Aube Th115 Settings

parkingnotice

Hi All. I have a 12 x 12 stand-alone office. It is heavily insulated on all 6 sides and has electric radiant floor under tile inside. 

Initially I set the Aube to “AF” mode, but it was still warm outside (Northeast). Now that it is cold, a strange thing is happening. The set point is 72, but the temp inside is 64 and yet I only have a single “wave” of heat, instead of 5 “waves” indicating full steam ahead. 

I dug in further and it seems all roads point to setting the Tstat to “F”, Floor sensor only mode. (Yes, it has a floor sensor). Does that make sense? I was thinking having the floor plus the air measured made the most sense. 

GGross

Personally I like to set thermostats that are capable of both Air and Floor, to the setting that uses both air and floor. Sounds like you were doing that already? What floor temperature does your thermostat show? and what is the floor temperature limit set at currently? We already know the thermostat is not reaching air temperature, but if the max floor temp has been reached it will prioritize that setting so that no damage is done to the floor. I am not specifically familiar with that brand thermostat, I generally use Tekmar but the function and end goals should be the same

parkingnotice

Thanks for the response. I have the setting on both Air and Floor. The room temp is 64 and the set point is 72. The max floor temp is factory set at 82.
Do you think the floor has reached its max? I can’t imagine that. Seems if the floor was 82 degrees it would be much warmer inside. 

Several instructional videos on the TH115 suggested always using Floor only, but didn’t explain why or in what circumstances. 

I’m going to try switching to Floor only and see what happens. Then maybe I’ll switch to Air only and see what happens…

GGross

I would think if the floor were 82 it would heat the space to setpoint. It could be another issue, possibly a section of the electric radiant burnt out? I don't have much experience with electric radiant, mostly just hot water, but a customer of mine had a burnt out element and the manufacturer sent this device that could spot issues in the electric radiant elements.

For the sake of curiosity change the thermostat to floor mode and see what temperature the room reaches. that factory setting of 82 is a good spot to leave the max floor temp.

parkingnotice

The electric is a single run of wiring so no chance of a section burning out. I set the unit to Floor only and sure enough the temp said 82. So I set it back to Air plus Floor and disconnected the Floor sensor so now it’s just on Air sensor. Immediately it kicked on and I’ve got 5 “waves” of heat going. 

I know the max is set to 82 at the factory, but should I worry if it gets hotter than that. The manual says it can reach 104. It’s embedded in concrete leveler and tile. 

GGross

Max floor temp for most flooring is 85 F anything over that will run the risk of damaging the floor or concrete itself

parkingnotice

Any thoughts on why an 82 degree tile floor can’t get the room up to 72? It’s a 12 x 12 footprint. 2 double (but small) windows and a door with a window. It is well insulated and brand new, every crack foamed or caulked etc. Not even a wisp of a draft in there. Seems to me like it should be heating up to 72 just fine. It’s 40 outside. 

hot_rod

The floor surface has much to do with comfort. Above 82 some folks experience sweaty feet
In commercial shops, where occupants are wearing shoe surface can run a bit higher.

Here is the math for calculating floor output.
This assumes most of the surface it at temperature. Wide tube spacing throws it off.

82 surface in a 68° ambient room would be around 82-68= 14 X 2= 28 btu/sq. ft.

Got access to an infrared camera? That is a good way to look at radiant surface output.

Here is a heat transfer plate, and panel radiator example.

parkingnotice

Thanks for your reply hot_rod. Indeed, shoes are worn inside and the occupant likes it rather on the warm side. 

I think you are referring to hydronic heat when you mention tube spacing? This is electric radiant, but nonetheless I imagine the numbers are the same. I think you are saying that with the floor at 82, in order to maintain 68 in the room I need an output of 28 BTUs per sqFt. Is that correct? The system installed in this floor is 240v, 9amps and has a maximum output of 2460 watts. Seems that should give me plenty of BTUs per Sqft unless I am missing something. 

GGross

I suppose it is worth asking this @parkingnotice you are not turning the heat off when you leave the office or setting a set-back function correct? I am not too familiar with the electric radiant element, but generally speaking in-floor heat is slow to react. Generally for comfort I would recommend keeping a constant temperature setpoint in the room.

I am curious what the layout of this heating element looks like, the placement of the floor temp sensor, as well as any set-back temp you have on the thermostat, or if the system gets turned off when you leave the office for the day

parkingnotice

Good question, GGross. The back story is that my whole main residence has hydronic radiant flooring so I am very familiar with how these systems work. My Tekmar, in the house, is set at a constant 68, year round. It works beautifully. So, yes, the Aube, out in the office is set to manual function with a constant set point day and night. 

I just went out there. The room is at 70 and the floor is at 82. It is currently on the Air plus Floor sensor function and the set point is at 72, but no heat is being delivered because of the 82 limit on the floor sensor. Earlier I disconnected the floor sensor for a couple of hours and the room temp shot right up to 74. I reconnected the floor sensor and it told me the floor temp was 93! 

I’m not sure what is my next step. I’m considering overriding the floor limiter and setting it at 90 and then seeing what happens. 

GGross

@parkingnotice

If you are quite sure the layout is good, and the elements are working I would move that temperature up just a little at a time. Maybe set it to 85 first and see what you get out of it? I would still keep your air temp setting on the thermostat to eliminate any overheating.

It would seem if the layout is correct the only way to lower the temperature of the floor and keep the same room temp would be to tighten up the building envelope, but you had said it was pretty well insulated already

parkingnotice

Thanks for your input. I’m of the same mind. I’ll keep testing it this week. 

Brent H.

Have you done a heat loss to determine if the floor is capable of heating the space? I have a similar thermostat used in my bathroom but it is only used to keep the floor warm for foot comfort. Baseboard heat is used for the actual space heating.