Modifying aricond. for heating, cooling and hot water

[kimusabi]

Hello,


I plan to modify 2 Panasonic E15 airconditioners and use them for hot water heating and house heating/cooling.

System would work in two modes:

1. use of original indoor unit (valves A closed, valves B opened)

- in the summer used for cooling the house and transferring this heat into hot water tank. Excess heat would be emitted in the ambient thru outdoor unit heat exchanger (hex).

- in midseason for heating the house and hot water. First hot water is heated. When it could'n absorb heat from refrigerant, heat would be emitter thru indoor unit hex. Heat source is outdoor hex.



2. Use of outdoor units for floor heating (valves A open, B closed)

- use in winter, system takes the heat from outdoor unit hex and delivers to hot water and floor heating hex. Priority is hot water.


Let's leave automatization issues and focus on thermodynamics (not my strong point).

Eno od dveh klim bi predelal tako, da bi dodal izmenjevalec za san. vodo. Moč klime bi reguliral tako, da bi senzor dal na dvižni vod (torej bi reguliral temp. dvižnega voda) na cca 30 stopinj.


At first hot sanitary water takes all the heat and its temp. rises. When it heats up, floor hex takes up the load.

For times, when no demand for heating/cooling, and hot water needs to be heated, there is solenoid, which bypasses indor (or floor heating) hex and aircondition unit takes the heat from outdoor unit to the hot water tank.


Questions, which emerged during this system design:


1. how hot would hot water be assuming there is no water consumption? What would be max pressure in hot water tank hex and how much in floor heating hex?

2. could this system work at all?

3. any suggestions or critics welcome


p.s. for those who are not familiar with this aircondition it is 15.000 btu inverter type.


regards!

location of the drawing (I am not allowed to post links yet):

wwwDOTelektronikDOTsi/phpATM/getimg.php?image=/TC_en.jpg

replace DOT with .

[Brian_UK]

To save the -DOT here is link..

www.elektronik.si/phpATM/getimg.php?image=/TC_en.jpg

The hot water temperature will never get higher than your refrigerant hot gas temperature.

Others can ad their comments too.

[BritCit_Juve]

In these projects the problems are usually how to control the system, how to regulate the head pressure when the heat exchanger can't cope with the heat to be rejected. You would need a variable water flow or have the condenser in series with the hex during coolig.
The hot water would rarely get above 40°C at best.
the system can work and there are several variations out there. The cost usually outweighs the benefits however.
Some use 'economizer' circuits to heat a cylinder of water that is then used to feed the hot water tank. these are usually in series with the condenser.
very few are available that use a heat exchanger sized for the unit total heat rejection.

[nike123]

Questions, which emerged during this system design:


1. how hot would hot water be assuming there is no water consumption?

You cannot allow more than 45°C with this setup because higher than that you will overheat compressor. Also, when water is to cold you will have over-condensing and too low condensing pressure. Your condensation must be within certain limits.

If you, instead, put small plate (or shell and tube) heat exchanger in discharge pipe of about 3000-4000 btu, as desuperheater, then you could heat water till 65-70°C without any concern of compressor overheating.

Maybe you should contact Prof. Dr. Orest Fabris at Fakultet Strojarstva Elektrotehnike i Brodogradnje (FESB) in Split Croatia.
He has developed Klima-Bojler (airconditioner-boiler) device in cooperation with Končar Croartia
http://www.kt.fesb.hr/index.htm
http://www.uredidom.com/PODRU%C4%8CJA/GRIJANJEKLIMAdetalji/tabid/87/ItemID/5/View/Details/Default.aspx
http://www.kt.fesb.hr/Slobodna%20Dalmacija.htm

He could assist you, if he has will to do so.

My advice is to find some air to water heat pump with desuperheater (for sanitary water preparation) and sufficent capacity for your floor heating and leave these air conditioners as they are for cooling purpose.