Hi - I’m just getting started with HA and would like to control our non-combi heating and hot water system comprising:
Ideal type-E boiler (with hot water storage tank), pump, 2 solenoid valves and radiators.
Control is a Honeywell ST9400C 7 day timer, which is a pain to program and has no seasons so I have redo it for winter/summer. I hate it!
Hardware requirements:
230v (UK spec)
5 wire / 2 channels (separate switching of heating and hot water valves).
Can I use a tuya compatible wifi smart thermostat with Local Tuya in HA and still be able to use its hardware LCD panel if HA/wifi goes down or for simple override control?
The ones on ebay I’ve seen for about £35 seem to all have 4 wires (plus a sensor circuit). An option would to use three wifi relays but then I’m 100% reliant on HA and I lose control of the heating system if HA goes down :-/
I want to see just how cheaply this can be done, but want to avoid google, hive, ecobee etc anyway. What are my options?
I have this Z-wave Relay from Heatit and it seems to be designed for controlling boilers so something similar to your purpose? It only has a single relay though You would be able to control the boiler but not the valves?
I have just finished implementing a driver for it for SmartThings so that it can be used through the SmartThings integration.
I will be using it to control underfloor heating. I can control it (ie switch the relay) from either HA or directly with SmartThings. I also have a separate wireless room thermostat (also from heatit) configured through one of the z-wave associations to switch the relay based on the room temperature.
They also have a firmware update for it that I am using, that allows the relay to function as a thermostat with floor heat limitation.
Heatit have a z-wave solution for switching water valves too.
I’d look at controlling the system on the low-voltage (thermostat) side before trying to switch the 230V side.
Frankly, the cheapest, easiest and most functional solution might be a new, smarter thermostat. Get one which integrates with HA (my US Honeywell does, I assume their UK versions can, too) and you can use all the power of HA automations to schedule.
This also gives you two fail-safe modes. If HA fails, you can still use the vendor’s cloud-based smart controls. And if both HA and your internet connection fail, your thermostat will still manage your heating system in stand-alone mode, which includes all the scheduling you programmed into it using either the thermostat panel or their app.
I don’t know what your climate is like, but I’d be reluctant to depend entirely on HA for any critical system. At the very minimum, I’d install a “dumb” thermostat and use relays and GPIO pins to supplement the thermostat controls, but the thermostat could always overrule that and power the system if all else fails and the temperature falls below it’s pre-set value.
Our system doesn’t even have a thermostat, lol! It just comes on and off on a schedule. Extremely low-fi. The heating scheduling just gets switched off completely when the weather gets warmer and we gradually get used to the cold before it eventually gets turned back on in winter.
The current controller is Honeywell, so at least there’d likely be one that would work with how it’s current’y set up.
A smart thermostat was what I was after - the super-cheap chinese generic ones. Like this (but only 4 wire):
Just found this one, which has 5 wire option like the Honeywell:
Looks like I’m thinking about this all wrong… all I need to do is add the thermostat to the existing Honeywell timer and set that to run the heating continuously - the smart switch will do all the automation and I will retain a failover… I think!? Controlling the hot water might be trickier, as it needs to monitor the water tank temp, though I doubt this will benefit from any HA automation.
You would be able to control the boiler but not the valves?