EcoRenovator - View Single Post - Another DIY HP Waterheater (pics and info)

NiHaoMike · 12-30-13, 05:32 PM

Why R134a instead of R290 or R433b/ES22a? What you essentially did was a double "Davuluri Treatment". Your max temp is going to be limited by the discharge temperature limit of the compressor, for which R290 (or R433b, which is mostly R290) would do better than R134a as it doesn't superheat as much on compression. (Counterintuitively, that's actually more of a problem at low ambient temperature since the compression ratio goes up.) The reduced suction pressure avoids compressor overload at high ambient, but just going from R410a to R290 will do it for any reasonable ambient temperature.

You can get a good boost in efficiency by swapping the PSC fan and pump for ECM. As a bonus, a variable speed pump lets you take advantage of stratification by drawing cold water from the bottom and putting in hot water at the top of the tank.

BTW, for best efficiency, operate at 105F or so most of the time and use remote control (with a timer) to boost it up to 140F for washing dishes.

12-30-13, 05:32 PM	#5
NiHaoMike Supreme EcoRenovator Join Date: Oct 2008 Location: Austin, TX Posts: 1,154 Thanks: 14 Thanked 257 Times in 241 Posts	Why R134a instead of R290 or R433b/ES22a? What you essentially did was a double "Davuluri Treatment". Your max temp is going to be limited by the discharge temperature limit of the compressor, for which R290 (or R433b, which is mostly R290) would do better than R134a as it doesn't superheat as much on compression. (Counterintuitively, that's actually more of a problem at low ambient temperature since the compression ratio goes up.) The reduced suction pressure avoids compressor overload at high ambient, but just going from R410a to R290 will do it for any reasonable ambient temperature. You can get a good boost in efficiency by swapping the PSC fan and pump for ECM. As a bonus, a variable speed pump lets you take advantage of stratification by drawing cold water from the bottom and putting in hot water at the top of the tank. BTW, for best efficiency, operate at 105F or so most of the time and use remote control (with a timer) to boost it up to 140F for washing dishes. __________________ To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...