This little electric point-of-use water heater is sized to fit under a sink and combines tankless water-heater technology with a 4-gallon minitank to provide hot water without waiting for it to come through the lines from a bigger tank. The Ariston GL4 plugs into an ordinary outlet, and owners say it's easy to install. The main drawback is that the temperature controls are hard to access. Since it can be hooked up to an incoming hot water line from a bigger water heater, it's important to install a thermal expansion tank between the two -- something most municipal building codes require anyway. The flow rate is enough for most bathroom sinks or workshops. If you need hot water for a shower, consider the bigger 7-gallon Bosch Ariston GL6 Plus.
We found informative owner-written reviews about the Bosch Ariston point-of-use water heaters at Amazon.com, HomeDepot.com, FaucetDirect.com and AceHardware.com. The Bosch GL4 also earns a recommendation at Bestcovery.com, and brief reviews at Treehugger.com and Metaeffcient.com highlight its most useful features.
Our Sources: Bosch Water Heater Reviews
Nearly three dozen owners rate and review the Ariston GL4 at this online retail site. The vast majority give it positive reviews. One owner reports that it added sediment to his water lines.
Review: Bosch GL4 Ariston 4-Gallon Point-of-Use Indoor Electric Mini-Tank Water Heater, Contributors to Amazon.com
More than a dozen owners give the Ariston GL4 mostly positive reviews here, especially for boosting a storage-tank water heater on long pipe runs. A few note quality-control problems or find it doesn't produce enough hot water for a shower, while others have it serving more than one faucet; one says it easily replaces a 30-gallon water heater. One professional says this water heater often starts to leak after three or four years, so it must be replaced under warranty, a nuisance.
Review: Ariston 4.0 Gallon Point of Use Electric Water Heater, Contributors to HomeDepot.com
The handful of owners reviewing the Ariston GL4 recommend it for workshop use or at a bathroom sink. The one dissatisfied buyer wants more than two minutes at a time of hot water.
Review: Bosch GL4 Ariston 4-Gallon Point-of-Use Indoor Electric Mini-Tank Water Heater, Contributors to FaucetDirect.com
Based on an analysis of features rather than on personal testing, this review ranks the Bosch Ariston GL4 second to the smaller GL2.5 as the best point-of-use water heater, but apparently this is only because the smaller unit costs less and might be adequate for many users.
Review: Bosch Ariston GL4 Electric Mini Tank Water Heater, Mariette Mifflin
This brief review notes that although there are more efficient water heaters available, the Bosch Ariston point-of-use water heaters make "an easy retrofit" with no extra cost for plumbing or wiring.
Review: Ariston Point-Of-Use Hot Water Heaters, Justin Thomas, May 19, 2005
A handful of owners give the smaller but similar Ariston GL2.5 water heater mixed reviews. Complaints range from difficulty accessing the temperature controls to a bursting tank.
Review: Ariston Electric Mini Tank Water Heater (GL2.5), Contributors to AceHardware.com