Under each sink where you want ‘instant’ hot water you place a special valve, the Astro Express Valve that connects between the hot water line and the cold water line.
Today I stumbled on a website with a hot water recirculation system that I had never heard of before, the Astro Express System, manufactured by Armstrong.
It looks very similar to the Grundfos Comfort system. These systems are touted for solving your slow hot water problem.
This hot water circulating system places a typical recirculation pump such as those manufactured by Taco and Grunfos at the outlet of the water heater so that it pumps hot water out of the heater and into the hot water pipe.
Under each sink where you want “instant” hot water you place a special valve, the Astro Express Valve that connects between the hot water line and the cold water line. By hooking this valve between the hot and cold water lines you create a “loop” so the pump can pump water through the hot water piping to the valve, through the valve, into the cold water pipe, and back to the water heater inlet.
If none of the valves are open, then the pump does not pump any water, but when any of the valves open the hot water begins flowing through the loop sending hot water towards the fixture and the valve that is open. If more than one valve is open then hot water will flow towards both valves.
The Armstrong Express Valve
The Express Valve is a temperature controlled valve, opening when it is cold, and closing when it gets hot. Since the pump is running continuously (controlled by a timer), these valves will open and close periodically keeping the water temperature within a narrow range at the valve.
In effect, you have a very slow hot water circulating system. The result is you have a temperature gradient that starts with piping hot water at the start, (the water heater outlet), and luke warm water at the finish, (the water heater inlet). The temperature at the fixture where the valve is located is at the set point of the valve closing temperature.
Armstrong does not mention on the web site what the set point temperature is, and maybe it’s adjustable. Since a human has a body temperature of about 98 degrees, anything cooler than 98 degrees will feel cool to the touch, so I would suspect about 100 degrees could be considered hot, although I would consider it just barely warm.
You don’t want to set the temperature too high, because remember, there is this temperature gradient that means the water on both sides of the valve will be about the same. Now the cold water line no longer has cold water in it, it’s cooled off hot water, and it starts out at the set point temperature and gradually cools down as it gets closer to the water heater inlet and the end of its journey through the loop.
Recirculation Systems Waste Energy
One problem with this type of system is that since you are continuously circulating water that is cooling off, you have to keep turning on the water heater to keep the tank of water hot. You are wasting a significant amount of energy. It’s not a green product in so far as energy efficiency goes.
By using a timer as Armstrong does, you can reduce the energy wastage by only running the system during periods of the day when you expect to use hot water, and turn it off while you are asleep.
As far as I am concerned though, I do not want anything in my home controlled by a timer. For one thing, when there is a power outage I have to go reset the damned timers. For another, suppose I get up in the middle of the night and want hot water for something.
Warm Water Circulating Systems Waste Water
I think that these types of hot water circulating systems can waste as much or more water than they save. It depends on the human behavior side of the equation. With this system installed in your home, you will no longer get what you consider to be cold water out of the cold water tap when you turn it on.
At first it will be of course almost the same temperature as the hot water since it is right there at the valve and should be at the set point temperature.
If you want a drink of cold water you will have to purge the warm water from the pipes, running it down the drain. True, when you turn on the hot water faucet you won’t get cold water; it will be warm water at the set point temperature. But the “hot” water is still back at the water heater, so to get truly hot water you will need to purge the warm water from the line and wait for the hot. More water down the drain.
Tankless Water Heaters – It Won’t Work With Them
Because tankless water heaters need at least one half gallon per minute of water flow through them to start the Express Hot Water System will not turn them on. So obviously, tankless water heaters are incompatible with these warm water recirculation systems.
In conclusion, I would not really want this type of hot water circulating system in my home. I like the cold water to at least seem cold, and I want HOT water without running water down the drain. I also don’t want my water heating bill to go up, which it would with this system.
For me, an on demand type hot water system would be much more appropriate.