Tankless Water Heater - does it waste water?

kellertx5er wrote:

mrkoje wrote:
I don't have a tankless in my trailer but I do have one in my house. We have a recirculating pump that is also installed. What this does is take the water that is already in the lines and recirculates it back through the heater. It will do this until the water in the lines is hot thus minimizing the amount of water that is wasted. You might be able to integrate something like this if you are installing or thinking about installing a tankless system.

So what is actually happening is you are using the hot water supply and return lines to store heated water. Isn't that what the tank on a conventional water heater does? Plus I would argue that a water heater tank has better insulation than the piping does. Add in the energy used by the circulating pump and it sounds like a tough argument for the energy 'savings' of the tankless. Hot water quicker, yes. Less energy? don't think so.

I am aware the subject at hand is WATER savings not energy savings, but true conservation does not waste one commodity in the course of saving another.

I don't know about other recirculation systems but my residential install has a button I can push which activates the pump. All it does is recirculate what is in the lines back through the heater for a "second pass" type of deal. Keep in mind that during this time there is no water being used or sent down the drain wasted. II don't know enough about the tankless systems to argue that there is energy savings but I would imagine there would be potential for that over a traditional tank heater. The tankless is only using energy when you actually need it vs the tank constantly using energy to maintain a temperature across 50-100 gallons.