Thermal Pump


Developed by Dipl. Eng. Emil Penchev, BEn


Here, I will describe some of my recent projects.


One of my projects was the designing of a water-heating system for home use by means of a fireplace of small size and low burning material consumption. Over 3 years, I altered it according to the experiment results in order to achieve better efficiency and lower consumption. With that fireplace I used to heat a 100 m2 two-floor house by use of panel radiators, whereby the wood consumption was relatively low. According to my calculations and estimates, if I replace the radiators with modern convectors, I will be able to achieve the effect over a twice as large an area. In that case, I will have to consider and design some automated protection device, because in case of emergency electricity shut-down, the system will still need to cool down.


The second project I have accomplished and that has been in operation for several years now is an Air-Water Thermal Pump. In this way, I obtain ever better efficiency and comfort with very low electricity consumption. In the graphic below you may see the system. I use a copper brazed stainless steel heat exchanger working at 43 bar, to replace the air-conditioner internal module. I have connected the system in such a way that apart from working as an air-water thermal pump, it can be run as an ordinary air-conditioner with its own internal module in air-air mode.




For the purpose of the project I use an ordinary inverter air-conditioner to heat the water system. I have decided in favour of panel radiators due to several factors that are important for our family.

1. Good thermal output at a low temperature of the fluid

2. Lack of air drafts leading to discomfort, allergies, and noise

3. Comparatively low price

In cooling mode, the radiators may not be used, and for that purpose we need convectors. There is a large variety on the market. I am, however, developing a model of my own, which os in compliance with the interior design and can be hidden inside the walls. They are suitable to use for heating, as well, especially if a room needs to be heated up rapidly. After 2 years of experimenting and modifications I have achieved 600-700W consumption to maintain temperature 21ОС in the entire house of 100 m2, simultaneously heating the water needed for the household. For that purpose, I use a two-serpentine boiler and the heating occurs through the serpentine connected to the water circle. The water in the boiler heats up to 42-46 ОС. When the pre-set Т is reached, or the air-conditioner is defrosting, I use Solenoid Valve to switch the boiler off from the consumption circuit, and I control it by means of a microcontroller that I have developed with a software programmer. The system is under continuous improvement.

I am also working on a control panel to manage and control the entire system that could be connected to a computer, by means of a cable or a bluetooth unit, so that the user will be able to watch the temperature and electricity consumption drawings in real time. Moreover, several solar collectors may be connected to the system, so that in sunny days the electricity consumption will be very low and better energy efficiency will be achieved. The value of that system in terms of input materials, labour and heaters excluded, was around 1000 EUR (whereby the price of the air-conditioner is 800 EUR). In the accomplished system I have also connected the fireplace, in case that the outside temperatures drop so low that the air-conditioner cannot switch on, or as an alternative means of heating, in case you would like to enjoy the live fire at home.

In the microcontroller mentioned earlier, I have integrated the water pump control, the turn on/off of the boiler for household needs, the turn on/off of the solar installation, as well as a power consumption meter. I am planning to enhance that microcontroller in the future to add individual temperature settings for up to 8 rooms. That way, the user will be able to control the individual room temperatures and shut the heating off in each room, notwithstanding whether the heating is accomplished by use of a radiator or a convector. Presently, I am trying to input a thermal meter in the basic version, so that we may control the output power following the heat exchanger.  I enclose a drawing of the controller.




I have finished the making of the controller. There are still some software details to accomplish. The microcontroller is able to control temperatures, send the data to a PC via Bluetooth in order to make diagrams, and there is a thermal meter that measures the output power in kWh. The logo on the controller is by my design, and is our company logo.

Here is the ready-made product:



Emil Penchev, B.En.