Attention K. Lichtenvort
Dated:
Subject:
21 February 2012
LOT1 and PFHRD
Dear Miss Lichtenvort,
In my function as representative of the Dutch boiler manufacturers in EHI and in the European
Standard committee TC109, I have the following requests:
A general request is to follow the existing European Standards in the methods for labelling boilers.
In the opinion of VFK, the amendment M/495 for implementing the LOT 1 and 2 rules in the
European Standards must be applied only for new test methods and or new applications, which are
not foreseen in the existing European Standards. Changing or ignoring existing European
Standards will cause a lot of agitation in the standard committees and will cause a delay in making
new rules for the new applications in the European Standards as needed for the labelling method.
An example are the rules under LOT2 where the EN13203-2 method is referenced. In LOT1
however the EN 13203-2 method is not referenced. An other example is the proposed test method
for determinate the PFHRD performance.
A specific request is to correct the method for the PFHRD technology. We found some serious
technical mistakes which have to be corrected.
We also found a serious problem in the “installer-label”. The method for this label creates an
unacceptable label difference for the PFHRD technology completely integrated in a boiler against
the separate supplied PFHRD technology. This means a non-level playing field for all kind of
constructions.
The performances of the PFHRD technology can be better integrated in the normal label for the
domestic hot water performances.
For our statements, explanations and proposals for correction see the following pages.
Yours Sincerely
On behalf of VFK,
Paul Overman
The PFHRD is a relative new development.
The introduction of the PFHRD in the labelling was only in 2011.
The method for testing and calculation the PFHRD contribution is partly renewed in the LOT1
version 2012.
The method 2012 is not correct and corrections are needed for:
A)
B)
C)
D)
E)
the determination of the indirect saving
missing of the direct saving in the LOT1 method
reference, use and implementation of European Standards for PFHRD
correct use of a control correction for PFHRD
installer label for a combination with PFHRD technology
Without the corrections, the presented contribution of a PFHRD application will be wrong, will give
a non level playing field for manufacturers and will frustrate standard committees.
Technology of PFHRD
The PFHRD technology is based on the use of an (extra) heat exchanger, placed in the in the flue
gasses of gas appliances.
With this heat exchanger, a part of the energy of the flue losses during both the production for
domestic hot water and the production for central heating could be transferred to the domestic hot
water.
1) Direct saving of the PFHRD technology
In the LOT1 method, the annual gas and electricity consumption is based on a 24 hours test
method. In the 24 hours method, there is only a demand for domestic hot water. The method gives
the efficiency for domestic hot water during the summer period.
By using the PFHRD technology, an appliance will have an increased efficiency for this summer
period. In the LOT 1 method, the efficiency over summer and winter is equal.
The difference for the appliance with and without PFHRD is expressed in the so called “direct
saving”.
2) Indirect saving of the PFHRD technology
In a normal appliance, the flue losses during the production for central heating are real losses. By
using the PFHRD technology, a part of these flue losses will transfer to the domestic hot water.
During periods of the production of central heating the flue losses are (partly) transferred tot the
energy storage for domestic hot water. With the energy in the storage the production of domestic
hot water can partly covered. A saving on the primary energy consumption will be reached. This is
the so called indirect saving.
A) LOT1 method for the determination of the indirect saving
For the PFHRD technology a serious mistake is made in the calculation for the yearly indirect
saving. This mistake gives a 40% overrate of the contribution of the indirect saving. The mistake is
that the PFHRD performance is based on a passive flue heat recovery from central heating losses
during the whole year. The passive flue heat recovery however is only in the winter period. A
weighting over a summer and a winter situation is missing.
The heat demand is 0,6*366*Qref. The annual electricity consumption (AEC) and annual fuel
consumption (AFC) are also based on the 0,6*366*Qref.
The 0,6 reduction factor is over the whole year and is applicable in both summer and winter period.
It means that also for the PFHRD contribution combitrans, the same 0,6 correction must be used.
The formula now is:
PFHRD  0,6 * 366 * Qref * [
1
1

]
CC * AEC  AFC  combitrans CC * AEC  AFC
The formula must be:
PFHRD  0,6 * 366 * Qref *[
1
1

]
CC * AEC  AFC  0,6 * combitrans CC * AEC  AFC
In the formula, the Q ref , combitrans and AEC are expressed in kWh energy.
The AFC is expressed in GJ! A recalculation for AFC to kWh is needed.
The following formula is the correct formula:
PFHRD  0,6 * 366 * Qref * [
1
1

]
1000 * AFC
1000 * AFC
CC * AEC 
 0,6 * combitrans CC * AEC 
3,6
3,6
With:
AEC = 0,6*366*Qelec in kWh
AFC = 0,6*366*Qfuel in GJ
combitrans  5280 * MIN [ Pstore, Ptap]
Remark: also the definition of AEC, AFC and combitrans are changed, was:
AEC = 220* Qelek in kWh
AFC = 220*Qfuel in GJ
combitrans  5124 * MIN [ Pstore, Ptap; Pflue]
See also the explanation in annex 1.
B) Missing of the direct saving in the LOT1 method
For the PFHRD as a separate unit, the contribution on the efficiency of domestic hot water is given
in the PFHRD factor. This PFHRD factor gives only the indirect saving. In the label method, the
total efficiency with PFHRD is the addition of the efficiency of the combination boiler without
PFHRD in % and the PFHRD factor in %.
With this method, the direct saving of the PFHRD during periods of the production of domestic hot
water is ignored. The correct performance during the production of domestic hot water for the
combination of combination boiler and PFHRD can only proved by testing the combination in the 24
hour test.
This means that for a combination boiler, the efficiency of the “normal” 24 hours test must be
ignored and a new efficiency of the 24 hours test including a PFHRD must be introduced.
After that the PFHRD factor can be added to the “normal” 24 hours efficiency including the PFHRD.
Remark: The PFHRD technology is not only for combination boilers. The direct saving of a PFHRD
can also used in dedicated water heaters.
C) Reference, use and implementation European Standards for PFHRD
EN 13203-2
In LOT2, reference is made to EN 13203-2.
In LOT1, the reference to EN 13203-2 is missing.
The in LOT1 described test method for the domestic hot water performance of combination is
coming from the EN13203-2. The EN 13203-2 however is not the obvious test method. This in
contradiction to LOT2, where the EN 13203-2 is obvious.
This contradiction must be corrected.
In the EN 13203-2, the better performance of a combination heater in the winter period is
expressed.
In the version 2011 of LOT 1, the better performances of a combination heater in the winter period
was expressed by giving a positive 5% default correction on the summer efficiency.
In the version 2012 of LOT1, this correction is deleted.
Deleting of the default 5% value is correct, because a default value is not corresponding the EN
13203-2 method. A reference to the EN 13203-2 however is missing and the proposed test method
for the domestic hot water performance is not corresponding the EN 13203-2. In the EN 13203-2
method, a correction is given for the better performance of the combination heater during the winter
period. With this correction a level playing field is created for all kind of technologies for the
domestic hot water production.
The EN 13203-2 is accepted in a normal process for Standards. It could give a tremendous conflict
in the standard committee TC109 if the rules under EN 13203-2 must be changed because of
conflicting rules of LOT1. Also TC109 is requested for implementing the LOT1 rules in the
standards. But this request is done for new applications or missing elements in the existing
standards like the PFHRD application. There was no request for changing the rules in existing
standards.
The proposal is to follow the complete EN 13203-2 standard in LOT1, including the weighted
correction for combination heaters for summer and winter.
Remark: this proposal is not only for PFHRD applications but for all gas combination boilers.
EN 15502
Rules in LOT 1 are given for the PFHRD application.
The indirect saving of the PFHR technology in the winter period is based on a 50% part load of the
boiler at water temperatures over the boiler 55/45 degrees. These circumstances are not foreseen
in the TC 109 standards.
To prevent overheating, the PFHRD application is only applicable for condensing boilers. In the TC
109 standards is for condensing boilers, the part load efficiency defined on a part load of 30% at a
water return temperature of 30 degrees. A second efficiency is given for nominal load at water
temperatures 60/80. The presentation of the boiler performances for heating under these
circumstances are accepted all over Europe during a long period. The nominal load test is used for
the determination of the nominal capacity for the central heating, needed under extreme conditions
for heating up the house after a night set back and at extreme low outside temperature. The part
load efficiency is used for the average expected stationary situations (during the day).
There is no reason at all to change these defined circumstances for the test method for the boiler
efficiency for heating for only a PFHRD application.
The average stationary condition is the 30 part load at 30 ‘C. Only after a night set back, the
nominal load will be used. But this is only for short periods whit only a few tappings. After the
warming up period, the part load is following with lower flue temperatures. This lower temperatures
will decrease the temperature of the PFHRD storage if the storage was on a high temperature
because of the warming up period.
A test method with an “average” part load between the nominal load and the 30% load and an
“average” water temperature between the 60/80 and 30 ‘C gives a non realistic presentation of the
normal use of boilers and gives a non realistic saving of the PFHRD technology.
At the proposed 50% load at 45/55 a condensing boiler will hardly use the latent heat or in other
words: with the proposed test method it is said that that under normal conditions, a condensing
boiler will hardly use the latent heat ! This is not to maintain !
The proposal is to follow for the PFHRD test the normal EN 15502 test requirements for
condensing boilers (30% part load, return temperature 30 ‘C).
See also Annex 2
D) Correct use of a control correction for PFHRD
For boiler space heaters, boiler combination heaters and cogeneration space heaters, the default
negative correction F(1) is 3 %.
Additional (positive) default values are used for the contribution of temperature controls to the
seasonal space heating energy efficiency of packages of space heater, temperature control and
solar-only system or of packages of combination heater, temperature control, solar-only system
and passive flue heat recovery device.
The PFHRD application is based on a passive contribution because of flue losses during the
heating function. A PFHRD has no influence on the efficiency for heating at all. There is no reason
to give a PFHRD application an additional positive correction because of the control.
The additional positive correction for the application of a PFHRD technology must be deleted.
E) Installer label for a combination with PFHRD technology
Of course, for a separate PFHRD, a correct formula in which both the direct saving and the indirect
saving are expressed, can be developed.
First point is that however, with a non separate PFHRD, the PFHRD is part of the boiler. With the
PFHRD as part of the boiler, there is no possibility to determinate the direct saving Second point is
that in the existing proposal the requirement is that the performances of the PFHRD are for
specified combination heaters. There will be no expression of the PFHRD contribution for not
specified combinations. With that, there is no need for an installers label; there will always be a
unique combination of combination boiler with separate or build in PFHRD technology.
For the PFHRD technology, the normal label for domestic hot water can used, based on the 24
hours test method in LOT 1 and LOT2 and for the combination boilers the input of the indirect
saving in LOT1.
With this method a wished level playing field for all constructions in both LOT1 and LOT2 is
created.
Annex 1:
Correction of the PFHRD formula
The PFHRD calculation in the version 2011 was difficult to understand because of missing
definitions.
The calculation in the version 2012 is more clear. Because of this it’s easy to see that the
calculation is wrong.
The contribution of a PFHRD in % is given as:
PFHRD  0,6 * 366 * Qref * [
1
1

]
CC * AEC  AFC  combitrans CC * AEC  AFC
or
PFHRD 
CC=
0,6 * 366 * Qref
0,6 * 366 * Qref

CC * AEC  AFC  combitrans CC * AEC  AFC
conversion coefficient = 2,5
AEC = annual electricity consumption defined as 220* Qelek (expressed in kWh)
AFC = annual fuel consumption defined as 220*Qfuel (expressed in GJ)
First of all, AFC must corrected from GJ tot kWh.
The annual consumptions are defined on 220 (days)
The annual heat demand for domestic hot water is defined as 0,6*366*Q = 219,6*Q
The expressions for annual heat demand and consumptions must be based on equal times, so
definitions for AEC and AFC must be changed from 220*Qelec and 220*Qfuel in 0,6*366*Qelec
and 0,6*366*Qfuel
Filling in the correct CC, AEC and AFC gives:
PFHRD 
0,6 * 366 * Qref
0,6 * 366 * Qref

2,5 * 0,6 * 366 * Qelec  0,6 * 366 * Qfuel  combitrans 2,5 * 0,6 * 366 * Qelec  0,6 * 366 * Qfuel
Combitrans is defined as combitrans  allhrs * MIN [ Pstore, Ptap; Pflue] with allhrs=5124.
combitrans  5124 * MIN [ Pstore, Ptap; Pflue]
The reason for allhrs= 5124 is not clear. 5124/24=213,5 days. Based on the winter period of 220
days is must be 5280 hours
The Pflue is not defined. It’s not necessary to define it because it’s physical impossible that Pflue is
less than Pstore.
Proposal for combitrans:
combitrans  5280 * MIN [ Pstore, Ptap]
Given that 0,6*366 = 219,6 and the 220 days is roughly equal, the formula can expressed as:
PFHRD 
Qref
Qref

2,5 * Qelec  Qfuel  combitrans,24 2,5 * Qelec  Qfuel
In which combitrans,24 = 24*MIN[Pstore;Ptap;Pfuel]
or
PFHRD   w int er   summer
This shows the absolute nonsense of the proposal. The contribution of the PFHRD in this formula
is here based on a continue use of central heating all over the year !!!!
Reason for this mistake is that for the calculation of combitrans the performance is based on a daily
use of Qref over the complete winter periode. However, for the yearly consumed hot water energy,
a factor 0,6 is inserted. This factor must be used in both the winter period and the summer period.
So, also for the calculation of combitrans.
The correct formula must be:
PFHRD  0,6 * 366 * Qref *[
1
1

]
CC * AEC  AFC  0,6 * combitrans CC * AEC  AFC
With the correction for AFC (expressed in GJ) to kWh it gives the formula
PFHRD  0,6 * 366 * Qref * [
With:
AEC = 0,6*366*Qelec in kWh
AFC = 0,6*366*Qfuel in GJ
Combitrans = 5280*
1
1

]
1000 * AFC
1000 * AFC
CC * AEC 
 0,6 * combitrans CC * AEC 
3,6
3,6
Annex 2
PFHRD test methode
The influence of the test method is made in the combination of boiler tests and a simulation model.
Tapping program M
The results are calculated with the corrected PFHRD formula of annex 1.
With a PFHRD, a first increase of the efficiency is realised during the use of hot water. It’s
expressed in the test under the summer conditions. This is not expressed in the PFHRD. It’s
only expressed in the summer efficiency if the combination of a combination boiler and
PFHRD is tested for the domestic hot water performance.
A second increase of the efficiency is created during the winter period in which the losses during
the heating function are used for a pre heating of the domestic hot water. This increase is the
PFHRD expression.
The conclusion is that in the comparison of the efficiency of a combination heater without
the PFHRD and the efficiency of a combination heater with the PFHRD, the PFHRD
expression is not complete.
Efficiency of the
original appliance
without PFHRD
Efficiency with original
appliance +PFHRD
and test method
PFHRD 50% part load
and water
temperatures 45/55
Efficiency with original
appliance +PFHRD
and test method
PFHRD 30% part load
and return water
temperature 30 ‘C
Efficiency summer
72,8 %
80,2 %
80,2 %
Efficiency winter
72,8 %
157,2 %
111,9 %
33,5 %
16,5 %
72,8 %
113,7 %
96,7 %
A
A+
A
56 %
32,8 %
PFHRD
Efficiency year
label
Saving by PFHRD with
regard to original
appliance
Saving by PFHRD in
limited field
experiences
30-42 %
It shows that a promise (to the end consumer) for a 56% energy saving under the proposed test
method (50% part load at 45/55 water temperatures)
is extreme too much.
It shows also that a promise (to the end consumer) for a 33% energy saving under the proposed
test method (30% part load at 30 ‘C return water temperature) is a realistic claim.