT5MB connects directly to a 230V mains circuit. In England and Wales, connecting or modifying a mains circuit in a kitchen or bathroom is notifiable work under Part P of the Building Regulations and should be carried out by a competent person (typically a registered electrician). In other rooms the requirement depends on the nature of the circuit work. In Scotland, all electrical work in a dwelling must comply with the Building (Scotland) Regulations. Always consult a qualified electrician for mains installation work.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"wu-faq-item\"\u003e\n    \u003ch3\u003eHow do I add this to a wireless WisuLink system?\u003c\/h3\u003e\n    \u003cp\u003eThe HT5MB does not have built-in wireless capability. To connect it to a WisuLink wireless network — for example, to integrate it with battery-powered wireless smoke alarms in other rooms — you need to add the \u003cstrong\u003eDHI-HY-MRF50-R8 Wireless Interconnect Module\u003c\/strong\u003e (sold separately). This module plugs into the alarm's base connector and enables it to communicate wirelessly via the WisuLink 868 MHz mesh. Once paired, it will both receive and transmit alarm signals wirelessly to all other linked devices. Note: the HT5MA includes wireless capability built-in and does not require an additional module.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"wu-faq-item\"\u003e\n    \u003ch3\u003eCan I receive smartphone notifications when this alarm triggers?\u003c\/h3\u003e\n    \u003cp\u003eYes, but it requires two additional components. First, you need to add the \u003cstrong\u003eDHI-HY-MRF50-R8 wireless module\u003c\/strong\u003e to bring the HT5MB onto the WisuLink network. Then, adding the \u003cstrong\u003eDHI-HY-GW01A Wisualarm Internet Gateway\u003c\/strong\u003e to the WisuLink network connects all paired devices to the internet, enabling push notifications to the free Wisualarm app on your smartphone. If you primarily want wireless interconnect and app notifications from the outset, consider the \u003cstrong\u003eDHI-HY-HT5MA\u003c\/strong\u003e which has WisuLink built-in.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"wu-faq-item\"\u003e\n    \u003ch3\u003eHow often should I replace the 9V backup battery?\u003c\/h3\u003e\n    \u003cp\u003eThe unit will alert you when the backup battery is depleted via the yellow LED flashing once per minute and an audible beep. As a general maintenance practice, it is good practice to test the alarm monthly (press the test button) and replace the 9V battery at least once a year, or at whatever interval your property management schedule or regulations require. In Scotland, the Tolerable Standard requires that smoke and heat alarms are regularly tested and maintained — battery replacement forms part of this obligation.\u003c\/p\u003e\n  \u003c\/div\u003e\n\u003c\/div\u003e","brand":"Wisualarm","offers":[{"title":"Default Title","offer_id":63582299717981,"sku":"DHI-HY-HT5MB","price":27.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0958\/2051\/3629\/files\/wisualarm-hy-ht5mb-mains-powered-heat-alarm.webp?v=1771923819","url":"https:\/\/qualityheating.co.uk\/products\/wisualarm-mains-powered-heat-alarm-grade-d2-class-a1-54-65-c-9v-battery-backup-wired-interconnect","provider":"AIZO Quality Heating","version":"1.0","type":"link"}