Ground sourced heat pump – Experiencing 7 years of operation

In this post I will share most useful experiences related to the 7 years of operation of my ground sourced heat pump. Most wanted facts about heat pump operations:

• Costs: In first years operating costs (heating area 150m2, good insulation, county EU Slovenia) were from 250€ to 350€ for one winter season.
• Operation time: The heat pump was in operation 3,5 hours on average per day.
• Geothermal collector efficiency: At the beginning of the winter season the water from the geothermal collector was about 10,5 degrees Celsius.  At the end of the winter season the water from the geothermal collector was about 7 degrees Celsius.

The pump was running very smoothly without any problems ... until. Two years ago I noticed that my heat pump runs more and more hours per day. At the end it was running almost 5 hours on average. From 3,5 hours to 5 hours  ... what happened?! The winters were comparable in last years, the settings of the heat pump were the same, the geothermal collector was working O.K. So? I called the maintenance team of the producer of the heat pump. They showed up very quickly in few days. We found out an oil stain inside the heat pump below the compresor and we found out that cooling gas level is too low. After checking and screwing some pipes we added the cooling gas to the correct level. We started the machine, made some tests and ... it was running like new and it still do. The cost for the maintenance was 70€ and it was worth paying this money, because the pump will again run more efficient this winter. Having any additional questions ... just post a comment and I will try to answer asap.

Thank you all for sharing useful experiences and issues for geothermal heat pumps

Hi All. I was reading those days your posts and comments on the last post of my blog. I found them very useful. I didn't know that the providers of heating services are so well organized and experienced. I believe the links provided are useful and also some others readers of this blog could benefit. Here I'm listing your links again. Meanwhile I would like to inform you that I'm preparing a new post where I will introduce my already 7 years of experience with operating a ground sourced heat pump.

Links I found them useful:

• http://www.alloysafe.com/
• http://www.allwhvacr.com/
• http://www.polyteck.co.uk/electrician
• http://www.heatpumpreview.net/
• http://www.we-heat.com/
• http://www.pumpsolutions.com.au/
• http://www.acmasters.com/
• http://varme.proffsofferter.se/
• http://www.comacpumpandwell.com/geothermalsystems.html
• http://www.cambridgeheat.com/heat-pumps.php
• http://www.cosmopolitanmechanical.com/
• http://www.bestfurnaces.ca/
• http://www.cambridgeheat.com/furnace.php
• http://www.alliedphs.com/
• http://www.cosmopolitanheating.com/furnaces.html
• http://www.bernardinosairconditioning.com/
• http://www.servicedoctors.net/heating/heat-pump-installation
• http://www.jimdorseyandson.com/about-us/
• http://www.blaircoheating.com/ductless-heat-pumps

Thank you again.

What type of heat pump to choose? – PART 3

After you found out that your building does not have too much specific heat losses and would be suitable for installing heat pump, you must consider what type of heat pump to install and how powerful should it be.

For choosing a type of heat pump you must first decide what will be the source of energy. I would recommend deciding according to the following sequence. If you have a plenty of land space around your house, at least double or triple of house quadrature, I would recommend installing horizontal collector based heat pump. If you have underground water sources I would recommend to install ground water based heat pump – in that case you must drill two wells 20 – 50 meters deep to reach underground water. If you don’t have neither a lot of space around your house, neither underground water, I would recommend installing vertical geo-collector based heat pump as I did. This option is expensive but very reliable; you must drill one or two wells from 60 to 150 meters. In case none of above options suits your situation, then I would recommend installing air sourced heat pump that is using outdoor air as source of energy. This is the cheapest solution, but also less effective in comparison to others. I would not recommend installing outdoor air sourced heat pump if winter temperatures frequently drops under -5 degrees Celsius.

To be on a safe side I would recommend making few calculations before deciding. Find an engineer and decide together. Maybe you would be able to decide what type of heat pump to choose, but you will definitely need help when deciding how powerful the heat pump should be and how much of energy resources it will require – there are a lot of factors to be considered (type of heating, winter temperatures, specific heat loss, peak winter temperatures…).

What type of heat pump to choose? – PART 2

First step is to calculate how much specific heat loss your building has per square meter of usable floors (heat loss in W/m2). If your house has more than 60W/m2 maximum specific heat loss then I would not recommend installing heat pump. You should first think of additional insulation of the house. Typical house where heat pump is much recommended:

• Net floor area = 150m2


• Needed heat per year = 45kWh/m2 per year


• Max Specific Heat loss 35 W/m2

To calculate heat loss you need a bit of engineering and mathematics, but I would recommend finding an engineer who has experience in calculating building heat loss. It also depends in what climate area you are living, what are your additional heat sources during the winter (solar roof, windows to the south…).