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zone valves vs zone pumps

And there is also the possability of using 2 smaller pumps in parallel for the heating zones. With one pump dead, you would still get about 70% of the flow. The problem would be that the system would work so well on one pump that you might not know that there is a problem until both pumps fail.



  • KW_2
    KW_2 Member Posts: 27
    zone valves vs zone pumps

    Question to you hydronic pros from a general contractor...
    My first project with in-floor radiant. Getting two perspectives and wondering if you have some opinions. I've been lurking about on the Wall for zome time:

    one installer says he will not use a central pump with zone valves due to high rate of zone valve "problems". He only installs separate pumps for each zone - at about $500 per zone for pump/controls - so most of his project employ very few zones.

    Another company says that one of the biggest advantages to in-floor radiant is the ability to deliver heat only where desired - so believes in multi-zoned systems i.e., each occupant can have their bedroom at their own preferred temp. They say that using zone pumps makes this cost prohibitive - whereas using zone valves makes this 'zonability' affordable.

    So...anyone care to weigh-in on this - zone valves vs zone pumps - in terms of reliability, overall complexity of the system, and bottom-line for the project - homeowner comfort (and cost too!).

    Thanks in advance,
  • singh
    singh Member Posts: 866

    Try using both.
    Pumps and then zone valves or telestats off manifolds
    for like temperature requirements.
  • ALH_4
    ALH_4 Member Posts: 1,790
    Zone Valves

    I much prefer the zone valve versus zone pump design. It allows you to distribute multi-zone manifolds throughout the house in order to not have to hone-run every zone. Depending on how spread out a house is, this can be a definite advantage.

    There are zone valves out there that do not have a very good track record. Some of these have been very popular. Our chosen zone valves are manufactured by Caleffi. There are many others of similar design that are good also. White Rodgers makes a 3-wire zone valve that must be powered to open or close.

  • J.C.A._3
    J.C.A._3 Member Posts: 2,981
    Like ME always says.....

    The best answer is "it depends...."

    If you're looking at multiple flooring materials and temps., a pump for each might be the right way to go. If everything is "one temperature", a single pump and bypass differential with zone valves may be the way to go.P/S could hold some validation also,but with multiple mixing devices to be thrown in.

    Again, it depends on so many factors. Mixing devices add some resistance to flow and can be a make or break point in the process of deciding which way to go.Add in the many different devices that can add or subtract from the needed requirements, (pressure differential bypass valves, flow setters and the like..)and figure the cost of doing the job each way. The pumps may be the best alternative in some situations, where other times zone valves could be a better alternative and less costly when bidding the job.(pump curves could put you right on the hairy edge in some cases)

    See the reasoning? It really does depend ! Something to confuse you further. Chris
  • Tim Doran
    Tim Doran Member Posts: 208
    Simple Approach

    I use a simple approach to this. If the flow and head requirements of multiple zones, requiring a common water temperature can be met with one reasonable circ and a few loop valve actuators why use two? Once the flow and/or head get out the the range of something reasonable(off the shelf, readily available, etc) I go to two pumps.

    Tim D.
  • Weezbo
    Weezbo Member Posts: 6,232
    thats ,how they say ,ambiguous *~/:)

    thinking of Just Radiant? well, what about the indirect domestic recirc system? wouldnt happen to have a coil,couple different temps of radiant,...radiant ceilings in bedrooms,radiant wall or heated bath tubs, a few radiant pannels,pre heater coil,seperate HX for small 20 man bath tub:) indoor wave maker,jot remote headers at distant locations, chunk of baseboard convectors under the twenty feet of rising glass,radiant posts or beams ,i belive i could rambel on a couple more pages,thing is it could depend on a group of variables.

    my first preference would be ZV's though, it is because i like using low voltage, then the next deal would be that i like modulating controls so, that brings on sub stations and thier own injection pump and system pump, take the HX to the coil not the coil to the heat exchanger... that way everything is in one place and a guy can deal with it,something also to be said for evrything in the boiler room so you dont have to run about looking for things too. that though is seldom the case . i like things in balance however that doesnt mean i just buy into rehau or wirsbo premade headers and a large pump someplace whisteling the water thru the system i have 11 zones and of those all will have a zone valve,one group of 4 will have its own injection pump and system pump one group of 3 will also have its own injection pump and system pump,one will be a 100 K BTU coil,it will have its own HX and zone valves and pumps ,another is baseboard convectors which will have a take off with its own zone valve from a buderas pump block,2 other zones will be taken off for high temp SOG at the boiler with thier own take offs and zone valves , and last buh not least is the indirect that will be paralleled off the boiler with DPO over all of the above, with its own pump and zone valve. so i figure thats 9 pumps,13 zone valves and a modulating bypass and that is only for the system and one boiler,it has two.

    on antother house this year with all radiant and an indirect on a low mass boiler,i have 6 zones off the buffer tank which is fed by a stepped two zone valve arrangement with a modulating by bass and a heat exchanger at the boiler for a take off for the Domestic storage tank and recirc system for on demand hot water, with a pump driven off the tstat oin the tank,...so that would be two erie zone valves at the boiler with a modulating bypass ZV and a boiler pumb and one circ pump and a heat exchanger pump,one large system pump off the buffer tank that lash up feeds,and6 zone valves for the field....i havent put the final twist to that one just yet it gets an out door reset,as well, and a pressure differential bypass.

    so where i might like to say Pumps or Zone valves are the only game in town, id rather say that there are many variations on a theme and whatever brings it all together in balance thats my favorite line of endeavour. we have many tools and stradgies to choose from and will be having even more in the near future....for example as much as i like zone valves the Wilo pumps would make a healthy contribution to a revised stradgey or two when they become available, likely i would use pressure valves and wilo pumps and go for Caleffi conrtols to intergrate the fields and equipment associated with comfort in a home.
  • Joe Mattiello
    Joe Mattiello Member Posts: 703
    Zonevalves manual bypass a plus

    Zone valves or circulators, you will get a lot of opinions on this one. I’ll add my two cents. If you lose power and you ignite the burner with a match have the boiler ramp up to high limit, you can open the manual bypass lever on the Taco 570 series zonevalve, and have the hot water thermal siphon through your home keeping you nice and toasty for your thanksgiving dinner. For your reference I have attached the catalog data on the Taco valves. Have a great holiday!!

    Taco, Inc.
    Joe Mattiello
    Technical Service Technician
    [email protected]
    401-942-8000 X 484
    Joe Mattiello
    N. E. Regional Manger, Commercial Products
    Taco Comfort Solutions
  • Ron Schroeder
    Ron Schroeder Member Posts: 998

    I try to use zone valves as much as possable to save energy. Caleffi, Taco ESP, and several other zone valves use 3 watts or less while a typical pump uses 75 watts. I always put the indirect on it's own circ because a zone valve would usually be a bottleneck and reduce it's recovery.

    My own system has an indirect on a 007 circ and 13 zones on a small 18 watt circ from Laing. If I had zoned it all with individual 007's, all of the pumps would put off enough heat to heat my house without firing the boiler. ;-)

  • Brian_7
    Brian_7 Member Posts: 18
    Pumps vs. ZV'S

    Greetings. A few more points to consider on this topic.

    If a single pump is used with ZV's and it fails while the homeowner is on holidays his system is totally without heat, = possible frozen pipes etc. If several smaller pumps are used the system can still limp along if one of them fails. Improved reliability through redundancy.

    If one pump is used it must be sized sufficiently large so as to accommodate the condition where the entire system is calling for heat. In the situation where only one zone is calling for heat the pump is then oversized for efficient operation. Several properly-sized, smaller pumps would be more economical because only the amount of power required at any particular time would be consumed.

    The consequenses of the failure of a ZV are also much less severe that the failure of a single pump. Lose a loop or zone; not an emergency.

    How do the above mentioned theories translate to the real world you might ask? Well my home IFR heating system relies on a single pump, as designed and recommended by an internationaly recognized name in the business, against my own design concerns. The name-brand pump that was installed failed in the first year of use and had I not a gas stove and wood fireplace for backup I would have been totally without heat.

    I would therefor echo the suggestions made by others here that a combination of the two design philosophies would be prudent.

    Best regards. - Brian.
  • ALH_4
    ALH_4 Member Posts: 1,790

    It is a weakness that there is only one pump and it dies with no backup.

    But what about P/S piping when the primary pump dies?

    A single pump w/zv's may be oversized much of the time, but, unless each zone is quite large, individual zone pumps are oversized all of the time. It's pretty impressive what a Brute or 007 can do.

  • Ron Schroeder
    Ron Schroeder Member Posts: 998

    Hi Brian,

    While having 2 circs for the heating zones with half of the zones on each circ would give the best reliability, my own system will give enough gravity convection with the pump off to keep the house above 50 degrees at zero outside with a dead pump. The zone valves are on the supply side of each zone and I have a thermal drop loop on the return of each zone (instead of flow-checks)to prevent single pipe ghost flow.

  • BillW@honeywell
    BillW@honeywell Member Posts: 1,099
    Honeywell has...

    several zone valve options, the standard V8043 1000 series, the premium V80435000's with quick release top, slow close, silent motor and the rack/pinion drive, slow closing PowerTrack valves, MZV series. The MZV's are also available prefabbed in 3 or 4 zone manifolds. Available from any hydronic oriented Honeywell distributor.
  • Brian_7
    Brian_7 Member Posts: 18

    Hi Ron -
    I'm curious. How did you determine your dead-pump convection capability?
    Also - maybe it would be just as good to have the second pump not plumbed in and just have it on hand as a spare for an immediate switch when the other one dies!?
    - Brian.
  • Ron Schroeder
    Ron Schroeder Member Posts: 998

    Hi Brian,

    That was easy, I just disconnected the power from the circ.

    BTW, since I use B&G iso flanges, changing the circ is very easy.

  • match light?

    Who still installs boilers that can be ignited with a match? How does that match lighting ceremony help someone with a fuel oil burner?
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