ISY heated bathroom floor thermostat control

[elite-rob]

Hello All,

I am doing a major renovation to the master bathroom and one of the new “features” is a heated floor.

Since everything in my home is already controlled by the ISY (or Nest), I was curious if anyone had any suggestions on a thermostat that may be able to integrate as well?

I’d rather not introduce a new system/app, if I can avoid it.

I know there are Insteon thermostats, but I believe a “floor thermostat” is a different beast.

I’m open to any suggestions.

Many thanks in advance!

[larryllix]

There always needs to be a mechanical overheating contact to shut off the floor heat. ISY can control the on/off cycle times on a schedule or with sensing feedback but a fail-safe stat should always be hardwired, so you don't create a dangerous situation. The probe should preferably be in contact with the floor.

You will need the floor stat regardless. Use it as an all-else-fails contact.

[elite-rob]

Thanks for the reply..... I definitely want things to be safe.

In order for ISY to have any control of it at all, is there a certain item I have to purchase?

[larryllix]

There is probably much better ways to do this but my first thought would be a wired in Insteon module and a CAO wireless Tag either on the floor, or a model with an external probe on the floor up shoved up through the plywood against the tile with the Tag below for battery changes.

There will be 1 wire probe with CPU box type solutions also.

A few years back many were using Insteon stats with a remote sensor wired into the cut PCB foils that went to the internal sensor. A little coarse temperature but could work.

For a large thermal mass heating I would be designing a PWM control algorithm instead of a simple bang/bang method (Just On or Off based on a temperature).
With large thermal mass heating the delay of a bang-bang stat method would give you huge waves of heat and/or cold because the response is really slow. ISY could alleviate that with some thinking about cycle length variations or voltage dimming modules.

[kck]

When we did our bathroom floor they wanted to install a "smart" thermostat for it but that was going to make it hard to control from my ISY.  So I had them install the dumb mechanical dial thermostat and then put the circuit on an Insteon switch.  We never change the temperature setting on the floor anyway - it is either on or off.  The dumb thermostat has the sensor in the floor (it is specifically a thermostat for a floor heater).  Then my programming handles turning the floor heat on or off as a simple on/off switch.  Works great.

[elite-rob]

Thank you VERY much larryllix and kck.

Really appreciate the insight.

I doubt I’m really ever going to play with the temperature, so putting in a “dumb” switch that can be on/off triggered via Insteon programming could be the best move.

I do want to keep things simple.

Cheers!

[apostolakisl]

I don't have any heated floors, but it was always my impression that heated bathroom floors weren't intended to heat the room but rather make the floor feel good on the bare foot. The small space application ones I have seen use electric resistance heating elements in the floor which you would not want to use for general heating since it is by far the least cost effective way to produce heat.  Seeing as this is a new feature in a renovation, the room must already have some other heat source which I presume will continue to provide the bulk of the heating.  

I googled the floor thermostats and they appear to be a specialized thing that I doubt will integrate with ISY.  However, I don't see any reason you couldn't put an on/off relay switch on the wires as they go into the thermostat.  This assumes that your thermostat is a dumb thermostat that doesn't get all screwed up if you cut power to it.  To install something like this you would need to be certain that you install a box big enough to handle the thermostat and inline linc.  The in-line linc relay can handle 20amps at 240v, which I suspect is plenty for a single bathroom floor.

In contrast to people who have in-floor radiant heat via circulating hot water where the water is heated by a more cost effective method.  But I have not seen this done when only using it for a single bathroom.  One website I just read is giving very misleading information.  They claim how efficient electric floor heating is because it is 100% energy efficient.  That technically is true, but it is using a fuel source that (depending on the location) is far more expensive per btu as compared to say natural gas or propane.

 

[larryllix]

After a decade of fiddling with my basement slab floor heat I have discovered something that nobody would/could tell me when I was designing it.
If your floor is X degrees, the room air will be that same temperature or even slightly warmer, unless you have an open window. My son tried the "warm bathroom floor" and found out very quickly it can make the room very uncomfortable. Design to run at the desired air temperature.

You only need to take the chill off the tile and it won't feel warm at that temperature, without overheating the room. Ensuite bathrooms are a problem if you don't like to sleep in a tropical bedroom next to it, with the door open.

[apostolakisl]

1 hour ago, larryllix said:

After a decade of fiddling with my basement slab floor heat I have discovered something that nobody would/could tell me when I was designing it.
If your floor is X degrees, the room air will be that same temperature or even slightly warmer, unless you have an open window. My son tried the "warm bathroom floor" and found out very quickly it can make the room very uncomfortable. Design to run at the desired air temperature.

You only need to take the chill off the tile and it won't feel warm at that temperature, without overheating the room. Ensuite bathrooms are a problem if you don't like to sleep in a tropical bedroom next to it, with the door open.

That goes with my thoughts that you just want it to flip on at typical bathroom times.  Of course the number of square feet will have a huge impact.  You might consider only heating the floor in front of the sinks, toilet, and shower.  In that case you might just leave it on all the time in the winter.  Maybe a total of 15 square feet.  You would have to look up the btu's to know how that will affect the entire bedroom suite.

[Brian H]

One of the places I worked had heat in the concrete floor. If the heat went off and no body noticed. Sometime it took over a day to cool down enough to notice. It also took a day or so to warm up again.

[larryllix]

2 minutes ago, Brian H said:

One of the places I worked had heat in the concrete floor. If the heat went off and no body noticed. Sometime it took over a day to cool down enough to notice. It also took a day or so to warm up again.

My basement slab is heated and a major player in my home heating. When I vacation, I was setting it back to 10c but when I got home it would take so long to get the house heated up we would get up in the morning to a still cold house. At full blast (185,000 BTU/Hr.) my house rises aprox. 1 degree C per hour at about freezing temperatures outside.

In the dead of winter getting home at 10 PM and resuming the stat,  the house is still really cold in the morning at 10 AM. My advanced recovery starts between 2 AM and 5 AM each morning (ISY decides) to reach the normal 22.5c by noon each day.

On the other side of the coin, my house takes about 7 days to fall back to 10c in the dead of winter (aprox -20c).  Yup. 4,000 tonnes of concrete slows the heat, up and  down.

Ecobee stats have really helped.

[apostolakisl]

I suspect that just warming up some quarter inch thick tiles in front of your sink or shower wouldn't take more than 15 minutes.  Not exactly the same thing as warming up a slab where the intention is to actually heat the structure, not just make the floor feel nice under your toes.

[larryllix]

I suspect that just warming up some quarter inch thick tiles in front of your sink or shower wouldn't take more than 15 minutes.  Not exactly the same thing as warming up a slab where the intention is to actually heat the structure, not just make the floor feel nice under your toes.

For sure. I was warned that heating up my plywood floor takes a much h more frequent pipe placement (6 to 9 inches apart) compared to a concrete slab at about 12 to 18 inches apart or you will feel hot and cold strips.

The best is my basement shower stall where it is always warm and in 12 years has never been squeegied and doesn't grow mold like the unheated one. Dries in minutes.

Sent from my SM-G930W8 using Tapatalk

[apostolakisl]

59 minutes ago, larryllix said:

For sure. I was warned that heating up my plywood floor takes a much h more frequent pipe placement (6 to 9 inches apart) compared to a concrete slab at about 12 to 18 inches apart or you will feel hot and cold strips.

The best is my basement shower stall where it is always warm and in 12 years has never been squeegied and doesn't grow mold like the unheated one. Dries in minutes.

Sent from my SM-G930W8 using Tapatalk
 

Yeah, wood is an insulator and tile is a reasonable conductor, so you would need closer together pipes in wood.  I'm guessing the OP is using the electric ones, and by the appearance of it, they seem to have the heating elements lined up very close together.

[kohai]

I have a bathroom with a heating element under the tile.  I had to replace the controller 2 years ago and installed one by Nuheat.  They sold a wifi version at the time but I didn't get that version.  Now days with polyglot doing interesting things, I wonder if the wifi Nuheat can be tied in.

 

Nuheat Home Radiant Floor Heating Dual Voltage Progamble Thermostat by Nuheat

Here's a wifi/nest compatible version:

Nuheat with wifi and nest support

Looks like the samsung smart things people are integrating and IFTTT may have support:

Smart things forum

[elite-rob]

Hello Everyone,

Thanks for all the discussion.

I ended up buying a NuHeat Siganture thermostat.

It seemed like the best/easiest result.

It should be getting installed this week so we'll see how it goes!

[larryllix]

On 1/7/2019 at 3:15 PM, apostolakisl said:

Yeah, wood is an insulator and tile is a reasonable conductor, so you would need closer together pipes in wood.  I'm guessing the OP is using the electric ones, and by the appearance of it, they seem to have the heating elements lined up very close together.

For after-the-install regular floors you can mount the PEX piping underneath using heat spreader plates, cross-sectioned like an Omega with about 9-12" wide "serifs" on the omega shape. This makes the pipes easy to mount, spreads out the heat, and allows for PEX expansion and contraction, being quite extreme and will make snapping noise if not provided for. Some of these heat spreader plates come with two troughs in them for  two PEX pipe runs in one joist gap  (14.5"). The only ones I found at the time, were single trough units, so I alternated them between pipe run sides so they fit into the joist gaps. Dumb thing after 5-6 years now I have never hooked them into the manifold for our ensuite bathroom. The rest are in the basement slab.

 The guy, building his house across the street, had  "egg-crate" looking styrofoam blocks for under his basement slab. They acted as an under slab insulators as well as a form to wind his pex piping into, with fixed spacing. He told me the PEX just wedges into them and stays put.  Doing mine in the winter, we fought like crazy with 3000' of cold PEX that didn't like to stay where it was put. Thousands of tie-wraps onto 6" grid steel and wife still has the arthritis in her fingers to prove she is a tie-wrap expert.