12kW eh….. seems large. What did the heat loss calcs show your heating load to be?

Hi. Unfortunately it was an eco4 grant installation so I doubt they even bothered with heat loss calcs. Likely just a guess and slap it in. 🤣

12kw does seem about right when speaking to others and what size they have. 

The house is 164sq/m detached in an exposed spot near the coast in Pembrokeshire. 

Some pictures of the plumbing in/around the area of the UVC if you could sir... We'll see if we can figure out how this is plumbed up and address the short cycling.

@hughf of course. But what is a UVC? 🙈

Might've just worked it out, unvented cylinder?

@craig1980 Yes, UVC is plumber slang for Unvented Cylinder.

OK, so we've got a standard Samsung setup with two external pumps (Why they can't put the pump in the monobloc is beyond me). The pump that is directly below the port marked 'Heat Pump return' - does that have one or two cables connected to it?

@hughf just one cable to each one.

For information this is my flow temps now. It currently runs for around 7-8 mins then off for 3-4 mins. When running it's using 0.8kw. 

It's 10 degrees windy and raining here today.

Posted by: @craig1980

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it was an eco4 grant installation so I doubt they even bothered with heat loss calcs.

Then they've left themselves in a tricky position as regards Part-L Section-7 of the Building Regulations:

and Sections 3 & 4 of the same Part-L

You could contact your Local Planning Authority's Building Control Dept and ask if they have been properly notified about the installation at your site. They have the power of enforcement if the terms of the Building Act have not been complied with.

You should have a schematic of your installation and notes on how to operate/maintain it. It isn't sufficient to give you a pile of manufacturers' manuals for the individual component parts of the system! 🤔 

Within the documentation which you do have, there should also be a response from National Grid Electricity Distribution (formerly Western Power). Your installer will have filed an application under the regulations for Low Carbon Technology (LCT). You would need that response if you ever wanted to sell the property because it's the only evidence you have of compliance.

Posted by: @craig1980

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My question is how can I stop the short cycling and how can I improve efficiency? 

Firstly I'd be pretty pleased to have a COP between 3.4 - 3.7 on a new ASHP installation that's still suffering from cycling 😊 

But there are others here with more knowledge than I about how to attempt a remedy.

Posted by: @craig1980

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The house is 164sq/m detached in an exposed spot near the coast in Pembrokeshire.

That sounds like a great location for a wind-turbine and storage battery to run the ASHP at low cost over winter.

Have your visits to this forum yet enabled you to find the live topic about Wind Turbines and Planning?