Zone Valves Versus Pumps

[Bricks]

Was just talking to the dealer I am getting my EKO 40 through. He is recomending going to all pumps for the four zones versus running one pump and zone valves. His comments were, zone valves are harder to replace and identify which one if having a problem, or where the problem arises, zone valves build up with water contaminants faster so need replacing more often. Pumps he says go out just unbolt and replace zone valves are difficult to replace. ?????????

So what is the scoop one better then the other?

 

[stee6043]

If installed correctly with shut-offs and unions I'd think the replacement aspect would be a wash. My only concern with running one pump and a bunch of zone valves would be having a single point of failure. I personally prefer having more than one pump in my system. If one goes down I don't loose the whole shot. I only loose that zone. And if I recall correctly my three speed Grundfos pumps are cheaper than Taco zone valves....

But on the other hand....pumps use electricity so less is more. ha. It's never an easy answer....

 

[Chris Hoskin]

one big advantage of going with one circ pump and zone valves is that you could take advantage of variable speed pump technology like the Grundfos Alpha and dramatically reduce the electricity consumption of your system. Like gas and oil boilers, wood and pellet boilers are getting pretty close to plateau - ing as far as future efficiency gains go. In other words, if you buy a wood gasification boiler today, there is not going to be a boiler with a huge increase in efficiency five years from now. So, this means it makes sense to look at the rest of your heating system for efficiency gains and electrical consumption is a great place to start.

Chris

 

[Sting]

Pumps to zone - thats not wrong - there really isn't wrong and right - every load is different so there is no generic right and wrong. ME-- I was taught by a dead guy "plumbers zone with pumps and heating guys zone with zone valves.

Its all good!

But the above comment re: one is harder to replace/trouble-shoot than the other

Now that's just BULL $hit -- sounds like the dealer has a stock of something he wants to sell.

 

[Nofossil]

I've replaced both - zone valves are easier IMHO. The parts that fail are dry and can be replaced with a screwdriver. In a simple system, zone valves work very nicely in that they provide a flow resistance sufficient so that the circ is on a different point of it's operating curve depending on how many zones are open. They use a LOT less power than circulators, and there's almost no chance of ghost flow problems.

One problem with zone valves is that they don't allow you to easily tailor flow rates for different zones. Not an issue in most residential systems, but circulators do give you more control.

 

[WRVERMONT]

Well said Chris. With improved zone valve tech on the rise and adaptive ECM circulator pumps, I'm likeing overall efficiency of the zone valved system.
I think the future is likely the zone valve approach. With larger multi zone radiant runs, using pumps seems to make sense.

 

[Chris S]

I disagree, I think the future is in small low wattage circulators. That being said the systems we currently install use a mix of zone valves and circulators as the situation warrants.
I was on a job last year- all baseboard heat, 6 zones none larger than 15,000 btu with most at half of that run by 6 circulators. This is imo overkill, a waste of electricity, and overpumped in most instances. This same system could be run with one ecm circulator, and zone valves. Energy consumption would be less, as would installation cost. Zone valves have their place, as do circulators. In most residential applications that I see zone valves are all that is needed.

 

[DaveBP]

zone valves are harder to ............ identify which one if having a problem,

If it's cold outside and one of the zones stopped supplying heat, why wouldn't you know which zone it was, valves or circulators? Your wife would let you know pretty quickly. And your fingers could tell you which pipes were warm and which were cold.
If the zone valves are crudding up, that's a water problem, not a valve problem.

EDIT: And if you have a system with widely varying loads at different temperatures, that might best be served by a primary/secondary arrangement which would necessarily have a circulator for each different zone.

Just no universal answer. Too many different designs out there.

 

[in hot water]

if your zone valves are plugging up with contaminates you have a water or fluid issue, not a zone valve issue. That same "rouge" fluid will also do the same to the pump impeller and volute. Sounds like open system "baggage."

Most all brands of valves now have pop tops to replace the motor and drive with the flick of a lever, no tools required. It's very rare to find the valve portion failed. Unless you are pumping cement, or contaminates

Typical wet rotor pumps are fairly in-efficient devices. Operating at the best possible point on their curve, maybe 22% wire to water efficiency. Sleeve bearings, rotor sloshing in the fluid, etc, all contribute to this.

A system moving a 60K load with five 80W (400W) zone pumps at 20% efficiency??? Why?

With zone valves, the best current method is to use a single ECM circulator. Wilo, Laing, and now Grundfos have them available.

Here is the new Grundfos Alpha on my solar drainback. It replaces a 15-58 that consumed @ 78 watts to do the same job.

The display on the Alpha flashes back and forth from Watts to GPM. As the load changes ie. zone valves close, the power consumption drops. This circ can deadhead all day long at about a 7W draw. So you don't really even a relay to start it. Plug it into the wall and the onboard electronics handle the rest.

I'd still suggest a relay, why waste even the 5-7 watts.

Yes, they are more money, the price is dropping with more players in the market, but do the math for the operating costs over a 20 year life expectancy. Plus excessive velocity and all the other hydraulics they solve by modulating based on load.

If a failure is a concern, keep a standard 15-58 on hand for an emergency replacement, find very inexpensive, out of date code, "spare" circs on e-bay.

Always install circs with good isolation valves on both sides, in the event you need to replace one.

hr

 

[dogwood]

HR, If you are using a single ECM pump, and zone valves instead of circs, is there some way to differentiate for the Grundfos Alpha when one zone requires a different number of GPMs than a second zone might? I thought you had to use multiple different size circs to accomplish that instead of zone valves.

Mike

 

[in hot water]

One way is to use a manifold with the flowsetter and meters built in. At least on radiant or home run radiators or baseboard systems. How are you setting flow rates on zone valved systems, with fixed speed circs, now?

Many installers us PAB pressure activated bypass valves if they have 4 zones or more. This valve bypasses some flow as valve shut off to prevent excessive velocity in one or two zones. Typically with a small circ, and a flat curve circ, it isn't much of a problem. The old B&G;series 100 circs were great for that flat curve profile

The new delta P(pressure differential) circs "know" when the flow changes "electronically". Then it ramps up or down according to the load. Some will even "learn" the hydraulics, temperatures, etc. The Wilo watches system temperatures, in the volute, and can go into nightime setback on it's own!



hr

 

[solarguy]

Both have their place depending upon the application. Like Sting said, plumbers zone w/ circs, heating guys zone w/ valves. I heard that statement back in chicago & denver almost 30 years ago & it's true. I think most plumbers zone w/ circs so they don't have to get involved in control wiring...

Zone valves are cheaper to install if you roll the circ relay, flanges & adapters into the equation.

I lean towards zone valves because when you zone w/ circs in most cases you're pumping too much water. I've yet to see a house mouse heating contractor balance a hydronic loop on a zone. If your zone only requires 15,000 btu's than that's 1.5 gpm if we're talking about standard baseboard. Take a look at pump curve for a standard 007 or 3 speed grundfoss, you're pumping alot more than 1.5 gpm. Now throw 4 or 6 zones into that equation & you're pumping 10 times more water thru the heating system than is required. That is a waste of thermal & electrical energy. There is the time in the shoulder months when only a single zone will be calling & the water flows thru like a freight train but in normal winter conditions zone valves w/ a single pump makes the most sense.

Look at larger commercial projects, engineers spec out zone valves.

Bob

 

[heaterman]

As always, it depends. There are pros and cons each way.
Zone pumps give some redundancy to your system, In your case if one gave up the ghost you would still have 3 zones with heat. Not so with ZV's. On the other hand if all four zone pumps were running at the same time you could be pulling as much as 300 watts+ which adds up over the course of a winter. Zoning a residential system with pumps pretty much eliminates any problems with unequal flow through the various sones. They will all likely be over pumped to a certain extent.
A zone valve system will consume fewer watts of juice over its lifespan by a pretty wide margin. The problem is on 99% of the ZV systems I see, one critical component is always left out. That component is a differential pressure bypass valve. This valve is piped into the system between the supply and return and "unloads" to relieve excess pressure/flow in instances where only one or two zones are calling for heat. If it's not there the full output of the circ will be dumped into possibly only one zone. The new circ like HotRod described are ideal for a ZV system because they will adjust to a predetermined Head pressure regardless of how many zones are open or closed. The Wilo brand will adjust to either pressure or temp drop across the system and I think the Grundfos Alpha may also.

Choose your poison.

 

[Medman]

OK, the Alpha looks like the solution for my re-plumbing project. I am switching from circs to zone valves, following the "Simplest Pressurized System" plan, in order to maximixe the heat stored in my tank.

What is the cost for the Alpha or Alpha2, and where I can I buy it?

 

[Chris Hoskin]

Medman, your local Westburne or Emco should have it in stock. Pricing will be around $400.00CA I would guess.

 

[DaveBP]

Patriot Supply has the best price I've seen so far. $275US

(broken link removed to http://www.patriot-supply.com/products/showitem.cfm/200930)