DIY Air-to-Water with old R407C on/off outdoor unit - Page 2

apophis · 07-19-15, 11:13 AM

AC_hacker, thanks for the reply, and welcome to Finland

This summer has been so cold that we are going straight from winter to autumn and next winter. Spring was also missing this year.

Determining the actual COP is a challenge. Nibe tank is a two part 'tank-in-a-tank' where the floor heating water is sepatated from the domestic water.

Domestic water part (upper) is 170 litres and the floor heater part (lower) is 70 litres. Refrigerant loop is at the lower part of the tank. When domestic hot water is consumed it is reflected to the bottom part temparature but the effect is delayed because of the separated parts.

So there is layering of the water in both parts and the upper part is separated from the lower.

I have estimated the COP to be near 3, but determining the exact value is very difficult.

AC_Hacker · 07-19-15, 11:33 AM

Quote:

Originally Posted by apophis

AC_hacker, thanks for the reply, and welcome to Finland

This summer has been so cold that we are going straight from winter to autumn and next winter. Spring was also missing this year.

Determining the actual COP is a challenge. Nibe tank is a two part 'tank-in-a-tank' where the floor heating water is sepatated from the domestic water.

Domestic water part (upper) is 170 litres and the floor heater part (lower) is 70 litres. Refrigerant loop is at the lower part of the tank. When domestic hot water is consumed it is reflected to the bottom part temparature but the effect is delayed because of the separated parts.

So there is layering of the water in both parts and the upper part is separated from the lower.

I have estimated the COP to be near 3, but determining the exact value is very difficult.

Sounds like a wonderful design!

And very complex to try to do a simple model of.

I think that a trial & error approach will be your best bet.

* * *

But your report on the weather sounds serious.

No summer! Well, the only advantage I can think of is that there should be far fewer bugs in the future.

But if this continues, there will be far fewer people...

Is there any speculation as to why this has happened? Is it just a a temporary accident of nature? Could there be a change in the thermohaline circulation cycle? If this second situation is happening, the consequences could be catastrophic.

Sincerely,

-AC

apophis · 07-19-15, 11:55 AM

Weather in Finland is very much affected by the wind direction and placement of the large high and low pressure areas. If wind blows from the arctic then it is cold, if wrom south, then it can be quite warm even in January or February.

Last summer was very warm and there was two longer periods of over 26 deg celcius. This summer at our location there has been no single day over 26 deg celcius official measurement!

Last autumn and winter there was quite big and long lasting eruption of Bardarbunga volcano in Iceland. It released masses of sulphur dioxide to athmosphere and nobody knows if that may have some climatic effect at least locally.

In general there is lot of interest in air-to-water pumps in Finland but we are missing budget pumps form the market. Also there is growing interest in R290 because of very low price and wide availability. Only minus is the flammability, but that risk can be minimized.

Usually DIY folks use plate exchangers in floor heating return line and for example some off the shelf R410A inverter and indoor unit connected as a 'dummy' and its sensors separated.

Domestic water heaters like this project are more rare. Actually I can use this for the floor heating as well, but on the other hand it is not needed until ambient temp drops to near zero.

I have read some good builds from this forum and found lots of good information!

07-19-15, 11:13 AM	#11
apophis Lurking Renovator Join Date: Jul 2015 Location: Finland Posts: 11 Thanks: 0 Thanked 0 Times in 0 Posts	AC_hacker, thanks for the reply, and welcome to Finland This summer has been so cold that we are going straight from winter to autumn and next winter. Spring was also missing this year. Determining the actual COP is a challenge. Nibe tank is a two part 'tank-in-a-tank' where the floor heating water is sepatated from the domestic water. Domestic water part (upper) is 170 litres and the floor heater part (lower) is 70 litres. Refrigerant loop is at the lower part of the tank. When domestic hot water is consumed it is reflected to the bottom part temparature but the effect is delayed because of the separated parts. So there is layering of the water in both parts and the upper part is separated from the lower. I have estimated the COP to be near 3, but determining the exact value is very difficult.

07-19-15, 11:55 AM	#13
apophis Lurking Renovator Join Date: Jul 2015 Location: Finland Posts: 11 Thanks: 0 Thanked 0 Times in 0 Posts	Weather in Finland is very much affected by the wind direction and placement of the large high and low pressure areas. If wind blows from the arctic then it is cold, if wrom south, then it can be quite warm even in January or February. Last summer was very warm and there was two longer periods of over 26 deg celcius. This summer at our location there has been no single day over 26 deg celcius official measurement! Last autumn and winter there was quite big and long lasting eruption of Bardarbunga volcano in Iceland. It released masses of sulphur dioxide to athmosphere and nobody knows if that may have some climatic effect at least locally. In general there is lot of interest in air-to-water pumps in Finland but we are missing budget pumps form the market. Also there is growing interest in R290 because of very low price and wide availability. Only minus is the flammability, but that risk can be minimized. Usually DIY folks use plate exchangers in floor heating return line and for example some off the shelf R410A inverter and indoor unit connected as a 'dummy' and its sensors separated. Domestic water heaters like this project are more rare. Actually I can use this for the floor heating as well, but on the other hand it is not needed until ambient temp drops to near zero. I have read some good builds from this forum and found lots of good information!