Can of worms...

Charlie from wmass

I learn from many things. Data from reliable sources is my favorite thing to learn from. Single speed pumps are great for boilers piped to systems with hydraulic separation from the heat emitters. I also like single speed for indirect water heaters. The rebate is nice though. I sell things that work. I do not throw in things. I factor in my costs and a profit. I am pretty sure that is how business works.

Rich_49

Single speed pumps are just fine for IDWH's . Acceptable for boilers too , that's probably why most mod cons have S & R sensors to know at what rate to fire .

Paul48

Let's be clear.....Those would be sources that you "believed" to be reliable. Charlie....You have small children......I'm sure you've noticed that they will ask you "why" in the middle of a group of 50 people. They don't care, they want to know. It's only when we get older, that we will no longer do that, for fear of ridicule.

Charlie from wmass

my kids are told to save their questions. Then I take the time to answer them in depth. I am just saying this is a debate about nothing as the result is, with proper engineering, the same. In order to maintain a given DT you need to slow the pump rate to allow for the heat emitters to drop the heat, to adjust with a DP you slow the pump rate to match the resistance to given parameters. In doing so you increase the DT as compared to a set speed pump through the same zone. In practice a DT pump gives a DP and a DP pump gives a DT. To confuse things if we use indoor and outdoor resets we make DP or DT pumps and zoning unnecessary. Like the constant circulation systems. If we have a system that runs every zone all the time and simply adjusts the feed rate of b.t.u.s into the mix would that not be more efficient?

Rich_49

Charlie , it is not possible for a Delta P pump to insure a specific Delta T . If thsi were not the case Grundfos and Wilo , for instance would have no need to offer an additional sensor to make their Stratos and Magna circs capable of Delta T setpoint .

It is however possible for a Delta T circ to vary flow and as we all are aware with various flow rates through the same circuits so will change pressure . At least that is what I thought quite awhile ago .

Paul48

I haven't seen him in a while, but I think Jean-David Beyer encountered this problem with a DT circ. Oh, and he took a lot of heat for saying he got more heat pumping faster. He has an over-sized mod/con and was trying to minimize short cycling.