CO2 heat pump

moan 77

anybody know anything about a air to water heat pump made by sanyo that uses C02 and a two stage compressor and will give a water temp of +65c even with an outdoor temp of -15c with a cop of 2.7. Any experience of these would be great or running cost and do they really work, compared to the other air to water heat pumps that use fridge gas.

heinbloed

moan 77 wrote: »

anybody know anything about a air to water heat pump made by sanyo that uses C02 and a two stage compressor and will give a water temp of +65c even with an outdoor temp of -15c with a cop of 2.7. Any experience of these would be great or running cost and do they really work, compared to the other air to water heat pumps that use fridge gas.

Keep in mind that the COP of a HP is not to be mixed up with the energy efficiency of a heating system equipped with such a device.
The energy efficiency of a heating system equipped with a HP is usually much lower than the stated/meassured COP of the HP itself.

Getting a water temperature of 65 degrees Celsius (at what flow rate?) with a domestic air to water heatpump without using extra (electric resistance) heating elements is unheard off - by me.

moan 77

i know as the best i heard to date was +45/+50c, but these use fridge gas as R407c or R410a, but they tell me they can get +65c without electric heaters its all down to the system using C02 as the gas and a two stage compressor, or so i am told. The down side is the drop in the cop

heinbloed

Can these claims be backed up by independant and PUBLISHED reports of certified bodys?
Buchs in Switzerland maybe?
It would be great to have such devices available, the heating market could be revolutionised.

mobsydney

CO2 heat pumps are already widely in use in Japan and Korea, as well as much of northern Europe. 65degC is easily achieved on domestic units, and larger units are quite capable of 85degC and higher. Such temperatures are unimaginable with "normal" fridge gases, but because CO2 operates in the so-called "transcritical" cycle in a heat pump, high temperatures are achieved easily and efficiently.
Expect to see a lot more of these units!!!

al2009

Link: http://uk.sanyo.com/aircon/products/CO2-ECO-Heating-System/Introduction/

we're just starting to see these units impact the irish market, they have an uphill struggle due to a lot misinformation and poor education from previous heat pumps.

Heinblod is correct, COP is a very inaccurate gauge of efficiency, our industry is switching to the SEER, seasonal energy efficiency rating, this takes into account all energy input to a heat pump, I don't know when it will become standard though.

al

heinbloed

A COP of 3.1 when harvesting into an outside temperature of +7 degrees Celsius is pretty trash. Direct electric heating would be more environment friendly and cheaper as well.
Fusing with 10-52 Amp means 3-phase connection and metering, if going for night safer electricity the standing charges are very high.
"Avoiding anual safety checks with a HP " as stated in the S.... homepage is a false promise, compressors should always be inspected for loss of refrigerants, for safety reasons.
Asian HP manufacturers have their own modus operandy when it comes to making money with the ignorant consumers, there are plenty of court reported cases.
One here for example:

http://www.theage.com.au/technology/lg-fridges-lifes-not-so-good-20100317-qcu8.html

moan 77

So what should i do, forget about the Co2 unit and go for system with the normal gas. All the salesmen say there unit is better than the next so does anyone have advise.

heinbloed

@ moan 77:
What ever you decide for: get the maximium anual energy consumption guaranteed in writing. If the seller is not willing to guarantee what he/she says when being alone with the potential buyer forget this seller.
There are EN standards which are known to energy suppliers/heating system installers.
These standards set clearly the conditions on how to calculate home energy demands.

Ask the seller if he/she is not competent enough to do such a calculation and sign for it.
Most HP manufacturers offer this calculation service for their sales staff as part of the business partnership.
You can get precise numbers (EN based calculations) from them. But you have to ask.