DOMESTIC AIR CONDITIONING
The
water loop
The use of heat pumps in both heating and cooling is increasing, nowhere more so than in residential applications as demonstrated by Clivet.
T
he water loop system or WLHP (Water Loop Heat Pump) is a suitable system for many diff erent types of application such as
shopping centres, offi ces, hotels etc. It is basically a two pipe hydraulic circuit connecting multiple water to air refrigerant heat pumps (terminal units), kept at neutral temperature by injection and rejection systems. Even though the energy transfer capability, recovery and positive thermal inertia are inherent characteristics of WLHP technology, the water loop can be connected to other recovery devices thus increasing the potential overall effi ciency of the system.
This brief description is easy to understand and shows the great advantages off ered by a water loop heat pump system: ■ A very simple system to design, install and maintain (just two hydraulic pipes passing through the building);
■ No thermal energy losses in distribution and no need for pipework insulation;
■ No limits in size for the system; ■ No refrigerant pipes passing through building. F-gas inspection is not necessary nor leak detection devices for terminal units due to the low refrigerant charge.
52 March 2017
These advantages make the WLHP a winning system over other systems such as VRF or other hydronic systems.
Typical use
Typical temperatures of the water loop are around 30°C in summer and around 20°C in winter. Using a air source heat pump to keep the water loop temperature stable is a very effi cient solution. It uses renewable energy and the implementation of it is easy.
The control strategy could vary according to various factors, but one of the main methods that can be used is to vary the water loop temperature according to outdoor temperature. An eff ective use is to keep the loop temperature at a certain diff erence with outdoor temperature, usually not higher than 18°C TD in summer and not lower than 30°C TD in winter.
Implementing a simple hydraulic circuit like the one in the picture below leads to a high level of control fl exibility on the loop and, at the same time optimal running condition for the heat pump, guaranteeing effi ciency and reliability for the whole system.
The three port valve will control the water
loop temperature, using a temperature probe located downstream. With this scheme the heat pump hydraulic circuit (primary) and the proper loop are disconnected and it is possible then to have an effi cient and reliable system with the chance of management of two circuits at diff erent temperature. Adding to this schematic a buff er tank on the primary (heat pump hydraulic circuit) we can get higher system inertia and better performances during simultaneous heating and cooling demand.
In the scheme the heat pump embodies a pumping station for water circulation through the primary circuit.
RHI
In England, Scotland and Wales a specifi c incentive for heating through renewables is available.
From the OFGEM website: “The Non-Domestic Renewable Heat Incentive (RHI) is a government environmental programme that provides fi nancial incentives to increase the uptake of renewable heat by businesses, the public sector and non- profi t organisations. Eligible installations receive quarterly payments over 20 years based on the amount of heat generated.”
www.acr-news.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72
