Why Your Heat Pump May Not Need a Buffer or Repipe After All

Comments · 212

• HE

  @HeatGeek · 1 year ago (edited) · pinned

  The test rig is still running well as of 31 July, installed early May

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• TW

  @twelvebears1971 · 1 year ago

  I love the fact that Heat Geek and Urban Plumbers are actually building and testing stuff rather than simply automatically accepting existing thinking and practices.

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• US

  @user-fc6bs9oe1i · 1 year ago

  I recently had a Vaillant 7 kW heat pump installed in my bungalow. The heat pump is 20m from the hot water tank. All radiators are on 10mm pipe to the loft where 22m pipe is used. I asked British Gas, EDF and Aria for quotes. All wanted to have a buffer tank and place the heat pump outside a bedroom window to be closer to the water tank. In the end I chose Urban Plumbers who used 28mm pipe for the 20m run from the heat pump to the water tank location. The resulting flow rate was more than sufficient to meet the heat pump requirement. All working fine and I am very pleased with the installation.

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• DA

  @davidstorm4015 · 1 year ago

  Thank god for Heat Geek, we might actually get some sensible changes in the heating industry within the next decade.  So many dinosaurs are still not extinct.

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• LE

  @leaf-ng3jz · 1 year ago

  These guys really know what they are talking about. I had a big issue with a bad  installer and they really helped me and put me in contact with one of their trained and trusted installers who sorted out all of the issues. We did not need a buffer but did need some more efficient radiators. System now works really well and is proving to be cost effective.

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• BA

  @basdoeksen7776 · 1 year ago

  Some real world experience: in my own house I ran a pump in series for two heating seasons when I had a heat pump with a somewhat small capacity circulation pump and high flow requirements (OEG/Aircal 1st gen R32 monoblock). The secundary pump was controlled by the heat pump. No hunting, no noise, no problems.

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• UP

  @UpsideDownFork · 1 year ago

  This is what YouTube was made for! Love experiments like this!

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• TO

  @tonyoosten5860 · 1 year ago

  As a chemical engineer pumps in series is regularly done in process plants where different pressures are needed across manufacturing sites.

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• MR

  @MrKlawUK · 1 year ago

  for UK where we’ve ripped out so many tanks and moved to combi, anything that reduces the complexity and additional space needs is an important improvement.

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• JE

  @JezClimas · 1 year ago

  Yeah, you can put pumps in series without breaking the pumps or having the flow go crazy. It doesn't give you loads and loads of extra flow though. The pumps in series end up with a composite pump curve where the pressure is higher for the same flows. You can add up the head of each pump and each flow to get a new combined pump curve. The pressure loss of the circuit increases with the square of the flow. If you have twice as much head available you'd get 1.4 times the flow. But because the flow does increase the head slightly decreases. When I've worked it through in the past (commercial job, I messed up the pipe sizing) adding a second pump only increased the flow by 35%. So it's not useless to do, but it's not going to make a critical difference that often.

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• YN

  @yngndrw. · 1 year ago (edited)

  This makes a lot of sense, given that they are not positive displacement pumps.<br><br>Your test may well prove that you can use two pumps in series without hunting, but it would be good to also test your theory about where the rule comes from - That it&apos;s no longer an issue due to the use of inverter-driven pumps. I.e. Please also test with older pumps, with the expectation that you should see the hunting issue. (I suspect you still won&apos;t see it)

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• OD

  @odinnln5694 · 10 months ago

  I have had heat pumps in series for years, no hunting. In series add the heads, in parallel increase the flow.

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