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General => Temperature Monitoring & HVAC Control => Topic started by: thetwc on April 21, 2016, 05:26:50 pm

Title: Dimmer on a towel rail
Post by: thetwc on April 21, 2016, 05:26:50 pm
I would like to have a dimmer on a 150w electric towel rail in our downstairs toilet (small room). I have a few Qubino relays around the place so I'm happy to get another and I like the built in temperature sensors. (I'm z-wave plus too)
There's no other temperature reporting in the room so I will need some sort of sensor.

Which qubino device would you recommend?  I'm confused by these thermostat devices.

I was going to have a pleg with the following rough conditions.
Movement in the house, maintain a room temperature of 20degC
No movement in the house, maintain a room temperature of 16degC
Overnight off
On for an hour at 6am week days up to 20degC
Each condition could have the temperature maintained by varying the dimmer level.

All of this is doable with a standard dimmer device in Vera and pleg.
But, how do the thermostat devices appear? Do they have set points and appear like a normal thermostat? Would a thermostat be a better device for this installation?

I also have a left over temperature sensor from a qubino relay. If I go down the line of a flush thermostat, could this be used?

Thanks
Title: Re: Dimmer on a towel rail
Post by: zedrally on April 22, 2016, 01:12:42 am
The Flush Thermostat comes with a temp probe.

I'd be going in the direction of a Flush 1 and probe and PLEG
Title: Re: Dimmer on a towel rail
Post by: thetwc on April 22, 2016, 01:38:36 am
Does the flush thermostat appear as a device in Vera with a set point,up/down arrows, current temperature ?
Title: Re: Dimmer on a towel rail
Post by: zedrally on April 22, 2016, 03:05:22 am
I don't know.
I have one sample (Gen 3) but never set it up. The Gen 5 may be very different.
Title: Re: Dimmer on a towel rail
Post by: thetwc on April 22, 2016, 07:53:51 am
Thank you.

Looking at the Qubino website, there are 3 types of the thermostats:
Flush on/off, flush heat and cool, flush PWM.

Any ideas which to run 240v 150w heating element.
I like the thought of a continually variable output (ie, the towel rail might remain warm to maintain the room temperature, not just on and off)  Is that what the PWM would do?

Cheers.
Title: Re: Dimmer on a towel rail
Post by: Slartibartfast on April 22, 2016, 08:11:55 am
Thank you.

Looking at the Qubino website, there are 3 types of the thermostats:
Flush on/off, flush heat and cool, flush PWM.

Any ideas which to run 240v 150w heating element.
I like the thought of a continually variable output (ie, the towel rail might remain warm to maintain the room temperature, not just on and off)  Is that what the PWM would do?

Cheers.
I suggest the flush on/off.  Why?

1)  It is 240V with 200w capable output.
2)  You can change the set temperature via switch inputs if you want. For example you can use it to set higher if you decide to run a bath without having to get out your tablet/phone.
3)  Variable control of a 150w heater seems excessive. A 150w heater surely cannot have that much range of heat output that varying the output will make much difference.

Just my thoughts.
Title: Re: Dimmer on a towel rail
Post by: thetwc on April 22, 2016, 01:33:28 pm
I suggest the flush on/off.  Why?

1)  It is 240V with 200w capable output.
2)  You can change the set temperature via switch inputs if you want. For example you can use it to set higher if you decide to run a bath without having to get out your tablet/phone.
3)  Variable control of a 150w heater seems excessive. A 150w heater surely cannot have that much range of heat output that varying the output will make much difference.

Just my thoughts.
Thank you.
Good calls.
I wasn't going to put any switches on, at this stage anyway. It's only a downstairs toilet and a small room, so it's a little bit of heating for the room and to dry the hand towel. Having the dimmer element was for that purpose, so it might be on low through the day to dry the hand towel.
I do take you points though. The joys of home automation: being able to over complicate simple tasks :)
Title: Re: Dimmer on a towel rail
Post by: Slartibartfast on April 22, 2016, 01:44:14 pm
You could still look into the PWM version out of interest, particularly if you can do it at the same price. It would need more careful setup into what percentage full load it gives out per degree below target to get a good hysteresis. I still think 150W is too low to worry about it but it may still be worth it for experience of the device.

You could then come on hee as the expert!   8)
Title: Re: Dimmer on a towel rail
Post by: thetwc on April 22, 2016, 03:38:51 pm
Yikes. A bit of googling on PID calculations - it's going to be challenging to get it right and working perfectly. I love a challenge! 
Just need the PWM to come in stock and will give it a go.
Thanks.
Title: Re: Dimmer on a towel rail
Post by: Slartibartfast on April 22, 2016, 03:42:01 pm
Yikes. A bit of googling on PID calculations - it's going to be challenging to get it right and working perfectly. I love a challenge! 
Just need the PWM to come in stock and will give it a go.
Thanks.
Keep us updated as it is an interesting device
Title: Re: Dimmer on a towel rail
Post by: kwieto on November 21, 2018, 10:11:04 am
Talking about update, did you set this installation? What is your experience?
I'm considering using PWM thermostat to steer a fireplace fan heating the house, considering PWM or ON/OFF thermostat to do that job.