For the past 2 years I’ve been using a Shelly Plus 1 to handle calls to the gas boiler for hot water. I have 300L hot water storage in the loft and the Shelly triggers heating for a short period 3x a day, essentially ensuring that we always have hot water available to us.
The boiler is in the lift, the Shelly 1 lives in a patress box inside the passage cupboard (which also has the hot and cold water supply pipes running though it reticulating to rads and taps both upstairs and downstairs.
There’s a ceiling mounted Uniquiti AP located about 2m away and the Shelly shows WiFi RSSI: -41 dBm, so there’s no issue with WiFi signal. It’s also programmed to reference chrony (running on my HA server) as its NTP server.
Yet, the POS periodically fails to trigger the boiler, and for the last week has completely failed to do so.
A few searches point to these things usually failing around 7y in , and also being doggedly stupid enough to try stick to the same AP even if there’s a closer one with better signal nearby (all my AP’s share the same SSID and I’m not about to change that just to accommodate a wifi relay).
I also have the Shelly 1 configured as a momentary switch so we can manually call for hot water if there’s a need to. For the past week, this has had no effect, so I’m guessing the relay has failed.
So after that long sob story, what do people recommend as a controller. Should I just reinsert the Honeywell that we had and revert to having to manually managing season change etc?
Check the software is the latest version. There have been some added parameters and algorithm changes in the WiFi area recently that may dramatically improve your performance. Check the documentation at WiFi Component - ESPHome - Smart Home Made Simple if you are using ESPHome firmware for control.
You may also wish to consider monitoring the hot water temperature rather than three short bursts of heat boost a day, for efficiency and to save your relay life span.
Your signal strength to your local AP is only part of the picture. What is the wireless signal strength from there to your main router and over to your HomeAssistant server, or is it via Ethernet?
Is the failure to trigger your boiler a software issue, a communications issue, or failure of the relay to turn on? Could it be a rusty connection point at the end of the wiring that just needs tightening?
What are the power draw requirements for your boiler? Is it at the upper end of your Shelly specifications? Three switches a day, over seven years is only a tad over 15,000 operations, truly well within most relay specifications. If the current requirements are high, the relay contacts may be burnt or pitted. The cheaper solution is to replace the relay, the optimum solution is to add a contactor, suitably rated and designed for specifically this purpose. Let us know the make and model of your boiler, as it may already have one internally.
At present I’ve got the Shelly doing it’s own thing, no control or scheduling from HA, though I may add a button to be able to trigger the momentary switch. The Shelly’s firmware is the latest available beta (just updated).
I’d love to be able to do that but have no idea how to do so. I have two unvented cylinders in the loft, each providing 150l. I imagine it entails replacing the cyliner thermostats with a smart equivalent - would that last in extreme loft temperatures?
The AP is wired to a a Unifi POE switch that serves as the backbone for all networking connectivity in the house.
If I trigger the Shelly from it’s web UI I hear the relay click. Testing for voltage between O and N there’s 240v when triggered. What I don’t hear is any valve movement and water flow. I know the boiler is working because the upstairs and downstairs rads (on separate thermostats) are working fine.
The boiler, valves and thermostats all take their power from the same fused spur, so unlikely valves are not powered.
The boiler pulls 48W at full load, 13W at part load and 7W when idling.
So what I’m surmising is that it may not be the Shelly at fault, but a valve motor that’s failed. Will have to wait for the tanks to fall below temp again and see what the story is.
Irrespective, some tips as to what can be done to measure HW temp in the cylinders would be appreciated.
Did some more testing, that Shelly is faulty. It turns the switch off inside 30 seconds even if put into detached mode and contact O not wired. Shorted O and L with a Wago 221 and HW circuit is working again.
So back to the original question, is there a Honeywell or other quality device that speaks HA I could drop in? Unless I want to risk divorce it must be capable of working independently (incl. automatic failover) in the event HA for whatever reason is not available.
If that is truly your boiler load current draw readings (only tens of Watts), then you should be calling a HVAC Specialist professional rather than continuing to debug your issue over the internet with random strangers. It indicates you are in way over your head, and probably your choice of which Shelly model to initially use may need clarification.
A DS18B20 zip tied to your pipe close to the boiler (on the outside of the pipe) used as a sensor should give you fairly consistent temperatures for comparison. They will not be 100% the water temperature, but close enough for making switching calculations. You are not measuring hot water in the cylinders, just at the cylinders. If your pipes are insulated for heat loss prevention, just slip it under the insulation where it enters the cylinder and thermal conduction should take care of the rest. It will be a few degrees less, but consistently and repeatably so. The alternative to have a thermostat sensor in direct contact with the hot water inside the cylinder raises potential waterproofing and corrosion issues. In this case ‘good enough’ bests accuracy - you can measure the hot water temperature at the tap for calibration purposes, and adjust the heat loss value of the piping as an offset in your code. Remember there will be a sudden rise in temperature at your sensor when hot water flows past it, rather than being conducted through the pipework from the boiler, so you may want to read about filters, delays and smoothing in your ESPHome notes.
The same ESP32 you might consider monitoring your two boiler water temperatures could be pressed into driving a relay to switch the suitably rated contactor (ask the specialist) for switching your boiler on and off.
This would make your Shelly redundant, and make using ESPHome an easy integration into HomeAssistant for your hot water needs as well as optimising power usage, once you plot and understand the relationship between hot water temperature changes over time, with regular and irregular consumption patterns, and time of day usage patterns for your boiler boosts.
You (and your wife) will be shocked at the inefficiencies of your present setup, just boosting the temperature on a timer three times a day, and the efficiency gains and power savings that can be achieved through smart automation.
With all due respect, I’d posit that in this instance the shoe is on the other foot. It’s a gas boiler, not an immersion heater. The immersion heating is entirely independent of the gas boiler and only used as a backup, because using gas for heating is a lot cheaper than using electricity.
An assumption on my part: Could you confirm this is a TLA abbrev for “Piece Of Sh!t”, and refers to the Shelly, or something else?
You never answered that question. Now we have multiple heaters entering the fray, both gas boilers and electrical immersion, and your Shelly connected to what, and switching what? How are the gas boilers and immersion heater controlled? Integrated or independent?
Your HVAC specialist will also ask the very same questions, using your existing setup as the starting base for troubleshooting as well as possible improvements in how to balance capabilities vs cost.
Regardless of whatever energy source (or combination) you are using, monitoring your existing temperature to make smart decisions is going to make improvements in efficiency compared to boosting three times a day irrespective of current needs. If you are able to utilise the cheaper energy source (in your case gas) to optimise the temperature to suit your needs which may vary during the day and night rather than aim for that one short peak requirement to be retained continually, any changes may provide long term savings and may possibly make your immersion heating requirements superfluous, or very rarely used. Not knowing is a large part of the problem. Monitoring and understanding becomes a big part of the solution. Your wife will love the daily and weekly HomeAssistant graphs to understand how you can save costs.
The monitoring suggestion, using DS18B20’s as temperature sensors is elegant as well as cheap, as it uses the One Wire protocol, so you can monitor at multiple locations using the same ESP32 GPIO pin with multiple sensors. Adding a relay or two to the same setup becomes easy with ESPHome code to electrically switch any gas valves or electrical contactors. If unsure of loft temperatures, just add one extra DS18B20 for that too! It is rated up to +125°C. Keeping your ESP32 away from extreme temperatures is recommended - most ESP32 versions have an internal thermometers for chip temperature you can also monitor as a ESPHome sensor. Your utility cupboard sounds like a good place to locate it, however be mindful of long cable run issues. I suggest install the ESP32 for temperature monitoring purposes anyway, and add the relay board later, if required. Both are cheap, commonly available, and easily integrated.
Your non-smart thermostats inside the boilers may logically be in series with the energy source, hence preventing any boosting. It may just need examination of the wiring logic and a simple change. Again, insufficient information on model name and number to make specific suggestions to your setup. You may be able to set them at a suitable lower (but still comfortable) temperature for fail-safe fallback in case your home automation setup fails, another of your concerns covered, depending on how everything is configured and wired.
It’s a Worcester Bosch Greenstar 8000 Life GR8300iW 35 S. Your take on POS is correct - over the past 3 years I’ve had intermittent issues with it failing to trigger the boiler before its recent hardware failure culminating in my removing it.
The immersion heating in the unvented cylinders is usually off at the consumer unit as it’s only used as last resort. When on, it’s also controlled via a Shelly which triggers a contactor. The Shelly is triggered via its web interface or via a pushbutton in HA Just as is the case with the boiler side, whether or not the immersion heating draws power is controlled by the control thermostat and thermal cutout in the cylinders.
To keep things simple you can assume that nothing in the wiring logic is any different to what it would be if there were no Shellies in the mix. The shellies basically replaced what would have been a traditional controller unit. At present, with the Shelly removed the boiler is firing anytime the control thermostat in a cylinder falls below its set temp. Inefficient,yes… and agree adding a temp sensor enabling more intelligent heating would be useful - nobody is disagreeing with you on that front.
Disclaimer: I have no connection with any of the items listed above, either intellectually or financially. I just found there is a rich set of commands already built into your Bosch unit that you may be able to harness for peak efficiency via the EMS interface and closely integrate into HomeAssistant. My earlier comments regarding deploying DS18B20’s still apply, and you may be able to customize the code to include these sensors with your EMS ESP32 source code and send them with your other MQTT data, or just simply use another ESP32 - they are quite cheap.
Already own the BBQKees unit, just haven’t gotten round to installing it as I have to get into the loft and take the boiler cover off in a confined space.
Your wallet will thank you. Install all the DS18B20’s while you are up there, and run the three wires needed (for one or more devices) back to your cupboard.
Why you want to replace Shelly, before you understand the issue?
Since you use Shelly builtin webserver, turn on the debug logs. Then turn the relay on and go to debug logs to see what happens after 30s.
Timer? Overheating?
I think the issue is well understood, the Shelly is faulty, probably because there was no RC snubber in the mix and every time it fired it would trigger two valve motors in the event that heat was called for. Since removing it I’ve enjoyed hot water on demand (obviously at a cost).
I’ll experiment with it separately and see if the debug logs have anything to say. Gut though, is it’ll need replacing, this time with a RC snubber in the mix.