DO s and DON Ts of HPWH INSTALLATIONS DR. CARL C. HILLER, P.E. APPLIED ENERGY TECHNOLOGY

DO s and DON Ts of HPWH INSTALLATIONS DR. CARL C. HILLER, P.E. APPLIED ENERGY TECHNOLOGY

4 STEPS to a GOOD HPWH INSTALLATION - Select an appropriate HPWH for the application - Install it properly - Operate it properly - Maintain it properly ALL EASIER SAID THAN DONE!

HPWH CAPABILITY CONSIDERATIONS HP heating rate Backup heating rate & configuration Tank size Temperature limitations Controls behaviors Defrost behaviors Ductability Airflow levels Sound levels

MOST COMMON HPWH OWNER COMPLAINTS: Noise Drafts Reliability & Maintenance Failed after the warranty complaints

NOISE AND DRAFT ISSUES A hpwh installed in or near an occupied area needs to be very quiet (e.g. select a quiet unit, use sound deadening materials, ducting &/or enclosure) When installed in an occupied area, hpwh air flow needs to be low and probably needs to be directable (i.e. needs to be ductable) to reduce drafts

WHAT MAKES A HPWH NOISY? Fan/blower High airflow rates Restricted air flow-recirculation vorticies Compressor Noise increases as water temp. increases As lift increases Vibration transmission thru piping Sound direction and reflection (can create a sound amplification effect)

REDUCING NOISE Make sound directional - ducting Padding/sound deadening/enclosure Reduce vibration transmissions Rubber mounts Rubber pipe isolators Reduce sound reflection and focusing Use a different hpwh (e.g. a ductable or quieter one) Move the water heater Use a timer on hpwh Don t use a hpwh

REDUCING DRAFTS Duct the air Move the water heater Use different hpwh Use a timer on hpwh Don t use a hpwh

AIR DUCTING ISSUES Need unrestricted discharge and return air paths Can t duct a hpwh very far, if at all Need to avoid appliance backdrafting Need to avoid air infiltration Need to avoid hpwh reverse airflow

GENERAL HPWH REQUIREMENTS: Need adequate air source (large enough room ~ 800-1000 cu ft) Need air & water temperatures within limits stated by mfg. Need clearance around hpwh For maintenance (~ 6-36 inches on all sides varies by brand) To avoid air reingestion (~ 60+ inches on air discharge, 6-24 inches on air intake)

HPWH DISASSEMBLY-A.O.SMITH

HPWH DISASSEMBLY-GE

HPWH DISASSEMBLY-AIR TAP

HPWH DISASSEMBLY-STIEBEL ELTRON

HPWH DISASSEMBLY-NYLETHERM

HPWH DISASSEMBLY-ETECH

HPWH CLEARANCE ISSUES Often difficult to install with adequate clearance May need to move WH location May need to remove hwph for maintenance May not be able to use hpwh

EXAMPLE RESISTANCE INSTALLATION

HPWH CAPABILITY CONSIDERATIONS HP heating rate Backup heating rate Tank size Temperature limitations Controls behaviors Defrost behaviors Ductability Airflow levels Sound levels

HPWH CAPABILITY Use big enough tank for family Need quick recovery or larger tank Use larger tank to improve efficiency (reduce backup resistance use) Needs adequate hot water if hp section inoperable (some units don t) Select a hpwh with low air temp limits & defrost capability needed for your climate & WH location

Defrost HPWH CAPABILITY (cont.) all hpwhs need a defrost capability (e.g. dirty air filter) Passive (comp. off, fan on) Reverse cycle Simple off not all have it

HPWH OPERATION Usually set mode to allow some backup resistance use Usually set to the lowest temp. that provides adequate hot water Sometimes set higher temp. to reduce backup resistance use (and use a mixing valve)

HPWH MAINTENANCE Make sure unit has an air filter Keep air filter clean Understand & maintain condensate drain Pump sometimes needed Make sure maintenance personnel know what they are doing

SUMMARY Latest generation hpwhs are OK, but all need improvements, and all have shortcomings Plan accordingly Plan for maintenance There is a need for remote-mount hpwhs HPWHs can be used in many places, but not everywhere