Sizing a pump for multi zone

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Old 01-19-17, 06:11 PM
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Sizing a pump for multi zone

I want to choose the appropriate Taco pump for my hot water baseboard hydronic heating system.

I have 3 zones each with a zone valve, t-stat, etc.

Taco provides a chart to choose a pump using GPM and the Head calculation.

When you have 3 zones, do you sum all 3 head calculations or do you just use the biggest when choosing a pump???

Same for GPM?? Sum em up of choose biggest??
 
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Old 01-20-17, 07:23 AM
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I would call Taco since the elevation where the single pipe from the boiler splits into three, one for each zone, affects the head requirement for the circ pump. They can also tell you the GPM requirement, but if all 3 zones can require heat simultaneously, the GPM would be times 3 for a single zone in my opinion.
 
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Old 01-20-17, 10:15 AM
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The new ECM variable speed pumps with auto sensing of deltaT or pressure make selection much easier. It may not be “one size fits all” but for a multi zone residential system like carlg's they will automatically adjust to changing load conditions. You are not locked into one fixed pump curve.

ECM's pumps save up to 85% electricity. Those with auto sensing adjust, real-time to changing multi zone conditions.

A best buy is the Grunfos Alpha 15-55F, sku 59896877 for $170. The bottom of the line Taco 00e ECM is $20 less but without auto sensing. The Taco Viridian deltaT models start at $210 and up.

If you do not like the Grundfos Alpha "AutoAdapt" feature just pick one of six pressure or volume selections.

The Alpha can be also be used without zone valve end switches. If left powered on, with zone valves closed, it idles at one watt until one or more valves open then ramps up. Welcome to the modern world!
 

Last edited by doughess; 01-20-17 at 11:35 AM.
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Old 01-21-17, 02:08 PM
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@doug..... thanks for the detailed description of the circulator pumps available.
 
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Old 01-27-17, 11:40 AM
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Pump Selection Post Update

A best buy is the Grunfos Alpha 15-55F, sku 59896877 for $170. The bottom of the line Taco 00e ECM is $20 less but without auto sensing. The Taco Viridian deltaT models start at $210 and up.
New version of the Taco 007e mentioned in the prior post is 007e3 designed as a replacement for old multi tap speed motors. It has 3 manually selected speeds but no automatic pressure or volume settings.

Major advantages ECM pumps/circulators along with lower electrical costs, are sensing and control of pressure and volume that enables automatic adjustment to changing situations.

Boilers/burners with Out-Door-Reset have less deltaT issues.

I have 250 ft of 1" copper pipe with convector tee's feeding 13 convectors in multiple zones. Last year replaced a defective, big old Bell & Gosset Series 100 circulator (new price $295)with a physically smaller Gundfos Alpha for $170. The oil can has been retired to the garage, less vibration, noise, better performance and user CONTROL.

Am am old timer who likes to fix things, but find in the heating world newer is often better and cheaper.
 

Last edited by doughess; 01-27-17 at 12:06 PM.
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