pandora-health

I stopped arguing with people, so I started arguing with the whole internet instead :)

I run daily comparisons between a gas boiler and a heat pump in the UK. Given that gas is cheaper than electricity, a well-installed and well-controlled gas boiler can still be cheaper to run. Heat pump running costs can drop drastically when combined with solar and battery storage, but that requires a much greater upfront investment.

https://x.com/AO7186252340513

https://bsky.app/profile/showpiece.bsky.social

Checkout NodoShop, the WiFi board version.

If your boiler supports OpenTherm then get this thermostat controller https://github.com/Alexwijn/SAT

Weather comp + low load comp + PID which means your room temperature works at the precision range supported by your temperature sensor. In my case, within 0.02 Celsius. Saves energy and makes your house more comfortable. Operated via home assistant.

See real time data in Grafana

https://gasboiler.grafana.net/public-dashboards/8d44381aafa9...

Or Emoncms

https://emoncms.org/app/view?name=MyBoilerIdealLogicH24Opent...

Check out SAT Smart Autotune Thermostat https://github.com/Alexwijn/SAT

Its heating curve is corrected by a PID. Room temperature precision is within 0.1 Celsius.

Less gas consumption, lower bills and higher comfort :)

The only open source implementation of OpenTherm (and EMS bus too now) that actually works (unlike commercial thermostats) and provides low load and weather compensation at the same time is:

https://github.com/Alexwijn/SAT

PID is used to smooth out weather compensation errors.

See my grafana for realtime boiler and cost data:

https://gasboiler.grafana.net/public-dashboards/8d44381aafa9...

https://github.com/Alexwijn/SAT for your boiler (and thermostats)

Wait until you discover https://github.com/Alexwijn/SAT your smart autotune thermostat!

If your HVAC supports OpenTherm, check out https://github.com/Alexwijn/SAT

You can have your thermostat in home assistant and make your HVAC run as efficiently as possible at the same time.

See https://news.ycombinator.com/item?id=40052824

Thanks! SAT (Smart Autotune Thermostat) is a free integration you can add to Home Assistant, which can work with your existing thermostat but the intention is that it replaces it altogether (SAT becomes your virtual thermostat). There are many more features but it's best to head to https://github.com/Alexwijn/SAT for details.

OpenTherm is a standard communications protocol which SAT uses, however, you need this hardware:

https://www.nodo-shop.nl/en/featured/211-opentherm-gateway.h... - board

https://www.nodo-shop.nl/en/our-products/213-wemos-d1-mini.h... - WEMOS D1 MINI

https://www.nodo-shop.nl/en/solder-service/202-soldering-ser... - soldering service

It costs €29.50 + €6.25 + €7.50 soldering service + delivery , so that it comes as a ready kit for you.

You also need an indoor temperature sensor. You can get a zigbee device, such as - https://www.zigbee2mqtt.io/devices/WSDCGQ12LM.html

For outdoor temperature, Home Assistant will cover that out of box.

The installation is usually very simple, you connect two cables to the boiler and its OpenTherm module in the boiler and then it uses MQTT to connect to Home Assistant via WiFi. If you are not comfortable touching the boiler, ask your plumber to help you.

By the way, that hardware is much cheaper than Hive which does not support OpenTherm at all. Google Nest does but is so extremely limited, and from my experience, it was cycling too often and did not autotune which is the main reason why you want SAT.

If you check the manufacturer of your boiler and its model, you should be able to find out if your boiler supports OpenTherm.

This is new build~ (2017) and the heat recovery system was installed when it was built but we are not the first owners of the house and personally, I would probably not try to retrofit such system.

Here are two other boilers I found for comparison:

https://emoncms.org/app/view?name=GlowWormBoiler&readkey=88a...

https://emoncms.org/app/view?name=TomsBoiler&readkey=484aa31...

Thanks for your question! It’s definitely been more about passion than payback. The energy savings are there for sure, but for me, the real value has been in the learning and doing as well as the result, house climate control with constant comfort.

I will have to wait for a year to compare the data of total gas cost with the previous year.

If I was renovating and starting from scratch, I would probably invest in a ground source heat pump, which can offer climate control in summer and winter.

To calculate the cost using a UK gas price we would want to have assumed an efficiency in HHV. This is because UK gas prices are given on an HHV basis. Either convention can be used as long as all of our fuel consumptions, efficiencies and energy prices are given on the same basis. Consistency is crucial.

I agree, 25 SSI adjusted and above begins to feel too warm but that's why I set it at slightly cool instead.

Yes, that's what I noticed in the previous house, where the water tank was connected to a solar thermal panel. Solar thermal panel heats the oil inside it and the heat is exchanged between the water tank and the panel during the day when it's sunny. That system was about 60% efficient throughout the year but I did notice that the temperatures would go down really fast and that didn't feel efficient.

Yes, it's between 40-60% on average. Here's a snapshot https://snapshots.raintank.io/dashboard/snapshot/OvZOk9eb6gL...

Yes, there are hybrid heat pumps that can work with gas boilers. Such system can help to reduce gas usage by up to 70%. I am considering it :)

I use something called Summer Simmer Index, which means that my target temperature takes into account indoor humidity. I feed Home Assistant RAW indoor temperature, and SAT (the integration), converts it to SSI.

https://blog.gcwizard.net/manual/en/summer-simmer-index-perc...

21.3 – 25 °C Somewhat cool. Most people feel comfortable. 25 – 28.3 °C Optimal. Almost everyone feels comfortable. 28.3 – 32.8 °C Somewhat hot. Most people feel comfortable.

I see where you coming from and even if the simple calculation is not what it is in real life, it's definitely running more efficiently than it would otherwise. Also, there are other benefits. Mainly, climate control, which means that the room temperature is very precisely at the target level at all times, within 0.3 C degree on average. And when you have constant temperature at all times, it feels very comfortable, and you can't tell whether heating is on or off.

I agree, most boilers, left without proper tuning are running below 90% efficiency, most likely about 80%. A 10% increase at the country level would be significant.

No, I haven't seen that data for my boiler but it would be useful. Even though cycles might be shorter, note that the temperature that the whole system is exposed to is much lower on average. A typical boiler will run at 70 degrees, compared to mine at about 40-45.

There are three showers and two baths in the house. All upstairs, which allows for the pipes to recover some of the heat on the way down. This excludes sinks where you most likely to use cooler, if not cold water. I take the maximum efficiency of heat recovered with a pinch of salt, but the hot water tank seems to last for longer heat-wise, compared to the one I had in the previous house, without such system.

Regarding gas condensing boilers and their efficiency, the notion of them achieving over 100% efficiency, as measured by the Lower Heating Value (LHV) of the fuel, really showcases the value of recapturing latent heat. When we burn natural gas, besides generating heat, water vapor is produced as a byproduct. Traditional boilers expel this vapor and its associated latent heat through the flue, wasting a significant portion of energy. Condensing boilers, however, are designed to cool the exhaust gases to a point where the water vapor condenses back into liquid, reclaiming that latent heat. This process effectively allows the system to extract more heat from the combustion than the calorific value of the gas would suggest possible, if you only consider the LHV, which excludes the heat contained in the steam. Consequently, when this extra captured heat is added to the overall heat output, it can push the efficiency of the boiler beyond 100% using LHV calculations.

I’d like to show you the real-time performance of my gas condensing boiler, arguably the most efficient online boiler in the UK (out of all online boilers :) ).

Enjoy! And ask any questions if you have any. Thanks.