One area of audit failure is when a boiler is incorrectly identified. This can lead to a variance in the rating
and/or the recommendations on the EPC. If the rating varies by more than 5 SAP points or if there is an
incorrect recommendation (or lack of correct recommendation), then the EPC will fail for technical reasons
and you will need to relodge the report. It is therefore vital that you identify the boiler correctly.
This document will focus on the heating systems that are identifiable via the PCDF database and via the
SAP table method. It will also focus on the traditional heating systems involving a boiler. Any heating system
that can ONLY be inputted via the SAP table method is not included. The rarer systems are also not
covered. You should consult the RdSAP Methodology Manual, located in the Stroma members area, for a
more detailed breakdown of all heating systems available in RdSAP.
Let’s begin by looking at the type of boiler in a domestic property. Boilers are split into two types of system:
Regular/standard boilers (sometimes called system boilers)
If you assess a property with a regular boiler (this is a boiler that does space heating only). The water heating should be provided by the main system, even if the tank has an immersion heater. This is assumed to heat the water in summer and should not be selected.
A regular boiler can be described and identified as:
The boiler heats the water that flows around the heating and hot water systems.
The water used for heating is fed from a header or feed tank usually found in the loft.
As the water flows around the heating system, it expands. An expansion pipe is fitted to the heating system to discharge any build up in pressure in the system to the header tank.
More modern sealed systems do not require the feed/expansion tank as they have expansion vessels instead.
Usually only 3 pipes (gas supply, flow and return)
Hot water tank usually present
Simple boiler design – few controls on boiler
You should always record the heating system via the PCDF method if you can identify the make and model of the boiler. A photograph should be taken to prove this. If you cannot locate the boiler in the PCDF or the boiler has no make and/or model qualifier then you should use the SAP table data entry method.
Regular Boiler with no cylinder located As mentioned above, you would typically find this type of boiler in conjunction with a hot water cylinder. From time to time, you may find that you cannot locate the cylinder. In this case please enter the following:
Your site notes should back this up (i.e. a relevant note or photo showing suspected location). If you can be sure that the cylinder has been removed, then you need to do the following in the RSAP+ software:
Water Heating Type – No Water Heating Present
You will need to document this adequately in your site notes – i.e. annotated photo showing space where cylinder should be with disconnected pipework.
You should always record the heating system via the PCDF method if you can identify the make and model of the boiler. A photograph should be taken to prove this. If you cannot locate the boiler in the PCDF or the boiler has no make and/or model qualifier then you should use the SAP Table data entry method.
These are more efficient/more modern versions of the two standard types of boiler. There are:
Condensing combi boilers; and
Condensing regular boilers
They are identified by the presence of a white or grey plastic pipe that carries the liquid condensate from the
Condensing combi with white pipe Condensate pipe on exterior of property
You should always record the heating system via the PCDF method if you can identify the make and model of the boiler. A photograph should be taken to prove this. If you cannot locate the boiler in the PCDF or the boiler has no make and/or model qualifier then you should use the SAP table data entry method. Back Boiler
Another common type of heating system uses a back boiler for heat and water heat generation.
Back boilers can be fuelled by many fuel types. They are normally located behind a fire – hence the name
They are always standard boilers connected to a cylinder, or there will be a multipoint water heater
elsewhere in the property.
A clue to their location is that the programmer is normally located on the chimney breast, next to the fire
which contains the back boiler.
It is possible to install a modern condensing back boiler, but they are difficult to upgrade due to their location.
Instead of upgrading the back boiler, the boiler is normally relocated and a standard or combi condensing
boiler is installed. Therefore back boilers are becoming rarer as time goes on.
The key to identification is locating the boiler itself. It is likely that that a boiler won’t be immediately found
within the property, but there will be a gas fire with radiators present. The boiler will be hidden behind the fire
making the exact make and model difficult to ascertain. Indeed, it becomes very difficult to take photographic
evidence of the make and model as the identification panel is often difficult to access.
Electric CPSU This appliance incorporates the provision of space heating and hot water. The hot water store should be at least 70L and integral to the appliance.
Key ways to identify a CPSU:
The appliance is larger than a conventional boiler and floor mounted
There will be no separate hot water tank
Electric CPSUs are similar to gas CPSUs – it must have at least 270l of water storage o Otherwise it should be classed as an electric water storage boiler
All units are quite large, around 1.8m tall and usually found in a ventilated internal cupboard. If a CPSU is selected in the software it is not necessary to include the cylinder details as this information is assumed by RdSAP. In the water heating section of the software select ‘from main system’ and ‘no cylinder.’
Electric Central Heating
Electric central heating can be found in several different forms. They are not normally found on the PCDF but there are certain systems are on the database, so this should be consulted first before using the SAP data entry method.
Electric direct acting boiler This boiler type is increasing in popularity, particularly in modern flat developments. The unit is a narrow device about 1 metre long. It can provide wet central heating and hot water if connected to a hot water tank. The units are usually found attached to the wall in a cupboard with the hot water tank. They can be fitted in properties with peak or dual rate tariffs but they are not considered to be storage systems as they do not fully utilise the off peak rate. Common examples of an electric direct acting boiler are the Heatrae Sadia Amptec and Trianco Aztec Classic. Key ways to identify an electric direct acting boiler:
Attached to a pipe in a cupboard (airing cupboard)
Normally next to the water cylinder
It is about 1m tall
Electric CPSU and electric storage boiler These look similar but the key distinctions are as follows:
An electric CPSU will have a storage capacity of at least 270L and will be around 1.8m tall
An electric storage boiler will have less than 270L of water storage and will be smaller
Electric dry core storage boiler This works in a similar way to an electric storage heater, using off peak electricity to heat bricks inside the boiler. Heat from the bricks is blown onto an air-to-water heat exchanger to provide space and water heating.
Heating systems: Boiler Identification
We have now covered the main type of heating systems. We will now cover the two methods of entering these into the software:
Via the PCDF database
Via a generic description using the SAP table data entry
Incorrect boiler identification is a major audit failure point. Over 40% of incorrect boiler identification
results in audit failure. The errors which are identified under the boiler identification tab are:
The incorrect boiler has been entered onto the software according to the evidence provided
We have been unable to verify the make and model of the boiler due to insufficient evidence of the
boiler ID plate (blurred photographs or none at all)
The DEA has provided no photos of the boiler identifying features to allow the auditor to enter a
generic model into the software.
There are two methods of entering in a boiler:
Via the PCDF database – if the make and model are known and the exact boiler appears in the
Via the SAP table data entry method – if the boiler isn’t in the PCDF or cannot be identified