ICS 97.100.99; 27.160  
 
Reference number  
DRS 213: 2022 
© RSB 202 2 
  
 RWANDA 
STANDARD  DRS 
213 
 
Second  edition  
2022-mm-dd 
 
 
 Domestic storage solar water heating 
systems  —Test method s  
   
DRS 213: 2022 
©RSB 2022 - All rights reserved                 ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition 
 
 
 
 
 
 
 
 
© RSB 2022 
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without 
prior written permission from R SB. 
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Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS 213: 2022 
iii                ©RSB 202 2 - All rights reserved  
 Contents  Page 
1 Scope  ................................ ................................ ................................ ................................ .............  1 
2 Normative references  ................................ ................................ ................................ ...................  1 
3 Terms and definitions  ................................ ................................ ................................ ..................  1 
4 Mechanical qualification tests for collectors  ................................ ................................ ............  1 
4.1 Sequence of tests  ................................ ................................ ................................ .........................  1 
4.2 Stagnation test for collectors  ................................ ................................ ................................ ...... 2 
4.3 Test for mechanical strength  ................................ ................................ ................................ ...... 2 
4.4 Test for resistance to rain penetration of collectors  ................................ ................................  4 
4.5 Test for resistance of collectors to hail damage  ................................ ................................ ....... 5 
4.6 Test for resistance to freezing  ................................ ................................ ................................ .... 5 
4.7 Test for resistance to dezincification  ................................ ................................ .........................  6 
4.8 Test for water absorption of composite and plastics components (excluding pipes)  .........  7 
4.9 Test for resistance of collectors to hail damage  ................................ ................................ ....... 7 
4.10  Test for resistance to freezing  ................................ ................................ ................................ .... 8 
4.11  Test for resistance to dezincification  ................................ ................................ .........................  9 
4.12  Test for water absorption of composite and plastics components (excluding pipes)  .........  9 
4.13  Test for corrosion resistance (excluding pipes)  ................................ ................................ ..... 10 
 DRS 213: 2022 
©RSB 2022 - All rights reserved                 iv 
 Foreword   
Rwanda Standard s are prepared  by Technical Committees and approved by Rwanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards adopted 
by Technical committ ees are ratified  by me mbers of RSB Board of Director s for publication and gazettment as 
Rwanda Standards.  
DRS 213 was prepared by Technical Committee RSB/TC 049, Solar energy  systems  and accessories . 
In the preparation of this standard, reference was made to the following standard s: 
1) SANS 6210: 2011 , Domestic solar water heaters — Mechanical qualification tests  
2) ISO 9806: 2013 , Solar energy — Solar thermal collectors — Test methods  
The assistance derived from the above source is hereby acknowledged with thanks.   
Committee membership  
The following organizations were represented on the Technical Committee s on Solar energy  systems  and 
accessories  (RSB/TC 049) in the preparation of this standard.  
LE-GTSIM Ltd   
Ministry of Infrastructure  
Rwanda Energy Group/Energy Development Corporation Limited (EDCL)  
Rwanda Military Hospital (RMH)  
University of Rwanda  - College of Science and Technology (UR -CST)  
TEECCSM Ltd  
Rwanda Standards Board (R SB) - Secretariat  DRS 213: 2022 
1                ©RSB 202 2 - All rights reserved  
 Domestic storage solar water heating systems — Test methods  
1 Scope   
This Draft Rwanda Standard specifies test methods for domestic storage solar water heat ing system s. 
2  Normative references   
The following documents are referred to in the text in such a way that some or all of  their content constitutes 
requirements of this document.  For dated referen ces, only the edition  cited applies. For undated references, the 
latest edition of the referenced document (including any amendments) applies.  
RS ISO 6509 -1, Corrosion of metals and alloys — Determination of dezincification resistance of copper alloys 
with zinc — Part 1: Test method    
RS ISO 6509 -2, Corrosion of metals and alloys — Determination of dezincification resistance of copper alloys 
with zinc — Part 2: Assessment criteria  
DRS 212 , Domestic storage solar water heat ing systems — Requirements  
RS ISO 9227 , Corrosion tests in artificial atmosphere salt spray  test  
ISO 9459-1, Solar heating — Domestic water heating systems — Part 1: Performance rating procedure using 
indoor test methods  
ISO 9459 -2, Solar heating — Domestic water heati ng systems — Part 2:  Outdoor test methods for system 
performance characterization and yearly performance prediction of solar -only systems  
3 Terms and definitions   
For the purposes of this standard, the terms and definitions given in DRS 212 apply.  
4 Mechanical qualification tests for collectors  
4.1 Sequence of tests  
Carry out the tests given in 4.2 - 4.6 on the same water heater and in the sequence given.   
©RSB 2022 - All rights reserved                 2 
 4.2 Stagnation test for collectors  
4.2.1  Preparation  
Mount the collector of the water heater as in practice, with the inlets closed and the outlets open, and in a run -
dry condition, with no transfer fluid anywhere in the collector . 
4.2.2  Procedure   
Expose the collector to insulation over  a period of 15 - 30 consecutive days, keeping a record of the daily 
insulation and the weather, until at least 315 MJm2 cumulative insulation or 30 days is reached.  
4.2.3  Evaluation  
Inspect the test installation regularly during this test, and each time record the date, the time of day, and any 
occurrence of changes that might impair the continued operation of the water heater, such as:  
a) deformation of any part of the collector;  
b)  vapour deposition on the underside of the collector cover;  
c) degradation of pai nt, sealants or insulation; or  
d) degradation of the absorber paint film.  
4.3 Test for mechanical strength  
4.3.1  Test sample  
The solar water heater presented for testing shall be a complete operating unit of one of the following types:  
a) close -coupled water heater ; 
b) integral water heater;  
c) separate storage tank, collector and interconnecting pipe work coupled together in an acceptable 
manner; or  
d) any other water heater erected and coupled in an acceptable manner.  
4.3.2  Resistance to vacuum (closed type and open outlet type wa ter heaters)  
The water container shall be so designed and constructed that, when subjected to the vacuum test, it does not 
collapse or implode.  
4.3.3  Test for resistance to vacuum  
Fill the container with water, close the outlet pipe (with a plug if necessary), a nd subject the container to a 
vacuum of 15 kPa maintained for 30 min. After 30 min relieve the vacuum and check for compliance with the 
requirements of 4.3.2.  DRS 213: 2022 
3                ©RSB 202 2 - All rights reserved  
 4.3.4  Fatigue and hydrostatic pressure test  
Use the test method given in 4.3.5 and 4.3.6 and test the w ater heater at a pressure equal to the marked working 
pressure. In the case of open (non -pressure) type water heaters, use a pressure of 50 kPa.  
4.3.4.1  Resistance to fatigue (all closed type water heaters)  
The container of a closed type water heater shall be so d esigned and constructed that, when subjected to the 
fatigue test given in 4.3.5 : 
a) the container shall, during the test, show no sign of leakage or any deformation that may impair its 
performance; and  
b) when relevant, the lining shall, at the conclusion of the  test, still remain intact.  
4.3.4.2  Resistance to hydrostatic pressure (closed, open outlet and cistern type water heaters)  
4.3.4.2.1  Closed type water heaters  
When tested in accordance with 4.3.6.1, a closed type water heater shall withstand the hydrostatic test pressure 
without leakage, collapse or any deformation that may impair its operation.  
4.3.4.2.2  Open outlet and cistern type water heaters  
When tested in accordance with 4.3.6.2, an open outlet type and a cistern type water heater shall withstand the 
hydrostatic test  pressure without leakage, collapse or any deformation that may impair its performance.  
4.3.5  Test for resistance to fatigue (closed type water heaters)  
4.3.5.1  Connect the cycling timer to the water heater, one valve fitted close to the water heater inlet and the 
other valve close to the water heater outlet. Connect the inlet valve to a water supply (ambient temperature) at 
a pressure equal to the rated pressure  of the water heater under test subject to a tolerance . 
4.3.5.2  Fill the water heater with water, ensuring that no air is entrapped, and set the cycling timer in action.  
4.3.5.3  Adjust the setting of the valves to ensure that, during each cycle the water p ressure in the water heater 
rises to the rated pressure of the water heater % and reduces to a value of between 5 % and 10 % of the rated 
working pressure.  
4.3.5.4  Subject the water heater to 250 000 cycles under these conditions.  
4.3.5.5  During the test, inspect the container for any deformation or leakage and verify for compliance with the 
requirements of 4.3.4.1a). At the conclusion of the test visually examine any lining, when relevant, for 
compliance with the requirements of 4.3.4.1b).   
©RSB 2022 - All rights reserved                 4 
 4.3.6  Test for resista nce to hydrostatic pressure (closed, open and cistern type water heaters)  
4.3.6.1  Closed water heaters  
At the conclusion of the fatigue test, close the outlet pipe of the water heater, subject the water container for 15 
min to the appropriate hydrostatic test pres sure given in column 2 of Table 1 and then examine the water 
container for compliance with the requirements of 4.3.4.2.1.  
Table 1 — Test pressure  
1 2 
  
Type of water heater  Hydrostatic test pressure  
  
Rated at ≤ 50 kPa  50 kPa  
  
Rated at > 50 kPa  2 × working pressure  
  
 
4.3.6.2  Open outlet and cistern type water heaters  
Subject cistern type water heaters and open outlet type water heaters (after the vacuum test) for 15 min to the 
appropriate hydrostatic test pressure given in column 2 of table 1 and examine the water container for 
compliance with the requirements of 4.3.4.2.2.  
4.4 Test for resistance to rain penetration of collectors  
4.4.1  Apparatus  
4.4.1.1  Apparatus fitted with 12 spray nozzles of which the mounting positions can be so adjusted that the water 
sprays are directed onto the joints along the top and sides of the collector cover. The capacity of the nozzles is 
such that they deliver 165 L of wat er per hour . 
4.4.1.2  Test nozzles shall not be closer than 10 cm from the collectors.  
4.4.2  Preparation of test collector  
4.4.2.1  Test shall be performed on a fully assembled system.  
4.4.2.2  Electrical components intended for indoor installation shall be protect ed against contact with water.  
4.4.3  Procedure  
Spray the collector for 5 min every 30 min for a period of 3 h, allowing the run -off water to drain away through 
the drain connection.  DRS 213: 2022 
5                ©RSB 202 2 - All rights reserved  
 4.4.3  Evaluation  
Observe whether the interior of the collector remains free from  accumulated water, and evaluate in accordance 
with 4.2.3.  
4.5 Test for resistance of collectors to hail damage  
4.5.1  Procedure  
4.5.1.1  Use a suitable apparatus that can fire an ice ball onto the test sample. Ensure that the ice ball is fired at the 
appropriate aper ture area of the collector which is either:  
a) the collector cover or, when it forms a permanent part of the collector, the hail screen of a covered collector;  
b) the open absorber surface of unglazed or unprotected flat plate collectors; or  
c) the evacuated tubes (as fitted on the system), to 12 perpendicular impacts (for flat plate collectors), each with an 
impact energy of 11 J ± 1 J, and delivered to various points on the tested surface.  
d)  
e) 4.5.1. 2 Ensure that eight of these points are between  30 mm and 50 mm from the inner edge of the collector.  
4.5.1. 3 In the case of evacuated tubes, only apply one impact to each tube at different positions.  
4.5.1. 4 Ensure that at least one tube is impacted not less than 100 mm from the exposed bottom end, an d at least one tube 
is impacted not less than 100 mm from the exposed top end.  
4.5.1. 5 All components of a solar water heating system including temperature and pressure control equipment shall 
comply with the relevant approved product standards. Installati on of a solar water heating system shall be in 
accordance with Annex A.  
4.5.2  Evaluation  
Observe whether the collector or evacuated tubes suffers any damage that could impair its normal operation, and evaluate 
in accordance with RS 212.  
4.6 Test for resistance to freezing  
4.6.1  General  
The transfer fluid used for this test shall be the same type and concentration as for all other tests on this system, 
specifically in accordance with the thermal performance test given ISO  9459 -1 and ISO 9459 -2. 
4.6.2  Test room  
A cold room in which the temperature can be controlled to any specific temperature of between −20 °C and + 20 °C.  
4.6.3  Procedure  
4.6.3.1  When i nstall ing the system in the cold room , ensure that:   
©RSB 2022 - All rights reserved                 6 
 a) it is filled to its normal capacity with the intended circulating flu id; 
b) it is at its marked design pressure;  
c) it is at its marked design pressure;  
d) all operating components are be fitted in an acceptable manner and positioned as specified by the 
manufacturer;  
e) the water temperature is between 30 °C and 37 °C;  
f) electrical heating elements are disconnected;  
g) any backup batteries shall be fully charged for the start of the test, and these batteries shall not be charged 
for the duration of all the test cycles; and  
h) batteries and control panels are allowed to be outsid e of the test room.  
4.6.3.2  Switch off the electrical supply, including PV cells, to the system, and connect any backup batteries.  
4.6.3.3  Reduce the test room temperature to 5 °C ± 3 °C. Maintain this temperature for 180 min.  
4.6.3.4  Reduce the test room temperature to −20 °C ± 3 °C in no longer than 60 min. Maintain this temperature 
for 120 min.  
4.6.3.5  Increase the test room temperature to 20 °C ± 5 °C.  
4.6.3.6  Disconnect any backup battery.  
4.6.3.7  Maintain the test room temperatur e to 20 °C ± 5 °C for a minimum of 360 min.  
4.6.3.8  Inspect the system for any failures.  
4.6.3.9  Repeat the procedure described in 4.6.3.1 to 4.6.3.5 a further three times. Ensure that a total of four test 
cycles are completed. These steps can be repeated immediately, or with a time delay.  
NOTE This procedure does not allow for testing of systems that include drain down valves, dumping valves, anti -freeze 
valves for freeze protection.  
4.6.4  Evaluation  
Inspect all the components installed in test room, and perform  a pressure test (see 4.3.4). If necessary, identify any physical 
damage that could impair normal operation.  
4.7 Test for resistance to dezincification  
Use the method given in RS ISO 6509  (part 1 and 2)  to test all brass components in direct contact with potable water.  DRS 213: 2022 
7                ©RSB 202 2 - All rights reserved  
 4.8 Test for water absorption of composite and plastics components (excluding pipes)  
4.8.1  Preparation  
Cut a test specimen of the composite or plastics, of size approximately 50 mm × 50 mm from each  sample. Seal 
composite specimens round the cut edges with a water -resistant sealing material to an acceptable thickness.  
4.8.2  Procedure  
Weigh the specimen to an accuracy of 0.05 %. Place it in a beaker of distilled water at room temperature for 28 
days. Remove  the specimen from the water, wipe off all surface moisture, and weigh the specimen again.  
4.8.3  Evaluation  
Observe whether the interior of the collector remains free from accumulated water, and evaluate in accordance 
with 4.2.3.  
4.9 Test for resistance of collector s to hail damage  
4.9.1  Procedure  
4.9.1.1 Use a suitable apparatus that can fire an ice ball onto the test sample. Ensure that the ice ball is fired at the 
appropriate aperture area of the collector which is either:  
a) the collector cover or, when it forms a permanent part of the collector, the hail  screen of a covered collector;  
b) the open absorber surface of unglazed or unprotected flat plate collector; or  
c) the evacuated tubes (as fitted on the system), to 12 perpendicular impacts (for flat plate collector), each with an 
impact energy of 11 J ± 1 J, a nd delivered to various points on the tested surface. Ensure that eight of these points 
are between 30 mm and 50 mm from the inner edge of the collector.  
4.9.1.2 In the case of evacuated tubes, only apply one impact to each tube at different positions.  
Ensure that at least one tube is impacted not less than 100 mm from the exposed bottom end, and at least one tube is 
impacted not less than 100 mm from the exposed top end.  
All components of a solar water heating system including temperature and  pressure control equipment shall comply 
with the relevant approved product standards. Installation of a solar water heating system shall be in accordance with 
annex A.  
4.9.2  Evaluation  
Observe whether the collector or evacuated tubes suffers any damage that cou ld impair its normal operation, and evaluate 
in accordance with RS 212.   
©RSB 2022 - All rights reserved                 8 
 4.10 Test for resistance to freezing  
4.10.1  General  
The transfer fluid used for this test shall be the same type and concentration as for all other tests on this system, 
specifically in accordance  with the thermal performance test given ISO 9459 -1 and ISO 9459 -2. 
4.10.2  Test room  
A cold room in which the temperature can be controlled to any specific temperature of between −20 °C and + 20 °C.  
4.10.3  Procedure  
4.6.3.1  Install the system in the cold room. Ensure that:  
a) it is filled to its normal capacity with the intended circulating fluid;  
b) it is at its marked design pressure;  
c) it is at its marked design pressure;  
d) all operating components are be fitted in an acceptable manner and positioned as specified by the 
manufacturer;  
e) the water temperature is between 30 °C and 37 °C;  
f) electrical heating elements are disconnected;  
g) any backup batteries shall be fully charged for the start of the test, and these batteries shall not be charged 
for the duration of all the test cycles; and  
h) batteries and control panels are allowed to be outside of the test room.  
4.6.3.2  Switch off the electrical supply, including PV cells, to the system, and connect any backup batteries.  
4.6.3.3  Reduce the test room temperature to 5 °C ± 3 °C. Maintain this temperature for 180 min.  
4.6.3.4  Reduce the test room temperature to −20 °C ± 3 °C in no longer than 60 min. Maintain this temperature 
for 120 min.  
4.6.3.5  Increase the test room temperature to 20 °C ± 5 °C.  
4.6.3.6  Disconnect any backup battery.  
4.6.3.7  Maintain the test room temperature to 20 °C ± 5 °C for a minimum of 360 min.  DRS 213: 2022 
9                ©RSB 202 2 - All rights reserved  
 4.6.3.8  Inspect the system for any failures.  
4.6.3.9  Repeat the procedure described in 4.6.3.1 to 4.6.3.5 a further three times. Ensure that  a total of four test 
cycles are completed. These steps can be repeated immediately, or with a time delay.  
NOTE This procedure does not allow for testing of systems that include drain down valves, dumping valves, anti -
freeze valves for freeze protection.  
4.10.4  Evaluation  
Inspect all the components installed in test room, and perform a pressure test (see 4.3.4). If necessary, identify any physic al 
damage that could impair normal operation.  
4.11 Test for resistance to dezincification  
Use the method given in RS ISO 6509 (part 1 and 2) to test all brass components in direct contact with potable water.  
4.12 Test for water absorption of composite and plastics components (excluding pipes)  
4.12.1  Preparation  
Cut a test specimen of the composite or plastics, of size approximately 50 mm × 5 0 mm from each sample. Seal 
composite specimens round the cut edges with a water -resistant sealing material to an acceptable thickness.  
4.12.2  Procedure  
Weigh the specimen to an accuracy of 0.05 %. Place it in a beaker of distilled water at room temperature for 2 8 
days. Remove the specimen from the water, wipe off all surface moisture, and weigh the specimen again.  
4.12.3  Calculation  
Calculate the water absorption, expressed as a percentage by mass, using the following equation:  
𝐴−𝐵
𝐴 ×100 
where,  
B is the mass of the specimen after immersion, expressed in grams (g); and  
Ais the mass of the specimen before immersion, expressed in grams (g).   
©RSB 2022 - All rights reserved                 10 
 4.13 Test for corrosion resistance (excluding pipes)  
4.13.1  Procedure  
4.9.1.1  Visually inspect all exposed surfaces for any  signs of corrosion that formed during the test 
process.  
4.9.1.2  If any corrosion is identified, perform a 1 000 h salt fog test on acceptably sized and prepared 
samples of the metallic materials (except intrinsically corrosion -resistant materials) of thos e system 
components that are exposed to the environment, in accordance with RS ISO 9227.  
4.9.1.3  Seal the cut surfaces carefully with a compatible and corrosion -resistant coating before the 
salt fog test is started.  
NOTE  In the case of large components, ac ceptably sized test specimens may have to be cut out.  
4.13.2  Evaluation  
Immediately after completing the salt fog test, inspect the samples first for penetration of the coating 
and then for any corrosion of the basic material under the coating. Compare the result s with the 
requirements of the relevant specification.  
 
 
 
 
 DRS 213: 2022 
 
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