ODW-099A is the smallest unit, suitable for apartments or single shower usage. It delivers 5.0 GPM at 40 deg. temperature rise. The 099A refers to the Btu/h, here 99,000.
ODW-120A is the next unit up, delivers 5.8 GPM as the 40 deg, delta, 120,000 Btu/h. This unit is suitable for mostly one shower usage.
ODW-180A is the 180,000 Btu/h gas input unit and delivers 6.8 GPM, well suited for two shower usage.
ODW-199A is the largest unit at 199,000 Btu/h delivering 8.2 GPM. Here you can run a couple of showers and the kitchen sink all at the same time.
They are all built the same way and have the efficiencies between 91% to 92%. This allows the unit to be vented with regular PVC as opposed to the lower efficient units that must use very pricey stainless steel venting.
What is different between the models are the gas burners and the heat exchangers. All other components are the same. They are well engineered; all the valves are cast aluminum or other alloy, no plastics. Even the fan inside is made of cast metal. Most other brands have a lot of plastic inside of them. Plastic just tends to break easier and sooner.
Compared to Noritz or Takagi or Navien it is not crammed inside and it does the heating with a lot fewer parts.
The burner and heat exchanger are sealed combustion but very easy to get to. These units are very easy to service. Some other brands have literally jammed the units and as soon the cover is taken off the wiring pops out of the unit.
The gas modulating valves and water mixing valves are easy accessible are one can easily indentify all the parts, including the sensors.
All these units are condensing units and produce condensation. The condensation is lightly acidic (pH 3-4). They all have a built in neutralizer. With other brands you have to treat that condensate water outside the heater with filtration or other means at additional cost before it can be drained. Most municipalities require the condensation to be treated before it is drained.
The heat exchanger is stainless steel alloy and carries a 15 year warranty, like most other brands. The burners are cast aluminum. Unlike many other brands where the electronic is in the open here these units have them in a container where it is protected from accidental water exposure to it.
When operating the unit is very quiet, maybe that is why it is called Quietside. All the water connections are high quality Brass and Copper. There is even a pressure relieve valve, not really needed. The casing is metal with powder coated paint, it should last well.
The unit has a remote control for temperature control and allows connection of an optional second remote. This could be practical for example when installed in a bathroom with a tub where water for the tub can be set to higher temperature as it cools quicker.
Water pressure loss is not noticeable, good pressure and volume. For liquid propane gas there is a burner kit that can easily be installed.
Overall it is a very good unit. It has good warranty and should last a long time, easy to install. It is made in South Korea.
For more info visit us at http://www.justtankless.com
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Just Tankless is specialized in Tankless Water Heating for domestic water and hydronic floor heating and other boiler applications for residential, commercial and industrial. Just Tankless is certified by all major manufactures.