1 T-sat, 3 zone valves

Central5036

Can anyone give me a definite answer on how to control 3 zone valves with 1 thermostat? Honeywell V8043 zone valves on manifold with one Taco 007 pump. 40W transformer. Total of 6 zones altogether. Just have a lot of coming on and off with so many zones.

Jamie Hall

Not sure that transformer has enough power to handle three zone valves at once... 7.7 VA each. Should be. Just wire them in parallel.

Central5036

Could you tell me how to do that? Simple T-stats. two wire, just heat.

Jamie Hall

Before I do that... may I ask why it is you are controlling three zone valves with one thermostat?

But it's basically pretty simple: take the two thermostat wires and connect with three additional wires each, so that you end up with three wire ends from each of the two thermostat wires. Then take a pair of those wires and connect them to each of the zone valves just as if there were no other wires..

There are other ways to do it, but they are harder to describe.

HomerJSmith

Central5036, you're not specific enough. What does the 40 VA transformer control? Is this an auxiliary transformer or a transformer in an aquastat or zone valve control box. Is it just 3 zone valves that you want to connect together? What opens the other 3 zone valves; is it the same transformer? What turns the Taco pump on? Do you have 6 thermostat now and want to make it 4 thermostats?

You have to add up all the VA's being used in the circuit and it has to be less than 40VA.

The 3 zone valves can be connected in parallel to one thermostat, under certain conditions. 1) There can be only one transformer operating the 3 valves unless the additional transformer is in phase with the first one. 2) The current draw must be less than the rating of the transformer. 3) The current draw of the thermostat, if not a mercury bulb, but a relay must be capable of switching 23VA.

Central5036

WOW. I guess I will leave it alone. Sounds way to complicated now. To answer your question though, the reason I want to connect them is because I have one for living room, one for dining room, one for master bed, one for bath, one for cellar. Do not know why it was done like this but it seems to cycle on and off a lot. When one room reaches temp. it seems like another room is calling and it kicks the pump on again. Just thought it would cut down on the pump trying to work with one thermostats instead of three. The one transformer controls all the zone valves. There is a green Taco box with a green and red light on it that turns the pump on and off.

STEVEusaPA

I think you have the right motive as you discovered the small zones are problematic.
What does you piping look like? Can you draw up a diagram? Maybe with some near boiler repiping you can combine the 3 zones on one circ.

Alan Welch

What about lowering the temperature settings, the pump would run longer to satisfy zones, but might use less fuel for burner. Had a customer once where circulator ran constantly, and call for heat would fire up burner,seemed pretty efficient. Do you get hot water from the boiler?

HomerJSmith

What is the model # of the Taco green box? I suspect that it is a ZVC-405 or 406.

You could run the whole kittin caboodle off one thermostat, but what would happen is that some zones may be too hot and some zones too cold. The purpose of zoning is to control the temperature of each zone independently because zones differ in their need for heat.

Rooms that are contiguous like the dining rm or living rm could be run off one thermostat if open to each other. Some people like the bedroom cooler and can adjust the thermostat accordingly that's why it is zoned.

Don't worry about the pump. The boiler turns the pump on when there is a demand for heat. The thermostat tell the Taco box to turn on the boiler. The boiler is going to run and the pumps going to pump whether you have 1 thermostat or 5.

HomerJSmith

As long as there is a call for heat the boiler will keep the pump running whether the boiler is firing or not. If you are worried about the boiler firing on and off in a short period of time (short cycling), then what you can do is lower the boiler water delivery temperature assuming that you have an abundant amount of heat emitters, like a lot of baseboard. But, I don't know your system.

HomerJSmith

As long as there is a call for heat the boiler will keep the pump running whether the boiler is firing or not. If you are worried about the boiler firing on and off in a short period of time (short cycling), then what you can do is lower the boiler water delivery temperature assuming that you have an abundant amount of heat emitters, like a lot of baseboard. But, I don't know your system. I'm assuming a reservoir boiler.

JohnNY

Here.

HomerJSmith

JohnNY, it all depends on what the thermostat is controlling, the zone valves directly or a Taco green box.

JohnNY

You mean a relay panel? He's saying he's got "a green and red light". It doesn't sound like a multi-zone panel. Anyway, it was fun to draw that little diagram.