Leaving gas behind, and monitoring my home energy usage with Home Assistant

So earlier this year, I took the all-electric jump given the dubious nature of the East coast gas market, and what the air quality monitor we had near our kitchen showed every time we fired up the gas cooktop.

• Upped solar from ~7kW to ~17kW
• Replaced Fronius Primo grid tied inverter with Sigenergy hybrid
  (... anyone want an old Fronius Primo? ... it's sitting on floor of my garage)
• Added Sigenergy ~32kWh battery)
• Added Sigenergy whole home gateway
• Replaced central gas heating with additional RCACs (Reverse Cycle Air Conditioners)
• Replaced gas cooktop with Westinghouse induction (20A model, boost on a single zone at a time, needed stonemason with full PPE to work with manufactured stone counter top; already had a separate electric oven)
• Replaced gas instant HWS (Hot Water Service; was a failed gas boosted solar, where solar loop had failed) with Aqua Pro heat pump HWS
• Decommissioned the gas connection to our house (retailer arranged for distributor to come out to house, remove the meter, and disconnect the line at the street) 

Who did it for me? 

I ended up using the company All Electric Homes (AEH) through the Hume Energy Upgrades (HEU) administered by the Yarra Energy Foundation (YAF). AEH is part of the "Wanta" group of companies:

• Want A Sparky
• Want A Heat Pump
• All Electric Homes

They provided a full-service electrification package to me (except for decommissioning the gas connection to my house, which I did through my energy retailer). Initially I was quoted for some lesser featured, entry level units, but I decided to go for a more featured Sigenergy system. All in all, it cost me in the ballpark of mid $40k range... I figured if I did it through a council vetted program, it may not be the cheapest, but the organisation is more likely to be around for the longer term).

I went for the Sigenergy system on the basis that:

• I'd seen positive reviews, particularly from the likes of Artisan Electrics in the UK 
• I'd read up on the issue they had with single phase 240V connections, and the steps they'd taken to both mitigate and then solve the issue (design of single phase connector allowing loose connections redesigned more similarly to 3 phase connector) 
• The feature vs. price of the Sigenergy compared with European manufacturers
• The relative polish of the Sigenergy vs. its Chinese compatriots
• The configuration and telemetry available from the unit
• That it's extendible, receives frequent firmware updates 

There was one problem we had post install of everything, and that was the drain hoses for at least two of the new RCACs came loose, and we had some condensate running down the walls in a couple of rooms. They quickly came out within 2 days of the problem being reported, and refitted the drain connections and secured them. 

In more detail...

The solar and batteries

 

 

The house came with ~7kW of solar (the right hand pink array in the picture), and a Fronius Primo grid tied inverter. When I moved across to additional solar, and a battery, the Fronius Primo was disconnected and the new and existing strings were fed directly into the Sigenergy inverter to reduce DC -> AC -> DC losses for more efficient battery charging.

The RCACs

The house already had two Samsung "The Triangle" "SmartWiFi" RCACs, but this only covered the main open living area, and the master bedroom. Decommissioning the central gas heat, we added two split systems, one with four heads, one with a single head, all Mitsubishi Electric. Happily all of them came standard with a WiFi module.

Now all rooms in the house, except for the entrance way, corridor, bathrooms, laundry, toilets, and garage have RCAC. The rear of house heads all share a compressor. The new one in front room has its own.

The cooktop

We had a "builder's special" four burner gas cooktop that came with the house (nothing against the former owner at all - that's just what gets bundled with new builds). It did the job, but had all the issues that go along with gas. This was replaced with a Westinghouse unit. It's capped at 20A, so not the most intensive induction cooktop, but has done everything we've needed of it. It will only allow one zone to use boost, and if you have more than one zone at a time, it will ensure that the power use is capped to 20A by balancing between the zones.

The hot water system

The old system was a "gas boosted solar" unit from Rheem. Such units were one of the options that were mandatory when the house was built, but they suffered from a problem where, after a time, the circulation pump for the solar component would break down, meaning that they essentially were just a gas instant unit (the "gas boost" was just a gas instant unit on the output of the tank, that would kick in to reach set temp). As the circulation pump had broken down, we had a plumber bypass the tank and pump for a time, and just used gas.

With prices rising on gas, however, I decided to swap it out for an Aqua Plus unit.

Not much trace of the gas into the house

... save the pipe coming out of the house - the pipe from the street has been flush cut with the driveway.

Thoughts about device choice 

Truth be told I'm not entirely convinced by the Aqua Plus HWS - you can't set which time of day it does its weekly heat disinfect, so it will never be when the sun is shining to use excess solar. It's hard coded to Mondays between 1am-7am to crank the set temperature to from normal 55C to 65C to reduce the chance of things like Legionnaires breeding in the tank, but it would be nice to be able to do this during excess-solar events where available. I'm also wondering if it's a large enough capacity and/or insulated well enough.

I also think with the additional electrical load (what was gas load is now electric), perhaps we should have gone for an even bigger battery, particularly during cloudier times of the year where it could be more about grid arbitrage than raw solar input. The battery was sized upon my prior daily electrical usage, but that was with gas appliances. You live and learn :) ... I haven't gone to time of day tariff yet, as I want to get a handle on my newly increased electrical usage first. I'm currently on about ~25c/kWh flat.

It might have been nice to move to a 900mm width cooktop, rather than sticking with 600mm, especially since we had to have the stonemason in anyway, but then we would probably have been looking at needing a cabinet maker as well to adapt things.

Bringing it all together 

The HWS (Tuya control, Tuya Local HACS compatible with some quirks), the Mitsubishi Electric RCACs (ECHONETLite control), and the Sigenergy (Modbus TCP HACS) plant all happily connect into Home Assistant, so I can see my power stats, and how often my heat pump is running etc. through Home Assistant. I haven't done any state based automations... yet...

I also managed to drag my pre-existing Samsung pre-Smartthings "The Triangle" RCACs kicking and screaming into Home Assistant, using an old Android phone to pair (Samsung don't support the app anymore, and it uses older encryption not supported by newer Android anymore), and then the climate_ip HACS plugin for HA integration. I suspect I'll post more about this soon.

Power monitoring 

 

I've added IKEA Grillplats Matter over Thread plugs to several key home devices to monitor their power usage:

• My desk (computers etc.)
• My partner's desk (computers etc.)
• Fridge (Samsung SRF719CDLS)
• Freezer (Haier chest freezer)
• Washer (front loader - Bosch Series 8, pre-WiFi)
• Dryer (heat pump - Bosch Series 8, pre-WiFi)
• Dishwasher (Bosch Series 8, integrated via Home Connect to Home Assistant, but has no power monitoring inbuilt)

I'd like to get a better idea of other circuits in the house, but I suspect this is going to need current clamps fitted to each circuit. I've seen some ideal devices for this, like the Emporia Vue, IoTaWatt (likely best for AU RCM compliance), and Refoss devices. The trick would be fitting such devices within an Australian single DIN Clipsal sub board (they're bloody cramped; of course having any hard wiring done by a licensed electrician to obtain a Certificate of Electrical Safety). I wonder how others have done with such compact boards compared, with say, the North American boards that tend to have a lot more space between the breakers and the case.

Water monitoring

  

I've started a project to look at monitoring my water consumption, and bringing that into Home Assistant also. My water utility uses an Elster V100 water meter at my premises, and I've sought and received permission from them to deploy an Elster/Honeywell MEB7454-T T-Probe (magnetic reed switch) designed for the meter (it just slides into a ready-provided monitoring port, covered by a plastic plug). I'm in the process of looking designing a Zigbee connected pulse counter given lack of availability of things like the Lixee ZiPulses device outside of Europe, that WiFi tends to use more power, that Matter doesn't really have a pulse counter class yet, and that ZWave has all sorts of annoying regional frequency variations.

HVAC: Better zoning, and dealing with stale air 

As part of the electrification of the house, and to qualify for government rebates, the old central gas heater system was decommissioned by the installers. This involved them cutting all the internal wiring, drilling some holes in the combustion chamber, and capping the gas connection to the heater. As my roof is tiled and covered in solar, however, there is no easy way to remove the bulk of the gas heater through the only access to the roofspace.

With RCACs, it allows for heating of specific rooms, but to make them efficient, you don't want them trying to heat/cool more than they have to. As the house was built in the '00s however, there's a lot of "open plan" design, with multiple rooms connected without doors or screens.

With hard surfaces in most of the house, sound also carries quite a great distance. The diagram below shows the layout of the house (with the original two RCACs). You can see the front left room (bottom), entry way, kitchen/living, rear right room, and rear left corridor are open, connected spaces with a total of three RCAC heads across them.

 

Maybe room dividers are required? 

For both HVAC efficiency, and sound control, I'd like to introduce some room dividers such as heavy curtains or other acoustic and temperature appropriate devices, to allow better zoning of the installed HVAC units.

However, closing off areas means that there is a need to consider CO2 and other things contributing to the need to cycle the air out.

Potential retasking of decommissioned gas heater as an air handler? 

I've examined the decommissioned gas heater (Bonaire MB3 25I) and determined that whilst it was appropriately decommissioned as a heater for the purposes of government RCAC rebates (controller removed, gas chamber drilled, gas line disconnected etc.), it could still be retasked as purely an air handler - the 240VAC, 600W circulation fan still being in operational condition. My thoughts are, with some air quality sensors about the house, an appropriate smart switch, and perhaps some electronically controlled baffles, I could leverage the existing ducting to circulate air about the house as required, with the option of potentially drawing in fresh air to the house if required.

If I allowed for the room dividers to let air out, but not in, then positive air pressure within the rooms could make its way to the return, central to the house, and if the return air was detected as having poor quality, to draw in some fresh air as required. I'm interested in what people think about this.