Zone valves vs. circulators

Darrell

I've done several jobs with 007's instead of Zonevalves for a couple of reasons. They are cheaper here, they are quicker to pipe up, they seem to be a bit more reliable, purging is a snap, and the flow rates can be taken into account, (assuming ones does the math).

An interesting side effect is that "less than qualified technical help" is less inclined to mess with a line volt circ as opposed to a low volt ZV...'cuz anybody at the local watering hole can do 24v you know! Ya just start jumping out all the little wire thingys and it'll work. Don't know why that box with the blinky lights it making such a funny noise...stupid engineers make these things way more comlicated than they need to be anyway just so's we gotta call some overpriced serviceman.

Sigh!

Reed

Zone valves vs. circulators

I'ne allways used zone valves but on the last few jobs I've used flo-cont and circs and seem to like it better. No hammer. Any opinions? THANKS!

Reed

Zone valves vs. circulators

When piping out boilers for hot water BB heating system I've allways used zone valves for each zone (rarely, but sometimes a hammer problem) and on the last few jobs I've used flo-cont and circs for each and seem to like it better. Any opions? THANKS!

S Ebels

Depends on the job

Sometimes due to variations of head in the different zones it's best to use circ's. If everything is fairly even flow-wise, ZV's will do the job nicely with less amp draw. Multiple circ's do offer the advantage of still having heat if one fails vs the single circ usually found on a ZV system. On multiple temp systems, you'll nearly always use a minimum of one circ per temp.

bob_84

I was under the impression that zone valves are not full port such as the 11/4 size and the BTU's would be reduced ? Also what happens when you have a large pump to handle multiple zone valves and only one zone valve is open, pump is to large now?

S Ebels

Ideally

Any zone valve system should incorporate a pressure differential bypass which is set to allow some of the excess flow back to the return. This avoids flow noise and other issues when only one zone is open.
Some of the new variable speed circs (Wilo) are aimed at this problem also.

Unknown

I agree, This is what I use

http://www.taco-hvac.com/en/products/Differential+Bypass+Valve/products.html?current_category=204



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subcooler

Ideally

A multiple circ. set-up would require a bypass on every zone if you logic is correct.

S Ebels

Could be true

If you're running an 011 or a 26-99 on a 3/4" zone.

I'm assuming that a person using circs would have the intelligence to size them according to the flow required. I have to admit, that seems to be quite a stretch for some.

Also have to say that I've seen some bizarre stuff on ZV systems too........like this one. 90K btu boiler, 1,800 sq ft house with 3/4" zone piping and 5 zones, none longer than 90' round trip and the contractor had a 43-75 Grundfos hung on it. Temp drop through the longest zone was like 2.5*. The BB literally hummed. I still have that circ sitting in the shop and I shake my head in amazement once in a while when I see it. BTW, the manifold piping was also 3/4" on that one.

mp1969

You are right about the long runs in a series loop system!

If one sizes main pump(s) properly and uses a reverse return system, zone valves work extremely well and the system is balanced due to first one supplied is the last one returned.

A lot of well laid out commercial and institutional buildings are done this way with great sucess.

If you want to use a series loop system with zone valves I would bring almost equal length loop returns back to the bolier room and have a purge valve for each zone in the equipment or boiler room.

Have your supplier or hydronic designer size the pump(s) if that is a problem. This is usually a service they offer if you buy from a bonofide "heating wholesaler"

There are many great installers who lack design skills and almost as many great designers who rarely install systems!!!

Did I denote a little sarcasm about proper pump sizing???

MP 1969 (the lonesome poster)

Peace!

subcooler

Circs

The first two circs. you listed are the standard install circs for all the wood burners out there. Hehehehe

Bob Sweet

Subcoolers gotta a point

even running a 15-58 on it's lowest speed has the potential to create velocity and noise issues that could create problems on a radiant circ zoned system. At 4 gpm available head is 7 thats way more than required for most looped zones. If the theory holds true for zv's than the same would hold true for the circs. Right?

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subcooler

Circs

Circs are way over used, people have been taught to pump the zone. That's to bad because it only takes a little extra thought to lay out a system the way Gil would have.

frank_47

taco 007 circulator

Does it matter on the position you mount this circulator

John White

Taco 007

Yes, it matters. With 20# pressure(I think) it can be mounted vertically. Horizontally of course is fine.
Just never hang a wet rotor circ with the motor down.
John White

subcooler

007

or motor up

brucewo1b

subcooler

motor up is ok as long as you have 20PSI in the system, gee how did Johnny White know that though;-)

Joe Mattiello

Taco zonevalves operate different from fast acting solenoid types, because it closes slowly and no water hammer occurs. Zoning with zonevalves is an excellent alternative to zoning with circulators. If you use zone valves, and 1 system pump you should size the circulator to meet the system design obviously, but when selecting the right candidate select a pump that has a relatively flat curve to avoid velocity issues when only one zone is open. This is good design practice because the system dynamics are constantly changing.

frank_47

taco 007 circulator

thanks for the information.

S Ebels

Sarcasm.........me?

Surely you jest my good man!

S Ebels

For the most part, I agree

I see some of these systems in the magazines with a row of circs across the length of the mechanical room and my head starts going .........."let's see, hmmmm 32 circs @ .85A each = 27.2A hummmmmm 27.2A X 120V = 3,264 watts....... whewwwwweeeeeeeee!, that's about 10,000 btu's!!!! hmmmm,,,,,,, huummmmmm!!!!!!

I can see clearly now said the blind man! They're heating the house with inverse, bipolarly disordered electric heat in the shoulder seasons by letting the circs add their heat to the system! Why didn't I think of that!!!

Sarcasm....... from little ol' me?

I think the real answer is the classic, It depends. You do what the situation calls for and what is in the best interest of the consumer. Some jobs want circs some want ZV's and some want a combo. The trick is knowing the difference.

S Ebels

Who's Johnny White?

> motor up is ok as long as you have 20PSI in the

> system, gee how did Johnny White know that

> though;-)

S Ebels

Who's Johnny White?

> motor up is ok as long as you have 20PSI in the

> system, gee how did Johnny White know that

> though;-)

S Ebels

Who's Johnny White?

NOT!!!!! (there's that cussed sarcasm again)



I would say if you can't find out something regarding a Taco circ from him, you probably aren't going to find it out at all.

subcooler

I see

32 circs. and think what an idiot because the mid range gpm on those little circs added all together is about 320gpm.
What a waste especially when they are moving 3-4 gpm on a ¾” zone!!! Ikarumbah.

Bob Sweet

I guess I\"m having a hard time

understanding why ideally any zone valve system should require a PDB. I dont think thats an accurate statement.If designed properly you could have one pump with enough gpm/hd to accomodate design day conditions as well as produce no more head (on a mild day) than a single zone circ on a circ pumped system. At that point all things being equal a pdp should be used on all circ. pumps.

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subcooler

You said it all

The pumps are for the jobs where people can't calculate the zone. As far as purging, if you had the correct piping and flows it would take care of its self.

Darrell

Lest I get relegated to the list of hacks that can't or won't do the math...I can and do. But, as a serviceman, I almost never get to work on perfectly designed systems, no matter who the installer was. Low bid rules. Low bid rules out alot of the cool things that we see in the catalogs and hear about in seminars. Low bid rules out piping by the numbers. Low bid rules out long term reliabilty and functionality. Most systems are "designed" inside of an envelope of acceptable parameters. Ideally, the decision to use circs or zone valves should be made by the numbers, but, ultimately, that decision is usually made by expedience, cost, and availability of materials. I sometimes install a new boiler in my line of work...and almost never get to redesign the piping of the house...it is a constant in the equation...whether good or bad...and that will dictate my choice of zoning equipment.

For a simple system that is easy to maintain it is tough to beat primary/secondary boiler piping and circs for zone control. I think that is what the original poster was wanting to know.

Darrell

Geez...that kinda sounds like I am tired and grumpy! I don't mean it to be so...I am tired...but I'M NOT GRUMPY!!!!