Ok, I understand what you are asking SB, or at least I think I do. With a point of use water heater, Yes, I see no reason for a pump. However, with a tankless W/H, you can trick the water heater into believing there is an open faucet by using a closed loop system, and it will heat the water in the pipe. ( A closed system is a recirculation loop for water (or other liquid) where once it is set up and running, no new liquid is introduced into the system.)
They also have a second system, which is exactly what I have here at my current house. By using a small pump, the water is forced through the hot water pipe and with the assistance if a thermostatically controlled bypass valve, is pushed back into the cold water line until it reaches 105 degrees, therefore sending hot water up to the faucet so the water is pretty much instant hot.
Here is the write up about what I was referring to from the Grundos pump folks.
Grundfos Comfort System - Hot Water Recirculation System The water circulation system that eliminates cold water runoff at the faucet using a bypass valve and pump with a timer to control water flow. Hot Water Recirculation - Special Features- The ultimate in convenience is having hot water instantly available at sinks, appliances and bathroom faucets. The elimination of time spent waiting is especially convenient in areas where the installation of low flow showerheads and faucets are required by law. Hot water recirculation improves the efficiency and effectiveness of household appliances including washing machines and dishwashers by having hot water available instantly. Users can save energy by setting the 24 hour programmable timer to make hot water available during peak demand times, such as early morning and in the evening. The recirculation pump can be installed by a certified contractor in two hours. For the average home, hot water recirculation systems generally cost a few hundred dollars, including parts and installation. A wet rotor design for whisper-quiet and maintenance-free operation. Stainless steel rotor cladding and canister construction, an exclusive UP 15 series feature, ensures corrosion-resistance and extended product durability. A low-watt, two-pole motor combined with low-flow performance ensures minimum water heater operating costs, pipe and water heater wear and energy consumption. Significant water (and sewer) disposal savings, retaining the 12,000 to 38,000 gallons of water a typical U.S. home wastes annually waiting for hot water. Some fast-growing counties are making the installation of hot water recirculation pumps mandatory for all new construction projects.
They also have a second system, which is exactly what I have here at my current house. By using a small pump, the water is forced through the hot water pipe and with the assistance if a thermostatically controlled bypass valve, is pushed back into the cold water line until it reaches 105 degrees, therefore sending hot water up to the faucet so the water is pretty much instant hot.
Here is the write up about what I was referring to from the Grundos pump folks.
Grundfos Comfort System - Hot Water Recirculation System The water circulation system that eliminates cold water runoff at the faucet using a bypass valve and pump with a timer to control water flow. Hot Water Recirculation - Special Features- The ultimate in convenience is having hot water instantly available at sinks, appliances and bathroom faucets. The elimination of time spent waiting is especially convenient in areas where the installation of low flow showerheads and faucets are required by law. Hot water recirculation improves the efficiency and effectiveness of household appliances including washing machines and dishwashers by having hot water available instantly. Users can save energy by setting the 24 hour programmable timer to make hot water available during peak demand times, such as early morning and in the evening. The recirculation pump can be installed by a certified contractor in two hours. For the average home, hot water recirculation systems generally cost a few hundred dollars, including parts and installation. A wet rotor design for whisper-quiet and maintenance-free operation. Stainless steel rotor cladding and canister construction, an exclusive UP 15 series feature, ensures corrosion-resistance and extended product durability. A low-watt, two-pole motor combined with low-flow performance ensures minimum water heater operating costs, pipe and water heater wear and energy consumption. Significant water (and sewer) disposal savings, retaining the 12,000 to 38,000 gallons of water a typical U.S. home wastes annually waiting for hot water. Some fast-growing counties are making the installation of hot water recirculation pumps mandatory for all new construction projects.
