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Thermostat - do I need one?
Hi Guys,
Can I ask your opinion on thermostats? I am about to do a complete refurbishment starting with the heating system. And I was just wondering if I need a thermostat at all or what purpose it would serve in larger home where there is home automation controller like Homey? In smaller-mid size apartment it is most straight forward and simplest way control the heating. That is clear.
In my case there are 3-4 heating zones. I need these because not all room has the same thermal loss, radiator and they are occupied at different times. To control each zones individually, I have Danfoss TRVs (radiator valves controlled via Z-wave). The issue with most thermostats like Nest that they cant control multiple zones and communicate with TRVs.
And the top of it I will have a far-infrared underfloor heating in the living room. That is definitely something what thermostats can`t control. That will need a z-wave relay.
I have Fibaro multi sensors which includes temperature sensor as well.
So I got thinking what is the point to have a thermostat in such scenario? Homey can read values from the sensors and directly control the relays and the TRVs.
What do you think?
Comments
I'm not the most tech savvy, so I don't think I am the right person to explain the need for a thermostat in your system (though, shouldn't there always be a central component that can control the boiler?), but with regard to multiple zones and underfloor heating...
Have you looked at the Honeywell Evohome? It's not cheap, but it DOES have support for multiple zones and an optional component for underfloor heating... (it has its own equivalents for the Danfoss TRVs as well)
Thanks Bumblez. I had the impression that the boiler control is just and on/off thing, at least my existing boiler (will be replaced) works on that way. Yes indeed Honeywell Evohome is quite comprehensive system but right it is quite expensive too. And not sure when this will be supported by homey while z-wave is supported. Will Evohome give added value or just added cost?
For me Evohome gives added value even without Homey. ;-)
What added value it has what a homey based system cant provide? Please dont misunderstand me, I am not arguing just trying to get more input for the decision.
It brings comfort. With evohome I can divide my home into zones and set the desired temp levels with the help of a schedule and overrides to this schedule.
Before, the whole house was connected to one thermostat which was in the living room.
I can't say that homey cannot provide this, but it will not give you these functions out-of-the-box.
You will need effort to make this work.
I myself will use Homey to connect to the Evohome system to make it smarter (things like geofencing and interaction with other sensors).
Somebody mentioned Benext heating control :
Speakes z-wave and is able to override your thermostat (if compatible).
IFAIK this way you can implement zones and rules/event/triggers with homey and your Danfoss valves.
Investment is not that big (99 euro) apart from the danfoss valves and the z-wave controller which you already have.
I had a look at that link, but I don't see a mention anywhere that this works with multiple zones and/or underfloor heating systems!?! How would that work?
It is not a thermostat. There is an input on this for thermostat. This is a boiler control. Am I correct in assuming that I can use a fibaro relay unit to control the boiler? The Evohome TRVs are using the 868 MHZ frequency. This is the frequency used by Z-wave if I am correct. Is this TRV Z-wave by any chance?
I'm not an expert, but from what I have read, a thermostat will ensure your boiler works more efficiently. OpenTherm compatible heaters for example allows a boiler to decide how high it should be heating the water by comparing the current with the desired temperature. Most modern boilers/thermostats can also factor in the outside temperature to ensure the water temperature is always optimal. Lower (but not too low) water temperature can greatly increase the efficiency of the entire heating system.
Some boilers (like mine) even allow you to configure when to prepare hot water in advance for a shower. I'm currently not using this feature as I think it is slightly more efficient to never pre-heat water, so I trade energy for some comfort.
If you have a slightly intelligent boiler and thermostat, you will definitely benefit. When we moved in our current apartment, I replaced a medium sized radiator with a large second hand design radiator, lowered the target water temperature to 55C and upgraded the thermostat to one with a programmable timer. We use HALF the amount of gas compared to the previous occupant and well below the average compared to some of my neighbors I talked to.
Remember: the simple solutions have the highest return of investment.
Well I'm not sure but for zone heating, you need input from a thermostat. Normaly you would have one thermostat in the livingroom which is responsable for the temperature in the whole house. Now since you can overide this value via this zwave controlled device en each valve has it's own thermostat, it should be possible that the valve in the livingroom is closed because the temperature is reached, the temperature in the bathroom is below the setpoint which is notified by homey who overrides the thermostat value to start the boiler and this way only warms the bathroom till the setpoint is reached.
For zone heating to work you should have a bypass in your system.
With non intelligent zone heating you should have a boiler which heats the circuit continuesly.
This way you can start heating by overriding the central thermostat.
Please note that these are only my thoughts. Please let me know if I talk bullsh*t :-)
Thank you rscheers and thank you JaapPelt for the nice explanation, halving the heating cost is really great. I started to read about the OpenTherm and I can`t find Boiler what uses this interface. I am planning to have either Vaillant or Bosch boiler which are the big and reliable brands and none of those have OpenTherm interface. Googled OpenTherm boilers but practically it came back blank. What am I missing?
I agree with you that simple solutions have the highest return investment. That is why I am thinking to get have less element and one brain in the heating system.
blusser: What bypass you meant? I dont think that boiler would heat the circuit continuously, if the temperature values received form the fibaro sensors are all equal or higher than the target temperature in each zone than homey could send signal to the relay or whatever is needed to stop the heating.
I have a Vailliant boiler myself with Opentherm module. Works great :-)
You need a bypass in your circuit, because the boiler pump will operate even if the RTVs are all closed.
So it needs a closed circuitloop/bypass.
Thank you guys for the great help, getting close to the full picture. rscheers what Vaillant boiler/module do you have, is that module came with boiler or you had to purchase separately? Why the pump of the boiler still works when the target temperature has been reached in all rooms?
I have the Vaillant Eco-Tec Plus CW5+ (http://www.vaillant.com/customers/products/ecotec-plus-256.en_ex.html) with Opentherm module (it's installed as an option).
The pump runs to keep the heat distributed throughout the circuit even if the boiler is not heating .
AFAIK you can stop heating the circuit by using the benext heating control because this way you can override the main thermostat temperature. so this way you save extra energy.
If a specific room then needs heating, just increase the main tempature again (via homey)
If you by a boiler in the Netherlands, it's probably an OpenTherm (unless you buy a Nefit). US never has OpenTherm as far as I know. Don't know what the rest of the world uses...
Expecting a 50% savings is probably not realistic for most people. Commercial smart thermostats often claim 20%-40% saving depending on the boldness of the company in question. But since it is all relative, you never know.
Apology for the radio silence on my end, I have contacted couple of manufacturers and were waiting for their feedback. Although UK is in Europe most things are quite different on the island: driving on left side, using different sockets, imperial measurements and even line voltage is still well above the European norm, etc. Thats the British way. So it is same story when it gets to the heating systems. I have contacted OpenTherm Association but they did not bother to get back to me. Based on the feedback from the boiler manufacturers no one is using OpenTherm here. Vaillant and Glow Worm is using the eBUS (Energy Bus) which has quite similar to OpenTherm. Vaillant is not willing to sell their products with the OpenTherm module rscheers has mentioned (at least here in the UK). Worcester Bosch uses the Junkers HT BUS. Baxi has the simple on/off solution.
The heating industry is as messy as the home automation industry with all various protocols they use. The solution is to simply supporting all the systems. TADO just does that. They support EBUS, OpenTherm, Junkers HT BUS and many other systems. No other thermostat does that. I came across tado before but I did not like the look of it but giving another thought, it blends into the wall and anyway don’t want to interact with it (automate the system and don’t touch it again). They will open their API in the near future so it can be supported by Homey. But why would life be nice and sweet, it needs to be bitter-sweet. The big downside of Tado is that the schedule is note stored locally, it is in the cloud. So if it loses the connection it will heat the system to the last scheduled temperature. You can potentially burn more money with it than saving if your ISP is not reliable. Utterly dumb!
Regarding Nest: it is a very stylish product and has a great UI and apps. However it has no added value when compared to the solution I have described in the first post. No modulation or receiving feedback from the boiler or any sort communication with the boiler. It does nothing just turns on and off the boiler. You can do that with homey and a cheap relay unit.
Have you considered moving to the mainland?...
Mainland America or Europe?
Sometimes the folks here pretends that the island is in the middle of the Atlantic ocean or close to American shores.
Hahaha
the UK is little America...
@Honey, do they sell Remeha in the UK? They use the OpenTherm protocol. At this moment I can read out my heater via an Arduino with WiFi shield sonnected to a webserver on my NAS. When Homey enters my house I'll change from WiFi to an other protocol. But as a proof of concept it works pretty nice. But in the ens I've a little work to do so I can read out the faultcodes and runtimes.
@PeterGroeneweg Looks very nice. What module from Remeha is it? How did you manage that with a Arduino? Do you have a howto or link?
@ Kasteleman, I've got a Calenta. Remeha sell's a cable which can be connected to the heater for maintenance purposes. They also have a free (Recom) software available to use with the cable. Robert Hekkers found out that it is a FTDI cable with a 4P4C connector.
I've connected this port to the Serial1 port of an Arduino Mega and put some software in it to send a request to the heater. Then the heater responds by sending the requested information back to the Arduino which analysis the data and then make it available for a API request which is done via the NAS.
If you want to have more detailed information, send me a PM with your e-mail address so I can send you some information.
That is really nice Peter. Good job. They only serve large businesses in the UK, they dont sell products for domestic customers.
Ah, that's a shame... If you give me the money I will send one to you :P.
Wish to import such things from the continent. But it is like importing cars… you can`t register it (not cost effectively).
Nest is comming with an OpenTherm version:http://tweakers.net/nieuws/106347/nest-brengt-nieuwe-versie-uit-met-opentherm-ondersteuning.html#r_8017385