The Metlund D’Mand system pump model S-70T and the Chilipepper CP6000 hot water demand systems are compared. The author is the inventor of both systems.
Hot Water Demand Systems for Faster Hot Water and Water Conservation
This article compares two hot water demand systems, the ACT Metlund D’mand S-70T and the Chilipepper CP6000.
Demand type hot water delivery systems are designed to speed up the delivery of hot water to your fixtures without running any water down the drain. These systems only operate when you “demand” your hot water by activating the pump. Usually that means pushing a button.
The pump is normally located under the sink from where the hot water is demanded. Depending on your plumbing layout one pump can service more than one and often all of the fixtures in a home.
Once activated the pump sends hot water from the water heater to the fixture, hopefully more quickly than if you just ran the faucet full-blast. The cooled off hot water in the hot water pipes is sent back to the water heater inlet via the cold water pipes.
When the pump senses an increase in temperature it shuts off. That prevents hot water from filling the cold water pipes. When the pump shuts off you have nearly instant hot water at the faucet, and no water was run down the drain.
The Metlund S-70T Hot Water Pump
The Metlund S-70T actually uses a Taco Inc, Model 008 Cartridge Circulator pump.
According to the Metlund web site the S-70T models are designed for homes under 3500 square feet and adequate for runs of up to 100 feet. The pump curves are shown below, and the curve marked 008″ is the curve for this pump.
Metlund lists the “performance” as “Gallons/Minute = 14” and “Total Head = 16 ft.” As can be seen from the pump graph curve #008, the 16 Ft.(7PSI) is the amount of back pressure needed to stop the pump from pumping any water.
The 14 gallons per minute is how much water the pump would pump if there was no backpressure at all. The actual flow that the pump produces depends on the backpressure produced by the friction of the water against the pipe wall as it flows.
For example, a flow of 3-1/2 gallons per minute through 100 feet of 1/2″ type L copper tubing requires a pressure of of 4.3 PSI (10 Ft. Head). 100 feet of pipe would service a fixture about 40 feet from the water heater. Any elbows or valves in the line add to the back pressure. Tankless water heaters require around 8 Ft. of Head (3-1/2 PSI) for a flow of 3-1/2 gallons per minute. Adding the two pressure drops together yields almost 8 PSI (18 Ft. Head).
Since that is above the cut-off pressure of the S-70T, it can never pump that much flow. So take what the Metlund web site says with a grain of salt.
If you have a tankless water heater that supplies a fixture 50 feet away, it’s unlikely that the Metlund model S-70T would even achieve a flow rate of 2 gallons per minute when used with a tankless water heater.
The pump must be plumbed to the water main side of the shut-off valves under the sink due to the low head capabilities of the pump, and the high head loss through the shut-off valves.
The Metlund pump shuts off when it senses an increase in temperature of 3 degrees .
The prices listed are from Metlund’s website.
S-70T-PF-R Kit ($518.65)
Same as S-70T-PF plus one remote control package.
Same as S-70T-PF plus one hard-wired motion sensor.
The Chilipepper Model CP6000 Demand Hot Water Pump
The Chilipepper was designed to be hooked up with hoses, and thus needed a much more powerful motor to overcome the head loss produced by the very small holes through typical faucet connections. The CP6000 has a maximum Head of 115 Ft (50 PSI).
Connection to the plumbing is done with the same type of supply hoses as most of today’s homes. The water supply to the house does not need to be turned off. You just shut off the angle stops under the sink, connect up the hoses, and turn the valves back on.
The powerful Chilipepper pump works great with any tankless water heater on the market regardless of brand or model.
The high rpm 1/3 horsepower motor does make noise, and you can hear it. It’s very handy to be able to hear the pump shut off, because that way you know when to turn on the faucet.