Help with Radiant heated Towel Bar

[dredman]

Ok one of the last things i need help with is the towel bar in the master bath. I had a plumber help me set up the entire radiant system. i have a loops (zones) for bedroom, bathroom, towel bar, and attic (not used att). My problem is that we didn't do anything to measure the heat on the towel bar. it didn't come with any type of thermostat. dont know if that is normal? Anyways my friend plumber who helped with the install said all we could do was use a battery operated thermostat. So here is my question: i have one yellow wire from the electronic mixing valve to attach to the thermostat. where does it go? to the heating power supply or the heating signal? so the idea was to use the battery operated thermostat as a time to open the valve in the mornings to allow the towles to heat. understanding that the towel bar coulnt' get any hotter then the water that was going to the bathroom floor. does any of this make sense? do i have any other options as to how to make the towel bar work? Dan on Long Island thanks

[jadnashua]

All you need is a low-voltage control timer if you're not going to install an aquastat on the thing. A setback thermostat could be used for this, but you need two wires - 24vac from the low-voltage transformer, which when the timer kicks on and the temp is not met would then connect that 24vac to the control line of the mixing valve (the other side of that transformer would already be connected to that device to then complete the circuit - the thermostat is just a single pole, normally open switch, well, single pole, double throw if it also works with cooling). Typically, that would be a zone valve, not a mixing valve, which would often be upstream of it.

You may not get all that much warmth to the towels. Typical radiant floor heating loops often are pretty low temperature - tends to work better with radiators where you're running hotter water. I have an electric heated towel bar connected to an in-wall timer (line voltage) that has built-in heat limiter thermostats that cycle, once it reaches its set temp. Even though I do have radiant heated floor there, this allows me to have a warm towel throughout the year, rather than only during the heating season (it seemed like a poor use of energy to bring the boiler up to temp to just heat the towel bar with its VERY small load). There's enough air movement around it that, even though the bars are too hot to touch for long, only get the towels warm, and if they are really thick, the outer surface may not get warm. Still, it's nice on a cold winter day and it does dry them much quicker than just hanging them up.

[dredman]

OK thanks. I made a mistake. I think my vavles are zone valves. so the yellow wire from the zone valve goes to the thermostat. i do have low voltage for the other thermostats. i don't have room to add and aqua stat so I am stuck with the set up i have. just can get the hot water to the towel bar. not sure what to do. I can post a pic if that would help

[jadnashua]

The thermostat is a fancy switch controlled by both a timer (assuming setback) and temperature. It needs to connect 24vac power to the zone valve. You need to find the 24vac from the controller (power supply) to get it to the thermostat, then, when it closes the switch, it goes to the zone valve to open it. You'll want to set the thermostat high enough so that it always runs when the setback is off (i.e., it returns to normal heating). WIthout more info on how you have things wired, there's no way to tell you how to add this in. Even if you get power to the zone valve, you need to have it wired so that turns on the circulator pump, or there'll be no heat in that zone. If you're using a zone controller, that would turn the circulator on and have the thermostat connections.