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Kensa GSHP finally installed - now to start the optimisation process

 
Grounds Source Heat Pump (GSHPs)
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 Algienon
(@algienon)
Eminent Member Member
Joined: 1 year ago
Posts: 14
Topic starter 23/05/2025 9:25 pm  

Hi all,

After more than two years of false starts and dubious advice, we finally had our heat pump installed. God help the push to decarbonise heat if every household has to go through the pulling of teeth that I had to endure! I'll save that journey for another day 😉 

Although the heat pump is operational, I won't consider the install complete until the company sends me the Handover pack that might answer some of my questions. The plumber gave me a brief handover, and while his work his well done, I'm not convinced he has much experience with GSHPs. I'm left with a raft of questions that the company or heat pump manufacturer (Kensa) might answer in the coming weeks, but I want to check with the collected Brain Trust to see if I'm asking the right questions so that I'm in a better position to understand or challenge what I'm told.

  • How should the GSHP be set up to operate? The plumber said treat it like a normal boiler and use the house thermostat/programmer to set when it comes on and at what target temp. Most people talk about heat pumps being on low and all the time. Is this different for ASHP/GSHP or Fixed/Variable output? The Kensa is fixed.
  • How do I set up weather compensation? The plumber and electrician both said I didn't need it. In fact, I had to be annoyingly persistent to even get the weather sensor that comes with the Kensa HP fitted.
  • Return CH temp has been set at 30 degrees at the moment, so about 35 going out. I'm assuming the weather compensation should be used to change this when the cold days return; rather than me changing the temp manually.
  • Do I need to set the setback temp if the system doesn't even come on overnight? Common sense says no.
  • There is a 3-way valve from the heat pump that feeds the CH and DHW. I'm guessing that although this allows both to be served at once that this is not optimal and I'd be better using the timers to deconflict each demand.
  • There is basic monitoring on the Kensa unit and nothing remote I can view from the comfort of the house. Are there third party system available and how easy are they to install?
  • The new DHW tank is as far as physically possible from the kitchen taps (approx 25 m of pipes). So we have a secondary return (SR) fitted to pre-charge the hot pipes in the house before the morning and evening rush. These are on another timer. How should the DHW and SR timers be set up to avoid unnecessary loss of heat?
  • Should TRVs all be opened to the max or can I use them to drop the temp in the bedrooms?
  • What sort of details should I be looking for in the handover pack?

Lots of questions and I'm sure there will be plenty more as the system starts to earn its keep in the autumn.

Algie

This topic was modified 2 months ago by Mars

   
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 Anonymous 5011
(@Anonymous 5011)
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Joined: 2 years ago
Posts: 563
23/05/2025 9:54 pm  

I would start by downloading the correct Kensa manual it will answer your questions in the most part.

Are you radiators or UFH or a mix?

Buffer or no buffer? If buffer did they follow Kensa plumbing schematic of a two port - so only two port connected one at bottom and one on top?


   
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 Algienon
(@algienon)
Eminent Member Member
Joined: 1 year ago
Posts: 14
Topic starter 23/05/2025 10:01 pm  

@johnmo I have the manuals - installation and user. Not necessarily the most user-friendly or aimed at system optimisation. I'll be calling Kensa once I have the handover pack and know what I want to ask.

All radiators. We had four upgraded.

100 litre buffer - 4 port configuration, which, to be fair, I have seen Kensa articles that recommend both 🙄 


   
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Mars
 Mars
(@editor)
Illustrious Member Admin
Joined: 4 years ago
Posts: 3363
23/05/2025 10:04 pm  

Welcome aboard, and first off, well done for pushing through. Sadly, your experience isn’t unusual, and I completely agree: if every household had to navigate the chaos you’ve just been through, we’re in serious trouble on the road to decarbonising heat.

You’ve raised all the right questions, and yes, a couple of alarm bells are ringing for me, especially around the weather compensation. When both the plumber and electrician say “you don’t need it,” yet it took you being annoyingly persistent just to get the supplied sensor fitted… that’s not a good sign.

Weather comp is essential for efficient heat pump operation… especially with fixed-output GSHPs like the Kensa. These systems benefit massively from gently adjusting the flow temperature in line with outdoor conditions.

As for “treat it like a boiler,” that’s another red flag. If you run it purely on on/off thermostat logic like a gas boiler, it will short cycle itself to death in shoulder seasons. It needs a different mindset: continuous, low-temperature flow that matches the building’s heat loss. You’re absolutely right that the 30C return and 35C flow is just for the mild months, but as outdoor temps drop, the curve should scale that up, automatically, which is exactly what weather comp is for.

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 Anonymous 5011
(@Anonymous 5011)
Noble Member
Joined: 2 years ago
Posts: 563
23/05/2025 10:16 pm  

Just had a quick scan of the manual and should be weather compensation enabled, so this is the correct mode to select.

Posted by: @algienon
↑

How do I set up weather compensation?

It's in the manual. But set min flow temp at 20 degs outside temp, then set your outside design temp at say 45 for a start. Then every 24 hrs tweek design day flow only down or up based on indoor temp.

Posted by: @algienon
↑

There is a 3-way valve from the heat pump that feeds the CH and DHW. I'm guessing that although this allows both to be served at once that this is not optimal and I'd be better using the timers to deconflict each demand.

Your system will run what is priority demand hot water. Hot water will always have priority over heating. The heat pump control will manage flue temp for cylinder heating. Just schedule to heat a couple of time a day at most 

Posted by: @algienon
↑

So we have a secondary return (SR) fitted to pre-charge the hot pipes in the house before the morning and evening rush.

The way you have set sounds about correct. Just make sure the time suit you.

Posted by: @algienon
↑

Should TRVs all be opened to the max or can I use them to drop the temp in the bedrooms?

Yes and yes

 

 

 


   
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