Search with Wattson

Notifications

Clear all

Joining the Renewable Heating Hub forums is completely free and only takes a minute. By registering you’ll be able to ask questions, join discussions, follow topics you’re interested in, bookmark useful threads and receive notifications when someone replies. Non-registered members also do not have access to our AI features. When choosing your username, please note that it cannot be changed later, so we recommend avoiding brand or product names. Before registering, please take a moment to read the Forum Rules & Terms of Use so we can keep the community helpful, respectful and informative for everyone. Thanks for joining!

How to balance a post buffer tank circulation pump?

Air Source Heat Pumps (ASHPs)

Last Post by Dunlorn 1 year ago

4 Posts

4 Users

1 Reactions

1,084 Views

RSS

Potatoman

(@potatoman)

Trusted Member Member

Joined: 2 years ago

Posts: 57

Topic starter 19/12/2024 10:54 pm [#1959]

Hi, has anybody managed to balance the circulating pump in the ASHP with the post buffer tank circulating pump, and if so how did you manage it. Thanks

Quote

Transparent

(@transparent)

Illustrious Member Moderator

Joined: 4 years ago

Posts: 3223

20/12/2024 1:10 pm

@potatoman - follow what @ashp-bobba is describing to @netdonkey over on this other topic.

He's addressing a very similar issue!

Save energy... recycle electrons!

ReplyQuote

Mars

(@editor)

Illustrious Member Admin

Joined: 5 years ago

Posts: 4678

20/12/2024 4:08 pm

@potatoman, to balance a buffer system effectively, both flow rates and flow temperatures on the primary and secondary sides must align perfectly.

Modern air source heat pumps modulate their flow temperature based on the controller’s set point, and many also adjust flow rates to maintain a specific Delta T (temperature difference) on the primary side of the buffer. However, the secondary side is less straightforward.

The secondary pump may regulate flow using pressure control methods, but it cannot directly maintain Delta T due to factors like zone valves or TRVs adjusting flow dynamically. This means the flow to individual emitters isn’t always consistent, which can affect balancing.

Emitters are sized for specific mean flow and return temperatures, and changes in flow rate can shift the Delta T, altering radiator output. Without precise control or measurement of both flow and temperature on the secondary side, true balancing isn’t achievable.

While buffers aren’t inherently bad, they’re often less effective with modern inverter-driven compressors, which perform best in direct systems. Buffers work better with fixed-compressor units, where control is based on return temperatures rather than flow temperatures.

For your specific question, balancing would require synchronising both pumps through careful calibration and possibly additional controls or sensors on the secondary side. However, this level of precision is rarely implemented in standard installations.

Get a copy of The Ultimate Guide to Heat Pumps

Subscribe and follow our YouTube channel!

ReplyQuote