Fixing a mess, Zone valves w/ no end switch wiring


Old 02-13-14, 09:02 PM
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Fixing a mess, Zone valves w/ no end switch wiring

I have been racking my brain all night trying to come up with a solution to this wiring problem.

I am installing a new wall hung Veissmann boiler. The existing system was pretty much always on. The building has 6 units, all of which I can not get in to. I have been told that they all have their own thermostats. Searching through the basement I found a lowly zone control valve. The end switch had not been wired. I have no access to the rest of the valves to wire them, but I did trace the wiring back to a mechanical room where I found a stack of transformers powered off the old Oil boiler switch.

I can not come up with a wiring diagram as the new boiler requires a 24v stat to turn it on and off. Closest thing I can think of is some sort of current relay around each stat wire, but I am not sure a stat wire has enough amperage to activate one.

Any help would be greatly appreciated, Alex
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Old 02-18-14, 03:15 PM
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Moved you over to the boiler section.
Old 02-18-14, 03:53 PM
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Tekmar house control.
Has 6 zones and it does not need end switches.
Can be set up to play well with Viesmann, but you'll need your wits about you to do it.
You would be able to use the Tekmar 2 wire stats, and 2 wire zone valves.
This is NOT going to be an inexpensive option, but it does give you a ton of great features, a very definable ODR curve, indoor feedback, energy managment, and the abilty to lock down the stats.

Another option is to just wire the stats to relays, one set of contacts drives the zone valve, and use the second set of contacts to act as your end switch. You can use a a Taco ZVC 400 series box and just jump the switch terminals for the zone valve. Add a 3 minute delay timer on the pump / boiler contacts to allow the zone valves to open fully before calling the circ.

Anytime you use a current transformer switch, you can adjust its turn on current by wrapping the current carrying wire around the core of the transformer.
If your current transformer needs 1 amp to engage, wrapping the wire around 10 times would engage at .1 amps.. 2 times .5 amps etc.. You get the idea.

Hope you work it out

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