For home HVAC systems, heat pumps seem to be the way of the future. When compared to electric heating they can be three to four times more efficient, and they don’t directly burn fossil fuels. They also have a leg up over standard air conditioning systems since they can provide both cooling and heating, and they can even be used on water heating systems. Their versatility seems unmatched, but it does come at a slight cost of complexity as [Janne] learned while trying to bring one back to life.
The heat pump here is a Samsung with some physical damage, as well as missing the indoor half of the system. Once the damage to the unit was repaired and refilled with refrigerant, [Janne] used an Optidrive E3 inverter controlled by an Arduino Mega to get the system functional since the original setup wouldn’t run the compressor without the indoor unit attached. The Arduino manages everything else on the system as well including all of the temperature sensors and fan motor control.
With everything up and running [Janne] connected the system to a swimming pool, which was able to heat the pool in about three hours using 60 kWh of energy. The system is surprisingly efficient especially compared to more traditional means of heating water, and repairing an old or damaged unit rather than buying a new one likely saves a significant amount of money as well. Heat pump projects are getting more common around here as well, and if you have one in your home take a look at this project which adds better climate control capabilities. to a wall mount unit.
cool
So hot right now.
” Warming 6.4m3 water 8 degrees requires around 60kWh energy. So, 20kW for 3 hours. Compressor was taking around 1.8kW when running.”
He used 5.4kwh, not 60kwh.
Well, he did do both. 60 kWh to heat the pool and 5.4 kWh to run the compressor.
The difference is that he only paid for the 5.4 kWh in electricity and the rest was free.
Technically correct, which is the best kind of correct.
Technical he used only 5.4 kWh of Energy to move Energy from point A to B which would be 19,44MJ of Energy, which is the unit for the work as well. It would have take him around 216 MJ to do the same work with en electric Element.
I was also like “what what” 60kwh??
!Remindme never to install! :)
For small temperature differences, heat pumps can have a CoP of 10-20.
The temperature difference between the pool and the ambient air was only 8 degrees C, which makes it easily plausible that a 2 kW heat pump would put out 20 kW of heating power (CoP 10), especially when starting when the temperature difference is essentially zero.
https://www.researchgate.net/figure/Plot-of-heat-pump-COP-versus-temperature-lift-assuming-a-typical-Carnot-factor-of-05_fig1_259284556
Note that the “temperature lift” is the difference between the evaporator and the condenser temperatures, which is always going to be greater than the difference between outdoors and indoors air temperature, or in this case the ambient air and the water. This is because the evaporator needs to be colder than the environment to pull heat in, and the condenser has to be warmer than the environment to push heat out.
Some temperature difference must exist in the device even when the intake air and the water in the pool are at the same temperature. Hence why the “infeasible” range above CoP 20, because you can’t have that small a temperature difference in practice. However, the better your heat conductivity in and out of the radiators, the closer you can get.
I didn’t need to save my heat pump, but I did use a Wemos D1 mini and a GitHub project to plug into all four of my wall units and add networked control to Home Assistant. Before they only used IR remotes in each room.
I’d like to hear more about this as there are a few infrared items around the house. Do you use ESPHome and an Infrared LED? Does it ‘learn’ from an existing remote?
The project I used is specifically for Mitsubishi heat pumps. It actually doesn’t use the infrared portion, instead it taps into an internal connector on a board meant to add network control over a proprietary system.
Somebody else must have decoded the signals and programmed them to be sent through the RX/TX pads on an ESP8266 board.
https://chrdavis.github.io/hacking-a-mitsubishi-heat-pump-Part-1/
I want heat pump systems to go further, it’d be really awesome to be able to attach a fridge to a line or other devices that could benefit from direct cooling/heating. Like having your water heater also just plug in to the system.
Fridges would be quieter and wouldn’t need to worry about ventilation, water heaters would be smaller since they wouldn’t need all the extra hardware.
I’d love if they could be plugged into like power outlets so we could even hook up any other random items to the system. (I want direct PC cooling)
I haven’t been keeping up that much, but I think the new Propane (R290) based heat pumps will circulate water rather than refrigerant (to keep the flammable stuff outside). In which case with the addition of some valves and a manifold could very easily be designed to do exactly what you are looking for. In fact you could bring both loops in and have the hot side loop go to the water heater and the cold side loop to the fridge. before they continue to their space heating cooling loops.
Air to water heat pump, more popular overseas but they’re available in the States. I installed in my home for heating, cooling and DHW. It’s monobloc so all I needed to know was plumbing. Not sure the logistics to chill a fridge but feasible if the unit is running the same cycle needed.
I agree with this sentiment, conceptually. Practically speaking, man if you think appliances are expensive now…
Theoretically, a home could be built with a central plant that provides chilled and heated water loops plumbed directly into the relevant appliances. Initially at least, I’d bet that cost to outfit a home with such appliances would be higher than we’re used to. Construction cost of the home would go up for sure.
There would be a ton of knock-on consequences compared to what we’re used to. For one thing, having a single point of failure that could bring down nearly every appliance in the home would be a new kind of stress.
I imagine there would still end up being auxiliary/boost/emergency type of heating and cooling mechanisms in appliances, adding to the cost problem.
The concept is not without precedent in industrial settings (by the zillion). The multi-hundred tons of cooling in a manufacturing facility where I worked is primarily sourced by a central chiller. (We didn’t use much heat, so that was all expelled as waste in that plant.) Despite my overall pessimistic sounding evaluation, I still think it would be an interesting paradigm to explore: think “home of the future” from those old World’s Fair newsreels.
That sounds like a modern town/city home in a district heating/cooling loop. Those already exist – though it’s just for the HVAC system and not for appliances like the fridge. I’m in one right now.
Besides hot and cold water, where the cold water is usually plenty cold from the pipes in the ground already, there aren’t any other appliances than the HVAC system that would benefit from being centralized. My freezer still needs its own compressor to make ice cubes, because the energy losses of pumping -20 C brine into my apartment from miles away would completely negate the point of efficiency. Likewise, I don’t get boiling water straight out of the tap because while the water starts pressurized at 110-120 C from the heating plant, it drops down to 50-60 C by the last building in the loop and below that it’s only useful for space heating and melting pavements in the winter. The regulated temperature at the tap is 55 C, so I can’t exactly brew tea with it – I still need the kettle.
As for the single point of failure: whenever there’s service work to be done, they send an SMS that you’re not getting hot water, or any water sometimes, for the next day or so until they fix the problem. There’s nothing you can do except deal with it. I usually draw two buckets of water in the evening and boil some of it in the kettle in the morning to wash myself. It happens once or twice a year.
I’m in Australia with a reverse cycle (heat pump) ducted aircon, a heat pump water heater for the house, a heat pump dryer and an EV with a heat pump for all heating/cooling. It’s great!
A “networked” system would be cool but would get rather complex running refrigerant pipes all around a house.
Air to water would be the way, just need to know plumbing.
They keep outlawing every refrigerant that works. They now have to resort to flammable refrigerants.
Supermarkets are running as fast as they can away from centralized units because of the large capacity of flammables and the large loss of high dollar traditional refrigerants in the case of a leak. Smaller isolated systems avoid those hazards.
In heat pump world, Mitsubishi is redesigning its city-multi line to be hydronic rather than refrigerant based to avoid flammables in inhabited spaces.
I would love for there to be a generic open source Arduino-based control system for Minisplits that could somehow be connected up to the electromechanical bits. I don’t imagine it would be too complex, Minisplits are all kind of the same under the hood. Then I could do more with my ESP8266 remote controller than just turning it on and off.
That would require industry standards.
You can do this with Mitsubishi units with their CN105 connector. That’s proprietary but reverse engineered.
Connecting directly to the hardware isn’t viable. You’d need protection systems, pump controls, multiple fan controls, fan louvre controls, temperature sensing, pressure sensing, solenoid controls…. all standardised
That’s exactly what I did with my four Mitsubishi units. I already had a bag of Wemos D1s from a previous project, and I flashed code from a GitHub page onto them. I bought some CN105 connectors and soldered them up.
They’re now in my Home Assistant dashboard. An additional benefit to smart control is that they now reveal the rooms’ temperature.
Yeah no. You are talking phase change. It’s a lot better to do a well and have a ground pump exchanging the liquid into the well loop and back through flooring tubes. Refrigeration is all well and good if it’s needed, but it is a huge energy sink and most people would be better served with a simple loop.
What are you talking about? This article is about heating a pool. Above ambient temperature. Above ground water temperature.
Amazing!!! Now heat the pool and cool the house at the same time!
Good point. That sounds very nice
Great project. I see that Janne keeps a nice blog with all kinds of revival projects, great!
I documented my heat pump hacking in a YT video https://youtu.be/sVCiTZo9j8I
Hi guys,
Anyone can explain this part of Arduino code related to EEV valve control?
void valveControl(float diff)
{
float diffDelta = diff-diffprev[0];
float compensation = diff+diffDelta2; //Why compensation is diff+diffDelta2 ?
logdata(“diff: “);
logdata(diff);
logdata(” diffdelta: “);
logdata(diffDelta);
diffprev[0]=diff;
if(compensation-100000) // Why pulseCounter is between values -100000 and 100000 ?
{
closeValve((4-compensation)5); // Why these values: ((4-compensation)5)?
}
}
else if(compensation>6 )
{
if(pulseCounter<100000)
{
openValve((compensation-6)5); // Also these values: ((compensation-6)5)?
}
}
else
{
logdata(" Target ");
}
}
int currentPin = 2;
void closeValve(int rounds)
{
logdata(” Close: “);
logdata(rounds);
for(int i = 0; i < rounds; i++) //10
{
currentPin–;
if(currentPin <2)
{
currentPin = 5;
}
digitalWrite(currentPin, ACTIVE_STATE);
delay(5);
digitalWrite(currentPin, IDLE_STATE);
pulseCounter--;
}
}
void openValve(int rounds)
{
logdata(” Open: “);
logdata(rounds);
for(int i = 0; i < rounds; i++)
{
currentPin++;
if(currentPin > 5)
{
currentPin = 2;
}
digitalWrite(currentPin, ACTIVE_STATE);
delay(5);
digitalWrite(currentPin, IDLE_STATE);
pulseCounter++;
}