HPWH Findings from Northern Climate Field Study ACEEE

HPWH Findings from Northern Climate Field Study ACEEE Hot Water Forum – Nashville February 23, 2015 Hugh Henderson CDH Energy Corp. Cazenovia, NY sponsored by: NYSERDA

Do HPWHs Make Sense in Northeast? • Many rural homes do not have natural gas – Fuel oil / wood widely used for space heating – Electric water heaters are common • Most homes have basements – HPWH pulls heat from the basement/ground … not the “home” – Dehumidifiers are widely used • Efficiency can be reasonable – Loads are high, capture waste heat – Efficiency can approach COP of 2? 2

Field Test Site • Remodeled Farm House – wet stone basement – new plumbing – oil boiler w/ indirect tank – use DH in summer • 2 to 5 occupants December 21 | 3

Instrumentation • 15 -minute data (1 sec scans) • Integrates ΔT and flow every second to get Q • Power and element status • Space conditions (T & RH) • Dehumidifier status • Pre-HPWH data collection (Nov-2012 to April 2013) December 21 | 4

HPWH • GE Geo. Spring™ HPWH purchased February 2013 – Model: GEH 50 DEEDSR – 50 gallon – 2. 4 EF – Set to “Hybrid” Mode December 21 | 5

Daily Efficiency vs. HW Load AVG=1. 4 @ 49 gal/day EF=2. 4 @ 64 gal/day Large draws hurt efficiency 6

Daily Power vs. HW Load December 21 | 7

What Drives Resistance Element Operation? December 21 | 8

Large Draws Drive Resist. Elements 2 cycles of element operation 1 cycle of element operation few minutes of unexplained operation December 21 | 9

Basement Space Conditions HPWH Installed December 21 | 10

Basement Space Daily Conditions HPWH lowered temperatures by 2 -4 F December 21 | 11

Basement Humidity vs. Outdoor Humidity Winter Summer December 21 | 12

Impact on Dehumidifier Performance December 21 | 13

How Does HPWH affect DH Runtime? December 21 | 14

Statistically Analyze Impact • Multi-linear Regression Model DH = a 0 + a 1×WO + a 2×HP where: DH - Dehumidifier Runtime (minutes/day) HP - HPWH Runtime (minutes/day) WO- Outdoor Humidity Ratio (lb/lb) • Coefficient a 2 indicates impact a 2 = -0. 215 “each hour of HPWH decreases DH runtime by 0. 2 hrs” T-ratio = 2. 5 “different from zero at 90% CI” December 21 | 15

Annual Dehumidifier Savings December 21 | 16

Summary • Overall COP is 1. 4 @ 49 gal/day – basement is colder (50 -65 F) – resistance elements respond to large draws (e. g. , 20 gal) – better controls could reduce element operation • HPWH impacts space conditions – operation lowered space temps by 2 -4 F • HPWH reduces Dehumidifer (DH) operation – Every 5 hours of HPWH operation reduces DH runtime by one hour – Saves an additional 84 k. Wh per year (10%) 17