Here is what these kinds of pumps do for you. Let’s say you have a residential boiler system with four zones and four electrically operated zone valves. Let’s also say you have a standard three piece circulator on the system. When all the zone valves are open the pump is running at full speed and pumping its full amount of gallons per minute that it is capable of. Things in the house are pretty quite. Now two of the zone valves close down because the rooms reached the temperatures that the thermostats called for. The pump doesn’t know any different. The pump doesn’t know that only half the flow is now needed. The pump is still turning full speed and making the attempt to move the same gallons per minute it was before. Now it won’t be able to move all the gallons it did before but it is going to try to. It’s going to try to ‘’stuff’’ as much gallons into the remaining two open zones as it can. This will make those two active zones noisier than before, it will increase erosion of the pipes more due to the increased velocity of the water, it will wear out the zone valves faster because they now open and close against a stronger flow of water, and most importantly these days is its wasting money and energy running a pump at full electric input when it would be nice if it slowed down in response to the reduced demand of the system. Like applying less pressure to the gas pedal of your car.
Wouldn’t it be nice if the pump could sense what’s going on in the system and ramp its speed and energy consumption up and down in response to what it is sensing?
Well the pumps are here! The pump industry has done just that. And these are really the pumps that should be on your boiler systems if you use zone valves or thermostatic radiator valves. Below are links that open up PDF files for two of the big players in the industry and their pumps that modulate. These pumps save energy which saves you money. When it’s time to update your pump, let’s update to these better pumps.