Taco ZVC excessive stand-by losses

EternalNoob

Anyone else frustrated by the Taco ZVC standby losses? I was tinkering with a ZVC406 to install at home and just for curiosity, put a current meter on it when in standby (no thermostats or zone valves plugged in) and was shocked and disappointed to discover it draws a quarter amp in standby. That's 30 watts, or about two+ 11 watt light-bulbs running all 24/7 all winter long. Seems like a ridiculous amount. To be sure i wasn't working with a dud, i checked the ZVC405 i just installed at a client's house and sure enough, same thing, .25 amps in standby. With thermostats on and zone-valves open the measured current does not change significantly. Most of the current is just the board itself. The SR502 that my ZVC406 is going to replace in order to zone-out my manifold draws 0 measurable amps when in standby, less than the error margin of my current meter apparently. WHAT GIVES? Also, I haven't used the Caleffi z-one yet, are they any better?

kcopp

Interesting.
I was actually going to be using this control in an off grid house soon and that would make a difference.

Jamie Hall

As standby losses go, that's not bad. Check your TV, 'phone charger, router, wi-fi, ...

STEVEusaPA

What happens if you disconnect the light for power indication, what is that drawing?

hot_rod

Here is a 4 zone Caleffi, with on 40Va transformer and a light running.
What type of zone valves actuators are you planning on running? Use the 250 mA for the least amount of draw.

I have some 12 and 24VDC solar, setpoint controls if you or any off griders want one.

EternalNoob

As far as I know, there is no switch to turn off the "power on" led when the unit is powered.

Thanks hotrod, I haven't been able to find a photo of the open board on the Caleffi panels.

On the ZVC405 (client's house) I'm using 3 (but expandable to 5 in the future) of the bluefin manifold-mount 2-wire zone valves. On the ZVC406 (home project) I'm planning to use 5 taco sentry (4-wire) ball-valves. In both cases I don't need a boiler circ pump or boiler end-switch, because i'm using dedicated-to-radiant water heaters. So i only need the control to power zone-valves and a single 120V end-switch for the radiant load-side circulator. Since the thermostats draw minimal amps to run, and the sentry valves only use amps when actuating and don't often do so simultateously, perhaps i don't need the two 40VA transformers provided on the ZVC, and the single 40VA transformer on the Caleffi will do fine.

GW

Don’t all transformers absorb energy (wattage)? 

Jamie Hall

GW said:

Don’t all transformers absorb energy (wattage)? 

Yes, but it shouldn't be much. 5 to 10 watts at most, if the secondary is open circuited. But... most wall warts and simple USB chargers are not open circuit secondaries and can draw 10 to 20 watts easily -- and the standby on such critters as TVs -- anything with a remote and always on standby -- and anything wi-fi connected is going to easily be 20 to 40 watts.

JUGHNE

Even GFCI receptacles have a phantom draw.
Enough to feel with your hand on a cool wall.
Shows up with a FLIR viewer.

hot_rod

EternalNoob said:

As far as I know, there is no switch to turn off the "power on" led when the unit is powered. Thanks hotrod, I haven't been able to find a photo of the open board on the Caleffi panels. On the ZVC405 (client's house) I'm using 3 (but expandable to 5 in the future) of the bluefin manifold-mount 2-wire zone valves. On the ZVC406 (home project) I'm planning to use 5 taco sentry (4-wire) ball-valves. In both cases I don't need a boiler circ pump or boiler end-switch, because i'm using dedicated-to-radiant water heaters. So i only need the control to power zone-valves and a single 120V end-switch for the radiant load-side circulator. Since the thermostats draw minimal amps to run, and the sentry valves only use amps when actuating and don't often do so simultateously, perhaps i don't need the two 40VA transformers provided on the ZVC, and the single 40VA transformer on the Caleffi will do fine.

Check the power draw on the zone valves you plan on using, in some cases only 3 or 4 of some thermal or capacitor type valves per 40 va transformer.
on a typical motorized ball valve power is only used to power open and power close, controlled by an end switch. I think the capacitor type pull pretty good current on recharge cycle.

Cap tube type controls are power free, if you are trying to eliminate electronics draw

Joe Mattiello

The on board transformers, or transformers in general draw current while in standby. Taco ZVC406 has two transformers to handle the load. The ZVC might draw a little more as it will have losses in the power supply circuit and is running the micro and power LED. Hopefully this helps. 

Taco Tech support at 401-942-8000 can answer additional questions. 

SteveSan

This is what I received from the product manager on a similar question:

Transformer are not 100% efficient, so when connected to line power constantly will draw some power even with minimal load like the green LED lamp on our zone controls. That is why a transformer is warm even without a load connected.
The thermostats require 24 volts AC power to operate that can only be supplied for a step-down transformer(s); not like your cell phone charged which is a DC power supply.
The difference between current draw on SR502 vs ZVC405 is, the SR502 has a single 15VA transformer and the ZVC405 has 2 @ 40VA transformers or 80VA; that is 5-6 X more transformer power