Zoning with pumps or valves

frank_25

> I have been a service tech for 12 years for a <BR>
> large mechanical company and recently took a job <BR>
> desiging, installing, and servicing for a smaller <BR>
> company. I've always has to fix what was aready <BR>
> installed. Now that I'm desiging systems, I would <BR>
> like to know what benifits there are to zoning <BR>
> with pumps vs. valves. <BR>
<BR>

radiant newbie

I have been a service tech for 12 years for a large mechanical company and recently took a job desiging, installing, and servicing for a smaller company. I've always has to fix what was aready installed. Now that I'm desiging systems, I would like to know what benifits there are to zoning with pumps vs. valves.

frank_25

pro and con

There have been sides taken on this issue many times. I like zone valves for a one or two family dwelling. But what do I know? I'm just a plumber.

gerry gill

pumps

no evil zone valves..

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Weezbo

I like the right thing for the right job

i think there is a time and place for everything.

i like zone valves for the most part... indirects ,... maybe i use both.

Boilerpro_5

When considering overall energy usage......

I pick zone valves for most smaller applications and pumps for larger. Most systems I design use full outdoor reset, which in turn means that nearly all zones are on most of the time. For small zones, under 40,000 btu/hr, there are virtually no efficient pumps available to do the job, so zone valves get used. The average small pumps....NRF-22, taco 007, GRundfos up 42 are well suited to 10 GPM, which translates to at least 100,000 btu/hr for many systems. Instead of using 6 pumps at 1.5 gpm for a 6 zone system, that would draw lets say 275 watts per hour during the heating season, considering some are off part of the time and lower power draw at lower flows, I would rather use a single 80 watt per hour pump. The operating cost savings of the single smaller pump over a typical heating season would be about $100.00.
On mid sized systems I generally use two standard pumps in Parallel with check valves on thier outlets, with zone valves. With this set up, I can get upward 40 GPM if I use NRF-33's, and built in back up should a pump fail. 40 GPM can heat upward 20,000 sq ft or more, depending on the efficiency of the system and structure and power usage is kept to a minimum.
I also would like to use power close, typically open zone valves, because with full reset, the valves would operate much less frequently. In addition, the valves would fail open, helping prevent freeze ups. Unfortunately, at this time, zone controls appear to be designed for power open applications only.

Boilerpro

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Unknown

as above

i use zone valves when the load is smaller than a grundfos 15-58's ability. generally whenever i can though, they use a lot less power. (3W compared to 50W)

@Boilerpro, we just got the new Heatlink/Statlink thermostats and you can configure them for use with normally open zone valves.

Josh_10

I agree 100% with Boilerpro. Zone valves with constant differential pump or a differential pressure by-pass. Why waste all that energy!

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Josh_10

Why do you say "evil zone valves"? Just curious. Is is troubleshooting or wiring? Or have you had bad luck?

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Tim_33

Commercial systems,

rarely, if ever, use zone circulators because of the quantity and consistencey of the loads. In smaller systems or those with greatly varying loads, times of use, etc., zoning with circulators makes more sense.

One way to look at it is: IF you need a differential pressure regulator in a small system, use zone circulators. Doing work against a DPR is a waste of energy.

Unknown

Manage your flow rates and frictional losses by good distribution design, and you can push 60-70kBTUs with a 3-speed Brute pump easily. Use larger dT's for areas that need lower water temps "naturally", and you won't even raise your system water temp doing it.

With that being possible, as an ex-zone-by-pump guy, I can say why do anything else? Pushing 60kBTUs with a 75 watt circulator is pretty sweet.

Steamhead (in transit)

I used to be a \"pumps-only\" guy

until I got into measuring delta-T on some of these baseboard loop systems. When you see a 3-degree delta-T across supply and return on a baseboard loop you know you aren't moving heat efficiently.

I now have a few 3-zone loop systems in average-sized homes running with Taco 555 series zone valves and a single Grundfos 15-42 circ. The slower flow rates result in greater delta-T and the baseboards work better. Interestingly enough, delta-T on these systems stays relatively constant no matter how many ZVs are open. The circ just shifts up or down its curve.

So I'd answer you with "whatever will give you the flow rates and delta-T you need".

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Josh_10

Sometimes you just need to say it simply! I think you nailed in one sentence everything that we are trying to say Steamhead...

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hr

when you zone with pumps

you should consider the work accomplished vs the power consumed. To use a row of 78 watt circs to move 1-3 gpm each doesn't look so good from an electrical consumption point of view.

We should be very close to getting our hands on delta P circs. This takes the PABs and their loss out of the equasion.

hot rod

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