Zone valves on loop away from boiler

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Old 11-09-18, 11:01 AM
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Zone valves on loop away from boiler

Is it possible to put zone valves on a hydronic system to add and remove rooms from a single loop? That is to say, can a single loop have zone valves at various rooms - away from the boiler - and each room have its own thermostat? I would like to use two zone valves off a loop that I have running to a bedroom on the second floor to supply heat to a new mud room that the pipes pass through. Is this a thing? Is there an add on controller for doing this, or would I need a new one at the boiler? Is there a better way? Thanks!
 
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Old 11-09-18, 11:45 AM
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S,
It is not so much a control thing as a piping thing. It all depends on how your system is piped.

If you have a simple loop system which means you emitters are part of the loop where the supply pipe leaves the boiler and goes to the first emitter then leaves the emitter and goes to the next and next and so on and then back to the boiler then NO you cannot add a zone valve in a room because if that ZV wasn't calling for heat it would stop the flow of water to anything beyond that point and would have no way to circulate back to the boiler and out again.

There are ways of zoning off your system or individual rooms but it would require different piping design.

Just a thought after rereading your post. If you have pipes already running through a new room you want to heat why not just add baseboard where the blank pipe is. As long as it's installed in that same loop and the water has to pass by you will have heat instead of just pipe.

It wouldn't be a separate zone but it would be heated.

Pics of the piping and system would be helpful if possible.

Hope this helps a little.
 
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Old 11-09-18, 02:08 PM
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Thanks Spott! I should have given more info. I have baseboard heat. Currently my system has a circulator for each zone with a taco control. I could just put a baseboard and get heat to the area but I was hoping to control the room separately as they will have different heat demands. This is what I had in mind.
 
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Old 11-09-18, 02:13 PM
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I hope the blue and red don't confuse... they were meant to show the different rooms, not hot and cold. Also the ends of the red pipe go direct to the boiler.
 
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Old 11-09-18, 03:08 PM
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s,
Are you saying that BLUE circuit is all by itself and will be 1 zone. If the BLUE is separate loop off the main that would be fine if installed as drawn.

Is the RED circuit to and from the boiler your main loop with other rooms on it or is that going to be an individual loop also.

If that is your main loop for the house by putting the ZV in where you want you will stop flow to everything upstream when it's closed.

What is your thinking on the check valve. With pumps you need flochecks but wit ZV no checks are needed because the ZV's are positive shutoffs and when no calling they're closed and no water can flow.
 
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Old 11-09-18, 03:45 PM
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The red circuit only gives heat to one room - a master bedroom. The blue circuit would be the new one. I drew it like that for simplicity... the red zone is much bigger but goes from the boiler, thru about twelve feet of baseboard and then returns to the boiler.

As for the "Check Valve" vs. "Flow Check" that is something I will have to read up on. I was thinking this would be needed if both zones were calling for heat at the same time. Perhaps this is best done with ball valves on the branches to balance the flows?
 
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Old 11-09-18, 04:06 PM
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Check valve not needed. Positive zone valve closures and pump pressure prevents back feeding into red return pipe.

I used a similar scheme with a 3 way valve to control radiant floor heat in master bath by short circuiting the master BR loop. I have two feeds and a common return. Two thermostats--one for Bath only, one for MBR+Bath combination.

With valve in one position (Bath only) it blocks water from entering BR loop and feeds directly into Bath loop to the return. With valve in other position (Bath +MBR) it sends water through the BR loop, then into the Bath loop and on to the return. No check valves or balancing valves where the two loops converge and no back feeding.

There is a Flo-Chek on the zone pipe where it comes off the boiler. I expect your MBR loop already has one there too.
 
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Old 11-09-18, 04:50 PM
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"Check Valve" vs. "Flow Check"
They both serve the same purpose except the flocheck has a knob for manual bypass and both only allow the water to only flow one way.

As was stated earlier, with zone valves also being directional valves and positive shutoffs there is no way for the water to back feed into another zone or circuit. If both zones call at once the water is going to flow in the direction of the pump, and if only 1 zone calls the ZV will prevent the water from back feeding into the other.

If you're more comfortable using them it won't hurt anything but as far as ball valves go you should use them anyway in case you have to isolate either zone for repairs.
2 ball valves and a drawoff for bleeding or draining per zone.

Electrically you will need a 24V 40VA transformer to power the new zones and 2 stats of course.
No new relays will be needed. Depending what brand of ZV's you use 2 wires from terminals 2&3 on TACO or the 2 RED wires on Honeywell will come back to TT on the aquastat to start the burner and pump on a call for heat.

Depending how many zones you already have and if they are pumps or zone valves you may have to add a flocheck to the main zone if it is a single zone system with no tankless.
 
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Old 11-09-18, 05:08 PM
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A couple of additional comments about check valves vs. flo-checks. Most flo-checks, e.g., Bell&Gossett, Taco, etc, have three ports: two inlets and one discharge - while conventional check valves have only two ports. The third port can sometimes come in handy when piping an hydronic system - I've used the third port for gauges or for combining two loops or feeds. Either type of check needs to be oriented correctly - gravity can cause the valve to open or close.
 
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Old 11-10-18, 08:48 AM
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I have more questions, but quickly: What is "TT"? Is it Thermostat Terminal? Confusing as I see alot of reference to "TT Terminals".
 
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Old 11-10-18, 10:02 AM
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"TT" is common usage for the terminals on an aqua stat or boiler control where the thermostat wires are connected to signal a call for heat. When using zone valves the end switch serves that purpose and is connected as Spott described.

TT is also sometimes used as an abbreviation for thermostat.
 
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Old 11-10-18, 10:11 AM
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TT in this case are the terminals on the aquastat . They are labled TT.
 
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