Critical Review - Stiebel Eltron WWK Series Heat Pump Hot Water System
Stiebel Eltron is one of the pioneers and industry benchmark for Heat Pump hot water systems across the world with the company dating back to 1924 and building heat pumps for over 40 years. German engineered for the world's most extreme environments, built in Slovakia and shipped straight to Australia they are the go-to system for Plumbers who know nothing but the best.
The Steibel Eltron WWK Heat Pump hot water system is available in four options. A 220L suitable in Queensland for a 3-4person family or 4–5person household with the built-in smart element, as well as a 300L option for a 5-6person household and a boosted smart element version for 6-7people. One of the only systems that can be installed internally, under a house or in a cavity with 13m2 free area the 220L systems fit nearly anywhere at just under 1600mm high and just over 1900mm for the 300L.
Just as feature packed as a lot of the other main contenders in the market but not with the end user customization ability the market is coming to expect. While the Stiebel Eltron WWK series does not have timer functions to control the unit it does have an innovative design where the unit can communicate directly with a number of smart solar inverters and run when load is low maximizing solar output and grid return. Another innovative feature is the maintenance free impressed anode. Instead of the unit using a conventional single of multi sacrificial another requiring replacement every 5 years the unit uses electrolysis to kill rust and corrosion and has a backup battery to run the system when the power is off.
Unlike a number of systems where the water is pumped from the heat exchange into a single outlet in the middle of the tank the Steibel Eltron WWK series uses a roll bond condenser for optimal heat transfer to the water and will produce hot water all the way down to an external ambient temperature of -5deg.
While a user adjustable timer at the unit would be a great addition installing a timer in the meter board is a great option to make the most of your solar system where the inverter does not have the function the communicate with the water heater. The WWK302H and WWK222H systems do come with the added benefit of a smart element to produce that extra hot water needed during times of high demand when the family comes over for Christmas.
With up to a near 4 point coefficient of performance rating and a 45dBa running noise level not only is the Stiebel extremely cheap to run but its so quiet you wont even know it's there. We have one installed at home behind our bedroom and we have not only never heard it inside we have to walk outside to confirm its still going, which it always is.
Moving from a Dux 250L which came with our previous property running on Tariff 33 to a Steibel Eltron WWK302H running in line with our solar and 7 people in the household has cut our possible hot water running expenditure by over $13,000 over the first 10 years. Not bad for additional $2000 outlay.
Noise wise the Stiebel Eltron WWK222 and 302 are both one of the best performers and though the figures come out of a lab and cannot be replicated in the real world, we cannot see Stiebel's claim of 45dBa as being inaccurate. The fan noise is consistent and low frequency, and the compressor sounds just like a refrigerator. We have installed them below bedrooms, outside bedrooms, across from the neighbours sunroom and only ever had two complaints, one was a fan damaged in transit and the other was never justified.
Build quality for a premium unit is just what you expect, premium. Everything fits well, is packaged nicely, runs when it should, produces what you expect and runs day in day out. People often ask why you would choose say a Stiebel Eltron WWK302 over an Evoheat 270 and its simple, when someone has a 12-15yr old Stiebel that's finally given up all they want is another one. They commend its longevity and always note the never got it serviced. When we replace an Evo heat is usually under 5 years old and the customer never wants to see a heat pump ever again. If you rated them on weight alone, they would also come out on top. These things are heavy and just moving them around you can tell there is no shortcuts taken when you get up over 130kg.
Warranty wise they are on the shorter side with 5-year cylinder and condenser warranty and a 2-year component warranty. Though they are shorter than a number of the lesser-known brands the after sales service is exceptional and really would you prefer a system with a 5-year warranty that never breaks down, or one with a 10-year warranty that breaks down yearly and they send you free spares for you to fork out thousands to get fitted?
Price as always is a huge factor when installing a new heat pump and both the WWK302 and WWK222 range are worth every cent. Starting at $3149 installed for the 220L range and $3299 installed for the 300L range its well worth the investment and when you take into account a premium standard electric system can set you back nearly $2000 your well over halfway there already.
The big question. Would we install an Stiebel Eltron WWK series heat pump in our own home? Most definitely, we did and already have. Its only two years in but hasn't skipped a beat and this thing gets worked hard, real hard. Seven people all nearly having two showers a day plus a bath and kids that love to run four shower heads at once for a slip and slide. Only thing i would change would be to install 2 next time so I don't get the drabs of hot water.
