DIY Water-to-Water Heatpump

[Michelle Konzack]

Hi *,

are there DIYer here which have build their own heatpump?

I can get from my distributor a Danfoss BD350GH/Twin compressor for only 480€+VAT.
It run from pure 24V and the power consumption is maximum 660W or 27A.
I think, this is very acceptable.

However I need two heat exchanger matching the BD350GH/Twin for MAXIMUM power output and heating only.

First one will coupled to the two 200m HDPE Pipes 40x2,4mm which are on the top of my EarthBattery, which can have up to 50degC.
But I will bypass the Compressor, as long as the 450m3 EarthBattery is hot enough to provide enough energy for my Underfloor Heating System.
Even if the temperature goes down to +20degC, the Greenhouse will stay above +10degC in the Winter


[B]Now I need help from someone, who can tell me how big the two heat exchanger must be.[/B]

[B]Also, How much heat do I realy get out of the HeatPump if the Inlet Temperature is 20-30degC?[/B]

AFAIK, the fist-formule 1:4 count only for realy high efficient HeatPumps, but they count this at 0degC I think.
Hence my one will be not a High-Efficient one, but one which run with a MUCH higher inlet temperature

From the theorie I should get by 20degC inlet temperature (flowrate up to 20l/min using an adjustable Grundfoss Alpha circulation pump), 660W power consumption at 24V roughly 2,6kW out of it right? (PLEASE correct me positive or negative)

Note:
Heating up the EarthBattery is done from a Fronius Symo 10kW, 18 solarpanels 550W, the Fronius Ohmpilot 9kW and a In-Flow Heater wit 3x3kW. The Symo deliver up to 15.000kWh a year, which is even MUCH more, as the EarthBattery build under my Winter-GreenHouse can take, hence from October when it become colder in Estonia, I can use the Fronius to even heat the House directly with electric.
The EarthBattery should store enough energy to provice me until beginning of January with enough heat.
Since I will have two Symo running, I have enough Energy from mid of January to power the HeatPump.

Any help welcome

Thanks in advance
Michelle

 

[NIFE]

Hi *,

are there DIYer here which have build their own heatpump?

I can get from my distributor a Danfoss BD350GH/Twin compressor for only 480€+VAT.
It run from pure 24V and the power consumption is maximum 660W or 27A.
I think, this is very acceptable.

However I need two heat exchanger matching the BD350GH/Twin for MAXIMUM power output and heating only.

First one will coupled to the two 200m HDPE Pipes 40x2,4mm which are on the top of my EarthBattery, which can have up to 50degC.
But I will bypass the Compressor, as long as the 450m3 EarthBattery is hot enough to provide enough energy for my Underfloor Heating System.
Even if the temperature goes down to +20degC, the Greenhouse will stay above +10degC in the Winter


[B]Now I need help from someone, who can tell me how big the two heat exchanger must be.[/B]

[B]Also, How much heat do I realy get out of the HeatPump if the Inlet Temperature is 20-30degC?[/B]

AFAIK, the fist-formule 1:4 count only for realy high efficient HeatPumps, but they count this at 0degC I think.
Hence my one will be not a High-Efficient one, but one which run with a MUCH higher inlet temperature

From the theorie I should get by 20degC inlet temperature (flowrate up to 20l/min using an adjustable Grundfoss Alpha circulation pump), 660W power consumption at 24V roughly 2,6kW out of it right? (PLEASE correct me positive or negative)

Note:
Heating up the EarthBattery is done from a Fronius Symo 10kW, 18 solarpanels 550W, the Fronius Ohmpilot 9kW and a In-Flow Heater wit 3x3kW. The Symo deliver up to 15.000kWh a year, which is even MUCH more, as the EarthBattery build under my Winter-GreenHouse can take, hence from October when it become colder in Estonia, I can use the Fronius to even heat the House directly with electric.
The EarthBattery should store enough energy to provice me until beginning of January with enough heat.
Since I will have two Symo running, I have enough Energy from mid of January to power the HeatPump.

Any help welcome

Thanks in advance
Michelle

"From the theorie I should get by 20degC inlet temperature (flowrate up to 20l/min using an adjustable Grundfoss Alpha circulation pump), 660W power consumption at 24V roughly 2,6kW out of it right? (PLEASE correct me positive or negative)"

Yes, your 2.6 KW out is roughly correct. 20l/m should be a sufficient flow rate. I am not sure about the 20C inlet temperature. It depends on the rate of heat exchange between the earth and the "200m HDPE Pipes 40x2,4mm" Please clarify the inside diameter of the pipe. Attached is a photo of a heat exchanger. It is a 12000BTU so about twice the size you need. That is ok as you can tune it by varying the water flow rate.
You can also make a straight one by putting a refrigeration tube inside another copper tube with counter- current water flow. I estimate it would need to be 3m long or less.

 

[NIFE]

Photo

 

[Michelle Konzack]

"From the theorie I should get by 20degC inlet temperature (flowrate up to 20l/min using an adjustable Grundfoss Alpha circulation pump), 660W power consumption at 24V roughly 2,6kW out of it right? (PLEASE correct me positive or negative)"

Yes, your 2.6 KW out is roughly correct. 20l/m should be a sufficient flow rate. I am not sure about the 20C inlet temperature. It depends on the rate of heat exchange between the earth and the "200m HDPE Pipes 40x2,4mm" Please clarify the inside diameter of the pipe. Attached is a photo of a heat exchanger. It is a 12000BTU so about twice the size you need. That is ok as you can tune it by varying the water flow rate.
You can also make a straight one by putting a refrigeration tube inside another copper tube with counter- current water flow. I estimate it would need to be 3m long or less.

35,2mm
It is the standard low pressure HDPE piupe used for Earth-Water Heatpumps.

Since with a bigger Heatpump e.G. NIBE (I think, it is Swedish) We getfrom the 2,4kW over 8kW out, but the inlet is only 8-10degC and there is 600m pipe in the ground.

This is why I think, that with 200m pipe, minimal 20degC Ground temperature and a 660W Compressor it should work very well.

Have only to find an Enterprise which sell me the right HeatExchangers (One for the Inlet side and one for the outlet)

Thankyou for your help

 

[NIFE]

35,2mm
It is the standard low pressure HDPE piupe used for Earth-Water Heatpumps.

Since with a bigger Heatpump e.G. NIBE (I think, it is Swedish) We getfrom the 2,4kW over 8kW out, but the inlet is only 8-10degC and there is 600m pipe in the ground.

This is why I think, that with 200m pipe, minimal 20degC Ground temperature and a 660W Compressor it should work very well.

Have only to find an Enterprise which sell me the right HeatExchangers (One for the Inlet side and one for the outlet)

Thankyou for your help

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