The most important design objective for a 4G Heat Network is to consistently achieve low return temperatures under all operating conditions.
Achieving consistently low return temperatures requires a complex interaction of several technologies:
Pressure Independent Thermostatic Radiator Valves (PI-TRVs), incorporate a maximum flow limiter (pre-settable) protected by an integral differential pressure controller valve (DPCV). This guarantees the required flow to each heat emitter despite varying load conditions.
Hence, a fast-commissioning process is achieved through an automatic balancing of the space heating circuits along with energy savings of 12%.
These, coupled with gas-filled thermostatic sensor heads ensure the fastest and most accurate response to room temperature changes (i.e., solar glare), improving indoor comfort. Achieving additional energy savings of 5-8% when compared with liquid-filled thermostatic sensor heads.
Towel rails usually only provide a small amount of heat, and when towels are placed over the rails, they will effectively insulate the rail surfaces, further reducing heat output and raising return temperatures.
Installing a Pressure Independent Return Temperature Limiter (PI-RTL) on the towel rail (as opposed to the collective space heating return) will guarantee low return temperatures from the towel rail without compromising function.
Traditional underfloor heating (UFH) manifolds are notoriously difficult to balance, especially when designed for a 10˚ C temperature differential (low flow rates). Typically, a flow limiter is integrated with a flow gauge on the manifold with a minimum practicable settable flow rate at 1 l/m. However, due to reductions in building heat demand lower flow rates are often required.
Different room sizes and circuit lengths will make the balancing of underfloor heating manifolds even more difficult, where even static full-load balancing may not be achieved. Any unbalanced circuits will exaggerate heat up times and over-and undershoots, leading to poor indoor comfort for the occupants.
The PI-UFH cartridge incorporates a (low) flow limiter (pre-setting) protected by an integral differential pressure controller. This guarantees the required flow to each zone despite varying load conditions. Hence, a fast-commissioning process is achieved through an automatic balancing of the underfloor heating circuits.
Indirect Heat Interface Units have a plate heat exchanger (PHEX) separating the heat network (HN) and space heating (SH) circuits. Consequently, the HIU energy meter only measures the HN flow rate, HN supply temperature and HN return temperature.
Traditionally temperature clamps are used to “verify” the commissioning of the space heating circuits, by measuring the temperature differential across each individual circuit.
In practice this is time consuming, inaccurate and can prove impossible when ambient temperatures are high.
By adding an ultrasonic metering station (UMS-54) on the space heating circuit connected to the energy meter allows accurate commissioning and verification of space heating flow rates and return temperatures even when ambient temperatures are high.
Pt40s supplied in the UK
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CP1 (2020) Design of Space Heating
CP1 (2020) Commissioning & Verification of Space Heating
A Residents' Guide to 4G Heat Networks
Pt40 Product Overview
Pt40 Technical Datasheet
Rt40 Technical Datasheet
Ultrasonic Metering Station - UMS 54
Ft40 Technical Datasheet
Pt40 Selection Sheet - Residential
Pt40 Selection Sheet - Commercial
Rt40 Selection Sheet
Kamstrup 603 with Ultrasonic Metering Station