Circulators or Zone Valves?

Hole drilling Noobie

Hello heating help...Im fairly new to the trade of Hydronics/Radiant distributions and everything else that goes along with it. Today I attended a presentation in albany hosted by Mike, a representative introducting and explaining Tekmars newest TN4 control., But my question is...Circulators or Zone Valves? I usually install systems that utilize Zone Valves but my fellow employee tells me that using circulators in lieu of zone valves was the way to go. Im interested in hearing other opinions before making my final determination. heating can you help?
-Santos

Hole drilling Noobie

Circulators or Zone Valves?

Hello heating help...Im fairly new to the trade of Hydronics/Radiant distributions and everything else that goes along with it. Today I attended a presentation in albany hosted by Mike, a representative introducting and explaining Tekmars newest TN4 control., But my question is...Circulators or Zone Valves? I usually install systems that utilize Zone Valves but my fellow employee tells me that using circulators in lieu of zone valves was the way to go. Im interested in hearing other opinions before making my final determination. heating can you help?
-Santos

Steve_35

It depends

on just what you're trying to accomplish. I prefer zone valves for basic systems and using a single circ. I like having the circ work year round. It usually requires less electricity to run a ZV than a circ. And the initial cost is less with ZVs than with circs.

However, circs are the only way to go if you have multiple teperatures or if you have systems with widely varying loads and pressure drops. If you use ZVs you want to check the velocity of each loop to make sure the circ you need to drive the WH doesn't cause excessive velocity in a short loop.

Boilerpro_3

My take on it

When I have many zones running the same supply temp I prefer zone valve. The chief reason lies in the fact of the power required and electrical usage of running all those small pumps. Many say it doesn't amount to much, but on a modern system with full reset, it does.
Let's say you have a small commercial building with 10 zones and you use 10 UP58's (about 90watts max each). Now typically they aren't running at full GPM output, so the draw of each unit may drop to 75watts. So at 75 watts x 10 = .75 KWH/ hour of use. Now over the course of a winter...say 200 days...that amounts to .75 times 24 times 200 = 3,600 kwh. Of course even with full reset you will probably see only about 80% run time, so 3600 times .8 equals 2880 KWH. Around here (northern IL) electrical before taxes is about .085 /kwh or about .10 per/kwh total.

So those 10 pumps cost you about $360.00 per year to operate. Probably an aboaut figure for heating a structure of that size would be about 3,600.00 in gas. Those 10 pumps just increased your basic fuel costs for heating by about 10%.
If you use 2 of those pumps piped in parallel for redundancy in case of pump failure and use zone valve, you should be able to cost you anual "fuel cost"(gas and electricity) about6 to 7 %.

This same reasoning also applies to most condensing type boilers. Many require big pumps that thier less "efficient" cast iron non condensing brothers do not need. You add this cost to the picture, the actual operating costs of these two types of boilers get much closer.
Watch those pumping needs...there are a few low head condensors out there.....such as the Dunkirks, the Hydrotherm Pulse and the newer Triangle Tube Prodigy. It doesn't seem to make much sense to try and save 15% on your gas usage by spending that much more on electricity.

Boilerpro

hr

A lot depends on how many BTUs

you are trying to move around. A basic 1/12 hp circ will easily move 10 gpm at 10' or 100,000 BTU/hr in a radiant system. In this case, with all the same water temperature zone one pump and zone valves.

Multiple temperature systems work best with multiple mixing devices and circs, although ZV can be used down stream of the mixed temperature circs.

I limit myself to 5 ZV per pump, and include a PAB valve to compensate for flow rates as different ZVs open and close.

ZV tend to come in cheaper when you consider a circ should have isolation valve(s) a check, or two, and a relay to switch it.

Zone valves need a transformer, and some times the boiler supplied transformer has some spare capacity to run a few ZVs.

Some ZVs like those on radiant manifolds allow you to adjust, and dial in, flow rates.

Wet rotor circs are fairly inefficient devices. At the sweet spot (knee of the curve) they are between 20- 30% efficient. Move away from the "spot and they look pretty bad for fluid moved compared to energy consumed!

If your zone(s) requires only a few gpm, and a couple feet of head, why consume 80 watts just to slosh it around?

I feel it is sixes as far a reliability.

Either will provide good service if calculated and installed properly.

hot rod

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Ron Schroeder

I prefer zone valves too but I usually opt for the lower energy usage ones like the Taco ESP or some of the european ones that draw 3 watts or less each. But even the normal Honeywell or Taco ZV's draw much less electrical power than a normal circ.

By the way, my own system is using 12 low wattage zone valves on one 33 watt circ. Only the DHW indirect is on it's own circ.

Ron

Nick_16

Zone valves

I use zone valves anywhere I can because they are cheaper to buy, work well, and take less electricity than a circulator. Although circulators do have some advantages. If a pump goes, only one zone will not have heat rather than your whole house. It really does depend on the project.