Zone valves vs circulators...

BillW@honeywell

Hi, Wallies! I'm back for a minute, and I'm asking YOU a question. In my travels, I've heard a lot about contractors now prefering to use circulators instead of zone valves on new residential hydronic installations, so I wanted some feedback from the pros. Are you doing this, and if you are, why? Thanks in advance, good to be back, if only to ask a question. I really miss this place!!!

Ron Schroeder_3

I use circualtors

because they start and stop more gently than a spring motor zone valve. Additionally, because the circulator is only responsible for a part of the whole load it can be substantially smaller than one that has to circulate an entire project.

bill clinton_3

zv vs circ

Used to be one of my favorite controversies. After many arguments I came down to this:
1. Zone valves are more compact and use less electric: Wet rotor circs have real world efficiencies somewhere around 10 %.
2. Zoning with circulators gives you lots of redundancy. In a zone valve system, if your single circ goes out, you got no heat--very bad if it's -40 out there.

I'm in Northern California: Zone valves are a no brainer to me. If I were in Vermont, I might choose otherwise.

Bill

hr

Depends on the job!

If I had a 6 zone house with a load of 80,000, why would I use 6 circs running at the botton, least efficient part of their curve. While consuming 78 watts of power each! 468 watts being consumed at a 10- 15% efficiency.

Now if each zone had a requirement of 7gpm so gpm at 5-7 feet of head, a circs would be a no brainer.

It doesn't have to be all or nothing. I'll often use several circs with a couple to 3 ZVs per circ, like the Weil Ultra job I recently posted.

Rule of thumb somewhere between 3- 4 gpm max on basic ZVs.

Keep in mind circs require relays, iso valves, and possibly check valves. All this is generally a bit more $$s than ZVs.

This has always been a Ford vs Chevy debate

Top quality ZVs allow some flow balance potential, soft operation, and equal proportion valve openings.

hot rod

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Unknown

We find the cost of pumps is not that much greater than ZVs, and in our experience pumps are much longer-lived than ZVs... especially in our fancy PWM or indoor/outdoor reset systems (read, lots of cycling on some or all zones).

However sometimes it's just too small to do with circulators. And Bean says there is a brand of ZVs out there with a fantasticly rare failure rate. If we can verify those we may start to switch more often, but for now the extra power consumption and few extra bucks up front wins in our systems for long-term reliability, simple system balancing, and easiest possible servicing when the pump does finally fail..

hr

Rob

do you supply flowsetters with the circs, or just let them run where they may? Suppose you have a bedroom zone requiring 1 GPM, which pump do you spec?

Suppose I pay 70 bucks for a ZV.

A circ at $80, set of iso flage at least $20, A Taco or HW switching relay perhaps $35. Skip the check, it's in my brand of circ That's $65 per zone more $$. More than a few bucks in my wallet. Times 6 zones $390.

What's in your wallet?

Here is a fairly typical radiant zone list. 007's on each and every zone? 400 watts to move 7.9 GPM! Really Use a system overlay curve sometime to see how those circs look at those numbers.

hot rod

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Unknown

We use 3-speed grundfos pumps, so there is some flexibility. Six at low speed use 270 watts.. a couple of lightbulbs. If a job has multiple single loop zones, that's when we switch, but frankly when the pressure sensitive pumps come out, if they are in the same price ballpark we'll probably use them instead.

I'm not sure how you are omitting relays from a ZV setup? At our cost figures, it's about $30-$40/zone more using pumps, using Erie ZVs.. if we were using $70 ZVs there would be next to no price differential, unless your ZVs come with a relay built in (I'm guessing, by the price differential), then the differrential would be about the same. Using ISO flanges, built in check, etc for the pumps, of course.

Plus it's not a direct trade. Take your "$390" cost savings, subtract back out the system pump you need.. how about a pressure bypass while you're at it... hmm.. that differential gets a bit smaller. What's that, $250? That's a callback, isn't it? That's what we don't get with pumps.

Like I said though, if anyone is using PWM thermostats or indoor/outdoor reset systems with a particular brand of ZVs and is not getting failures long-term... I'm all ears! I just haven't, to this point, been convinced that it's an equal comparison on quality and longetivity, and until I am, our systems stay pricier. But for a reason!

No comparisons to bang-bang Tstats though, please. We don't do those systems and the cycling rates are not even in the ballpark.

Unknown

For us

and our typical 2 zone homes , it's circulators .

lchmb

Toss up

Although I do like the idea of saving my customer's money on an install and down the road, I personally find in my area of NH that zv's do not hold up. On average in a winter I change 1 circulator to 10 zv's. That and like other's have mentioned, if I zone a house with zv's and that one circulator is the one I have fail and the customer is in Florida for two weeks.....ummmm what a mess...On another note Bill...this turned into a rather long discussion over on oiltechtalk....might want to check that out...

hr

Yes the delta P circs

will open some interesting doors

Generally package boilers come with a system circulator. They also have a transformer to drive 6 or so zone valves, as well as a relay to switch on that "free" circ. So really ZV are a fairly simple install, in that respect.

Either will get the job done, I like to keep options open. I've not had much problems with the Erie ZV I switched to 9 years ago. In fact, so far, no failures. I have had service calls to bump start frozen circs, more often than ZV problems. Probably a combo of pump brand and sticky water found in many of the early Heatway systems prevalent in this area.

I tried a few prefabed boxes with those Danfoss ZVs. It's a nice piece. Slow to go when you test or troubleshoot an eight zoner Just keep a collection or those mini metric allen keys you need to remove the heads for purging, service, etc. The early ones, used in the ZCPs did not have end switches, I believe current versions have this ability. That's a plus for Americanized systems.

hot rod

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THP_6

Amen

A person who knows how to pipe a job does not pump the job!

Unknown

Now that's interesting (and I am glad to hear it, we just switched to Erie last year). Have you been using PWM thermostats or anything similar to, say, Tekmar RTUs? I.E. Anything that cycles your zones more than a simple "raw" heat demand call would, to even out average run times and/or do "load balancing" across multiple zones?

hr

Now that I mentioned Erie

The Caleffi ZV is very similar but with a larger port, higher Cv. I have a sample, but haven't screwed with it much. Doesn't Roger the Caleffi guru live up in your neck of the woods? Check 'em out at radfest east, they have some unique stuff.

Since we have gone primarily to condensing boilers, and the current brand has an onboard outdoor reset, I feel ZV cycling should be minimized. Not a 100% constant circ by any means, but much less bang/bang than a stat to a one temperature boiler.

We have a few of the tekmar 511 and the Wirsbo counterpart t stats out there. This seems like the closest to ideal for a radiant stat. Once you get the owner/ operator over the programing hump, that small stat has a lot of features and benefits! Coupled with the slab, or floor, sensor it really does all you could ask for.

hot rod

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Andrew Hagen (ALH)

Zone Valves

We typically use a minimum of circulators with common supply and return pipes that connect to remote manifolds distributed strategically throughout the house. This saves substantial labor and materials compared to home-running every zone. When connected to a fully modulating boiler the thermostats act only as high limits for the rooms.

The modulating boilers really eliminate the need for a lot of complicated controls used to make a single stage boiler behave. Pumping every zone is really overkill in most residential situations. A variable speed 26-64 would be nice ;-)

-Andrew

Andrew Hagen (ALH)

Caleffi

Pardon me for butting in, but....

We've gone completely to Caleffi in the last year. Everything is very high quality and seems to be well designed. The manifold enclosures are very nice. The people are very helpful.

If only we had the selection the Italians have.....

-Andrew

Unknown

That's a good point with the reduction in cycling from outdoor reset. hmmmmm.... I need to get some kind of logger on one of our Tekmar 5** thermostats out there and see what actual field cycling is like one of these days...

Bill Nye_2

On a

On a "budget" job, the boiler comes w/a pump and it is already wired so adding two or three zone valves is way less labor and wiring.

When I have air handlers [fan coils] I prefer indidual pumps. Indirects too, I don't like zone valves on indirects.

I have very little trouble with Taco zone valves. I have had to change only a handful of valve bodies in my lifetime. Power heads, that's another story. But you can manually open them to prevent freeze up and you can change one in under ten minutes. The old green ones failed a lot, but the new Gold ones seem pretty good.

Too many zones! I have been in houses with a zone for every room. One house had 13 taco 110's !

How about one or two pumps a pressure differential by-pass and non-electric zone valves? Less electricity for sure.

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leo g_13

Bill

still use only your zone valves. We have had no real problems with them and they sit so pretty on that
Alberta Custom Tee!

I am so sure of your valves, that lately I have been entertaining the thought of ditching these persnickity actuators, for the remote header stations, and building my own with the aforementioned material.

To me personnaly, a lot of circs in a row, looks like a system on steroids. But as another said, if I lived in a cold climate, and not the temperant one I do live in, then yes, I would look at circs more seriously.

Leo G

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ScottMP

MY concern

is flowrate. How about a thirteen zone system with all zones calling during the coldest night of the year when we need output the most. How fast is the water flowing thur the boiler ? Fast enough for heat transfer ??

Not every job is the same.

Scott

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BillW@honeywell

Thanks, Guys!

Really appreciate the feedback!

Weezbo

light and sound

just got computer to GO again*~/:) ok so it needs HELP!

now that i got that out of my system..... I prefer using zone valves for the most part, among my favorites are :Taco,Caleffi,Erie...i particularily like the Taco as they have light and sound *~/:) some "zones" pretty much require a circ plate exchangers for an example,indirects for another(depending on piping stradgey) ie parrallel primary.... the Wilo circs i would suggest would be extremely useful yet i would refrain from using these in abundance on any one system also...and continue with the zone valves using the smallest wilo for the sub system or stations...

hr

If you must use ZVs on indirects

chose a high Cv version. That big, block of diecast, White Rogers is an excellent choice. Once you figure out how to wire the ****

If you want to dump 8 gpm (80,000 BTU/hr.) or more into an indirect, size the ZV accordingly.

I think Erie offers high Cv zone valves, typically not an "on the shelf" stock item.

hot rod

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Joe Mattiello

Zone valves or circulators?

This has always been the million dollar question. There are benefits both ways so I always leave it up to the engineer designing the system. Historically, zone valves were more commonly used when cost was an issue. Circulators always need a positive shutoff in some cases two one on the supply, and one on the return. Nowadays with the inception of wet rotor type circulators with the integral flow check valves, cost is no longer the determining factor. Someone’s correspondence picked up on one of the benefits of using circulators as opposed to zone valves, that is you will still have heat if one circulator fails. The other circulators will help carry the load by heating the other areas of the home. Please advise, if anyone has any specific questions.


Taco, Inc.
Joe Mattiello
Technical Service Technician
joemat@taco-hvac.com
401-942-8000 X 484
www.taco-hvac.com

heatboy

I'm with you............

I, too, had suffered from "gottapumpitis" during the early years. Now, it's a couple of pumps, ZVs and telestats where needed. Zone valve failures are very rare and piping becomes ridicoulusly simple with them. In a correct system, ZVs just become limit switches and most often GPM requirements dictate ZVs are a far better selection.

I'm from the KISA ;-) school, now.

Ron Schroeder_3

but it is not in the right place

in the piping. I know of no prepackaged boiler that has the circ on the supply side, do you?

hr

Fred

more and more the packaged boilers are shipping with the pump included in the box but not mounted on the boiler. It's taken years but this seems to be the better approch. Most knowledgable installers will "pump away" If not, circs on the return and ZVs on the supply do in fact work, there are probably thousands of them out there heating just fine.

The next step I would like to see boiler manufactures take, is to leave the circ out altogether. This allows the installer not only a brand choice of pump, but the ability to better size the pump. As pumps come in a lot more sizes these days.

Delta T and delta P pumps are certainly an option to be explored for boiler pumps, as you well know.

hot rod

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Andrew Hagen (ALH)

Expansion tank

Tee the expansion tank on the suction side of the pump and there's no problem.

-Andrew

Bob Sweet

Make it happen hr

I cant find enough uses for the 007s laying around.

S Davis

Zone Valves

We use zone valves or telestats, a pump for every zone is overkill unless you have real large zones like houses 8000sqft or larger on these we will use a pump per floor or wing along with zone valves or telestats, also why design your system to be less efficient than it can be.


S Davis

Apex Radiant Heating

Ron Schroeder_3

Viessmann already leaves the circulator choice

in the hands of the installers and are criticised for doing so because the other guy "throws them in".

Bill called for contractor preference when he launched this thread. Circs are mine. Zone valves are yours. The discussion was not started to see which is better.

Shalom

PS, I value your posts more than you know.