Greetings. New to this forum and need some thoughts. My wife and I just bought a 13 year old house with radiant heating. We live in Colorado at 7000 feet so it gets cold. We get into the teens at night and have our thermostats off but the house still stays at 68 degrees which is warmer than we want. I have noticed the 6 different stations coming on and off by themselves. Is there a master control that keeps the house at a certain temp? Confusing to me. Don't  think all stations would cycle by themselves. Any ideas on what is going on woud be great. Too hot to sleep and hate to open a window and waste energy. Thanks in advance.          
                                                              Elwood

If the stations turn off and on, something must be controlling them. Do you know what you have for thermostats?

They are regular honeywell 2 wire thermostats the way it looks. All thermostats are cycling on and off. Not just one.

the thermostats are cycling even though they are off? do all the zones cycle independently, or is everything coming off and on together?

can you affect any change in room temperatures at all by using the thermostats?

this might be tough to talk about without some pictures of the mech room or a sketch.

Each one is acting independently. Some go one and off on their own in the off position. Seems strange they would all do it and not just one area. If you move the thermostat up and ask for heat you do get a response from the thermostat. The controller will activate and heat will come out to that area.

are they programmable? you might have a schedule working against you. If these are the old mercury dial ones of course that isn't it, but I thought I'd check.

What is the controller you are using?

They do have a mecury tube inside the cover. The mecury shifts to one side or the other when you move them. They are not programmable.

what are the controllers you are using, and do you just have a boiler, or is there more to the system like solar, etc?

I don't have too many ideas here though, you might be best served getting someone to check it out in person.

Going to get someone in here today to help us figure this out. Going to change out all thermostats also. Is one better than the other? May put a couple programmable ones in the main areas and then regular ones in the other areas. Any suggestions would be helpful. Really enjoy the radiant heating. Just want to understand hows it all works and how to maintain it. Thanks Elwood

pretty hard to think your thermostats are the issue. simultaneous failure of multiple thermostats would be a pretty big coincidence.

That was my thought from the beginning. I have been pulling covers on the thermostats and I am finding the mercury bubble in different locations with the lever off. Again I have not messed with this stuff before so I am learning as I go. I read somewhere that there is a sensor that can be put outside the house that will read the weather and adjust the house accordingly. Not sure if I have that or not but it could explain a lot of things. Either way the old thermostats are outta here over the next few days.

It's worth getting the 6x 5grams= full ounce of mercury out of the house anyway (even if the likelihood of breakage is small, each one is worth ~1000 compact fluorescent light bulbs, in mercury content.)

These thermostats may have some adjustable anticipation built into them to deal with thermal time-lag issues, but I can't imagine anticipation overcoming a turn-down of 5F degrees.

Is this a radiant slab, or a (lower mass) staple-up under wooden sub-floors or similar?

If it's slabs, you can't get away with big setbacks- just keep the bedrooms at a tolerably low temp and keep it there. Standard programmable thermostats aren't likely to yield good results with radiant, it'll be even worse with slabs due to the much longer lags.

Stuck zone valves and convective flows are a common enough (and easy to fix) failure. Are you positive the systems are actively cycling on/off?

Yes I check them and sometimes they are on or off. It is radiant baseboard heating. Is there a link to fixing stuck zone valves? Would like to have that info for future use or just the knowledge. Mercury thermostats will be out of here today. Going to get something different shortly. Still not sure what to do as far as replacement.

Baseboards are different from what's usually referred to as "radiant heating", and just about any thermostat will do.  ("Radiant heating" has no baseboards or conventional radiators- the entire floor or ceiling is heated to act as a large low-temperature radiator.)

Is it possible that the thermostats are somehow cross-wired, so that a thermostat in one part of the house is turning on the pump or valve for different part of the house?  Odds are that all of the thermostats wire into a single zone-control box, which could itself be fried, but hooking up the wrong thermostat to a zone relay could create paradoxical results.  When you have 6 zones it's easy to screw up.

I was going by what I was told. Sorry if I led you guys down the wrong path. What is the correct term for what I have? There are 7 zone controls in the furnace room. They are running separate from each other. Will replace the thermostats and see what happens. Thanks for the info.

"Hydronic baseboard"  or just "baseboard" or "forced hot water", etc. are all terms that would apply to a heating system with baseboard convectors as the method of getting the heat into the rooms.

This is almost certainly NOT a thermostat problem but installing programmable thermostats and running night-time setbacks automatically can likely save you between 6-12% on your fuel consumption. By having it start warming up the place an hour before you get up has some comfort factor too. 

There are lots of decent programmable thermostats of varying complexity but unless you really need one, avoid buying the types that set a different setback program for every day of the week unless you want to spend the rest of your life programming them. Most people do just fine with a 5 & 2 (weekday/weekend) or a 5-1-1 (weekday/saturday/sunday) programming, with 4 programmable periods per day (morning wakeup/workday setback/evening activities/sleeping setback.)  In some zones where use is intermittent you may choose to just "set & forget" rather than use programmable setbacks.

So you are doing something to the thermostat that you think is turning the thermostat off but it is not.

What exactly are you doing when you think you are turning it off? Are you turning a switch on the thermostat to an "off" position? Or are you turning the temperature setting down to a lower temp setting?

Replaced all the thermostats and have mostly gained control of the heat but there are still some things we need to figure out. Might be some wiring issues as stated above. Trying to get someone in this area that is familiar with the system to look at it.