Dorchester DR-LA and DR-LP Brochure

Dorchester DR-LA & DR-LPFully Automatic & Permanent Pilot Direct Gas Fired Storage Water Heaters Continuous outputs 621 l/h to 2105 l/hHamworthy2 Reduced installation costs Direct fired to maximise seasonal efficiency Exceeds Part L minimum requirements System design flexibility Anode protection to guard for long life Easy service and maintenanceA choice of draught diverter on the DR-LA and DR-LP water heaters simplifies installation in replacement projects, to match existing flue systems.Horizontal flue off-take for simplifying the flue system when replacing old water heaters.Dorchester DR-LA & DR-LPDirect Gas FiredStorage Water HeatersOptions Natural gas or LPG Choice of flueoff-take position Unvented supply kit Electrical anode protection Close temperaturecontrol kit (DR-LA) Top to bottom pump recirculation kit Flexible replacement anodesHamworthy Dorchester DR-L water heaters offer a practical and efficient means of producing domestic hot water. These multi-tube gas fired storage water heaters are available with a choice of permanent pilot ignition through the DR-LP range, or with fully automatic ignition in the DR-LA range. All DR-L models are fitted with an atmospheric burner and are suitable for firing Natural gas or LPG.There are 7 models in the Dorchester DR-LA range with continuous outputs from 621 to 2105 litres/hour, based on a 44°C temperature rise. The DR-LP is available in 6 models, up to 1838 litres/hour .Storage capacities range from 264 to 374 litres. Dorchester water heaters are constructed from high grade steel and fully fabricated before the application of a high quality vitreous enamel lining, ensuring the integrity of the lining. The cylinder is insulated with a 50 mm layer of CFC-free foam to minimise standing losses. All Dorchester water heaters are designed to meet HSC requirements for the control of Legionellosis. Two large inspection doors provide access for servicing and maintenance and connections are provided to facilitate top to bottom recirculation which ensures an even temperature is maintained throughout the vessel, preventing stratification.Dorchester water heaters are suitable for open vented or unvented systems using an optional unvented supply kit.BENEFITS3Controlling LegionellaLegionella bacteria are common in natural water sources and therefore low concentrations may be present in many water systems. It is important that hot water services are designed and operated in such a way that these organisms are prevented from multiplying.Water temperature is a significant factor in controlling the risk, with optimum conditions for bacterial growth occurring between 20°C and 45°C.Regular cleaning of the system will help to avoid the build up of sediments which may harbour or provide nutrients for the bacteria.Water stagnation may encourage the growth of biofilm, which can provide local conditions that may promote the proliferation of legionella bacteria.Designed for SafetyThe Health and Safety Commission (HSC) approved code practice and guidance document L8, makes it clear that if the risk of Legionella is to be minimised, then the recommendations must be observed in so far as they relate to hot & cold water systems.Dorchester water heaters conform to these requirements as follows:• Access for cleaning.• Generous flow and return connections.• Adequately sized drain connection.• Base designed to avoid sludge traps.• Anodes to reduce metal corrosion.• Designed to meet unvented supply requirements.• Number of tappings correctly positioned to facilitate recirculation, destratification and to obviate stagnation areas.Typical LayoutDorchester DR-LA & DR-LPDraught diverter with choice of flue off-takeDorchester DR-LA, fully automatic model, with optionsThermostat pocketCombustion products discharge safety device Control panelControl thermostatClose temperature control kit (optional)Clean out doorDrain connectionGas control valveHot water outletPressure and temperature relief valve (optional with unvented kit)Top to bottom recirculation kit (optional)Clean out doorElectrical anode (optional)Cold water inletSight glassGas burner manifold4SpecificationDorchester DR-LA & DR-LPThe Hamworthy Dorchester range of water heaters offers plenty of choice in meeting hot water demands for a wide variety of commercial applications.With currently 7 ranges in the Dorchester family, comprising over 40 models, the DR-L water heaters provide traditional solutions for direct fired storage water heating.Manufactured to the highest standards using the latest production technology to ensure a high quality long lasting finish in every product configuration, the Dorchester range of water heaters exceed the minimum efficiency requirements of the latest Building Regulations, Part L.Compliance is assured with stringent controls in accordance with the European Standards for CE marking, and all models are Water Regulations Advisory Scheme (WRAS) approved.ConstructionThe water heater cylinders are constructed from high grade steel and coated with a high quality vitreous enamel lining. The fabrication of the cylinder and welding is completed fully before the glass lining is applied, ensuring that the integrity of the lining is not affected during manufacture. On completion of the fabrication, the cylinder undergoes a precise glass coating process where the unit is rotated in every direction to ensure an even coating is applied throughout. Surplus material is drained before the unit is baked at 840ºC to complete the adhesion of the lining to all internal surfaces of the cylinder, providing a high quality durable long lasting finish.The cylinder is covered with a 50mm layer of CFC free foam insulation to ensure that standing losses are kept to a minimum. The water heater is finished with a steel clad exterior to provide a robust and smart appearance.Inspection and Clean Out DoorsDorchester DR-LA and DR-LP models have two large inspection doors to provide easy access for the inspection and cleaning of the tank's interior, as required by the recommendations of the HSC for the control of Legionellosis, including legionnaires disease.Burner SystemThe burner arrangement consists of multiple stainless steel burner bars, the number of which varies according to the output of each model. The atmospheric burner assembly is mounted below the cylinder, and by nature of the design, is very quiet in operation.Heat ExchangerMultiple vertical fire tubes are arranged through the cylinder, and each fire tube is fitted with a steel baffle in order to maximise the heat transfer.The fire tubes exit the cylinder through a single terminal which is connected to the flue system via the draught diverter.Draught Diverter (Choice of flue off-take position)A draught diverter is supplied loose for fitting to the cylinder on site, and is specifically engineered to optimise the performance of each model. The draught diverter locates on a spigot on the heater flue connector and can be rotated to facilitate easier connection to the flue system.There is a choice of draught diverter available to simplify the flue arrangements on replacement projects. The draught diverter can be supplied with either an angled flue off-take of a horizontal off-take. See dimensional drawings on page 9 for more details. The draught diverter type must be specified at the time of ordering.Dorchester DR-LP, permanent pilot model.5Combustion Products Discharge Safety DeviceIf a water heater is to be installed in a habitable area then it is a requirement of EN 89 that it be fitted with a device that detects the spillage of combustion products and shuts down the appliance. A habitable area includes kitchens, shower blocks, workshops or any other area that is occupied.A combustion products discharge safety device is fitted as standard on DR-LA and DR-LP water heaters, and comprises a thermostat that is fitted to the rim of the draught diverter. In the event of flue gas spillage occurring, due to down draught or lack of buoyancy in the flue system, the thermostat will shutdown the heater.LPG FuelsAll Dorchester water heaters are suitable for Natural Gas or LPG fuel. The fuel type must be specified at the time of ordering.It is strongly recommended that on LPG installations, gas detection equipment is fitted and that this equipment is positioned near the heater and at low level. It is also imperative that the plant room is ventilated at high and low level.Permanent Pilot Ignition (DR-LP)On Dorchester DR-LP models there is a permanent pilot ignition system with automatic gas valve and safety pilot which is monitored by means of a thermocouple device. A piezo spark device is fitted to provide ignition for the pilot flame.Fully Automatic Ignition (DR-LA)Dorchester DR-LA models are equipped with a fully automatic ignition system. A fully electronic soft start gas valve and hot surface ignition ensures reliable burner operation.Anode ProtectionDR-LA and DR-LP models are all fitted with removable magnesium sacrificial anodes as standard, ensuring excellent protection against corrosion. Clearance is required above the unit for maintenance and replacement of the magnesium sacrificial anodes.Flexible Magnesium Sacrificial Anodes (Optional)Flexible replacement magnesium anodes can be ordered as an option where clearance above the unit is restricted. The fixed anodes can be used from installation, and when in need of replacement, then the flexible anodes can be used.Electrical Anode Protection (Optional)In areas of the country with particularly soft water supplies having electrical conductivity less than 200 micro-siemens, such as Scotland, Devon and Cornwall, magnesium sacrificial anodes may not be fully effective in providing protection against internal corrosion. The optional electrical protection replaces the magnesium sacrificial anodes and is effective in providing internal corrosion protection with water supplies having electrical conductivity levels as low as 125 micro-siemens. A further benefit of this system is that it can remove the need for the full clearance required for maintenance above the heater.It is essential for correct operation that an uninterrupted 24-hour power supply is maintained at all times to ensure proper protection of the unit.Electrical anode protection will be factory fitted where specified at the time of ordering.Open Vented or Sealed SystemsThe water heaters are suitable for open vented or unvented systems using an optional unvented supply kit. Unvented Supply Kit (Optional)All Dorchester water heaters are suitable for installation in direct unvented systems. The expansion vessel is sized for the water heater and local pipe work only, and should be re-sized if used on larger systems.Unvented supply kit for local use.The unvented supply kit allows the water heater to be fed directly from the mains water supply or from a booster pump set without the need for header tanks. The kit contains all the essential components to comply with the Water Supply (water fittings) Regulations 1999, including a suitably sized pressure and temperature relief valve, which locates directly into the water heater. Refer to page 10 for more details.Temperature ControlThe outlet temperature of the heater is regulated by the control thermostat which is housed in the control panel. The operating temperature set point is adjustable from 40°C to 70°C with two-stage limit protection. An intermediate limit temperature setting of 84°C will prevent the burner firing until temperature conditions return to normal, when the unit will reset automatically via the control panel. The high temperature limit setting is 93°C, at which point the unit will shut down and require manual reset.6SpecificationDorchester DR-LA & DR-LPTop to Bottom Pump Recirculation Kit (Optional)In order to prevent stratification within the heater, thus creating a zone of lower temperature water that can possibly lead to the proliferation of Legionella bacteria, a top to bottom re-circulation kit should be specified. The top to bottom circulator should be controlled to run during the anti-legionella purge cycle. Alternatively, by constantly returning water from the flow connection back into the base of the heater, a uniform temperature is maintained.The kit includes a pump, isolation valves, non-return valve and pipe work for fitting on site.Close Temperature Control Kit (Optional DR-LA)For applications requiring above average temperature control, an optional electronic thermostat kit can be fitted. This will provide close control of the flow temperature within ±2.5°C, dependent on the operating conditions.Control Panel - DR-LADR-LA, fully automatic models, have a pre-wired control panel which includes on/off switch, control thermostat, power indicator, lockout indicator and reset button. Volt free contacts and a frost protection thermostat are fitted as standard. A fully electronic soft start gas valve and hot surface ignition ensures reliable burner operation.Volt Free Contacts - DR-LADR-LA models are equipped with volt free contacts to facilitate remote signalling, for integration with a controls system or for remote monitoring.The volt free contacts indicate lockout and normal run conditions.Frost Protection - DR-LADorchester DR-LA water heaters are supplied as standard with a frost protection thermostat. When the on/off switch on the control panel is in the off position, the frost protection system will initiate firing of the burner when the stored water temperature falls below the set point, to provide protection against freezing in the cylinder.DeliveryDorchester water heaters are delivered factory assembled and mounted within protective frames, shrink wrapped and on a timber pallet base.Draught diverters are supplied separately in a cardboard carton for fitting on site.All Hamworthy products are delivered to site on a tail-lift vehicle, and deliveries are closely co-ordinated with the customer, to suit the on-site construction programme. Standard delivery is to ground level from the tail-lift vehicle. To enquire about special delivery services, please contact our customer services team. Tel: 0845 450 2865.CommissioningHamworthy Heating strongly recommend that all water heaters are commissioned by their service department who will issue an appliance log book that details the initial operating settings, and which can be used to record all future maintenance work.For more information on commissioning, contact Hamworthy Heating Service department. Telephone 0845 450 2866, or email service@hamworthy-heating.comMaintenanceInstalled water heaters will experience a wide variation in operating conditions that can occur due to the variable chemical nature of distributed water supplies. It is therefore strongly recommended that water heaters be drained and inspected within 3 months of the initial commissioning. Once the level of calcium deposition and rate of anode decay are established, a suitable maintenance schedule can be implemented, however as a minimum, all water heaters should be serviced annually.Water TreatmentDue to the variable chemical composition of distributed water supplies it is necessary to identify the properties of the cold water feed to the water heater, with the local water provider.Appropriate water treatment, where advised, to reduce scale build up, should be referred to water treatment specialists.Control Panel.Top to Bottom Recirculation Kit.Close Temperature Controller.7Technical DataDorchester DR-LA & DR-LPPerformance and General Data InformationModels DR-LA/LP 30DR-LA/LP 40DR-LA/LP 45DR-LA/LP 60DR-LA/LP 75DR-LA/LP 95DR-LA 110Continuous output with 44°C ?t l/h UK gal/h621 137822 181965 2121199 2641427 3141838 4052105 463Continuous output with 50°C ?t l/h UK gal/h546 120723 159849 1871055 2321256 2761617 3561852 407Storage capacity litres UK gal324 71374 82312 69351 77291 64265 58264 58Time to recover storage 44°C ?t mins 32 28 20 16 13 9 7Time to recover storage 50°C ?t mins 36 31 22 20 14 10 9Output maximumkW 31.7 42.0 49.3 61.2 72.9 93.9 107.5btu/h (x1000) 108 143 168 209 249 320 367Input (gross) maximumkW 41.4 55.5 65.2 81.0 96.4 124.2 140.5btu/h (x1000) 141 189 222 276 329 424 479Input (nett) maximumkW 37.3 50.0 58.7 73.0 86.8 111.9 126.6btu/h (x1000) 127 171 200 249 296 382 432Maximum water pressure bar 8Gas flow rate natural gas (G20) – Maximum m3/h 4.0 5.4 6.3 7.8 9.4 12.1 13.7Gas flow rate propane (G31) - Maximum m3/h 1.6 2.2 2.5 3.1 3.8 4.9 5.5Nominal gas inlet pressure natural gas (G20) mbar 20Maximum gas inlet pressure natural gas (G20) mbar 25Maximum flue gas temperature °C 180 200 200 180 180 200 185Water flow and inlet connection in 1½” RpGas connection in ¾” Rp 1” RpDrain connection in 1½” RpT & P Valve connection in 1” NPT 1½” RpDraught diverter spigot ID horizontal connection mm 150 180 225Draught diverter spigot ID angled connection mm 150 180 225Nominal supply voltage 230V, 1Ph, 50HzApprox. shipping weight kg 214 237 227 262 262 278 3308Dimensional DetailsDorchester DR-LA & DR-LPModels DR-LA/LP 30DR-LA/LP 40DR-LA/LP 45DR-LA/LP 60DR-LA/LP 75DR-LA/LP 95DR-LA 110Overall height A 1900 2100 1900 2040 2000 2025 2085Cylinder height B 1760 1960 1760 1900 1795 1810 1870Horizontal DD C 1640 1840 1640 1695 1565 1580 1640Angle 45° DD C 1480 1680 1480 1620 1510 1535 1595Horizontal DD D 285 325Angle 45° DD D 290 330Width inc. DD E 1100 1105Horizontal DD F 255 340 395Angle 45° DD F 355 390Flue spigot dia. G 150 180 225Flue centre line H 640 675Flue centre line J 1840 2040 1840 1980 1935 1950 2010Gas Connection Auto K 400 340 400 340 205Gas Connection Pilot K 205 145 205 145 NAHorizontal DD L 970 1055 1110Cold water inlet M 565 1810 1605 1750 1640 1655 1715Hot water outlet N 1605 1810 1605 1750 1640 1655 1715Inspection door P 730 670 740 765 855Drain R 500 515 500 455 525 540 595T&P valve S 1550 1760 1550 1700 1595 1600 1660Horizontal DD T 610 695 750Angle 45° DD T 745 750Horizontal DD V 360Angle 45° DD V 155 180DD= Draught Diverter Auto=DR-LA models Pilot=DR-LP modelsNote: The draught diverter rotation is slightly less than the open vented option, to allow clearance around T&P valve on unvented models.Unvented Water Heater Draught Diverter Rotation Open Vented Water Heater Draught Diverter RotationField of rotation fordraught diverter - 200°Field of rotation fordraught diverter - 243°Pipeconnections8° 8°12°55°T&P valvePipeconnectionsField of rotation fordraught diverter - 200°Field of rotation fordraught diverter - 243°Pipeconnections8° 8°12°55°T&P valvePipeconnections9Dimensional DetailsDorchester DR-LA & DR-LP1000800 D500500 50045710L1000TFVGS NKRMCAPB JGas connectionDrain valve &recirculationconnectionCold water inletInspection doorHot water outletT&P valveHorizontal Draught Diverter ArrangementGas connectionH45G710FV1000ABM RKPSCNJDrain valve &recirculationconnectionCold water inletInspection doorHot water outletT&P valve800500 E500500T1000DAngle 45° Draught Diverter ArrangementPlan View Side ViewNote: Draught diverter must be specified at time of ordering - Horizontal or 45 degree angled off-take.Plan View Side View10Unvented SystemsFollowing the publication of Part G3 of the Building Regulations, provisions were issued for the essential safety requirements necessary on unvented hot water storage systems.These requirements are now covered in law by The Water Supply (Water Fittings) Regulations 1999.The safety system comprises of a number of essential controls pre-set to specific and very important pressure and temperature levels.To ensure that the controls are correctly sized for application, set to appropriate levels and assembled in the correct order, Hamworthy Heating offer the unvented kit as a single WRAS approved “water train” with a separate temperature/pressure relief valve sized to suit the energy input of the heater.This considerably simplifies site installation, leaving the installer to connect from the water main to the water train and from the train to the heater.A connection is provided on all DR-L water heaters for the fitting of the temperature and pressure (T&P) relief valve, the discharge of which should be via an air break to a tundish.For comprehensive recommendations on the design, installation and testing of services supplying water within buildings, attention is drawn to the appropriate sections of BS 6700.Unvented Supply Kit (Optional)Each unvented supply kit is designed to be used with an individual water heater. Multiple water heater installations should be specified with one unvented supply kit per water heater.Each unvented supply kit comprises 1" nominal components as follows:• Strainer• Adjustable pressure reducing valvewith tapping points for inlet and outlet pressure measurement• Non return valve• ¾" Expansion relief valve, 6 bar• Temperature and pressure relief valve, 7 bar, 95°C• 24 Litre expansion vessel, 3.5 bar cushion pressureFor large hot water systems or systems with additional storage tanks, alternative expansion vessel capacity may be required. Consult with Technical team for full range of Hamworthy expansion vessels. Tel: 01202 662500.System SchematicsDorchester DR-LA & DR-LPHot water flowSecondary returnTemperatureand pressurerelief valve Top to bottomrecirculation kitHamworthy standardunvented kit assemblyMains coldwater supplyHot water flowSecondary returnMains cold water supplyHamworthy standardunvented kit assemblyTop to bottomrecirculation kitTemperatureand pressurerelief valveDirect unvented supply: single DR-L water heaterDirect unvented supply: two DR-L water heaters11System SchematicsDorchester DR-LA & DR-LPUnvented SystemsFor systems requiring peak load high volumes of hot water, Dorchester DR-L water heaters can be installed with additional storage tanks.Using a loading pump, water is transferred between the water heater and the storage tank creating a large volume hot water store.The loading pump can be thermostatically controlled to turn off once the storage tank reaches set point temperature, saving electrical energy.Cooler secondary return water is re-circulated to the water heater for re-heating.With unvented systems, additional expansion vessel capacity is required to cater for the storage tank volume.Secondary returnHot water flowRelief valveTemperature andpressure reliefvalveTop tobottomrecirculationkitLoadingpumpMains coldwater supplyHamworthy standardunvented kit assemblyDirect unvented supply: single DR-L water heater with storage tankOpen vent pipeCold feedHot water flowTop to bottomrecirculation kitSecondary returnRelief valveFeed andexpansion tankOpen vented supply DR-L water heaterOpen vented systemsWith open vented systems the feed and expansion tank must be sized to provide sufficient cold water storage and accommodate expanded system water without the risk of over flowing.System operating pressure is a direct result of the height of the feed and expansion tank. The feed and expansion tank must therefore be carefully located to ensure sufficient head pressure and flow is maintained at all outlets likely to be operating concurrently.The minimum recommended height for the bottom of the feed and expansion tank above the hot water heater is 2 metres12Power supplyAn independent isolator and fused electrical supply is recommended for each water heater. Supply 230 Volt, 50Hz, single phase. Wiring external to the water heater must be installed in accordance with IEE Regulations and any local regulations which apply. Wiring must be completed in heat resistant 3 core cable, size 1.00 mm2. External fuses should be 6 Amp.Remote EnableEach water heater has the facility for receiving a remote enable signal for connecting external controls such as remote time clocks or BMS. The hard wired link in the water heater control panel must first be removed and the appropriate terminals hard wired to external control. The remote enable control circuit operates at 230V and any external control must be equipped with a volt free contact switching circuit.Remote signallingDorchester DR-LA fully automatic water heaters are supplied with volt free contacts as standard to indicate lockout and normal run. Each set of contacts is BMS compatible and rated up to 230V. Normally open as well as normally closed contacts are provided with each set of contacts. Wiring DiagramsDorchester DR-LA & DR-LP1L1 L2 L3 NNL L LN2 3 4 5 6 7 8 9 10 11 12Remote enable -remove link - rated 230vSupply 230V 1Ph 50Hzfused 6 ampsSupply 230v 1Ph 50Hzfused 6 amps1N L1 L2 L3 NO NCC NO NCC LN LN L L L L LN N2 3 4 5 6 7 8 9 10 1112 13 14 15 16 17 18 19 23 2420 21 22Remote enable -remove link - rated 230vVolt free contact -lockout signalVolt free contact -normal run signalDorchester DR-LA Wiring TerminalsDorchester DR-LP Wiring Terminals13Sizing Guidance NotesDorchester DR-LA & DR-LP Water HeatersThe following notes are given for guide-line purposes and the assumptions made are general. The diversification of hot water requirements are great and each particular application must be examined in detail.General Guide-linesThere are applications where sizing a water heater is a straightforward exercise. An obvious example is an industrial hot water load for a process requiring a specific amount of hot water, in a specified time at a specified temperature. All that is required is the lowest cold water supply temperature and the heater/s output can be directly related to the amount of hot water required. If the load is continuous the heater or heaters must be sized to cope with the full amount. If the load is intermittent consideration can be given to a smaller heater installed in conjunction with a suitably sized storage tank. Other types of installations which can be easily sized are sports pavilions and leisure centres, especially those catering for team games, when a known number of players will use showers, baths etc at a known time.This is in effect the peak load when a large quantity of hot water may be dumped quickly since all showers may be running continuously. For sizing it is necessary to determine the duration of continuous use, which will depend on the maximum number of players using the showers. Showers can save water, but one shower running continuously for 1 hour can dump 328 l (72 gal). Multiplied by 10 or 20 this can represent a large load which is obviously best catered for by storage with a long recovery time. However, due consideration should be given to additional heaters and lower storage on the grounds of standby and cost.The third category comprises almost all other commercial and industrial applications where hot water demand is random. To size the hot water requirement it is necessary to determine when the demand is greatest. Obviously if the water heater can cope with the peak demand, the remainder will be adequately catered for. However, the heater cannot be sized on the assumption that all outlet appliances will run continuously for 1 hour since this will result in gross over -sizing of heaters. Since there are no common usage of diversity factors in general use, simple guide-lines and common sense must be used to estimate “how many times a bath will be used per hour or how long is an average shower, or how many people will bath rather than shower?” Listed below are a series of guide-lines which may prove helpful in sizing Hamworthy water heaters.Restaurants, Kitchens, etc Serving Main MealsEach meal will use:9 litres (2.0 gal) at 60°C (140°F) Made up from:3 litres (0.75 gal) preparation, 6 litres (1.25 gal) washing upThe peak period would be spread over 1, 2 or 3 hours etc, depending on the establishment.Bar sinks - allow 114 litres (25 gal) per hour.School kitchens in general use 30% less than restaurants but allowance should be made for the number of sittings. Hotels and MotelsAssume average occupancy as 1½ people per room unless specified as single rooms. Generally the peak will occur over a two hour period in the morning (7.0am-9am). In specialised hotels catering for specific functions (i.e. conferences) the peak could be reduced to one hour. For medium sized hotels 100-200 people allow 25-35 litres (6-8 gal) hot water per person over two hour peak period. For smaller hotels allow more per person-for larger hotels allow slightly less.These figures assume that mainly showers are used, one per room. For older hotels without showers and public bathrooms assume that baths are filled 3 or 4 times per hour.Always check restaurant load to ensure that peak morning capacity will cover it. Overall, allow 115-135 litres (25-30 gal) per guest per day.DormitoriesAllow 15 litres (3.2 gal) per man, 20 litres (4.2 gal) per woman over a peak 1 hour period.Flats and Apartment BlocksAssume average occupancy of 2½ people per flat. Allow 38 litres (8.4 gal) per person over a peak 3 hour period.Rest and Convalescent Homes - with Kitchen and LaundryAllow 38 litres (8.4 gal) per person over a peak 3 hour period.Industrial Shower RoomsAssume shower period to be 20 minutes at the end of each shift and that all showers and wash taps are running continuously for this period at full flow i.e. dump load ideal for heater plus storage application.School Changing RoomsAssume all showers and wash basins are used at full flow for 10 minutes after each gym period.OfficesAllow 1.5 litres (0.33 gal) per person per hour for 1 hour peak load.Commercial LaundryAllow 6 litres (1.25 gal) per lb of wash at 71°C (160°F).LaunderettesDetermine the cycle time of the machines (add 10 minutes for unloading and reloading). Calculate the number of cycles that occur in one hour and multiply the number of machines and then multiply by the amount of hot water used by one machine in one cycle to arrive at the maximum demand.Hairdressers and Beauty SalonsAllow 280 litres (63 gal) per hour of water at 60°C (140°F) per wash basin per peak demand.Hospitals etc.Demand will depend on the type of hospital, nursing home, etc. Overall consumption per person per day of hot water can range between 70 litres (15.4 gal) - 230 litres (52 gal).14Sizing Guidance NotesDorchester DR-LA & DR-LP Water HeatersIn all applications it is desirable to cross check general assumptions with actual flow rates and capacities and in applications where no general guidelines exist it may be necessary to calculate hot water demand by listing the number and type of appliance in use.The following tables gives the approximate flow rates for standard hot or mixed water fittings and the approximate capacity in normal use. By appraising what function appliances perform it is possible to determine peak usage i.e. 3 bath per hour, 2 showers each of 10 minutes, sinks filled one per hour, etc.Approximate Flow Rates From Standard FittingsFitingFlow ratel/s UK gal/minWash basin tap 0.15 2.0Wash basin spray tap 0.05 0.7Bath tap 0.30 4.0Sink tap 15mm 0.20 2.6Sink tap 20mm 0.30 4.0Shower spray head 0.15 2.0Shower 100mm rose 0.40 5.3Approximate Mixed, Hot and Cold Capacities of Appliances in Normal UseCold water 10°C (50°F), hot water 60°C (140°F), mixed water 40°C (104°F)ApplianceCapacity In Normal UseAmount of Hot WaterAmount of Cold WaterTemperature in Usel UK gal l UK gal l UK gal °C °FWash basin 5 1.1 3.0 0.66 2.0 0.44 40 104Bath 80 17.6 48.0 10.60 32.0 7.00 40 104Small sink 12 2.6 7.2 1.60 4.8 1.00 40 104Large sink 18 4.0 10.8 2.40 7.2 1.60 40 1041 min shower spray 9 2.0 5.4 1.20 3.6 0.80 40 1045 min shower spray 45 9.9 27 5.90 18.0 4.0 40 1041 min shower (100mm rose) 24 5.3 14.4 3.20 9.6 2.10 40 1045 min shower (100mm rose) 120 26.4 72.0 15.80 48.0 10.60 40 104The quantities of hot water shown above are only correct to those particular temperatures. For other combinations use the following formula to determine the proportion of hot water:Quantity of hot water = capacity of appliance x Mixed water temperature - Cold water temperature Hot water temperature - Cold water temperatureFactors at Various Cold Water and Mixed Water Temperature for Determining Hot Water quantity at 60°C (140°F)Cold Water Supply TemperatureMixed Water Temperature60°C 55°C 50°C 45°C 40°C 35°C 30°C5°C 1.0 0.91 0.82 0.73 0.64 0.55 0.4510°C 1.0 0.90 0.80 0.70 0.60 0.50 0.4015°C 1.0 0.89 0.78 0.67 0.55 0.44 0.3320°C 1.0 0.88 0.75 0.63 0.50 0.38 0.25As a further example the table opposite gives the factors by which the capacity of an appliance is multiplied to obtain the quantity of hot water required when stored at 60°C (140°F) for various cold water supply temperatures and various mixed water temperatures.15Having established the number of appliances, the usage, and the quantity of hot water required, the outputs of the heaters must be related to the hot water storage temperature. Any decrease in the cold water supply temperature or increase in the hot water storage temperature will result in a decreased output from the heater.The output figures given are based on a rise in the temperature of 44°C i.e. with a storage temperature of 60°C the cold water supply must be at 16°C. The following table indicates the continuous output of the heater with various temperature rises across the heaters.The normal maximum storage temperature is 60°C and hence 55°C is the maximum rise expected across the heater with a cold water supply temperature of 5°C. It is possible however that for certain applications a higher storage temperature will be required when, if the cold water supply temperature remains at 5°C the calorifier outputs will be further reduced.The question of additional storage if required and how much should be looked at in light of general consumption throughout the day, recovery times, whether the peak period is spread over 1 hour or 3 hours and whether a larger storage buffer than the calorifiers own storage is required to guard against the possibility of high flow rates at peak time.Where the installation requires the use of large volumes of hot water over short periods and a storage tank is specified, a loading pump will be required to transfer hot water from the calorifer into the storage tank. This should be a bronze pump and sized to suit the continuous output of the water heater under design temperature conditions.It is important that cold water supply capacities and pressures as well as pipe work layouts are suitable forhigh volume draw off at peak times to ensure satisfactory hot water delivery to draw off points.One or more storage tanks may be used in conjunction with Powerstock Calorifiers to satisfy hot water demand.ModelTemperature Rise Across Calorifier(Hot Water Temperature – Cold Water Supply Temperature 40°C (72°F) 44°C (80°F) 50°C (90°F) 55°C (100°F)DR-LA/LP 30 683 621 546 497DR-LA/LP 40 904 822 723 658DR-LA/LP 45 1062 965 849 772DR-LA/LP 60 1319 1199 1055 959DR-LA/LP 75 1570 1427 1256 1142DR-LA/LP 95 2022 1838 1617 1470DR-LA 110 2316 2105 1852 1684Powerstock Storage TanksHot Water StoragePowerstock hot water storage tanks are the perfect partner for Dorchester water heaters where large volumes of hot water are required with intermittent use.Available in 300, 500, 750 and 1000 litre capacities, these high quality glass lined storage tanks can be installed in single or multiple configurations to match the hot water demand.Powerstock storage tanks are WRAS approved and suitable for both unvented and open vented applications For further details of Powerstock Storage Tanks, refer to brochure 500002488.Options Unvented supply kit Top to bottom pump recirculation kit Electrical anode protection Electric immersion heater kitCustomer Service CentreHamworthy Heating Limited Fleets Corner, Poole, Dorset BH17 0HH Telephone: 0845 450 2865Email: sales@hamworthy-heating.comWeb: www.hamworthy-heating.comHamworthy reserves the right to make changes and improvements which may necessitate alteration to the specification without prior notice.500002519 AHamworthy Heating AccreditationsISO 9001 Quality Management SystemISO 14001 Environmental Management SystemOHSAS 18001 Health & Safety Management SystemThe printed version of this brochure is produced using environmentally friendly print solutions in partnership with our suppliers