reverse engineering my readiant heat flooring, few questions

[TT_Vert]

Looking at the wiring am I correct in assuming that the thermostat applies 24Vac to the zone valve which in turn uses the end switch to send a signal to the boiler to fire? It seems the end switch is at 24Vac when the valve is closed and 0Vac when the valve is open. I think I fried my thermostat today and I'm trying to understand how this thing works. As an aside who puts a cap right near the edge of the unit where one would pry the two case halves together? I guess I should have used a non metallic pry tool, bad on me too I suppose. Seems even w/ the heat off it is firing the boiler and the pump so I'm fairly certain the thermostat is the issue but no time like the present to try to understand the systems at this place I just acquired. I drew up a little wiring diagram too if that'd make any difference.

One thing that confused me if this is in fact true. Both end switches are seeing 24V when closed (or are they just switching the hot side?) so in theory if there was a power outage or a problem w/ the wiring for the end switch which caused 0 volts would the valve actually be opened? I would think that'd be a problem as as far as I can tell an open valve= end switch 0V. End switch 0V = boiler firing and pump on. Perhaps I'm wrong here?

Thanks much,

Dave

 

[yeldogt]

A system w/o a boiler circuit (loop) must use the end switch on the valve to tell the boiler to fire/ start the pump. It the boiler and pump went on at the same time it would not be able to circulate water. The end switch confirms that the valve is now open.

Someplace on the boiler -- there is a control that maintains the boiler water temp.

You need to get a copy of the owners manual -- read up on the way things work. Look at a little book ... "Pumping away" ... my bible.

 

[TT_Vert]

yeah I know how to adjust water temp. I'm just trying to understand this system fully before I need to KNOW how to fix it in winter. I was just curious about the 0V (Valve open) from 24V end switch voltage when the valve is closed. If that in fact turns on the pump and fires the boiler wouldn't the pump/boiler both be on in the event of any wiring issue causing 0V to that end valve?

That is primarily what I'm trying to understand. I read the installation manual, the instruction manual, etc. It just doesn't specify much about that end valve input/output aside from just a generic wiring diagram for each basic system.

Newbie question, how can i ID a boiler circuit (loop?)


Dave