ASHP and Wood pelet.

[doug]

Hi Guys.
Ive done a quote for supply and installation of an ashp which i thought was in the bag. However the customer now wants me to link a wood pelet stove into the system.
Im proposing to offer her something along thees lines what do you all think.

14KW ASHP and the wood pellet stove feeding into something like a 300L buffer tank via 2 coils.
The buffer tank, or hot water thermal store, call it what you like, would then be the heat source to feed the central heating and existing hot water cylinder.
Obviously the wood pellet circuit would need open venting.

 

[ecowarm]

You need to size to store to the size of the pellet stove @ 50l per kw output of stove and also make sure the thermal store is designed with the bottom coil to suit an ASHP. The pellet stove i would connect direct (no coil) and have a thermostatic mixer on the return of the stove to maintain the return temp at the required minimum temp to cut out condensation within the stove.

 

[Nostrum]

Why a pellet stove and ASHP is the heat loss greater than 14kw? I'd bin the existing cylinder and take H/W straight off the thermal store via a heat exchanger. As said above direct fed pellet stove and ASHP coil in bottom. No need to worry about pasteurisation cycle then, mains pressure hot water ASHP acts like a pre heat with wood pellet for hot water and back up when ASHP can't cope. In the summer you could use the ASHP on its own for hot water.