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What is Wrong with our Heat Pump Installation?

Air Source Heat Pumps (ASHPs)

Last Post by AllyFish 2 years ago

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Mars

(@editor)

Illustrious Member Admin

Joined: 5 years ago

Posts: 3844

Topic starter 24/04/2024 4:13 pm

Heat pumps are touted as a sustainable solution for home heating, but transitioning from traditional boiler systems can introduce significant challenges. In our case, the switch to a heat pump was far from seamless. Initially thought to be a moderately well-installed system, it turned out our ASHP was only about 60% effective. This discovery unfolded over years of trial and error, coupled with numerous conversation with professionals and with other homeowners on the Renewable Heating Hub Forums, highlighting a significant potential for improvement.

Realising the complexity of the issue, we engaged Ken Bone (@kenbone) from Ultimate Renewables. His thorough inspection revealed that our system was not only inefficient but also costly to operate. This scenario is not uncommon in homes where legacy heating systems may not be fully compatible or optimally configured for new technologies like air source heat pumps.

During a casual chat (see below) Ken discussed the nuances of our existing system's failures. Key issues included undersized piping that couldn’t handle the required output, leading to inefficient heating, especially noticeable at the far end of our house where radiators struggled to reach the desired temperature. Our system’s Coefficient of Performance (COP) was also underwhelming at 2.7.

Ken proposed several adjustments to enhance the system's performance – we'll be scheduling the work in, in due course. These included resizing and reallocating flow to balance the distribution between the underfloor heating and radiators. He also suggested revisiting the system’s buffer tank configuration to reduce heat loss and increase overall efficiency. His goal was to raise our COP from 2.7 to between 3.5 and 4.

The remediation involved not just technical adjustments but also a reevaluation of the control systems governing the heat pump and distribution network. Ken aimed to create a more 'open loop' system to decrease reliance on unnecessary pumps and valves that added complexity and cost. These changes promised not only to improve energy efficiency but also to enhance the comfort levels across different zones of our house.

This experience highlights a broader issue in renewable energy adoption: the necessity of proper design and installation. It underscores the importance of professional expertise, particularly when retrofitting modern systems like ASHPs into existing homes not originally designed for them.

Transitioning to renewable heating systems involves more than just replacing equipment; it requires a deep understanding of both the new technology and the existing home infrastructure. Our story is a poignant reminder of the value of getting the details right the first time around. For homeowners considering similar transitions, thorough professional assessments and interventions can significantly rectify initial inefficiencies, leading to better performance and greater satisfaction.

This topic was modified 2 years ago by Mars

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Graham

(@Graham)

Joined: 2 years ago

Posts: 4

24/04/2024 7:26 pm

I have the same problem,i am happy with heatpump. But the pipes in my house are 8mm upstairs with 10mm downstairs.
The engineer told me the 8mm would have to be changed, but the 10mm was ok.
No one told the installer, until i mentioned it to them.
After the work was completed, in 2 days.
No one came to check their work.
I had the system checked during a yearly service, and the engineer was appalled at the quality of the job.
The header tank which i top up when needed,is supported by a woven strap,screwed onto the joist behind it. If the strap fails my house would be flooded.from the loft down.
But as normal these companies are now gone.
My independent engineer is going to address the problems, with 22mm pipe runs instead of 10mm to get the heated water to rads quicker.
My house is cold because of the lower running temp.
I would have also liked an extra immersion heater that was separated from the heat pump. So i could independently control the hot water. Without running a 10kw heat pump in the summer.

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Toodles

(@toodles)

Illustrious Member Contributor

Joined: 3 years ago

Posts: 2360

25/04/2024 5:56 pm

Having to run the heat pump during the summer for DHW should not be a financial penalty; the heat pump should still have a respectable COP and better than using the grid to feed an immersion heater - unless you intend to use solar PV via a diverter to heat the water, your pump would still be the better plan. Regards, Toodles.

This post was modified 2 years ago by Toodles

Toodles, heats his home with cold draughts and cooks food with magnets.

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AllyFish

(@allyfish)

Noble Member Contributor

Joined: 3 years ago

Posts: 518

01/05/2024 7:59 am

Posted by: @toodles

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unless you intend to use solar PV via a diverter to heat the water, your pump would still be the better plan.

With BESS the ASHP is best. Charge battery for free from solar, then run ASHP in HW mode for an hour = free hot water + COP advantage that direct immersion via solar diverter doesn't give! 😀

This post was modified 2 years ago by Mars

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