© stroma development ltd 2013 | version 1.2 stroma – hot water systems hot water systems

© Stroma Development Ltd 2013 | Version 1.2Stroma – Hot Water Systems

Hot Water Systems


Water Heating

Main types• From main heating system:

– Regular boiler and hot water tank– Combi boiler

• From additional main system• From secondary heater• Electric immersion heater• Gas multi point heater• Electric instantaneous heater• Range cooker• Community heating


Water Heating

• If the water heating is supplied by the :– main system– additional main system – secondary system

It can be identified as such in the software

• Many hot water tanks have electric immersion heaters fitted, but they are only used as a back up, and are not the main way the water is heated

• Over the next few slides we will cover the different types of systems.


Hot Water Cylinder & Boiler – Indirect System

Non Condensing Regular Boiler feeding radiators and hot water cylinder.

Immersion heater

To taps

From cold water cistern

Flow from boiler

Return to boiler


Conventional System

Boiler

Sink

Sink

Mains water supply

Header tanks

Indirect hot water cylinder


Direct Cylinder

• Some older systems may not have the heat exchange coil in them• These are known as ‘direct’ cylinders as the heated water goes directly

into the cylinder

Immersion heater

To taps


Flow from boiler

Return to boiler


Electric Immersion - Dual


To taps


Sealed System

Most condensing boilers are fitted in a sealed system which has no expansion tanks, just small expansions vessels which take the pressure in the system.

Sink

Sink

Mains water supply

Indirect hot water cylinder

Expansion vessel

Expansion Vessel

Boiler


Pressurised System

• Note the expansion vessel above the hot water tank and below the boiler

• These are used to keep pressure in the system.


Encapsulated cylinders

• Encapsulated cylinders like this becoming more common, appear a lot in recently built properties.

• Tend to have a hard casing, cannot access insulation. Try and get manufacturers details in order to research, manufacturers website tend to have spec. It is fair to assume 50mm of spray foam insulation.


Thermal Storage System

• A thermal storage water cylinder reverses the normal process

• Cold water from the mains enters the coil at the top of the tank and is heated by the surrounding hot water before outputting to the taps.

• Hot water is therefore effectively provided on demand and at mains pressure.


Gledhill System

• Although this system is more efficient than a standard central heating system, RDSAP cannot account for it.

• If you come across a thermal storage system like this then treat it as a standard system with regular boiler and hot water tank.


Multi Point Gas Water Heater

Normally:• Older installations• Supplies hot water only• 3 pipes- gas pipe, cold water

supply, hot water draw off• Often in properties with basic

heating system, e.g. gas fires


Electric Instantaneous at Point of use Water Heaters

• In smaller properties you may come across this method of providing hot water.

• Usually a small unit located near the sink in the kitchen or bathroom.

• It heats the water as required, like an electric shower.


Water heating from additional boiler

• A boiler can provide domestic hot water only– if the specific boiler can be found on the boiler database it can be

entered as additional heating, with the floor area it heats entered as 0% and the water heating ‘from additional heating’

– If the boiler is not on the database it should be entered in the water heating section only, and not as additional heating. The type of boiler can be specified as

• Gas boiler/circulator for water heating only• Oil boiler/circulator for water heating only• Solid fuel boiler/circulator for water heating only


• If the water heating is supplied by a range cooker which does not provide the main heating then it can be specifically identified in the water heating

• The following options are available:– Gas, single burner with permanent pilot light– Gas, single burner with automatic ignition– Gas, twin burner with automatic ignition pre 1998– Oil, single burner– Oil, twin burner pre 1998– Solid fuel, integral oven and boiler– Solid fuel, independent oven and boiler

Water heating from Range cooker


Water heating from community heating

• If the community heating is providing domestic hot water only it can be specified in the water heating section as one of the following options

– Hot water only community scheme – boilers• This is the most likely option as most community heating is a

regular boiler system

– Hot water only community scheme – CHP• This means the community system has combined heat and power,

you must be sure this is present before specifying it

– Hot water only community scheme – heat pump• The community heating should be a heat pump rather than

standard boiler.


Solar Water Heating

If a property has solar heated water there must be:• Solar panels on roof• A store (Hot water tank)• Often additional controls


How Solar Water Heating Works

To taps


Flow from boiler

Return to boiler

Solar collector

Pump

Water heating system with solar collector and twin coil tank


Solar Heated Water

Solar water heating systems use the energy from the sun to heat water, most commonly in the UK for domestic hot water needs.

The systems use a heat collector, generally mounted on the roof in which a fluid is heated by the sun.

This fluid is used to heat up water that is stored in either a separate hot water cylinder or a twin coil hot water cylinder inside the building.

The systems work very successfully in all parts of the UK, as they can work in diffused light conditions.


Solar Heated Water

• There are two types of collector used for solar water heating applications: - Flat plate collectors

- Evacuated tube collectors

The flat plate collector is the predominant type used in domestic systems as they tend to be cheaper and more robust.


Solar Heated Water

Evacuated tube collectors are generally more expensive due to a more complex manufacturing process (to achieve the vacuum) but manufacturers generally claim better winter performance.


Solar Water Heating

• Where solar water heating is present there may be a control panel, these are easily identified by the symbols on the screen


Solar Water Heating

• If this system is present there will be a ‘yes/no’ option in the software. Selecting ‘yes’ will give you the option to enter further details.

• As with other manual entries, documentary evidence must be supplied in order to do so

• Selecting ‘no’ will assume the default value, which is a 3m2 flat glazed panel on a south facing roof


Solar water heating - software


Solar water heating

• Extended Data to be collected: – Collector type – flat plat, evacuated tube or unglazed– Area of panel (aperture) in m2

– Tilt– Orientation– Over shading– Zero loss efficiency – this figure should be in the system documentation– Heat loss coefficient - this figure should be in the system documentation– Solar store combined – is the store part of the existing hot water cylinder– Total hot water volume – if the store is combined, record the cylinder volume– Dedicated solar volume – if the store is separate, record the separate cylinder

volume– Solar circulating pump – is the pump powered by electricity, PV or unknown


Solar water heating

• RdSAP convention 9.09 states:

– Documentary evidence is required to over-write collector or solar stone values except that orientation, tilt and overshading can be overwritten with visual evidence

– If the panel/collector details are available but the solar store information is not, the default values can be used for the solar store

– If the solar store is combined and details are being recorded the volume of the combined cylinder must also be recorded.


Waste Water Heat Recovery

• What is it?– A waste water heat recovery system (WWHRS) uses a heat exchanger to

recover heat from waste warm water as it flows through the waste plumbing system

– This is used to pre-heat the cold water feed of a shower, combi boiler or hot water cylinder.

– The energy recovered depends on the temperature of the cold water feed to the dwelling (which varies by month) and the number and type of systems that are installed

• It is unlikely to be retro-fitted at a property, so it is more likely to be found in modern properties

• You will need documentary evidence to include it as it is unlikely to be visible



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As with FGHRS, WWHRS can only be recorded if it can be found in the database• Up to two of these systems can be entered• WWHRS only work in conjunction with mixer showers

• You will need to determine the following:– Number of rooms with bath and/or shower (any shower)– Number of rooms with mixer shower and No bath– Number of rooms with bath and mixer shower

This information is collected for every survey regardless of the presence of WWHRS. This data determines the recommendation for a WWHRS



• Identifying mixer showers– Mixer showers take water from both hot and cold water supplies. – They mix the hot and cold together to reach a desired temperature. – They generally flow faster than electric showers

• Instantaneous electric showers are not included in the mixer shower count, except for ‘Number of rooms with bath and/or shower’ field



• RdSAP convention 9.08 states:

– Include only if found in database. When the model cannot be found no default option is available but the presence of the device should be recorded in site notes

– Number of rooms with bath and/or shower includes rooms with only an electric shower. If two showers found in a room count as one.

– Only mixer showers count for waste water heat recover. Mixer shower means a shower where the hot water is provided by a boiler (combi or regular), heat pump or immersion heater. A mixer shower attached to bath taps is recorded as a mixer shower only if there is a permanent bracket over the bath and there is a shower curtain or screen.


Hot Water Cylinders

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Hot Water Tanks - Insulation

• The thickness of the insulation should be measured at a point where you can get through to the cylinder.

• With spray foam find an area where the foam has been cut away for connecting pipes

• If the insulation thickness falls between two options in the software then go with the lesser of the two.


Cylinderstat

• The only control a DEA is concerned with on a hot water tank is the cylinder stat.

• Usually to be held onto tank by wire• A common misconception is that a TRV can count as a cylinderstat.


Combined Hot and Cold Water Storage Unit

Cold feed

Flow from boiler

Return to boiler

Mains feed

Hot water

Immersion heater


Typical Hot Water Cylinder Sizes

• Getting the Cylinder size is crucial in your assessment this guide will help you

• Normal Size 90 – 130 Litres

• Medium Size 131- 170 Litres

• Large Size > 170 Litres

Dimensions H x W

Litres

825 x 450

900 x 400

900 x 450

1050 x 400

1050 x 450

1500 x 450

110

96

120

115

144

218


Software

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Any questions?

© stroma development ltd 2013 | version 1.2 stroma – hot water systems hot water systems

Documents

hot water tanks

domestic hot water

surrounding hot water

heated water

water heating section

stroma development

hot water tank combi

cold water supply