Anyone have any experience with Daikin equipment, particularly the home units? They're a Japanese company and have been around for years but apparently fairly new to US market. They offer an air to air split system that can support up to 8 indoor units with one outdoor unit, and offer heating COPs around 3 + at temps as cold as 5F. It's a variable refrigerant volume system. Altogether different from the usual. If their performance figures are right, they could be a real challenge to the efficiency and cost of geosource heat pumps.

LINK

I am pretty skeptical. If you buy one, be sure and let us know how well it works.

My flat (Milan, IT) has a Daikin air cooled VRV system with one external unit feeding two internal units as well as a single unit.  While I do not think the COP is that good (my landlord installed it when we moved in two years ago), it is VERY quiet and performs well in both heating and cooling modes.  The controls are very sophisticated.  Central heating in Milan is not turned on (by code) until Oct. 15 and then for a limited number of hours.  Having the ability to supplement heat with the VRV is nice.

In Europe, where heating is done with radiators or radiant and there are no forced air furnaces, split systems are about the only way to add air conditioning.  The internal wall mounted cassettes are not very pleasing to look at, but they work well.  In large rooms with big cassettes, high air velocity can be a problem.

Both Daikin and Mitsubishi also make water cooled VRV systems.  From memory, their COP was better than 4.  The water cooled VRV eliminate the problems and limitations with long runs of refrigerant pipe on large projects.  They are great for renovations.  I believe the smallest unit is about 5T, however, which makes them difficult for small residential units.  We evaluated them for use in our new office and residential projects here but decided to go with conventional (ground)water to water heat pumps.  These are large, central machines that provide heating and chilled water to 4 pipe fan coil systems. 

Milan has a high (and rising) water table and the city encourages the use of groundwater for cooling.  They desire to keep the water level in check to protect subway lines and utilities.  Groundwater is pumped through a heat exchanger for condenser water and then wasted to the sewer.  Yeah, I know......but it is how they want to do things.  We have space provisions for future cooling towers if groundwater becomes unavailable.

In any case, the COP of the latest VRV systems are impressive. They are proven in Europe and the far east, although the water cooled units are relatively new.  It used to be that large central machines were more efficient than small individual units, but today that is not always true.  Maybe the new tecchnology will "filter up" to the large equipment.

Ciao,
Bruce

Thanks for the comments, Bruce. I wish they offered an air to water system. My HVAC man is going to find out more about the Mitsubishi equipment in a few days, so maybe there's an option there.

Why do you say you do not think the COP is that good? According to their performance data it has a COP around 3 at 5F (-15C) and around 3.5 at 39F (4C). The COP does drop as the capacity of the connected units is a lesser percentage of the outdoor unit, down to about 2.5 at 5F for the 36k BtuH unit with 18k of indoor capacity.

The COP of most American heat pumps, Trane, Lennox, etc., drop down to 1 at temps in the mid 20s, below which they quit and you're on full electric resistance heat. One issue with the Daikin systems is electric resistance supplemental heat. Daikin bosses in Japan view electric heat solely as emergency backup which doesn't kick in until the room temp drops below 7F below set point, at which time the heat pump is locked out. The local distributor is trying hard to get them to change that so electric heat can start kicking in as supplemental heat when outdoor temps drop below the 5F point. That's the temp at which the VRV heat pump really starts to lose capability for heating.

I'm impressed with it. I've just spent several hours with the local distributor the last two days learning more about the system. In spite of planning for years to someday use hydronic radiant, I may capitulate to lower costs and go with it.

I will look at the data plate on the unit, but I don't think we have the latest high efficiency version.

Mitsubishi makes some kit called a "Heat Pump Boiler" that does make hot/cold water.  We were looking at their City Multi VRF system using water cooled compressors.

Link

Link

You can find the City Multi VRF under "products".

Ciao,

Bruce