Change zone priority on NTI/Taco boiler system ?

27 days ago

We have an NTI TFT 110 boiler that serves 19 zones (Taco controllers) of in-floor heating, DHW and a small bit of snow melt.

Each spring and fall we have instances of lack of DHW. Most years it's once or maybe twice per season. This spring we've had at least 7 instances of no hot water without excessive hot water use.

I'm GUESSING that it's a problem of it trying to maintain heat for our conservatory floor that is only on during spring and fall and could require significant resources. Am I correct that it will prioritize this until it reaches set point before attending to DHW?

Is there a way to prioritize DHW over the conservatory (and one or two other low priority zones)? Looking through the programming manual I didn't see anthing (though sounds like the TFTN might).

Thanks,

Featured Answer

PRO

Charles Ross Homes

13 days ago

Taco offers both 4-zone and 6-zone controllers which can be configured to have a priority zone. It's either zone 4 or zone 6, respectively. You also need to set the priority switch on the control board to "on." Doing so will give priority to, well, the priority zone and drop the others out for a period of up to one hour. So, you should be able to switch the inputs and outputs of your Mud Room and domestic hot water heater and achieve your intended result, albeit that you'll be disabling the other zones on the same controller for up to an hour.

Since you've determined the issue occurs only when there is demand for hydronic heat in the Conservatory, an alternative is to hardwire a control relay that drops out power to the Conservatory zone control value whenever there is demand for domestic hot water. That would allow the other zones on the controller to remain active.

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Comments (6)

wdccruise
22 days ago
Which model Taco controller(s) do you have?
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opaone
Original Author
14 days ago
last modified: 14 days ago
Sorry for the delay, had an unplanned trip...

I'm not seeing a model number on the outside but here's a photo of one. There are three total.

I can probably open it up to get the exact model #?
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PRO
Charles Ross Homes
14 days ago
You noted that your system includes 19 zones. The Taco controller shown is a 6-zone controller. Three of them would provide 3 x 6 = 18 zones of control. Is your domestic hot water heater controlled separately? Are the controllers interconnected in any way?
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opaone
Original Author
13 days ago
18 zones are on the Taco controllers. There's also a patio / snow melt zone that uses a separate relay as a valve controller..

From what I understand the boiler sees only two things; DHW and Central Heat. It has no idea about the 19 zones that comprise Central Heat and appears to always give priority to Central Heat.

From a wiring standpoint there appears to be only DHW Demand and Central Heat Demand. I think to give the conservatory lower priority than DHW would require a Central Heat Demand 2 and the ability to set its priorty to lower than DHW?
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opaone
Original Author
11 days ago
DHW is controlled directly by the boiler, not via a Taco controller.

I think the relay for the conservatory might be the ticket. It'd need to be based on DHW temp though so that anytime the DHW temp is below the trigger (I think 120°f) it will turn off until it's above mid-point. I should be able to do that with a temp sensor on the recirc.
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