Underfloor heat using baseboard thermostat - sensor question

[simonmason]

I have an underfloor heat system in my master bathroom.  It is electric, the mats are between the sub-floor and the tile - in the grout.  I have been using the thermostat that comes with the system but it is not smart.  So I have to live with the fact that it kicks in at the same time every day irrespective of the temperature in the room and whether we are home or not.  The thermostat switches the mats on and off - 110v wiring and has an external sensor - which is buried in the floor.
 
I was looking at the zwave baseboard thermostats.  If I were to hook one of these up then it looks like it could easily switch the mats on and off.
 
However, what about the temperature sensor?  The existing thermostat uses the temperature sensor to switch the mats on and off based on the temperature in the floor.  
 
If I were to switch to the baseboard thermostat then its built in temperature sensor would read the ambient temperature in the room.  In my mind this is actually preferred as we put the mats in to supplement the heating in the room - the bathroom is above the garage and has only one inside wall - and the room was perpetually cold.  Also, the mats have the added bonus of making it warm under foot.
 
Does anyone see any issue with hooking up this way and leaving the temp sensor in the floor out of the equation?  Thanks.

 

[chasers03]

I have installed a HAI/UPB 15 amp switch in place of the timer and put the thermostat on full in all 5 locations of floor heat.  I then program the OP II to time off and on to my liking assuming there is a warm up & cool down time.  Like it very much.

 

[wkearney99]

I switched from an old NuHeat schedule-only keypad in the old house, to a WarmUp touchscreen in our new house and recently to a new NuHeat wifi touchscreen.  The NuHeat is nice in that it can be controlled via an app, but most importantly it sets it's own time from the internet.  The WarmUp required I manually reset the time AND the schedules every time it lost power... which was too often.  
 
The WarmUp and NuHeat all use the same value sensor in the floor (whose rating escapes me at the moment).  They both had floor temp and ambient temp tracking.  

 

[Madcodger]

If you can make use of the in-floor sensor via the tstats wkearney99 mentions, that is often preferred for under floor radiant electric. Any type of radiant heat is a bit slow in its response time, so measuring air temp can lead to temp swings that are better to avoid for comfort. That said, there's no reason you can't measure air temp as the input as long as you have no danger of exceeding the manufacturer's rating for the floor temperature itself. Manufacturers of these systems often sell air temp-based tstats as their basic model, with floor temp sensing as an upgrade or deluxe package.

Personally, I'd really like to hear more about wkearney99's solution as I want to retain floor temp sensing in our bathrooms (heated with WarmlyYours product) but would be interested in moving to an automated tstat. The programmable stats they sell (I think they're made by Aube but am not sure) work well and are rock solid but when we are returning from a trip it would be nice to warm up the floors just as we do with our main HVAC.

 

[wkearney99]

I'm no expert regarding floor heating or thermostats.  But common sense dictates that it's best to use items intended for their purposes.  No doubt that thermostat and floor heat manufacturer's would gladly create only one kind of thermostat if it was possible to handle all kinds of heating element situations.  Reality is, they don't.  They make separate models for the different purposes.
 
From what I've been able to determine most (if not all) radiant heat floor systems all use the same kind/value of sensor for detecting temperature from the flooring.  This is true for NuHeat and WarmUp, as I've gone to one from the other with no negative effects.  
 
Having both air and floor temp sensing means the system has greater potential for being more efficient, energy-wise.  Just using air temp leaves open the chance for the floor being warmed much longer than necessary due to potential air current issues.  If the air sensor wasn't 'near enough' to the floor, and there was a draft from another HVAC system then it'd keep the floor mat making heat, only to have it lost to other spaces.  Most floor mats won't raise above a certain temperature, obviously, but one without accurate sensing would end up running a lot longer.
 
So if you have a working sensor and it's compatible then it would seem smart to use a floor heat thermostat designed for the purpose.  
 
What make/model thermostat were you using?

 

 

[simonmason]

The thermostat is marked www.thermosoft.com - the company I got the floor from.  I am sure it is an OEM unit - they don't show it on the web site any more.  The reason I am exploring this is to automate the thermostat.  Currently the only control I have is on and off twice a day during the week and once on the weekends.  Also, the thermostat will kick in regardless of the outside temperature.  I want to control the thermostat from my home automation controller so I can make sure it doesn't turn on in the summer, when we are away, etc.  Also, I want to have better control over the heat.  In the spring and fall the floor doesn't have to be on that high, but in the winter it needs turn on at a higher level.  Currently with the thermostat installed I can only set one temp each time it turns on.
 
Assuming I can use a baseboard heater to turn the floor on and off.  What if I were to use another device to wire the floor temp sensor to.  That way my home automation controller could monitor the temp in the floor.  Is there a simple wave device that allows a remote temp sensor?  Or a zwave baseboard heater thermostat that allows a remote temp sensor to be attached?