Daikin Altherma Heat Pump Pilot in West Tisbury


Daikin Altherma Air to Water Heat Pump Pilot Project in West Tisbury:
Ted Bayne and Lea Delacour live on Martha’s Vineyard in a 3,000 square foot home heated by radiant floors and a Viessmann propane boiler. Their goal was threefold – to find a heating source that would make their existing 90% efficient heating system more economical to run, would not involve destroying their extensive gardens with a geothermal installation, and would use electricity to operate – making their home ready for the “all-electric” island that Martha’s Vineyard will become in the near future. Until the arrival of the Daikin Altherma, there was no realistic or cost effective way to meet these goals. The Daikin Altherma provides geothermal levels of efficiency at a much reduced installation cost and can operate all winter long.


They contacted Nelson Mechanical Design (NMD) to design, engineer, and install an innovative heating system that would meet their three goals. NMD recommended the Daikin Altherma as the solution that uses electricity, operates at geothermal efficiency levels of 200 to 400%, has a tiny outside footprint, and heats water for the home’s radiant floors and domestic hot water system.



A Daikin Altherma outside condenser was connected through refrigerant lines to an inside Altherma hydrobox unit (that extracts the heat from the circulating refrigerant for use in the hot water system).



hydroboxAND control


(This is the inside hydrobox next to the integration controls NMD designed and assembled)





A Daikin motorized valve was installed to send hot water either to a Daikin domestic hot water tank or to the radiant heating system.






A control system was installed to integrate the new Daikin Altherma heat pump with the existing Viessmann boiler.




Innovation: Split up Domestic hot water and radiant heating

IMGOct 21 2015 12-17-29

This installation is innovative in several ways. The existing Viessmann boiler had been set up to heat the radiant floors and domestic hot water. NMD determined that the most effective way to use the Altherma to meet these needs was to split the Daikin’s radiant and domestic hot water output.



radiant buffer

Above a selectable outside temperature, the Daikin Altherma will do all of the domestic hot water heating and the Viessmann boiler will be off. Below this temperature, the Viessmann will do all of the domestic hot water heating and the Altherma will be off.




The two hot water tanks are connected together with automatic valves – when the Daikin is making domestic hot water, the Viessmann tank is serving as a pre-heat tank – likewise, when the Viessmann tank is on, the Daikin tank is the pre-heat tank. This means that all energy used to heat domestic hot water is never wasted, there is always plenty of hot water, and most of the time, the domestic hot water is made at heating efficiencies of 200% to 400% with the Altherma.

buffer and Viessman


Similarly, a selectable outside temperature also controls the radiant heating system. Above this temperature, the Daikin Altherma does all of the radiant heating at heating efficiencies of 200 to 400%.



Below this temperature, the Daikin Altherma continues to provide hot water to the radiant floors, but the Viessmann boiler is allowed to add only what additional heat is necessary to maintain inside comfort. This lets the Daikin Altherma work all winter long, providing heat to the radiant system while significantly reducing radiant heating costs.



A new approach to integration of Daikin Altherma with existing heating systems – “heat pump AND boiler”

Daikin currently describes three ways to use the Altherma – heat pump only, heat pump with back-up heater, and heat pump OR boiler. This installation adds a fourth way to the list – it uses the heat pump AND boiler all winter long. This increases the annual operating hours of the Altherma (which increases the annual efficiency of the heating system), increases the value of the Altherma installation (instead of having the heat pump idle during parts of the winter, it now operates continuously), and reduces the homeowner’s exposure to volatile fossil fuel prices (electricity costs change very slowly compared to propane costs over the heating season).

Homeowner Satisfaction:

Ted and Lea have not noticed any change in their winter comfort, but their operating costs have been signicantly reduced.

“When the Viessmann system and radiant heating became popular about 10 years ago, they were perceived to be the ultimate in heating comfort and efficiency. 10 years ago, 90% efficiency looked pretty good. But 90% efficiency is no longer good enough with today’s energy prices – the Daikin Altherma brings the efficiency of this system up towards 400%” – Brian Nelson, NMD

“It took some thought, but we cracked the “Viessmann code” and found a great way for the Altherma to greatly reduce annual operating costs and bring this heating system into the 21st century – quietly, simply, and all winter long.” – Brian Nelson, NMD

“We have designed and installed a lot of geothermal / radiant heating systems and see the Daikin Altherma taking over this market – it is just as efficient, much less expensive, and doesn’t require a geothermal field.” – Brian Nelson, NMD

Blueprint – BPAWUSE11-05R-BAYNE – Daikin AC

Bayne Res Altherma notes for M1 thru M5 031511bkn

Bayne Res M1 pdf preexisting Viessmann and Daikin buffer tank options 031511bkn

Bayne Res M2 pdf Altherma Viessmann retrofit piping 031511bkn

Bayne Res M3 pdf Altherma Viessmann building load heat output and dhw charts 031511bkn

Bayne Res M4 pdf Altherma Viessmann mix temp dhw on demand high temp control system 031511bkn

Bayne Res M5 pdf Altherma Viessmann hi temp mix temp dhw control system 031511bkn

Our goal is to be Martha’s Vineyard’s premier plumbing and HVAC shop – we appreciate the opportunity to show you some of our work.