Under floor heating (controllers and elements)

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SirHumphreyAppleby

2513 posts

Uber Geek

#306649 10-Aug-2023 10:20

I have been told we are installing underfloor heating in a bathroom renovation. An unnecessary addition in my opinion, but I've been overruled.

The biggest issue is around control. As this will be used by an older person, it is desirable to keep this as simple as possible - ideally, just a switch. Can anyone recommend a thermostat suitable for installation behind a simple switch? I.e. set once and forget it even exists.

Alternatively, does anyone know of suppliers offering certified PTC underfloor heating in NZ? I've been using PTC heaters in the greenhouse, and their self-regulating nature means I don't need a thermostat at all... I'm hoping the same would apply to underfloor heating.

bigreddog

160 posts

Master Geek

Subscriber

#3114069 10-Aug-2023 11:11

Nice simple thermostat with an integrated on/off switch - about $100 from memory

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jamesrt

1376 posts

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Lifetime subscriber

#3114076 10-Aug-2023 11:18

The underfloor heating we had with our build (10 years ago coming up, so not exactly new!) came with these:

Can control the floor AND also a heated towel rail, on independent daily timers, with dual off and on times per device - which means you can run the floor independently of the towel rail, and have them both come on and off 2x/day at different times.

The floor has a temperature sensor installed, and the unit can use that to control; so yes, functions as a thermostat too.

Very flexible; the installer can set it up; but it's easy to adjust if required - it really is just a set-n-forget thing; about the only tweaking we do is to push the off and on button when leaving the house for holidays.

SirHumphreyAppleby

2513 posts

Uber Geek

#3114080 10-Aug-2023 11:28

Sorry, I probably should have mentioned I was looking for something with a little less presence.

To be more specific, I was hoping to find something more like those cheap fan timers that switch on the extractor fan when the lights in the bathroom have been on for more than 30 seconds. They are hidden behind the light switch out of sight.

allio

864 posts

Ultimate Geek

#3114081 10-Aug-2023 11:30

Forget about the simplicity of the controller - what you want is something with a solid schedule feature. Once that's set up correctly it truly will be set and forget. I never turn mine on or off, I just occasionally adjust the schedule or check how much power it's used.

Ours are Devi (Touch model) and I have no complaints.

SirHumphreyAppleby:

Sorry, I probably should have mentioned I was looking for something with a little less presence.

To be more specific, I was hoping to find something more like those cheap fan timers that switch on the extractor fan when the lights in the bathroom have been on for more than 30 seconds. They are hidden behind the light switch out of sight.

There really isn't an equivalent to this for heated floors. They take several hours to reach full temperature. You either have it on a schedule or you leave it on all the time (and waste a tonne of power).

You could put a hidden simple timer in the wall (we have one of those with our heated towel rails) but then you won't be able to update the schedule, which is handy to do when the weather or your usage changes. And you're always going to need some kind of accessible controller so you can set the temperature. Might as well get a controller that can do both temperature and schedule.

itxtme

2050 posts

Uber Geek

#3114103 10-Aug-2023 13:35

From a technical standpoint I guess you could use any controller (like a towel rail or fan) that is rated higher than the wattage of the wiring system installed in the bathroom. The reality is though these systems normally run on a combination of timer and thermostat. And the probe is wired and installed below the tile. In fact most systems have two of them in case something goes wrong with one of the probes. Imagine how hot the floor could get if its left on with no thermal control.

Like someone said above, it take time for the heating to warm up the tiles - like an hour -so being on a light switch timer is not ideal.

We installed them during our renovations, and we do not use them at all. However for the extra cost, its worth it for resale etc. It cant be done retrospectively, and for some its a deal breaker with tiles.

Rodders1nz

29 posts

Geek

#3114129 10-Aug-2023 14:16

I have upgraded my underfloor controller after 2-3years, I have a DEV 530 for for sale for $40 plus postage if your keen.

https://www.devi.co.nz/products/in-slab-heating/devireg-tm-530

SirHumphreyAppleby

2513 posts

Uber Geek

#3116089 15-Aug-2023 12:37

Having discussed the matter further, I have now been told that waiting 30+ minutes for the floor to heat up isn't acceptable, and to get something with a timer, so the floor can be toasty warm in the mornings. Does anyone know of a WiFi (or even better, RJ45-connected) controller that can keep the time updated via NTP?

I don't want to have to set the clock every time I visit.

openmedia

3047 posts

Uber Geek

Trusted

#3116109 15-Aug-2023 12:56

Rodders1nz:

I have upgraded my underfloor controller after 2-3years, I have a DEV 530 for for sale for $40 plus postage if your keen.

https://www.devi.co.nz/products/in-slab-heating/devireg-tm-530

What did you upgrade to as we've got old Devi controllers.

Generally known online as OpenMedia, now working for Red Hat APAC as a Technology Evangelist and Portfolio Architect. Still playing with MythTV and digital media on the side.

Scott3

3339 posts

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Lifetime subscriber

#3116120 15-Aug-2023 13:19

Yeah, a unit with a schedule is what you want.

One with a temperature probe to measure the underfloor temp, rather than measuring the air temp.

Set it up with a simple switch to choose between the schedule and off. Avoid putting on the same faceplate as the light switch.

Don't know which units are compatible with time synchronization, but this does sound like a desirable feature.

itxtme

2050 posts

Uber Geek

#3116178 15-Aug-2023 13:49

I looked hard at this and honestly thought the smart units were ugly UI, pixilated and overpriced. So I got Warmfloor TH01 thermostats and Shelly Relay after the controller. Leave the thermostat always on, Use Shelly to control actual power getting to the floor based on timers, BUT if the floor reaches temperature say 21 degrees the TH01 cuts off power to the floor also, so no overheating.

Disadvantage is you cant see if the floor is getting power or not on the wall device - but if its set and forget and timer/temperature based do you care?

Edit - What it looks like (its installed over a standard wall box)

Rodders1nz

29 posts

Geek

#3116194 15-Aug-2023 14:16

Scott3:

Yeah, a unit with a schedule is what you want.

One with a temperature probe to measure the underfloor temp, rather than measuring the air temp.

Set it up with a simple switch to choose between the schedule and off. Avoid putting on the same faceplate as the light switch.

Don't know which units are compatible with time synchronization, but this does sound like a desirable feature.

We upgraded to a Thermfloor HT1 because we installed a solar system

https://www.thermafloor.co.nz/wp-content/uploads/2022/03/thermafloor_nz_christchurch_ht1-_user_manual.pdf

the unit must have a battery back up in because we didn't have to redo the time after a power cut