How many zones can you run with 1 load circulator?

[patch53]

Some systems run with a single load circulator w/ zone valves and others, like mine, have a taco on all 3 zones. Is it more efficient energy-wise to just use 1 circulator and zone valves rather than 3 pumps?

And is there a limit to the number of zones you can run off 1 circulator, or does it depend on things like length of runs, head, etc..

TIA, Pat

 

[Piker]

Definetly more energy efficient to have one pump with zone valves. A little more difficult to manage flow, however (unless you're using an alpha pump). The number of zones you can run off of a circ will be dependent upon heat load, flow rates, etc etc etc.

I have thus far been able to heat our entire home off of 1 15-58 grundfos pump set to low speed... with 4 zones, including DHW.

Cheers

 

[patch53]

Thanks Piker, thats what I thought. Do you just turn up the speed a notch on the Grundfos when you anticipate more heat load in the house?

Pat

 

[Piker]

Thanks Piker, thats what I thought. Do you just turn up the speed a notch on the Grundfos when you anticipate more heat load in the house?

Pat

Yep, but I haven't had to do that yet. Our place had a heat loss of around 110,000 on the calc... but average heat load for a 24 hour period has yet to peak above 35,000 this year (just doing the math off the heat storage tanks). I suspect once it's windy and -15 I could see a max average over 24 hours of around 80K? Maybe? Just guessing. At that point, The pump will probably have to be turned up a notch or two.

Cheers

 

[PJF1313]

Energy efficient wise - Yes

BUT (ain't there always) I would also keep a spare pump on hand, just in-case...
And also, if you do go that route, a spare valve.

 

[Piker]

Energy efficient wise - Yes

BUT (ain't there always) I would also keep a spare pump on hand, just in-case...
And also, if you do go that route, a spare valve.

Amen.

cheers

 

[Nofossil]

I ran six zones off of a Taco 007, now a Grundfos 15-58 (I think). Varying the pump speed is not as important as you would think. Zone valves are designed so that almost all of the head loss for each zone is in the zone valve itself. With only one zone open, there's a really high head loss and correspondingly less flow. As the second zone opens, the net head loss is about 50% less and the net flow is approximately doubled, and so on for each additional zone. It's not perfect, but its pretty darn close.

Circulators like the 007 that are designed for use with zone valves have a fairly linear relationship between head loss and flow rate over a wide range of flow rates.

I vary the speed on my Grundfos not based on the number of zones that are open, but rather to hit my target boiler outlet temp.

 

[patch53]

Yes, I totally agree with you guys about having spare parts available in case something fails.

I was looking at the Grundfos Alpha last night on their website, almost sounds too good to be true ! Anyone using one for their load circulator w/ zone valves?

TIA, Pat

 

[Jackpine Savage]

I have a Grundfos 15-58 with four zones hooked up. I will eventually have 6 zones. I do have a differential bypass valve to divert some of the flow if only a couple zones are calling for heat. I had already purchased and installed the components before I read about the Grundfoss Alpha, darn.

 

[Chris Hoskin]

if you are starting from scratch, it makes good sense to take a look at variable speed pumps like the Grundfos Alpha. There just aren't many opportunities to reduce energy consumption (of anything) by 50 - 80%! Gotta at least consider it. The way of the future to be sure. I posted a link in the "articles..." sticky:

http://www.pmmag.com/Articles/Column/BNP_GUID_9-5-2006_A_10000000000000479795

Excellent intro to the concept.

Chris