Samsung 12kW Air Source Heat Pump & 170L Cylinder And Nest Thermostats

[erment]

My brother has a three storey house and all storey have one manifold with pump for underfloor heating, and one Nest thermostat 3rd generation in each floor . G-F-Loft 

 Each floor has its own motorised zone valve , 

 

with gas boiler the setup is working perfectly as wiring centre is in place and the classic  switch line from wiring centre is   firing the boiler when is calling for heating . 
 

he wants to switch to 

Samsung 12kW Air Source Heat Pump & 170L Cylinder
 

can he keep same wiring centre and connect the boiler switch line to the Samsung heat pump so he doesn’t interfere much with the current set up . 
 

thank you in advance for your advice . 
erment 

[JohnMo]

A few issues 

 

12kW is huge has he actually done heat loss calcs.

 

Ideally with a heat pump you would have everything on or everything off as a huge heat pump needs huge flows. 12kW will need between 28 and 40L/min.

 

Why only a 170L cylinder as heat pump temps that is small there are two of us and we get though a 210L most days.

 

You ideally would need to control through the heat pump controller. You would also dump S or Y plan and install a 3 port diverter. Call for heat is normally controlled by heat pump.

[IGP]

What @JohnMo says. Just slapping a HP in and guessing at the setup with doing proper heat loss calculations, system design and using on/off controllers is asking for trouble. 

 

What is your brother’s aim with the swap to the heat pump (apart from doing the right thing environmentally)? Is it low running costs, or low installation costs?