Making room controller not turn on and off heating as frequently.

[Anders Windsor]

The room controller turns on and off the heating in my floors really frequently, maybe once or twice every minute. This is a bit extreme, is it possible to get it to have longer on and off periods?

[Duncan]

If you are using the intelligent room controllers then there isnt anything that can be done to change things. If you use the room controller (not intelligent? ) then you can set parameters for the PWM control

[BartVB]

I don't own a Loxone system (yet), haven't worked with the config system, but I can imagine that you can use the analogue output of the intelligent room controller (IRC) and feed it into a pulse width modulation block:

http://www.loxone.com/enen/service/documentation/loxone-config/function-blocks/pulse-width-modulation.html

The problem is that the IRC is made for a heating system where you don't switch on/off the heater but you open/close radiator or floor heating valves. With these valves it's not that much of a problem if you switch those every minute. Your main problem is that with the digital IRC output you can't change the PWM period, but you can do that with with the PWM block mentioned above. But I'm not sure if that would mess up the 'fuzzy logic' in the IRC. AFAIK it shouldn't but you might want to check that with Loxone support.

A more advanced solution would be using a PI or PID-controller block: 

http://www.loxone.com/enen/service/documentation/loxone-config/function-blocks/pid-controller.html

and control this based on the actual and target temperatures, but if you do that you remove most of the 'intelligence' of the IRC. The main disadvantage of that is that the system can't start heating up the house before a target temperature change. I.e. if you want to have the house at 19'C at 09:00 the IRC will start heating at 08:40. The PID block won't know about the upcoming temperature change until 09:00 so that's the earliest time that the system can start heating.

[Michael]

Hi,

Not really an answer, but I have similar interest with pwm on digital output with a period of eg. 1 - 2 mins, and I'm considering if the digital output of the mini-server or and extensions is suitable for this.

Loxone links to this datasheet:

http://www.loxone.com/tl_files/loxone/downloads/datasheets/FR/HF33F_en.pdf

In the specs it says:

Mechanical endurance: 10^7 OPS

Electrical endurance: 10^5 OPS

I don't really now what OPS stands for, but I would guess it is an operational cycle or similar.

Anyways, if the electrical endurande is 10^5 on/off cycles, that would give a lifetime with a 1-min period of:

10^5/ ( 24*60) = 69.4 days..

The mechanical endurance would last 19 years, I don't know if the endurance really is this skewed, or if I just don't know how to read the datasheet.

My load is only 24V and 2W, that will probably have an effect on the endurance.

It is 11 of these thermal wax actuators I'm considering driven, which regulates some water valves. I have district heating.

http://heating.danfoss.com/PCMPDF/TWA-Z_VDJCJ802.pdf

Sincerely

Michael

[Michael]

Hi Anders,

I asked Loxone, and I got the answer that 10^5 is the number of cycles the relay can take.

So if you are cycling your digital outs every few minutes, they will die within a few months.

Even at 100 times a day, they will wear out in under 3 years.

You (and I) probably need some equipment with a solid state relay.

Sincerely

Michael

[Duncan]

the cheapest way of fitting a large number of ssr outputs for heating actuator control is to use a dmx extension, and a muti-channel led dxm decoder, attached to a multi-ssr relay board

 

eg:

http://www.aliexpress.com/item/DIN-Rail-Mount-8-Channel-SSR-Solid-State-Relay-Interface-Module-AC100-240V-2A/2002312808.html gives you 8 ssr @2a 240v with a din rail mount - ideal for manifold actuators

the ssr run at 5v trigger

and

http://www.aliexpress.com/item/dmx-512-12-channel-Easy-DMX-LED-controller-decoder-dmx512-decoder-controlador-dmx-console/32256060052.html or similar is a decoder that can run at 5v also

this one is 12 channel, but you can find plenty of other dmx led decoders to match the number of channels or simply overlap unused dmx channels. Configure the dmx channels in loxone so that anything other than 0 gives you 100% output so the dmx led channel is either off or fully on.

 

so for a total of $67 or so you get 8 ssr dmx outputs.

[Michael]

Hi Duncan,

Great idea. The SSR's are cheap!

The Loxone DMX extension is quite costly, so if you do not have this one, it can be a bit expensive. But does scale quite well to 128 channels!

I guess you could also drive the SSR in other ways:

- Loxone Analog outputs

- RS485/RS232 I/O output module

- KNX I/O (eg. ABB UK/S 32.2)

- Ethernet I/O

   - Raspberry PI or similar

   - Commercial product

Is there other options?

[Duncan]

the ssr boards are very cheap - that company do the 2A versions (ok for inductive water pumps as well up to 1.6A, 8A stalled/surge current) and a 6A version for higher current requirements.

once you get a larger install with loxone, the dmx extension saves a fortune in other extensions, particularly when you start to add a quite few mains dimming channels or need lots of outputs for manifold zone switching - i think its still going to be the cheapest way, except maybe a raspberry pi but then you are possibly getting a bit techie - at least the dmx/dimmer/ssr option is all wiring and standard loxone coding which makes most people feel a little more comfortable

the knx route is too expensive, rs232 is one to one

[Michael]

Thanks for your insight, this gives me more to think about.
I had more or less ruled DMX out, but I can see it has some benefits.
You mentioned mains dimmer in DMX, do you have a favorite version? Preferably DIN mounted.

[Skarsol]

Isn't DMX for lighting? How are you using this to control other things? I guess using it as a basic on/off?

[Duncan]

dmx isnt just for lighting, its a very old standard for control of devices. - the main items are led dimmers, mains dimmers and relays - the relays act like any other loxone switched output so for example they are great for heating actuators.

[Skarsol]

Oh, neat, I don't know why I got the impression it was just for lighting. Thanks!

[TomM]

I second the use of DMX relays for heating control, exactly what we've done here and it works perfectly well (using mechanical relays at the moment but may change to SSRs if we encounter any issues)

Also, as someone mentioned RS232, if you're looking for a more cost effective solution that a Loxone RS232 extension, you could always use an IP to RS232 adapter and then use the UTP virtual inputs/outputs to control it.  I've connected an WTDIO digital I/O board using this technique and works really well.