# Heat pump water boiler (furnace)



## Boris (Nov 18, 2010)

*There are some very attractive to me statements similar to these:*

"Geothermal heat pumps (sometimes referred to as GeoExchange, earth-coupled, ground-source, or water-source heat pumps) have been in use since the late 1940s. Geothermal heat pumps (GHPs) use the constant temperature of the earth as the exchange medium instead of the outside air temperature. This allows the system to reach fairly *high efficiencies (300%-600%)* on the coldest of winter nights, compared to 175%-250% for air-source heat pumps on cool days.
While many parts of the country experience seasonal temperature extremes - from scorching heat in the summer to sub-zero cold in the winter - a few feet below the earth's surface the ground remains at a relatively constant temperature. Depending on latitude, ground temperatures range from 45Â°F (7Â°C) to 75Â°F (21Â°C). Like a cave, this ground temperature is warmer than the air above it during the winter and cooler than the air in the summer. The GHP takes advantage of this by exchanging heat with the earth through a ground heat exchanger."
http://www.energysavers.gov/your_home/space_heating_cooling/index.cfm/mytopic=12640


&#8220;&#8230;What's so compelling about geothermal technology? Energy efficiency. In a technology defined by numbers, here's a fact that everyone will understand: *With a geothermal system&#8211;they're also called geo-exchange systems&#8211;a reasonably tight 2000-sq.-ft. home can be heated and cooled for about $1 a day*. (Hard to believe???) Commensurate savings are common for larger homes. You'll pay several thousand more up front, but in many cases, the payback can come in as little as two or three years. And once the system is paid off, the annual return on investment can approach 20 percent. Add impressive durability and less-intrusive trenching methods and the scales begin to tip, at least in the new-home market&#8230;
&#8230;two quite different improvements in compressor design, both 25 percent to 30 percent more efficient than previous technologies&#8230;
Most compressor compartments also contain two add-ons&#8211;a resistance-heat grid and a desuperheater. Ground-source pumps in northern climates may need a little help on very cold days, and a small electric-resistance heater does the job. The added operating expense comes to about $30 to $40 a year. Though this may seem a net loss, it's really not. On-board resistance heat allows the pump and piping loop to be downsized slightly, which saves money&#8230;
A desuperheater is an auxiliary heat-recovery system that provides up to 60 percent of a home's domestic hot water.&#8221;
From: http://www.popularmechanics.com/home/improvement/energy-efficient/1274631

Unfortunately, in my climate an efficiency of almost all flat plate solar collectors is close to zero during cloudy or snowy days.
The evacuated tube solar collectors are more efficient here, but they are still too expensive &#8211; I need six of them to heat the whole house in any situation.
And my huge solar tank in the form of an indoor lap pool is not ready.

Nevertheless, during the heating seasons the ground temperature (temperature of the concrete slab in my basement) is VERY STABLE (about 55-60 degrees Fahrenheit).
Therefore my goal is to install my modified heat pump water boiler to the baseboards of one of my heating zones with main purpose to assist in offsetting of heating oil.
Therefore there is a good opportunity to utilize this ENDLESS UNDERGROUND HEAT/ temperature. 
My idea is very close to the classical Closed-Loop/Open-Loop Geothermal Systems, but I will try to utilize underground heat without any loops. In my case there are two sources of heat and two heat exchangers: concrete slab and concrete footing of my basement. 
My basement concrete slab (floor) is about 1,000 sq. feet and concrete footing is 12" X 16" X 130'. 


In this thread I will try to show How to build an inexpensive heat pump water boiler (or furnace) at home.

*The first step.*
In order to test an ability of your slab to transfer heat from the ground you should to perform some tests - see below:

















Frosted Evaporator (when fan turns Off)

Boris Romanov


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## Boris (Nov 18, 2010)

To control your Heat pump water boiler (furnace) you have to connect your thermostat to a Switching relay similar to this:












You can calculate a COP of your heat pump based on these facts: 
- 8.34 BTU's are required to raise 1 gallon of water 1 degree Fahrenheit.
- The Coefficient of Performance - COP - is the ratio of heat output to the amount of energy input of a heat pump.
For example, if your heat pump delivering 15000 Btu/h with a total input of 1 kW,
the COP of your heat pump is 15,000 (Btu/h) / (3,413 X 1 (kW)) = 4.4

I will post more details here: http://www.beebehavior.com/modified_heat_pump.php

Boris Romanov


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