ECM circulator selection

Solid_Fuel_Man

Working on a radiant job, and would like to employ an ECM circulator as there is a wide variation in how many actuators are open. I have 1 loop micro-zone in secretarial office, 12 loops on a ZV controlled manifold, and two other zones one 5 loops and one 6 loops with loop actuators. The micro-zone calls the most. This is an existing job with a grundfos 26-99 running this and as you can guess there is significant noise with the one loop zone calling.

I have three proposals to remedy the problem.

1. Install bypass valve
2. Put secretary on its own small circulator by itself
3. Install ECM circulator in place of the 26-99 sized correctly for the 4 zones in this section of the building.

All loops are 300' +/- 10% of 1/2 pex.
18 gpm @0.75 per loop.
Loop feet head 6.5
Feet head for piping fittings to manifolds 4
Total feet head 10.5

I think ECM is the most elegant solution of the 3 proposals. But am still a bit unclear on ecm selection as there are some variables. I assume the head is always the same only variance in flow so in this case .75-18gpm.

Is my math right? Help me choose the right circulator.

Taylor

hot_rod

26 99 is a high head circulator, not usually a good match with zone valves or actuators. With one or two zones calling you are running way up the curve. A bypass valve would help, or finding the correct delta P circ.

Rumor has it a 26 99 Alpha will be available soon Maybe an AHR release?

Solid_Fuel_Man

I was thinking the 26-99 was really not the correct circulator at all. If my math is right. This is just a typical 1/2 pex radiant slab setup. I'd like to go with a Taco product.

hot_rod

the 0010 is a nice flat curve pump, about ideal for your application, however not an ECM
The small Grundfos Magna is an amazing pump, a bit $$

Solid_Fuel_Man

This is where I'm fuzzy on variable speed selection. I'm only familiar with fixed speed selection.

hot_rod

Idronics 16 does a good job of explaining the various delta P modes available. Simply put the pump is constantly adjusting it's output as zones open and close.

An ideal pump curve would be straight line, as shown on the cover, the correct amount of flow provided as the loads change.


http://www.caleffi.com/sites/default/files/coll_attach_file/idronics_16_na_0.pdf

Gordy

The problem with reasonably priced ecms is there is none to match that slot your in with higher head, and flow rates until you take a huge price jump to a Magna say for instance.

Solid_Fuel_Man

That's what I was finding actually @Gordy
I started second guessing some things, which is why I posted the inquiry on here. I thing the best proposal for this job will be number 2. A 0015 on low speed will keep all parties happy and I will run the circulator with the 24v for the actuator and a RIBU1C.

Taylor

SWEI

Can you split the load so that multiple circs can serve it?

Mark Eatherton

I've successfully paralleled Alpha's before. Displaced a HUGE 208 3 ph pump that was causing every ZV in the property to bypass. Thank you Grundfos! (They donated the pumps to this non profit homeless shelter, Catholic Relief Housing)

ME

hot_rod

Mark Eatherton said:

I've successfully paralleled Alpha's before. Displaced a HUGE 208 3 ph pump that was causing every ZV in the property to bypass. Thank you Grundfos! (They donated the pumps to this non profit homeless shelter, Catholic Relief Housing)

I wondered about paralleling Alphas, do they need to be in a fixed speed mode?

ME

Mark Eatherton

No, left them on auto adapt, and they always read the same. Bypassing Zone Vales stopped, Sister Margaret got a membership at the local health club, KWH consumption dropped significantly and the employees in the building quit opening windows to stay comfortable.

I think a person could even break up their operation using a 2 stage thermostat, setting the second circulator to come on half way to design condition, and the other pump should react accordingly when the second circulator comes on line.

Kudos to Grundfos Corp and Matt Baker for the donation.

ME

Solid_Fuel_Man

@SWEI the amount of repipe to split the two larger zones is unfortunately going to be too complicated. This is all in a wall box concealing the manifolds and actuators. I'd still like to use variable speed to solve this though. I will be back on site in the next few weeks to get some feedback on proposals.