This appendix sets out the method to be used to determine the gross seasonal efficiency of domestic boilers in Ireland for inclusion in the HARP database, for particular gas and oil boilers when test data have been obtained to establish conformity with Council Directive 92/42/EEC1.
Manufacturers’ declarations of gross seasonal efficiency values calculated in this way should be accompanied by the form of words and certification below, and BER assessors should look for the same form of words in order to ascertain that the efficiency value referred to is appropriate for DEAP calculations.
Range cooker boilers with twin burners are covered here.
1 - Council Directive 92/42/EEC on efficiency requirements for new hot water boilers fired with liquid or gaseous fuels. Official Journal of the European Communities No L/167/17. 21 May 1992, p. 92.
A gas or liquid-fuelled appliance designed to provide hot water for space heating. It may be designed to provide domestic hot water as well.
A boiler designed to make use of the latent heat released by the condensation of water vapour in the combustion flue products. The boiler must allow the condensate to leave the heat exchanger in liquid form by way of a condensate drain. ‘Condensing’ may only be applied to the definitions below from “Regular boiler” to “Modulating combined primary storage unit (CPSU)” inclusive. Boilers not so designed, or without the means to remove the condensate in liquid form, are called non-condensing.
A boiler providing domestic hot water indirectly via a separate hot water storage cylinder which does not have the capability to provide domestic hot water directly (in other words, not a combination boiler).
A regular boiler without the capability to vary the fuel burning rate whilst maintaining continuous burner firing. This includes those with alternative burning rates set once only at time of installation, referred to as range rating.
A regular boiler with the capability to vary the fuel burning rate whilst maintaining continuous burner firing.
A boiler with the capability to provide domestic hot water directly, in some cases containing an internal hot water store.
A combination boiler without an internal hot water store, or with an internal hot water store of capacity less than 15 litres.
An instantaneous combination boiler that only has a single fuel burning rate for space heating. This includes appliances with alternative burning rates set once only at time of installation, referred to as range rating.
An instantaneous combination boiler with the capability to vary the fuel burning rate whilst maintaining continuous burner firing.
A combination boiler with an internal hot water store of capacity at least 15 litres but less than 70 litres,
OR
a combination boiler with an internal hot water store of capacity at least 70 litres, where the space heating circuit supply is not taken directly from the store. If the store is at least 70 litres and the space heating circuit supply is taken directly from the store, treat as a CPSU.
A storage combination boiler that only has a single fuel burning rate for space heating. This includes appliances with alternative burning rates set once only at time of installation, referred to as range rating.
A storage combination boiler with the capability to vary the fuel burning rate whilst maintaining continuous burner firing.
A single appliance designed to provide both space heating and domestic hot water with a burner that heats a thermal store containing mainly primary water which is common with the space heating circuit. The store must have a capacity of at least 70 litres and the feed to the space heating circuit must be taken directly from the store. The appliance does not have the capability to vary the fuel burning rate whilst maintaining continuous burner firing. This includes units with alternative burning rates set once only at time of installation, referred to as range rating.
A single appliance designed to provide both space heating and domestic hot water, where a burner heats a thermal store containing mainly primary water which is in common with the space heating circuit. The store must have a capacity of at least 70 litres and the space heating circuit supply must be taken directly from the store. The appliance has the capability to vary the fuel burning rate whilst maintaining continuous burner firing.
A non-condensing boiler designed as a low temperature boiler and tested as a low temperature boiler as prescribed by the Boiler Efficiency Directive (part load test carried out at average boiler temperature of 40°C).
A facility within an instantaneous combination boiler whereby water within the boiler may be kept hot while there is no demand. The water is kept hot either (i) solely by burning fuel or (ii) by electricity or (iii) both by burning fuel and by electricity, though not necessarily simultaneously. In some cases, it is not possible to identify if there is a keep-hot facility, if it is timed and the fuel type used for the keep-hot facility. In these cases, the following guidance applies:
The method of calculation is applicable only to boilers where the full load and the 30% part load efficiency values, obtained by the methods deemed to satisfy Council Directive 92/42/EEC, are available. These are net efficiency values. It is essential that both test results are available and that the tests are appropriate to the type of boiler as defined in Council Directive, otherwise the calculation cannot proceed.
In the calculation method, the data is first converted to gross efficiency under test conditions, and then converted to a seasonal efficiency value that applies under typical conditions of use in a dwelling, allowing for standing losses.
In this appendix, efficiencies are expressed in percent. Intermediate calculations should be done to at least four places of decimals of a percentage, and the final result rounded to one decimal place.
The procedure to be adopted in calculating the gross seasonal efficiency is as follows:
1. Determine fuel for boiler type.
The fuel for boiler type must be one of natural gas, LPG (butane or propane) or oil (kerosene or gas oil or biodiesel). The HARP gross seasonal efficiency cannot be calculated for other fuels for these appliances.
2. Obtain test data.
Retrieve the full-load net efficiency and 30% part-load net efficiency test results. Tests must have been carried out using the same fuel as the fuel for boiler type, except as provided in D4.
3. Reduce to maximum net efficiency values.
Table 4.17 gives the maximum values of net efficiency for each fuel that may be used for the purposes of DEAP. Reduce any greater test value to the appropriate value given in Table 4.17.
| Condensing boilers | Non-condensing boilers | ||
|---|---|---|---|
| Full load | 30% part load | Full load | 30% part load |
| 101.0 | 107.0 | 92.0 | 91.0 |
4. Convert the full and 30%-part load efficiencies from net values to gross.
Use the following equation with the appropriate factor from Table 4.18.
Egross = f × Enet
| Fuel | Net-to-gross conversion factor, f |
|---|---|
| Natural gas | 0.901 |
| LPG (propane or butane) | 0.921 |
| Oil (kerosene or gas oil or other biofuel) | 0.937 |
Where boiler test efficiency data is provided on a gross rather than net basis, then f is assumed to be 1. In this case, the maximum gross efficiency value is calculated by multiplying the Table 4.17 value by the net-to-gross conversion factor from Table 4.18. For example, the maximum full load gross efficiency where gross calorific value (GCV) based efficiency is provided for a condensing gas boiler is 0.901*101 = 91.001%.
5. Categorise the boiler
a) Select the appropriate category for the boiler according to the definitions given above.
b) If a gas or LPG boiler, determine whether it has a permanent pilot light:
if it has a permanent pilot light, set p = 1
if not, set p = 0
c) In the case of a storage combination boiler (either on/off or modulating), determine from the test report whether the losses from the store were included in the values reported (this depends on whether the store was connected to the boiler during the tests):
if the store loss is included, set b = 1
if not, set b = 0
d) In the case of a storage combination boiler or a CPSU, obtain the store volume, Vcs, in litres from the specification of the device and the standby loss factor, L, using the following equation:
if t < 10mm : L = 0.0945 – 0.0055t
if t ≥ 10mm : L = 0.394/t
where t is the thickness of the insulation of the store in mm.
6. Calculate the gross seasonal efficiency
a) Use the boiler category and other characteristics as defined in D1 (non-condensing or condensing; gas or LPG, or oil; on/off or modulating) to look up the appropriate HARP equation number in Table 4.19. If no equation number is given the calculation cannot proceed. Otherwise, select the appropriate equation from Table 4.20 or Table 4.21.
b) Substitute the gross full and part load efficiencies (found in step 4) and p, b, V and L (found in step 5). Round the result to one decimal place; to nearest 0.1%. Note the result as [x] for the purpose of the declaration below.
| HARP equation numbers for different boiler types | non-condensing (see D1.2) | low-temperature (see D1.15) | condensing (see D1.2) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Gas or LPG | Oil | Gas or LPG | Oil | ||||||
| on/off (see D1.4, D1.8, D1.11, D1.13) | Modulating (see D1.5, D1.9, D1.12, D1.14) | on/off (see D1.4, D1.8, D1.11) |
modulating (see D1.5, D1.9, D1.12) |
on/off (see D1.4, D1.8, D1.11, D1.13) | Modulating (see D1.5, D1.9, D1.12, D1.14) | on/off (see D1.4, D1.8, D1.11) |
modulating (see D1.5, D1.9, D1.12) |
||
|
regular boiler (see D1.4, D1.5) |
101 | 102 | 201 | X | X | 101 | 102 | 201 | X |
|
instantaneous combi boiler (see D1.7, D1.8, D1.9) |
103 | 104 | 202 | X | X | 103 | 104 | 202 | X |
|
storage combi boiler (see D1.10, D1.11, D1.12) |
105 | 106 | 203 | X | X | 105 | 106 | 203 | X |
|
combined primary storage unit (see D1.13, D1.14) |
107 | 107 | X | X | X | 107 | 107 | X | X |
| Gas or LPG boiler type | Eq. No. | Equation |
|---|---|---|
| D1.4: On/off regular | 101 | E = 0.5(Efull + Epart) – 2.5 – 4p |
| D1.5: Modulating regular | 102 | E = 0.5(Efull + Epart) – 2.0 – 4p |
| D1.8: On/off instantaneous combination | 103 | E = 0.5(Efull + Epart) – 2.8 – 4p |
| D1.9: Modulating instantaneous combination | 104 | E = 0.5(Efull + Epart) – 2.1 – 4p |
| D1.11: On/off storage combination | 105 | E = 0.5(Efull + Epart) – 2.8 + (0.209 × b × L × Vcs) – 4p |
| D1.12: Modulating storage combination | 106 | E = 0.5(Efull + Epart) – 1.7 + (0.209 × b × L × Vcs) – 4p |
|
D1.13: On/ off combined primary storage unit (condensing and non-condensing) D1.14: Modulating combined primary storage unit (condensing and non-condensing) |
107 | E = 0.5(Efull + Epart) – (0.539 × L × Vcs) – 4p |
| Oil boiler type | Eq. No. | Equation |
|---|---|---|
| D1.3: Regular | 201 | E = 0.5(Efull + Epart) |
| D1.7: Instantaneous combination | 202 | E = 0.5(Efull + Epart) – 2.8 |
| D1.10: Storage combination | 203 | E = 0.5(Efull + Epart) – 2.8 + (0.209 × b × L × Vcs) |
Manufacturers wishing to declare their products’ seasonal efficiencies for the specific purposes of calculating DEAP ratings can do so provided that:
a) they use the HARP calculation procedure given above; and
b) he necessary boiler test data and the calculations are certified by a notified body accredited for the testing of boilers by an EU national accreditation service. The notified body must certify that: ‘the full load and part load efficiency test results detailed in [insert reference to report on the efficiency tests] have been obtained by methods deemed to satisfy the Boiler Efficiency Directive’.
Where a manufacturer declares the HARP gross seasonal efficiency, it shall be expressed as:
“Gross seasonal Efficiency (HARP) = [x]%
The value is used in the Irish Government’s Dwelling Energy Assessment Procedure (DEAP) for energy rating of dwellings. The test data was certified by [insert name and/or identification of notified body].”
Data for several products may be presented in tabulated form, in which case the second paragraph of the declaration should be incorporated as a note to the table.
If the fuel for boiler type is LPG but the fuel used to obtain efficiency test results is natural gas, gross seasonal efficiency may be calculated subject to certain conditions using the procedure given below. The value of gross seasonal efficiency will be lower than if the fuel used to obtain the test results had been LPG.
Note: A non-condensing range cooker boiler without the capability to provide domestic hot water directly (in other words, not a combination boiler) may nevertheless provide domestic hot water indirectly via a separate hot water storage cylinder exactly matches the definition D1.3 for a regular boiler. Consequently, the methods deemed to satisfy 92/42/EEC for a regular boiler will equally satisfy this requirement for the equivalent type of range cooker boiler.
Efficiencies relate to heat transferred to water and are calculated with the cooker burner turned off.
When undertaking the efficiency test, record:
Note: Independent test laboratory is qualified in D6 b).
2. Calculate the gross seasonal efficiency according to D2 using the appropriate equation for a regular boiler.
3. Calculate the case heat emission at full load from
Φcase = Φinput,net – Φwater – Φflue,net
where
4. If Φcase exceeds either of 0.05 × Φwater or 1 kW, reduce Φcase to 0.05 × Φwater or 1 kW (whichever is the smaller).
5. Provide the values of Φcase and Φwater in kW as part of the test report.
Manufacturers wishing to declare their products’ gross seasonal efficiencies and case emission values for the specific purposes of calculating DEAP ratings can do so provided that:
a) They use the calculation procedure given in D5 above;
and,
b) The necessary boiler test data and calculations are certified by an independent test laboratory notified under the Council Directive 92/42/EEC on efficiency requirements for new hot-water boilers fired with liquid or gaseous fuels (known as a ’notified body’).
Where a manufacturer declares the seasonal efficiency and the case emission value, it shall be expressed as:
Data for several products may be presented in tabulated form where the last paragraph of the declaration should be incorporated as a note to the table.