Smart Heating - Measure hot water in the tank and don't turn on if there's Solar wate

Glenagoolie

Hi,

I'm wondering if any of leading Smart heating solutions (Tado, Hive, Netamo, etc) have the ability to measure the amount of hot water in the hot water cylinder?. Then only turn on the gas boiler if needed for more water for showers etc

I've a Solar panel so the boiler isn't the only thing generating hot water and don't want the boiler to fire when it's hot or we didn't use yesterday's water.

I appreciate any advice or pointers

Ron

ted1

Just use a cylinder thermostat

Glenagoolie

ted1 wrote: »

Just use a cylinder thermostat

Thanks Ted, I'm good with technology just a novice with plumbing.
I checked and there a thermostat attached (see pic attached)to the cylinder already, so I just leave it there and let the smart controller turn on the boiler for hot water. The boiler will get turned off by the Thermostat which will say there's already hot water? e.g. during the summer due to Solar

skrtxao

https://www.boards.ie/discussion/comment/106363329#Comment_106363329

Hi, wondering if you ever got a solution to check the temperature of the water in the cylinder and control the water heating based on this? It seems like a very obvious thing to do but really struggling to find information on how this can be done!

emaherx

https://www.boards.ie/discussion/comment/121107030#Comment_121107030

If your cylinder thermostat can call the boiler for heat that is all you really need (depends on how your heating system is wired though).

My own heating system was a complete disaster though with boiler on mechanical timer and thermostats just connected to valves with no control over boiler, these components were spread around the house too. I replaced the boiler timer with a smart switch, and the thermostats with smart thermostats. Now Home Assistant takes care of all the heating programming, if any zone stat calls for heat then the boiler fires, if none do then the boiler will not fire, if the hot water tank is hot from solar then it will not call for heat.

I've gone a step further using Home Assistant and use it to check the forecast at mid night, if the tank is cold and the coming day is forecast to be cloudy then the Immersion will come on using night rate electricity.

skrtxao

https://www.boards.ie/discussion/comment/121108167#Comment_121108167

"If your cylinder thermostat can call the boiler for heat that is all you really need (depends on how your heating system is wired though)."

"if the hot water tank is hot from solar then it will not call for heat."

The two points above you mention are exactly the two things I need to figure out. I have Google Nests in three different zones, so I'm hoping that once I get a way to check the cylinder's temperature in a smart way (i.e. digitalized and network-connected way), I should be able to get the boiler to fire only when needed connecting to the Nest app. to How do you check in your set up if the tank is hot from solar?

Thanks for your answers!

emaherx

1. Your solar panels have a controller and will always heat the water if there is enough solar - Just let it do it's thing no need to interfere with this process it will always have priority to heating the water.
2. Your Hot water thermostat reads the temperature of the hot water cylinder if it's not hot then it calls for heat from boiler. This is the simplest setup doesn't even need to be smart to work. A simple timer or the thermostats scheduler if built in can prevent the boiler heating the water during the day.

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But how does your current system work? What kind of thermostats do you have?

Problem is a lot of houses only have a timer which calls the boiler and thermostats if fitted only control a zone valve. Ideally the thermostats should have their own individual schedules and all be linked back to a single relay to call the boiler if any one of them is calling for heat. This can be achieved without the need for "smart/iot" devices.

It may be worth discussing with @deezell in this thread https://www.boards.ie/discussion/2057758281/home-heating-automation/p143 on the varous options, smart, dumb or otherwise.

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Having said that, this is the Home Automation and IOT forum. My own heating system is controlled completely by Home Assistant.

It wasn't convenient for me to run the cables from zone stats, hot-press and boiler back to a central point, so I went a completely DIY route which consists of:

• Smart switch on boiler.
• Smart Thermostats on main Zone Valves.
• Smart switch on Hot water valve.
• Smart switch with contactor for the Immersion.
• Arduino with 3 temperature probes, monitoring solar hot water tank: top, middle and bottom.
• Some Arduino Room Temperature sensors.
• Smart switches and TRV radiator Actuators in rooms with stoves/fireplaces to shut off the radiators when fire is lit.

A few features:

• Thermostats and hot water tank can call boiler when needed.
• Weather forecast can be used to predict when extra hot water boosting will be needed and take advantage of night rates.
• Full 7 day schedule with multiple configurable time slots for each zone
• In case of Home Assistant failure, heating can still work manually (but stats loose the ability to call for heat) .

Edit: (Because I didn't really answer your question)

 I'm hoping that once I get a way to check the cylinder's temperature in a smart way (i.e. digitalized and network-connected way), I should be able to get the boiler to fire only when needed connecting to the Nest app. to How do you check in your set up if the tank is hot from solar?

My cylinder has 3 temperature sensors connected to an Arduino.

• Top one is the temperature of water leaving the tank.
• Middle one is the boiler/ immersion temperature as they only heat half the tank.
• Bottom one is solar as it is the only source which heats from the bottom.

I monitor the solar but there is no need to do anything with it, I assume it is always heating if available and have no reason to want to stop it, so there is no need to control. Middle one is used to create virtual thermostats to control the smart switches for boiler and /or immersion, if tank is already hot from solar then they just won't call for heat.

xckjoo

https://www.boards.ie/discussion/comment/121130482#Comment_121130482

Sorry to hijack the thread but I'm looking to do something similar and was wondering where/how you attached the temperature sensors to the tank? I'm looking to add sensors to tell how much hot water is in the tank so we can know if there's enough for a things like showers. Right now I'm thinking I'd need a sensor about half way down the tank and one towards the bottom and the two measurements should let me estimate the amount of hot water in the tank, but can't see a way to do it other than cutting off some tank insulation (which I don't want to do unless I have to). Is that what you did or was the another approach I'm not thinking of?

Tree

If your tank doesn't have ports for thermometer probes, you'll need to make holes in the insulation. You should be able to make small holes with a drill bit by hand though, just the same size as the probe you're planning to use.

emaherx

Like @Tree says my tank has ports for the probes, you may have to make the holes in the insulation, but a little hole the width of the probe should not cause an issue.

xckjoo

Thanks guys. Wanted to make sure I wasn't missing anything before I went drilling. I'll have a better look over the holidays and see whats what.

emaherx

Just don't go using an actual drill! 😱