Home heating automation

If the zone valves which controls the HW heating is located in the same cabinet as the HW cylinder, you can easily fit a cylinder attached mechanical thermostat wired to the zone valve to close it when a set temperature is reached in the cylinder. This stat can be an insert, slid into a water sealed copper tube which is manufactured into the cylinder, or else a surface contact thermostat, located about two thirds of the way down on the cylinder, usually by cutting away a neat stat shaped rectangle of the cylinder insulation.

If the zone valves are rooms or floors away from the cylinder, I would suggest leaving the EPH as your HW timer/thermostat, and just replace the CH control of your system with a wireless smart stat like Hive or Tado.

In systems with HW timing only, there are certain protections available to prevent overheating. One is to program as few timer events or segments so that HW heating is limited to these short bursts. The other is to have your boiler temperature control set to a value just above your HW safe temperature, say at 62-65°. The boiler will stop burning when its jacket temperature reaches the limits, but will continue to pump to the cylinder if a HW timed event is on. The heat will transfer to the cylinder domestic hot water, but won't exceed the boiler setting, and HW is unlikely to reach this temperature as the heat transfer slows as the temperature difference in the heat exchange coils lessens, lowering the rate of transfer.

One final option to enable the use of mechanical cylinder is to purchase a remote relay transmitter receiver set, something that EPH actually make. There's also the option of trying out Sonoff thermostat probe and wireless receiver switches. Setting of HW temperature is something you set and forget, so electronic remote control systems are bit of overkill when a €15 stat on the tank can call off the boiler when HW temperature is reached.

Just remove the CH Switched Live from the EPH controller going to the CH zone valve, and replace with the new stat receiver's SL. You'll site this receiver near the valves. It's the valves' relays that fire the boiler.

How many zones btw, you have 4 motorised valves.

You need an extra Wiser Kit 1, a stat and single zone receiver, €127 from screwfix. Both kits from Screwfix will set you back €400, half the Ember cost. Better option too from Screwfix rather than Amazon for warranty etc.

Hive mini works our similarly, €177 for CH/HW kit, then €101 each for two more stats and receivers, total of €379. Hive active kit for 3 CH and HW a bit more, €494 for the active CH/HW and two extra Active stats and receivers.

Tado can only support one wireless thermostat in an App ' home' so two would have to be wired. The wireless CH/HW kit is a giveaway at €110, less than the €115 each for the two additional wired stats, total of €340 which if you can wire two of the CH zone valves back to the stats, is by far the best value, and probably the smartest featured system of them all.

Tado, Hive and Wiser all offer smart TRVs, and all can integrate with alexa/google/Home etc. Automation.

The stats are paired to the receivers (HUBr) using Zigbee low power wireless protocol which provide immediate control of the zone valves without WiFi or Internet. The HUBr are in turn connected to your App and the Internet by wifi to your router. Afaik more than one hubr can be accommodated in the app, you would need to open two accounts with different passwords to operate them separately.

With Hive it's more obvious at the physical layer, there's a seperate Internet hub device to bridge to the router, and you only need one, so your first hive kit has three items, stat, receiver and hub. Subsequent stat add-ons have stat and receiver without a hub.

Tado also used a hub, they call it the Bridge, but it can only take one CH/HW receiver (extension kit), the other stats need to be wired. Tado started as a smart replacement for existing zoned systems that had mechanical wall stats and possibly a zoned timer controller such as EPH. You just popped the Tado wired stats in place of the old mechanicals, and turned the zone timer(s) to always on, as timing and thermostatic control resides in the wired Tado wall stat. Their new TadoX model may go some way to enabling multiple wireless CH zones but it's heavily focused on zoning by TRV's rather than zone valves.

This model can be used in your system, whereby you open two (or all three) zone valves with one stat receiver, and add smart TRVs within the original zones to break it up with some or all individual room TRV control. This can be more cost effective than getting in a plumber to add zone valves. As the saying goes, there's more than one way to skin a cat.

Thought I'd post this for interest's sake.

Ive an older non-condensing boiler, 2002 Vokera 28e. It has a temperature dial on the front but is effectively left running at 70C as it's heating the hot-tank in the early morning and the rads then later on in the day. In the past I have knocked it back from 70C to 45C when I've just been heating the house alone as the boiler doesn't have a good modulation ratio, so it cycles constantly when at 70C.

So this week I made a set-back controller. It's an external variable resistor which is in parallel with the variable resistor in the temperature control dial. The variable resistor is controlled through a relay on an ESP32, so it's not in-circuit when the relay is open (normal state), but divides the resistance (drops the temperature to a pre-set set-back temperature) when the relay is engaged. It's controlled by ESPHOME and I have it setup so that when we call for radiator heating in Home Assistant the relay closes for the duration of the heating session and then goes back to an open state. It effectively means that only the radiators get 45C while the hot-tank gets heated at 70C.

The little black box is a mini 5v/3W power-supply.

https://makershop.ie/Electronics/Power/HLK-PM01

Yes, 45C is low, but fine in these evenings. I can ramp up the temps easily by twiddling that variable resistor knob by a few degrees. 😁

I think there's confusion here between Tapo, an opportunistic brand name for TP-Link products, and Tado, the German heating control manufacturer. Tapo uses the Zwave protocol. Tado uses the 6LoWpan proprietary protocol, which runs on the same European Z wave frequency, 868 Mhz. I'm not aware of Tado TRV's communicating with Z wave hubs.