HEATING | GAS-FIRED HEAT PUMPS (useful hot water output/energy input). This included non-condensing storage water heaters that were typically 0.6 efficient (that, for example, make up the majority of installations in homes in Florida), rising up to an efficiency of 0.85 for condensing continuous-flow water heaters. The efficiencies were shown to drop off significantly for storage systems in households that used less hot water than the average home, presumably as a result of a higher proportion of idling and storage losses. Installations of first-, second- and third-generation GAHP water heaters were shown to have efficiencies of 1.20 or more. He reported US homeowners typically spent $275 (220) on hot water heating per year, and was very aware that any new technology had to be moderately priced so that when consumers replaced their failed systems it was not at a much higher cost. At about $2,200 (1,780), a gas-fired heat pump water heater (GHPWH) had a retrofit capital cost that was about 20% greater than an electrical heat pump water heater (EHPWH) system. However, a retrofit of an EHPWH in place of a gas water heater would also require upgrades to the electrical service of the water heater (going from 115 to 230 volts AC), which would be a significant added cost to the EHPWH. Glanville highlighted a new generation of GHPWH that have been used in pilot schemes. They are designed to be a direct physical replacement for internallymounted storage hot water heaters, and offer significant improvements including a smaller footprint. They have smarter controls, which include more storage tank sensors to allow tighter control of supplementary electric heating and predictive cycling control. The core gas absorption system included: significantly improved designs to the solution pump; the development of a custom electronic expansion valve; and improvements to the flue gas condensing heat exchange. However, the form factor The Vuilleumier Cycle system uses natural gas as its primary fuel for heating and cooling. An air source heat exchanger captures renewable heat energy (RHE) from outside air The heat from the burner plus RHE from outside is sent to any radiator, air-handler, or underfloor heating system As an air conditioner, the system pulls heat out of the house and delivers it to hot water The same heat can be used for hot water delivery Vuilleumier heat pump Figure 3: Schematic of Vuilleumier cycle heat pump in a residential application (Source: Schwartz) No gas supply? Strict NOx targets? Awkward flue run? E-Tech will solve your problems Electric boilers from ACV UK Commercial and domestic Floor standing and wall hung Single phase and three phase Heating and hot water 9kW - 259kW For more information visit www.acv.com 36 May 2020 www.cibsejournal.com CIBSE May20 pp34-37 Supp GAHP.indd 36 24/04/2020 16:31