Hitachi ASHP - Freezing

nxdmsandkaskdjaqd

Moving to  a new build with a Hitachi ASHP - RAS-3WHVRP1.  Trying to understand the issue of freezing (if there is one).  Can any explain the freezing issue with respect to this heat pump?

MultiFuelBurner

What makes you think this model is susceptible to freezing up?

Netexporter

It is normal to get icing on the heat exchanger, in the UK, because of the relatively high humidity. Heat pumps are designed to go into a defrost cycle when ice build up is detected. Not a lot you can do about it, short of modifying our maritime climate.

Reed_Richards

The defrost cycle typically works by pumping warm water out of your house.  So heat pumps will often be installed with a buffer tank or a volumizer tank to ensure that there is sufficient water available to do this.

nxdmsandkaskdjaqd

Reed_Richards said:

The defrost cycle typically works by pumping warm water out of your house.  So heat pumps will often be installed with a buffer tank or a volumizer tank to ensure that there is sufficient water available to do this.

Would this be the small tank next to the large hot water storage unit?

MultiFuelBurner

Yep that's a buffer tank

https://www.kingspan.com/gb/en/knowledge-articles/do-i-need-buffer-tank/

Reed_Richards

The water from the heat pump should go in and out of the two connections at the top of the tank and the water returning to the heat pump should use the bottom two connections.  Hopefully this allows the water in the buffer tank to remain stratified so any mixing of flow and return water inside the buffer tank is minimised.  

nxdmsandkaskdjaqd

MultiFuelBurner said:

Yep that's a buffer tank

https://www.kingspan.com/gb/en/knowledge-articles/do-i-need-buffer-tank/

That's a good explanation of the purpose of the buffer tank.  Helped in my understanding. 

nxdmsandkaskdjaqd

In my understanding.  Could you tell me what this device is (arrow)?

Reed_Richards

Well a close-up would be helpful.  Is it a pump?

nxdmsandkaskdjaqd

Looks like a pump.