How to wire alpha2 into Taco 4 zone controller with outdoor reser

styxplo

I have the Taco 4 zone switching controller tied to a Taco PC700-2. How do I wire in the thermostat input for the zone with the Grundfos alpha2 that feeds 3 panel radiators with thermostat heads since there is no actual thermostat. I have R jumped to W right now but that zone is always calling for heat. I was thinking that it would only kick on the pump if my WWSD was satisfied so I turned it way down below the current outdoor temp, but the zone relay is still energized keeping the pump on???

Thanks Mark.

styxplo

Also. Is there anything special about how to put the temperature sensor into the immersion well in the buffer tank?

GroundUp

With TRVs I would typically hardwire the Alpha to be always on, with or without a pressure differential bypass depending on the system. For sensor bulbs in a well, I like to grease them up with anti-seize lubricant so there is a medium between the two surfaces. Both personal opinions, probably not the "right" way

hot_rod

Are you trying to fire the boiler when the Alpha on the TRVs zone starts? Do you need a wall thermostat if you have TRVs on the radiators?

The Alpha should stay powered in one of the delta P modes, just plug it in to a 120V circuit..

Here is a trick a friend in Alaska showed me. He wires an induction relay to the Alpha. It closes a contact when it senses current, which calls on the boiler via TT or the relay box.

So the TRV open, even a tiny amount. the Alpha senses the current draw, starts the boiler.

Look for a version with an adjustable trip.

http://www.phenixcontrols.com/Current_Sensor/Single_Phase/9993/?ga74661623075&gclid=EAIaIQobChMIjJuT8rz16AIVBV8NCh06CwWREAMYASAAEgJLkPD_BwE

styxplo

I think I will just hardwire it. I was just thinking that the alpha should shut off when I’m above my warm weather shut down temp. Is it ok to just leave it powered up all year??

That was my other concern. The way my control is setup I only care about the temp of the buffer when a thermostat calls. I like the induction relay idea. As it stands now the alpha could kick on and not fire the boiler

Thanks Mark. Stay safe out there.

Alan (California Radiant) Forbes

hot_rod said:

The Alpha should stay powered in one of the delta P modes, just plug it in to a 120V circuit..

Why not in AutoAdapt mode?

Here is a trick a friend in Alaska showed me. He wires an induction relay to the Alpha. It closes a contact when it senses current, which calls on the boiler via TT or the relay box.

Why take the trouble when you can use a zone valve control with an end switch to turn the pump on and off?

SuperTech

> @Alan (California Radiant) Forbes said:
> (Quote)
> Why take the trouble when you can use a zone valve control with an end switch to turn the pump on and off?

Why bother with the control? The pump will stop itself when the zone valves close. That's why the alpha is available with a plug on it so it can be plugged into an outlet

Alan (California Radiant) Forbes

I should have said:

Why take the trouble when you can use a zone valve control with an end switch to turn the boiler on and off?

hot_rod

I read it as he has one zone that is all TRVs, no wiring, so no way to engage relays

But he is pulling from a buffer, so no issue as the buffer should call the boiler when needed

styxplo

Just so I understand. If the radiators with the Trv’s open and cause the alpha to ramp up. Does the Taco controller care about the buffer tank temperature if no other zones TT’s are closed (if no other thermostat are calling). That is if the alpha zone pump is not actually tied to the controller. I hope I’m making sense.

hot_rod

What keeps the buffer tank temperature maintained?

If the tank is maintained and circulated via the boiler control directly, no interface with the relay control, then you are fine.

styxplo

I have the well temperature sensor from the Taco PC-700-2 outdoor reset controller in the buffer tank. I’m just not sure if it will tell the Taco zone controller to fire the boiler if there is no call on any of the thermostat inputs. If the buffer tank gets below the “turn on” temp it will send the signal to the zone controller, but will the zone controller actually fire the boiler just based on that or will it also need a thermostat contact to close??

Thanks Mark

Alan (California Radiant) Forbes

To keep the buffer tank charged independent of a call for heat, you would have to somehow create a constant demand to the PC700.

styxplo

Ok... Thanks Everybody.... I'm thinking that jumping the thermostat zone that is wired to the alpha might be the way to go. The alpha will always be powered up waiting to ramp up. The boiler will always be maintaining the temperature in the buffer because there will be a closed thermostat contact..... I think there is also a setting in the controls that keeps the buffer within a certain range. if the temperature drops out of the window it will fire the boiler to heat the buffer to the top end of the window. This might be another option if I just hardwire the alpha to 120 and remove the thermostat jumper

Stay safe Mark

Alan (California Radiant) Forbes

Somehow, I think we're going about this the wrong way. I'm not a pro on buffer tanks, but it seems as though your goal is to heat the water in the buffer tank as a function of outdoor reset, no? What's getting in the way is that the PC700 will only fire the boiler on a call for heat. I'd scrap the PC700 and find a stand-alone control for the buffer tank.

hot_rod

It kind of depends what you are asking the buffer tank to do. If you want it to provide run time without firing the boiler, ideally you heat the tank to a high temperature, say 180 if you have a cast boiler. Then pull the load side via and ODR control. That way you use the tank down to the lowest possible temperature.

Having the ODR on the boiler sort of defeats some of the buffer function. If you run to 180 and pull down to say 140, you have a 40°∆T to leverage. That "leverage" goes away if the tank is maintained at the ODR controlled temperature.

But still the tank could still be lessening the cycling on low load days, by just adding capacity for the ODR controlled boiler, and that is fine.

A simple way would be to insert the boiler operating sensor in the tank. Some boilers offer or ship with an additional sensor to use that way, connects to the supply sensor terminal, put it in a well in the buffer, and away you go.

Sounds like you are wanting to run like system 8-3 on page 23?


https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_17_na.pdf

styxplo

Sorry for the long winded response!!! This control stuff gets confusing.....

I have 4 zones total. 1 zone for the master bedroom was to small and is why I went with adding the buffer tank.

Hot_Rod... Yes that is exactly what I'm trying to do..although I have mechanical mixing valves and more zones..

Alan...I agree. In my head I was thinking that the boiler would only be concerned about maintaining the temp (based on ODR curve) in the buffer. Once any of my zones call for heat (to the PC700) and after some time the buffer tank gets drawn outside the lower window (monitored by the PC700-2) There would be a call to the boiler to fire. The boiler (modcon with built in pump) doesn't have an input for an external water temperature sensor, but it does have a built in ODR curve which is set to a slightly higher max temp then the PC700-2's curve and all other things being the same.

Any zone calls for heat...that zone pump kicks on, takes heat
from the buffer at first, until the buffer can no longer provide the right temperature water and gets below the window. At that point the boiler kicks on and supplies heat to the zone and also recharges the buffer tank.

This is where I get confused on this part of the control. Once the zone gets satisfied and the pump kicks off.....is the boiler supposed to continue to fire until the buffer tank gets back up to its temp based on the ODR curve

While I was writing this and thinking about it..... I guess it "boils" down to...... does the PC700-2 have control or the ability to fire the boiler whether or not the PC700 has any thermostat contacts closed....This really would solve the original question also. If the PC700-2 maintains the buffer tank temperature by firing the boiler independant of whether there is a zone thermostat calling for heat or not.

If it does then I don't need to jump the thermostat input for the zone wired to the alpha pump. I can just hardwire it. If it turns on and draws heat from the buffer. The buffer will drop below its temp setpoint and the boiler will fire from the PC700-2 call.

Alan (California Radiant) Forbes

The addition of the PC700 is really screwing things up for what you want to do. From what I can tell, it gets a demand signal from the zone control (valves or pumps?). If the buffer tank temperature is below the heating curve setpoint, it sends a signal back to the zone control to turn on the boiler and then when the temperature reaches that setpoint, it tells the zone control to turn off the boiler.

You have a condensing boiler; do what hot rod says. Have your boiler control the buffer to design temperature and let the PC700 and zone control take care of the load.

styxplo

I finally got the check valve I was waiting for delivered and installed and was able to test things out

If I leave the alpha zone thermostat input jumped the boiler pump runs constantly even if the boiler isn’t firing. No good

If don’t jump the thermostat input and hardwire the alpha there is a possibility of the alpha circulating cold water because there will be no call the fire the boiler

Talked to Taco tech support and the confirmed that the 700-2 AND the Taco pump controller both have to have a call for heat to fire the boiler.

I’m going to go with Hot_rods suggestion and use the current relay to trigger the zone input.

Thanks again. Mark

hot_rod

Here is the part, looks like Amazon has them!