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Temperature/Zone Control - Questions

plokie Member Posts: 2
Hello Everyone,

Have had a plumber in a couple times but getting nowhere in regards to controlling the homes temperature accurately.

Not too familiar with boiler systems but have a good understanding of construction in general and am pretty handy. As I'm not familiar with boiler systems I wanted to check whether what I think should be done makes sense or if there's better/alternative solutions.

Issue: temperature in the house gets too hot all the time unless many manifold circuits are manually closed.

My understanding:
-Boilers temperature is controlled with outdoor temperature sensor - temperature of hot water
-Heating system pump is always on (assumed it's set to auto adjusting volume based on demand or a fixed speed - haven't played around with it).
-Manifold circuits there's 5 thermostat controlled actuators & 11 manually controlled actuators

I'd think the house is always too hot due to the pump always running and 11 manually controlled actuators always being open (unless I constantly adjust them manually to be closed/open). I assume that as long as the boiler is set to heating and many zones being manually open the house would indefinitely heat to being too hot.

Simplest solution?
-I'm thinking to add electric actuators to all manifold circuits that are currently manual. Add circuits to the 5 thermostats already in place throughout the house (essentially creating 5 zones). Looks like currently the thermostats are directly wired to the actuators. I'd imagine I'd need a control box that the thermostat ties into and then outputs to multiple actuators (as directly wiring I'm assuming the voltage draw of multiple actuators exceeds the voltage supplied by the thermostat).

Open to any feedback/solutions and whether I'm on the right track with this or misunderstanding anything. If my above solution is the best I'd love some suggestions on a control box that allows 1 thermostat to control 4-5 actuators each.

Thank you.


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,817
    edited March 4
    The designer of that system has a lot to learn. Unless there is a very accurate outdoor reset curve that will make the 11 sectors or zones of that system operate at the exact correct temperature, (which is unlikely) then you need a thermostat or other temperature sensor to control how hot the rooms served by the 11 sectors or zones.

    Then after getting that exactly correct, the other 5 sectors or zones with the electric valves actuators should have been designed to overheat (on purpose or by accident) and therefore need additional means to shut them down so as not to overheat.

    The proper design would be to have electrical actuators on all 16 valves and thermostats to operate each valve accordingly. If the 16 loops are feeding 8 rooms, then one thermostat may need to operate 2 or 3 or 4 valve motors, and other thermostats may need to operate only one valve actuator. it all depends on how the system is laid out.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,817
    edited March 4
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Jamie Hall
    Jamie Hall Member Posts: 23,273
    As @EdTheHeaterMan said, your first step is to get the outdoor reset curve of that boiler adjusted properly. Clearly it isn't -- if it were, while you might get a bit too warm on a still sunny day, you would not significantly overheat.

    You'll also save some gas.

    Then see how that works out.

    You will likely need to have zone valves on all of the zones, not just a select assortment. To do that, you will need zone valve controllers (Taco, Caleffi to name two) to take the thermostat signals and provide the commands to the zone valves. A note on that: a thermostat is NOT a power source. All it is is a switch.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • hot_rod
    hot_rod Member Posts: 22,108
    10 loops at what length, I think you may need speed 2 or 3 on that Alpha.

    I don't like the bull head tee between the manifold. Flow doesn't always split the way you think it should. Do all the flowmeters read .5 gpm or so?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • plokie
    plokie Member Posts: 2
    Appreciate all the feedback so far. It's in line with what I was thinking except I wasn't aware the outdoor reset curve not being adjusted properly. To clarify it gets up to ~25 degrees Celsius - not sure if you consider than a bit too warm or significantly overheating - it's also a cooler period of the year still.

    What I'm thinking for adjusting the system - in terms of keeping it simple, easy and cost efficient.
    -Caleffi ZVR106 6 Zone Motorized Zone Valve ($389 CAD) (5 thermostats)
    -Wengart 2 wire AC24V Thermoelectric actuator WG2212 ($16.99 CAD) (actuators to be split among 5 existing thermostats)

    It seems all actuators are pretty much the same (many different brands/cosmetic look) spec wise. It's my understanding 2 wire or 4 wire actuator should be the same in functionality with this Zone Valve controller as long as I run a jumper between the end switch terminals? Thus, I figure I might as well get what is readily/cheaply available?

    Still planning on reading up on the outdoor reset curve as well as checking to make sure the flow meters are calibrated properly based on line sizes - given the disaster of the rest of this system.

    Just confirming this will all work prior to ordering parts, as I previously mentioned I don't normally work on boilers so it's nice to have a little confirmation.

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,817
    @plokie said ...Still planning on reading up on the outdoor reset curve as well as checking to make sure the flow meters are calibrated properly based on line sizes - given the disaster of the rest of this system...

    To put this in perspective, an outdoor reset curve can be plotted/adjusted to maintain an overall temperature on a well balanced system so that no room thermostats are needed. To give an example, I had a customer that purchased a new ModCon boiler and it was set up for the most efficient ODR operation curve. The problem was that this elderly woman wanted to set the thermostat at 80° because of low blood circulation. She just could not get warm with the home at 72°

    After the the new boller was installed and set up for this “efficient operation”, the boiler could not get any room in the home to go above 72°.Tthe thermostat was set on 80° but the boiler could not heat the home, according the the customer. This was very distressing after paying over 5 figures for a new system. So I set the reset curve and WWSD to heat the home as if the boiler did not have ODR at all. The home reached 80° and the customer was very happy. So that tells me that this customer's home was able to maintain a comfortabel 72° at the reset curve selected even with a constant call for heat from the thermostat.

    You may be able to get your reset curve to provide you with lower temperatures by making an adjustment to the reset curve and WWSC numbers available in the boiler control's menu. Then try some settings and adjust a little at a time. Maybe allow the building to acclimate to the new settings for 2 days before making another adjustment.

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Zman
    Zman Member Posts: 7,569
    If you intend to control more than one zone valve with one thermostat you may overload the transformer in the controller. Check the amp draw of the power head and the rating of the controller before attempting that.
    Usually, systems like yours would have a master t-stat to turn everything off when it gets too hot. Adding one would be worth a try.
    I agree that outdoor reset adjustments might help. Lower is better.
    I would also run the Alpha pump in a constant pressure mode rather than fixed speed. Try pushing the button until the middle wedge on the right lights up.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • hot_rod
    hot_rod Member Posts: 22,108
    Most of the thermal actuators "helmet head" are low current draw now, but check to be sure you want 250 milliamp type so you can get 7 or more on a 40Va transformer. Earlier versions were 800 mA.

    Low current draw actuators take a bit longer to power open as the heaters in them are smaller, to get the power consumption down.

    The Caleffi ZVC has two 40 Va in parallel, for a total of 80 Va across the 6 connections.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream