Underfloor tile heating controller

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Sideface

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#1285095 15-Apr-2015 20:15

I have 2 bathrooms with underfloor heating and with underfloor temperature sensors.

17 degrees (Centigrade) - just warm enough for bare feet ("not cold").
25 degrees - nice and warm.

My sensors read 2 degrees low (compared with the tile surface), so i use "19 degrees" baseline and "27 degrees" for shower time.

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gregmcc

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#1285099 15-Apr-2015 20:17

timmmay: I feel like I've just stepped into a lecture about two grades above what I understand!

trying to explain PID to someone who has no background in it is very hard.

with a standard setpoint on/off controller it has limitations, say your set point is 24deg

It heats until it sees 24deg and then stops, but as the heat transfer isn't instantly happening between the element and the temp sensor there is a bit of follow through, although the element is switched off it continue to rise to 28/29deg, the same as the temp drops, it goes way below the set point, down to even 19deg until the heat can transfer from the element to the temp probe.

the way around this is using a controller that had PID control, it learns how long to heat for to keep the temp at the set point, these unit can be quite expensive, but it all depends on how much money you want to spent and how accurate you want it to be.

Aredwood

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#1285105 15-Apr-2015 20:36

Just remembered I have this in my house.

It has 3 programmable temperatures (4 if you include the anti frost temp setting) That operate 1 per time period. And it even has PID settings (dip switches on the back to change)

It is Landis & Gyr brand. Looks quite old as alot of yellowing on the case. Im only using it as a glorified room thermometer. It is powered from 3x AA batteries. So it still maintains time even when not connected to anything. Have also seen very similar ones with Siemins branding. Maybe see if they are still made new. My one was made in 1995. Although supposedly this model had problems with the relays failing. (makes a loudish click when switching on and off).

And yes the room was actually that hot when the photo was taken.

Handle9

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#1285108 15-Apr-2015 20:41

Aredwood: Just remembered I have this in my house.

It has 3 programmable temperatures (4 if you include the anti frost temp setting) That operate 1 per time period. And it even has PID settings (dip switches on the back to change)

It is Landis & Gyr brand. Looks quite old as alot of yellowing on the case. Im only using it as a glorified room thermometer. It is powered from 3x AA batteries. So it still maintains time even when not connected to anything. Have also seen very similar ones with Siemins branding. Maybe see if they are still made new. My one was made in 1995. Although supposedly this model had problems with the relays failing. (makes a loudish click when switching on and off).

And yes the room was actually that hot when the photo was taken.

Wow a Chronogyr. That would be from the mid 1990s. If it hasn't even got Landis & Staefa branding it's out of the ark. You can't get sensors for them any more, they're long gone.

timmmay

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#1285119 15-Apr-2015 20:56

n4:
timmmay: I checked with devi, they only have two heat settings when I asked a year or two ago.

True. What I meant was you could send the comfort level at a point such that it is warm enough to stop the floor freezing overnight, but cool enough that day time temperatures would be high enough to keep the thermostat off.

Ah, I get you now, not quite here. It has to be heated at night, I aim for 19, if I set that during the day it'll be using more power than it needs to. I only go to 22 during showers too. Higher is nice but not really necessary for me.

Handle9

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#1285130 15-Apr-2015 21:11

timmmay:
n4:
timmmay: I checked with devi, they only have two heat settings when I asked a year or two ago.

True. What I meant was you could send the comfort level at a point such that it is warm enough to stop the floor freezing overnight, but cool enough that day time temperatures would be high enough to keep the thermostat off.

Ah, I get you now, not quite here. It has to be heated at night, I aim for 19, if I set that during the day it'll be using more power than it needs to. I only go to 22 during showers too. Higher is nice but not really necessary for me.

You're probably going to struggle to find something that does comfort, setback and off. To be honest to get that sort of functionality you're looking at either a smart relay or something like an Arduino. It doesn't help that your floor probe is a 12k NTC, it's not exactly a standard part.

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timmmay

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#1285270 16-Apr-2015 07:13

Handle9: You're probably going to struggle to find something that does comfort, setback and off. To be honest to get that sort of functionality you're looking at either a smart relay or something like an Arduino. It doesn't help that your floor probe is a 12k NTC, it's not exactly a standard part.

It's a shame the original one (and its replacement of the same brand/model) didn't work properly, it had exactly the features I wanted, other than controlling the temperature correctly.

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