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Replacement actuators for Viega manifold

eurban
eurban Member Posts: 30
Hello,
A good number of the thermal actuators on my 8 year old 10 loop Viega stainless steel manifold are no longer keeping their loop closed when it is inactive.
My first question is whether or not there is any practical way to repair these Viega Powerheads? Best as I can tell they need to be replaced but I figured I would ask . . .
If they need to be replaced, what is my best option(s) for replacement? Does it have to be Viega or will other brands fit? I figure I will go ahead and replace all of them. Cost is part of the decision process but I would also hope to find a replacement that will last more than the 8 years I got out of the Viega ones. They are 4 wire units by the way.
Thanks for any and all thoughts!

Comments

  • I've never tried to rebuild them since I believe they are sealed.



    https://www.amazon.com/Viega-15061-ProRadiant-Stainless-Manifold/dp/B008J2YPS4
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
  • eurban
    eurban Member Posts: 30
    Thanks,
    I didn't think they were rebuildable but I figured I would check . . .

    I have seen those on Amazon and they are an exact replacement. However, considering that they are $70 a piece, I need 10 and they have only seemed to last 8 years, I am hoping to find a longer lasting and or more cost effective option. I have put in a query with Supplyhouse but haven't heard back so I suppose I will need to give them a call. . .I was basically wondering if there were any better options than the original 15061s. Mr Pex with an adapter ring? etc etc.
    I'll post if I find a good option.
  • eurban
    eurban Member Posts: 30
    Here's what appears to be the more up to date Viega replacement.
    https://www.supplyhouse.com/Viega-15069-VIEGA-24-VAC-Powerhead-for-Stainless-Manifold-4-Wire
    I figure I will still check around to see if there are any non Viega options.
  • hot_rod
    hot_rod Member Posts: 18,190
    What is the failure? Are the heat motors failing or are they sticking? When the actual valve stem gets sticky or jammed it could keep eating up actuators. Those simple heat motor type actuators should last 15- 20 years if the fluid quality is good and maintained. With the actuator removed can you push the pin down easily?
    If they are tough to push down, or sticky, that could be the cause of failures
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • eurban
    eurban Member Posts: 30
    The problem is that the actuator seems to no longer have the "oomph" to hold the pin all the way up in the closed position. There is some flow in the loops that are supposed to be closed. I can push on the "button" on the end of the actuator to add a bit of extra push and the loop flow then shuts off only to flow again after I remove my finger pressure. When all the zones are off you can see the buttons sticking down slightly on the problem actuators. I'll attach a picture. If you look carefully you can see the "button" sticking down a bit more on the 3 loops closest to the left hand side.
    I researched this problem a while back and I did find some discussion (I think it was in the q&a section on Supplyhouse) where others were reporting similar problems and the diagnosis was failed actuator(s)
    That said, I certainly don't want to throw parts at it only to find the new ones damaged also. Do I need to remove / examine / clean the pin mechanisms on the Viega manifold?
    Thanks!
  • eurban
    eurban Member Posts: 30
    Could it be too much pressure in the system?
  • eurban
    eurban Member Posts: 30
    I checked system pressure was low if anything. I also removed number of the actuators from both the loops that are closing properly and ones that are. As best as I can tell, when I push on the pins the feel and resistance seem to be that same in the good and bad loops. Its too much resistance to do it with my bare thumb but they all move smoothly with a screwdriver pushing on the pin. Here's a picture with two of the powerheads pulled off. Note how the one on the left has browned in the area where it pushes the pin. Thoughts?
  • System pressure shouldn't make a difference, but the size of your pump certainly would, but not after years of working properly.

    Tell us what your system pressure is and the make and model of your pump just for the heck of it.

    If those are fine and the manifold valves are working properly, all that's left are the actuators.



    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
  • hot_rod
    hot_rod Member Posts: 18,190
    When you screw the actuator on the manifold it pushes the valve to the closed position. The actuator needs to be screwed on correctly or the valve may not be completely closed. The actuator needs to be exact in dimension or it can allow the valve to be held partially open. The spring in the valve works with the actuator, so that dimension is critical

    If replacement actuator are not built to the same exact tolerance the manifold port may not open or close completely

    Unfortunately it is tough to mix and match actuators. If a manifold manufacturer switches suppliers you can run into issues.

    I don’t think any radiant company builds their own manifolds or actuators?

    If ever the manifold valves leak around the stem or the valves seize and actuators fail prematurely it often is less $$ to replace compared to all rebuild parts
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • eurban
    eurban Member Posts: 30
    Thanks for all the comments.
    System pressure is right around 12PSI. The circulation pump to the manfiold is a Grundfos Alpha 15-55F/LC. If it matters, my boiler is a 2007 Burnham Freedom CM120 and its circ loop pump is a Taco 0014-F1 which is what came with the boiler. The manifold was installed in 2011or 12 so the actuators are 8-9 years old.
    The actuators have been working fine until this year. One oddity is that the 3 loops (I'm not 100% sure that there isn't another loop with issues) with the problem are on the same Zone. Their wires all go into an external junction box where they connect together and then go to my Taco 4 zone control box as a single wire. It is the first floor zone and is likely the most frequently operated one. I do wonder if a weakened connection or simply the fact that that zone has the most loops (4) on it has somehow caused those actuators to fail early?
    Hot Rod, the plastic rings that the actuators clip to are all fully tightened and the heads are fully clicked onto them. Regardless of what caused them to fail, I'm pretty sure that they are installed correctly and simply no longer hold the pin completely closed. If I was to replace the entire manifold, is there a brand that you recommend?
    I guess I should talk to SupplyHouse tomorrow and most likely order up the Viega 15069 actuators.
    Thanks!
  • eurban
    eurban Member Posts: 30
    More thinking here. . .
    Obviously, this has all worked OK for a number of years. Still, for a proper install, are 4 actuators too much to have on one loop on the Taco 4 zone controller? Are 9 actuators in total (may be even 10 with eventually adding the currently unhooked attic loop to the upstairs zone)?
    I certainly could put in a 5-6 Zone controller if it means proper operation of the actuators and a longer life.
  • eurban
    eurban Member Posts: 30
    I heard back from Supplyhouse and it looks like ONLY Viega actuators will work. The 15069 actuators are what they recommend.
    I am still wondering if the early failures have something to do with there being 4 actuators on one zone on my Taco 4 zone controller. Any thoughts out there as to whether or not this could be the root issue or is it simply that the actuators failed after 8 years of regular use / proper install?
    Bottom line is that I don't want to invest in new actuators and not address a fundamental flaw if there is on.
    Thanks!
    Eric
  • BillyO
    BillyO Member Posts: 276
    Sounds more like a transformer problem then an actuator issue.
  • Each Viega actuator is 1W and the transformer in the Taco ZVC is 40VA. I don't know how to reconcile the two to see how many actuators the transformer is capable of operating.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
  • hot_rod
    hot_rod Member Posts: 18,190
    most of the newest actuators are "low current draw" 250mA, so 10- 12 per 40 VA transformer. What is the rating on the models you have?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • eurban
    eurban Member Posts: 30
    The Specs for the 15061 Actuators is 75MA for the operating current and 250 MA for 2 minutes max for the "In rush current". I'm not sure what the in rush is telling me. I currently have 9 actuators and would like to eventually get the attic loop on line. The zone that seems to have most if not all the bad actuators is the largest and has 4 on it.
    Does it make a difference how the actuators are grouped? Say for an extreme example 7 on one zone and 1 on each of the other three zones?
    Obviously in my case when the 1st floor zone comes on all four of those actuators are going at the same time but I would expect that a properly specced zone controller should be able to handle ALL of the actuators coming on at once?
    Thanks!
    Eric
  • hot_rod
    hot_rod Member Posts: 18,190
    edited April 2020
    Those actuators are basically heat motors, that heat a wax or fluid which expands to open the valve. The inrush number is what it takes to start warming the motor, the lower number is the current to hold it open.

    How long at what current draws depends on the temperature of the valve. If the valve is mounted on a warm pipe the open quickly. In a cold garage for example the warm up takes longer. Low current draw require less power but take twice as long to open, that’s the trade off to allow more valves per transformer.

    It’s rare but possible for all valves to call open at the exact time. It can happen after an extended power outage.
    So by the book, multiply volts 24 by Amps of the actuator to come up with the VA. Most installers put more than the math allows😉

    With the Caleffi zone relays we have 2- 40 VA transformers parallel, so 80 VA available, some brands split the transformers, so be careful how many you wire to each output

    We have tested our relays with 12 low current draw actuators hitting.

    24V X .250Ma. 6 VA per actuator
    So 6 or 7 per 40VA transformer
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • eurban
    eurban Member Posts: 30
    Ok, so by the book I should really have only have 6 actuators on my 4 zone Taco controller.

    I also am pretty certain that 3 or 4 of my actuators have gone bad (power off and in their "rest" position they don't seem to be pushing the pin hard enough to close it).

    So I think my plan is to go ahead and open my wallet and buy 10 of the 15069 Viega actuators and replace the Taco 4 zone with a 6.

    I'm going to have to rewire for the new actuators so it won't be much more work to go ahead and swap the zone controller. I also will then have the ability to separately zone the attic and or the radiant floor (1st floor kitchen addition) if and when I want to. If (don't really know how likely this is?) the 4 zone controller was the root cause of the actuator failures then the new 6 zone controller should certainly be well up to the task of controlling 10 actuators.

    Here's the Taco 6 zone I am thinking about:
    https://www.supplyhouse.com/Taco-ZVC406-4-6-Zone-Valve-Control-Module-with-Priority

    I assume it should wire up pretty much the same as the 8 year old 4 Zone ZVC?

    Thanks again to all, especially Mr Hot Rod!
    Eric
  • hot_rod
    hot_rod Member Posts: 18,190
    Here is a look at the power consumption profile of 3 different Caleffi zone valves.
    The 644 is a motorized ball valve, once open there is no power draw.

    The Z one is a typical motor open, spring return. In the open position the motor stalls and basically becomes a resistor, hence they get very hot.

    This thermoelectric pulls high current then tapers off as the wax warms. The length of that curve would vary depending on how cold the valve is when it starts to warm, notice time on the lower axis. The 250 ma low power consumption would be a lower curve.

    So the question with thermo electric is how many, for how long at the full draw. Basically you overload the transformer for those few minutes when you exceed the VA of the transformer, voltage drops, not an issue with a thermo type, not a good idea within motor type ZV, however.

    The Caleffi ZVR 106, 6 zone relay box gives you 80VA across 6 connections. So you could put up to 5 low current draw actuators on one zone. Assuming the t-stat can handle that draw.

    Some other versions of thermo electric zone valves draw 1A, so
    24V X 1A= 24 VA. By the numbers 2 of this = 48VA. Although you commonly see 3 on a 40 VA.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    eurban
  • eurban
    eurban Member Posts: 30
    Viega specs the 15069 actuators at 300ma for the in rush and 1watt (42ma in this case) for the steady state draw.
    So for all 10 at 300ma that's 72VA at max draw and only 10VA for steady state.
    I guess the 40VA Taco that I currently have is not really an issue during most situations. Still I think having the additional zone flexibility will be good for us in the long run.
    How do I know if the Thermostat is up to the task of (4 zones so about 30VA during in rush)?
    Here's the ones we have. Basic Honeywell pros:
    https://www.supplyhouse.com/Honeywell-TH3110D1008-PRO-Non-Programmable-Digital-Thermostat-1H-1C-Horizontal-Mount-4881000-p?utm_source=bingad&utm_medium=sku&msclkid=4d792013e3ba11a5fb867e84a63d1260
  • If you're using a zone valve control, the current does not pass through the thermostat. When there is a call for heat, it closes a relay which transmits the power to the zone valves.

    I don't think I've ever seen a power rating on the relays for max. current flow.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour