Power open/close zone valve wiring question.

TAG

For ease of control I'm using 3 cross manifolds for my new house. This will allow easy thermostat connections and control of specific loops of the 2 for Warmboard and the one for the lower slab. The 4th manifold feeds 11 loops of underfloor plates -- this is a single room so there was no need for the expensive Cross. I'm wanting to use a simple zone valve. The system will have an Alpha pump. Do I need a special type of thermostat to run the power open/close valve .. or is there some other way to wire them?

The boiler (Viessmann 200) will be on ODR ... the zone/ thermostats are independent with the Alpha doing its thing. I'm not sure what the off off cycle of this room will be ... it may be on all the time or off most of the time. It's a large loft area ... seems silly to have a valve being powered 24/7

Jamie Hall

Power open and power close -- you will almost certainly need a relay for that. Most motorized valves have end switches, so that when the valve has powered to the end of the travel one way the power for that direction is shut off, so it's not powered 24/7 -- only when moving.

TAG

What sends them the other way ? Some seem to be spring and others are wax .... it looks like the Taco wax needs to be powered. What holds the spring type open if they are normally closed?

Jamie Hall

If a valve is a spring return, it will need to be powered to move -- and hold. On the other hand, if it is spring to open (normally open) you'd have to power it to close and hold.

Wax motors need power to operate (whichever way) and stay in position. If power is removed, they will return to their "normal" position -- whatever that is.

If it's power open and power close, then -- as i noted above -- it almost certainly will have end switches in both directions which will shut off power in that direction when the appropriate end switch is reached.

TAG

I'm still confused ..... since a typical thermostat is going to be normally open contacts. Say the Zone valve is normally closed .. when the thermostat calls for heat the zone valve opens and the water flows. Does not power need to stay on to keep the valve open? If not -- how will it close?

In my case: I hope once the system is operational I can tweak the flows throughout the house and just have the system running on the ODR. This thermostat will be set high so water is always flowing to this zone -- the zone valve will be open. The thermostats will be more or less "high limits" .. understand ?

This is a large open space at the top of the building -- so when many people are in the space or when its cold out and all the heat is running .... know I will need to turn this floor off.

Jamie Hall

If that's a spring return (or wax) normally closed valve, the power has to stay on as long as it is to be kept open.

If it's a power open, power close valve, then a simple thermostat simply won't work. You will have to have a relay to operate the valve. Relay is operated from the thermostat.

hot_rod

NC or NO is the lingo normally closed or open. Maybe 90% of zone valves are NC, power open spring close
Motorized ball valves often need power both direction, no power consumption when full open or full close.

TAG

So are you both confirming that a typical spring return NC zone valve will need to have power to it all the time to stay open?

Is this a problem for long term life ?

If yes to both above ... what's a possible solution ?

Matt_67

We have been using the taco zone sentry valves with good success. They are a 2-wire ball valve that uses an internal bank of capacitors to perform the power close function.

Jamie Hall

TAG said:

So are you both confirming that a typical spring return NC zone valve will need to have power to it all the time to stay open?

Is this a problem for long term life ?

If yes to both above ... what's a possible solution ?

Yes, no. Use a different vale as @Matt_67 suggested. Or not worry about it.

mattmia2

You will either power the valve or a number of relays to keep it on all the time. Either one is more or less designed to be on continuously for decades.

Alan (California Radiant) Forbes

Matt_67 said:

We have been using the taco zone sentry valves with good success. They are a 2-wire ball valve that uses an internal bank of capacitors to perform the power close function.

Excellent choice! Quiet, too.

In my case: I hope once the system is operational I can tweak the flows throughout the house and just have the system running on the ODR. This thermostat will be set high so water is always flowing to this zone -- the zone valve will be open. The thermostats will be more or less "high limits" .. understand ?

If you have your ODR dialed in, you shouldn't have to set this thermostat high. If you use your thermostats as high limits, why overheat this room? Once the thermostat is satisfied and the zone valve closes, the Alpha will slow to nothing or maybe even stop.

Solid_Fuel_Man

Or zone with purely mechanical thermostats. With matched ODR and radiation t-stats are just high limits. 

TAG

This property is a converted church (I have other posts) -- the floors are a single lower Slab in part of two buildings 1000sf -- most of the house is heated with 3000sf Warmboard on 3 levels. This zone valve will control one manifold -- 11 loops of 3/8 PEX tubing for the 4th level ... upper living room area (one room)

The water temp requirement for each is very close -- so I'm running one temp water from the Viessmann boiler. The buildings are spray foamed .... my guess is the large 1000sf living room at the top will not need all the BTUs from the heavy extruded retrofit plates. I did the heavy plates just in case. I can't really sub-zone that room so why buy the expensive Cross manifold. Just turn the whole thing off and on.

I have to set the boilers ODR to match the highest load -- so the water temp will be high for some areas (my guess) ... I want to be able to shut this area off ....understand?

Ideally ..some sort of proportional valve -- like I have on my panel radiators in another property. Where very hot water is pumped around and each radiator takes what it needs would be great .... but, I have never done this. I did see reference where people used Danfoss heads -- but, this seems to control one loop of a manifold ..not the whole thing.

My hope is that I can tweak the system over time and just let it all run ... but, I have to design in some safety . If I do get it all correct this zone valve will be powered on almost all the time.

Solid_Fuel_Man

You could consider NO zone valves, spring open, power closed. Then the majority of the time they are unpowered. You can do this with a small 24vac relay and use regular thermostats, or better yet, use a thermostat setup for power closed. 

TAG

SFM -- I looked at doing the reverse. But, I have the same problem since I really don't know how it will work.

Years ago in an early setup I was always replacing those $50 wax zone controllers

Solid_Fuel_Man

I've had EXCELLENT luck with Caleffi Z-One valves. Such good luck that I have never tried any others since first using them 10 years ago. 

I have heard, but not tried, great things about the Taco Century ball valve type as well.

Alan (California Radiant) Forbes

Years ago in an early setup I was always replacing those $50 wax zone controllers.

I've had the opposite experience.

TAG

Alan -- maybe loop is a better term. The actuators that sit on each loop valve on a manifold.