Well after assessing my needs I have determined the min/max deltas for the water inside to achieve a 21 - 25C room temp, I figure a 30C delta should be enough. To achieve this with good convection air flow. My water has to be from 50 to 70C. After determining the needed condensing temps, I searched for refrigerants with favourable pressure ranges and this is the list I compiled so far What you guys think?

R134a NBP: -26.1C; Ct:101.1C; Cp:589psi; BTU/Lb:1,806
R152a NBP: -24.0C; Ct:113.3C; Cp:656psi; BTU/Lb:7,481
R401a NBT: -34.4C; Ct:105.3C; Cp:669psi; BTU/Lb:- ---
Least ideal far as Ct and Cp go
R022- NBP: -40.8C; Ct:096.2C; Cp:600psi; BTU/Lb:0,946
R290- NBP: -42.2c; Ct:096.7C; Cp:616psi; BTU/Lb:21,625

Ct = Critical Temperature
Cp = Critical Pressure
NBP = Normal Boiling Point

R-152a so far looks like it will have the lowest head pressures at a condencing temp rang from 50-70C being its Ct is 113.3C and it has good moving capacity per Lb.

Max evap temp will be closely tied to the ambient air temps, the absalute min here in BC will be -10 and rarely at that, average is -05C for midle of winter So again its evap pressur looks to be faverable for the average winter temps. Only concern is I only have access currently to R-12 and R-22 TXVs, I suspect they should work after the necicary super heat corrections are made to the TXV providing they are at all needed!
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Ok got a base line.

Air source evap/Condenser:
7.034Kw/H (2Ton)
Water source Evap/Condenser:
5.28Kw/H (1.5Ton)
Compressor:
4.98Kw/H (1.42Ton)

Target room temp: 25C (77F) max ,((Heating mode))
Target water temp for heating mode 50C (122F) - 60C (140F) realistic?

Temp range on the air source Cond/evap -10C (14F)max to a max of 40C (104F)
I think it best to use some thing to ensure sufficient super heat during heating mode for when the weather gets warmer, to ensure it stays within range for cooling the compressor, like using a PWM that slows the fan as super heat goes up.

Now how do I determin air speed needed for thees values? If you can help point me in the right direction to calculating it out. Thanks.
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So Ok select a TXV with an MOP. Now the water exchanger will be using a head pressur modulated flow control valve, I plan to set it to fix the head the best it can to a stable High side, with this wouldn't the TXV all ready be stable?

As for the fan I was going to use a thermaly controlled PWM unit scaled to the PT chart of the refrigerant I'm planning to use, would this not be good enough?

Part Numbers & Specs
- Coax-2150-S-08-108 Coaxial heat exchanger, 1.5Ton

- V46AC-1C Head pressure modulated, flow control valve (3/4 NPT)

- 2K17C3R126A 17000BTU/H @ 54F evap R-22 rotary

- Temprite 340 series Oil sep 1/4 ODS

Apartment chararistics:
Window surface area total: 285.75 M^2 (937.5 F^2)
Floor Surface area total--: 214.27M^2 (703 F^2)
Air Volume total----------: 1,714.195M^3 (5,624F^3)
Room Width: 5.79M (19')
Room Length: 11.28M (37')
Room Hieght: 2.44M (8')
Room wall thickness .127M (5") R-20

Windows are all single pain with wooden framing and no sealing, Walls have a Delta of 13.4C (56F) between inside & out side. Roof is R-50 about 2 feet thick.

So with that I estimate heat loss for the whole place + 25% to be 1.75Kw/pH (5,958.4 BTU/pH) Using the formula: U * A^2 * Dt(F) = BTU/pH


This is from another thread that I sort of hijacked from US Iceman (Sorry!) So I figured I should move it to its own little thread. Any help or pointers will be greatly apreciated, this is the first such project of this scale other then making chillers!