Ground source heat pump – Top 5 mistakes

There are quite many failures or mistake when purchasing or installing ground source heat pumps. Here are top 5 I'm hearing from users:

1. The output power of the heat pump is too high or too low. The problem is that nobody made his homework. Nobody made calculations how much power is needed according to the heat loss of the house. Usually the customer buys too powerful heat pump.
2. The dimension of vertical or horizontal ground sourced collector is too small, too weak. Again nobody made his homework. There is absolute need that one engineer prepares the blueprint and proper energy/heat calculations for the heat pump and for the collector.
3. The low temperature heat pump is attached or installed to existing high temperature heating systems. This is usually a big mistake. In such cases heat pump can be used as secondary heat source for low temperatures, but for very cold days your should use more powerful and high temperature source (e.g. gas or oil).
4. Instead of existing furnace (oil, gas, wood) the heat pump of same power is installed. Usually this will not work. One one hand existing furnace was probably too much powerful and there is no need for the heat pump of the same power. On the other hand heat pump will probably ensure only temperatures up to 50 Celsius which is too low, unless high temperature heat pump is used. 
5. Installations in the ground are not of good quality. Since the investment in ground source collector is pretty high, the installation must be of 100% quality. No errors, damages or leaks are permitted. If there is a problem it is very hard first to find the spot of error and second the repairs are very expensive. The vertical collector must run without problems for 30 years. Request proper warranty.

When installing a heat pump in old house and old heating system, I would definitely propose to first insulate the house and change windows and after that install heat pump system.

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…).

How my Heat Pump was operating in winter 2007/2008

Here I’m describing shortly how my heat pump was operating last winter 2007/2008, what were the temperatures, what were the costs and other parameters.
An average temperature in year 2007 was around 12 degrees Celsius – Slovenia, central location (this temperature is above average for our location). The winter 2007/2008 was not so cold but lower temperatures lasted quite long time. Here is the data what was happening in heating season 2007/2008:

• We switched on heating in September 24th 2007 and was stopped in May 10th 2008. The heating season lasted 229 days.
• Heat pump was operating 680 hours (approximately 3 hours per day on average)
• Total costs of operating for the whole season were 230 EUR (2550 kWh) - 1 Euro per day.
• Minimum outer temperature was -9.9 degrees Celsius. This peak requested heat pump to run 4,5 hours per day.
• Room temperatures were from 20 – 21 degrees Celsius (night temperatures around 19)
• Temperatures of medium from vertical collector to Heat Pump were from 7 (coldest days) to 12 degrees Celsius (at the start and end of season).
• Temperatures of water in floor heating were adjusted from 26 up to 30 degrees Celsius (talking for returning line – water temperature coming from floor heating back to the Heat Pump).
  
  No maintenance was needed, no problems, just paying bills for electricity :-) I just switched on the heat pump in September and switched it off in May. If anybody has similar experience or totally different please add a comment. Thank you for reading and supporting this page.

Installing Heat Pump and Water Heater

My Heat Pump does not have all needed installation integrated (pumps, valves, expansion…) – it is not “Plug’n’Play” like someone from computer science would say. So the next step was preparing installation schema for external installations (pipes, pumps, wires, heat exchanger and water heater). Luckily I have some background on that subject so it was quite easy for me to prepare all schemas. At that time (2005) not many plumbers in our country have knowledge and skills to install heat pump … so learning again J. Nowadays many plumbers have required knowledge and skills. Here is the photo of already installed Heat Pump and Water Heater with all needed parts that enable heating and cooling. If somebody is interested in detailed installation schema please add your comment bellow with your opinion what do you think about this blog and don’t forget to add your e-mail and preferred language of the schema (currently: Slovenian, English). I will send the schema to you.
Coming next: How my heat pump is operating?

Buying a Heat Pump

Outer collector and pipe installations were already finished and it was time to select and buy the heart of the system, so called Heat pump. In Europe we have from 5 to maximum 10 well known and high quality heat pump production companies. I was investigating many of them and after that decided to buy a quality product from my country. When buying a heat pump you should be careful what to buy. You should consider many options:

• Do you plan to use the heat pump only for heating or also for hot water


• Do you plan to use a heat pump also for cooling the house during summer


• Do you prefer active (needs reversible heat pump) or passive cooling (less energy used for cooling)


• Do you prefer a product out of the box (this kind of heat pump already includes automatics, electric connections, pumps, valves, and also boiler) or do you prefer only bare heat pump with basic regulation and security automatics (you will have to install some parts additionally)

And most important: don’t forget to calculate carefully how much power you will need for heating the house. I have bought the heat pump with output power of 14kW, input power 3,1kW. It has a scroll compressor. It also has additional pipe heater of 6 kW for extremely cold winters (I didn’t use it so far). You can see the heat pump on the photo.

Calculation of energy losses and energy needs for the building

Building insulation is the most important factor when calculating energy loses or on the other hand energy needs for heating. Heating system must be aligned according to building energy loses. Here are my final numbers and calculations:

Building parameters:

• Building square meters (room surface): 180 square meters to heat
• Type of heating: ground heating
• Building walls: 30 cm brick and 10 cm isolation (glass wool)
• Building roof: wood structure with, 21 cm of isolation (glass wool), standard knauf
• Building ground floor (to the ground): 5 cm concrete, 8 cm isolation, 5 cm concrete, 40 cm sand layer
• Windows: thermo glass

Coefficients:

• Windows thermal transmittance: U=1,1W/m2K
• Glass wool thermal conductivity: 0,035 W/mK

Final calculation for heat pump system installation. We need:

• Heat pump with output power: 14kW + 6kW Optional Extra Heater for Extreme Low temperatures
• Geothermal vertical collector according to ground structure: 2x100m
• Water Heater: 300 liters

There were also other numbers and quite complicated parameters and calculations. I think shown numbers are enough to get an impression. I will put some calculations in PDF to this blog for download in near future.

Planning the Heat Pump project

After studying the technology of Heat Pumps, existing solutions in the region, local providers and companies, documents and other things related to the project, I have started with detailed planning of the project. I first tried to figure out and list all activities needed for the project, after that I tried to arrange them in to the correct order – what to do first and what to do next. I checked my list with several companies discussing this issue and that is how I supplemented my plan and also verify my project plan. After having all activities in right order I started to plan costs and deadlines of the project. To be as much as possible exact, I have spoken with several providers, drillers, manufactures to discover all costs and realistic deadlines. The result was almost 4 month long project plan. Of course, it is possible to finish after one month, but in that time it was not possible, because you have to wait for the equipment, for the drillers, for calculations… at that time only few installations existed and it was hard to get quality and available company for implementation.So what to do first… the first thing in my plan was activity “Calculation of energy losses and energy needs for the building”

Choosing renewable resource (source)

When deciding which renewable resource to use (air, ground water, water from lake or river, ground source – geothermal - heat of rocks) it is necessary to consider many aspects, the most important are:

• what resources are available in the neighborhood and what are temperatures (e.g. temperature of underground water)
• what resources you are allowed to use according to the local regulation (e.g. in some countries it is prohibited to use underground water in others you should get special permission from the government)
• what is your climate (winter air temperature)
• how much money are you prepared to spend for the project (e.g. air sourced heat pump installation is probably the cheapest, ground sourced heat pump (geothermal) installation with vertical collectors is probably the most expensive)
• are you planning to use your heat pump also for water heater
• are you planning to use your heat pump also for cooling
• how much isolation coat are you planning to put on to your house and what would be the energy loss of your house
• what kind of heating are you planning to implement (low temperature floor heating, high temperature)
• what is or should be coefficient of heat pump performance (I will explain this term latter)

When considering described issues you should definitely involve someone who is familiar or even better professional in those calculations. At the end you should know all calculations, energy loss, primary source temperature, type of heating (e.g. floor heating) and other parameters.
For my project I have engaged one local professional who was very familiar with this numbers and calculations. I have paid to him 100 € and it was worth paying. Finally I have decided to use ground sourced heat pump with vertical underground collectors (geothermal).

What is heat pump – explanation for beginners

You have probably noticed that warm air is rising behind your fridge when operating. Well your fridge is your every day heat pump cooling your food and at the same time heating your kitchen. This is the basic working principle for heat pumps – cooling down one medium (in case of fridge this is the food you have putted in) and at the same time warming up other medium (in case of fridge this is air in your kitchen). Similar to your fridge is also the operating principle of air conditioning device for cooling your home, deep freeze and other devices.
Why so much talking about heat pumps to be on of the cheapest ways to heat you home … it is because of simple calculation: for example you input in your heat pump about 80% of renewable resource, which is for free (e.g. water, air, earth), and 20% of electrical power = and you get 100% of energy for heating your home. That means that you pay only 20% of electricity to get 100% of heating power mostly because of renewable resource (see simple picture in this post). That is something to think about.

Maybe you are thinking now… is it possible to design cheap home made heat pump using old fridge or more of them… well, it is possible, but I will describe this maybe some other time.
Next … Choosing renewable resource for my Heat pump project.

How I started with Heat Pump Project

I was always amused with new technology that could help our earth to be cleaner and that could be used for more environment friendly living… so that is how it started. When internet era came I used my computer to search for solutions and I then I have found the right one at the right moment. I started to build my own house and I needed also heating. At this time (2000 – 2002) in my country (Slovenia) only some pilot projects concerning reusable energy were present and no advanced technology was available. I have searched the web and solutions in northern EU countries and worldwide. Then I found technology for using renewable energy with heat pumps for heating. I started to search the whole web for some solutions, pilot project, documentation, articles and so on. I learned a lot about this technology about renewable resources and that is how my project started.

See my next post: Heat Pump Project planning