- The document summarizes a presentation given at the XV European Conference in Milano about retrofitting existing heating systems with water-water heat pumps fed by low temperature water networks. - It describes a concept where high temperature heat pumps replace gas/oil boilers and are connected to a low temperature district heating pipe network as the heat source. This allows for easier installation than a standard high temperature network. - Analysis shows the system reduces urban pollution from combustion plants, has simple retrofit potential, lowers energy bills and maintenance costs, and pays for itself within 3-5 years for Italy depending on the installation and original fuel. It is an applicable solution for both existing and new buildings.

1. XV EUROPEAN CONFERENCE MILANO 7th
-8th
JUNE 2013 CSG
Latest Technology in Refrigeration and Air Conditioning
Under the Auspices of the PRESIDENCY OF THE COUNCIL OF MINISTERS
Retrofitting existing heating systems
with water-water heat pumps fed by
low temperature water networks
Marco Masoero, Chiara Silvi, Dipartimento Energia, Politecnico di Torino
Gianfranco Pellegrini, AREA Science Park, Trieste

2. 2
Concept
• Water-water high temperature heat pumps (Tsupply ≥ 60°C)
may replace gas / oil fueled boilers in conventional radiator
heating systems, which are common in Italian residential
buildings.
• The low temperature heat source is water distributed with a
district pipework (LTDH Low Temperature District Heating).
• The district pipework is easier to install and less invasive
than a standard high temperature DH one, since pipe
insulation is not needed.
• A heat exchanger connects the primary network (LTDH) with
the evaporator of the heat pump.
• The HP condenser produces hot water for space heating
and centralised SHW production (if present)

3. Low temperature heat source
Low temperature water may be provided by:
•sea, lakes, rivers, canals;
•unused pits;
•shallow table water;
•urban or industrial water mains;
•sewage systems;
•……..
3

4. The heat pump (TINA 115 kW)
4

5. Heat pump characteristics
• Two stage vapor compression cycle (working
fluid R 600 (n-Butane)
Property Value
Thermal power output 115 kW
Water supply temperature 60 – 80 °C
COP 3.9 – 3.0
Minimum water temperature 7°C
Water flow rate 1.7 – 6.0 L/s
Maximum electrical input 40 kW
5

6. 6
Central plant for space heating and SHW production
70°C
HT HP
12°C
7°C
80°C

7. 7
Supply from water mains
1"1/4
1" 1/4
1"1/4
1"1/4
Supply from shallow table water

8. 8
Analysis
GENERATORI TERMODINAMICI
Andamento degli investimenti
0
250.000
500.000
750.000
1.000.000
1.250.000
1.500.000
1.750.000
2.000.000
2.250.000
2.500.000
2.750.000
3.000.000
10 20 30 40 50 60 70 80 90 100
Numero di generatori da installare
(Generatore tipo da 100 kWt cadauno - Edificio tipo da 30.000 mc)
Investimento[€]
Costo centrali termiche
Costo allacciamenti
Costo rete
Investments vs. number
of heat pumps
Yearly expense
GENERATORI TERMODINAMICI
Analisi economica
0
100.000
200.000
300.000
400.000
500.000
600.000
700.000
800.000
900.000
1.000.000
10 20 30 40 50 60 70 80 90 100
Numero di generatori da installare
(Generatore tipo da 100 kWt cadauno - Edificio tipo da 30.000 mc)
Spesaannuariscaldamento[€]
Spesa annua attuale
Spesa annua prevista
GENERATORI TERMODINAMICI
Analisi energetica - TEP risparmiati
0
200
400
600
800
1.000
1.200
1.400
10 20 30 40 50 60 70 80 90 100
Numero di generatori da installare
(Generatore tipo da100kWt cadauno - Edificio tipo da 30.000mc)
TEP[TEP/anno]
Stato di fatto
Stato di progetto
TOE saved yearly
Emission reduction of CO2 Emission reduction of NOx

9. 9
Conclusions
• Reduction of urban pollution associated to combustion
heating plants.
• Simple retrofit: boilers are replaced by heat pumps
without modifying the heating system.
• Initial costs are balanced by reduction in energy bills
and maintenance cost (35÷60%).
• Payback time for Italy, based on climate and energy
rates: per l’Italia: 3÷5 years, depending on fuel and type
of installation.
• Solution applicable both to the existing stock
(residential, historical buildings, schools, hospitals,
commercial, industrial, etc.).
• At least 70% of energy input is renewable.

10. Thank you for your attention!
marco.masoero@polito.it
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