Hi all,

I am new to the world of heat pumps, having recently moved into a house that has an ASHP installed, and this forum has been providing me with a wealth of insights as I've been trying to learn more about the system, and diagnose some issues. I'm now at the point where I think I've done all I can on my own, so would love to draw on the expertise here - apologies for the long post! 

We moved in at the end of October - it was initially mild, and then we experienced a cold snap. I decided to book a service in as soon as I could, partly to make sure the system was setup adequately for the winter and also to help answer some questions I had. I decided not to use the company who had installed it (as the previous owners had been doing), and looked for a local firm listed on Grant's website that also had seemingly good reviews. I had the service done on Dec 17th, and unfortunately the person who came was about as useful as a chocolate teapot - he seemed flummoxed by the fact that our system was "different to how we install them", kept contradicting himself, wasn't listening to what I was trying to tell him and was treating me as if I was stupid. So that is what has lead me to trying to get to the bottom of things myself. 

I'll start by outlining our system, and then go through what I think the issues are/what I've discovered so far:

- We have a 4 bedroom house (built in 1996), with a Grant Aerona 3 17kW heat pump installed which replaced a previous oil fired boiler. We have radiators throughout the house, a mixture of K1/K2/K3s. We have a Salus thermostat in our hallway, which has programmable heating and hot water schedules. We've got it set to 18 degrees during the day, and dropping down to 16 at night. The last few days we're lucky if it hits 18 by 2pm. Unfortunately I don't have any info on what calcs were used when the system was spec'd, I just have an uncompleted commissioning document which is not very helpful!

- The first thing I noticed was that not all of the radiators feel as hot to the touch as each other, with the K1s feeling warm across the whole of the front panel and the K3s often not feeling that warm, or only slightly warm at the top or the panel and cold at the bottom (and by cold I mean it feels as if no hot water is reaching it). Not sure if this is normal or not. I also noticed during the cold snap that the radiators didn't seem to feel as warm as they did when it was warmer outside. I mentioned this during the service, and the person who did it reset all of the inlet valves to the same level. I've since tried to open some of the valves a bit more on the colder rads and I don't think it's made a noticeable difference.    

- When we'd been in the house about a week, I noticed that the system was calling for heat, but the heat pump wasn't on. I then went to the controller and saw a red light flashing and an error code (A1) being displayed. I then looked at the instructions that had been left for us by the previous owners, and they had highlighted that they had been told to expect this by the company who installed/serviced it. They had suggested that we press some buttons on the controller to reset the system, which then made it start working again. This happened about once a week for a few weeks, then didn't happen for a couple of weeks, then there was a period of it happening every day for a few days. I explained what had been happening to the person who did the service, and he wasn't really listening, but just suggested it might be due to the filters needing cleaning. Before he left he said he was confident that was what was causing the issue and that it "should be fine now" (I wasn't convinced). After that we saw the error code more than we ever had in the next few days. As I write this, it's settled down a bit, having shown the error code yesterday for the first time in three/four days. 

- Over the last couple of days, I have read the manual for the heat pump, and multiple forum posts/other articles online as I was convinced the system is not performing as it should be, and I wondered if something was off with the WC settings. Here is what the parameters are set to:

• 2100: 1
• 2102: 52
• 2103: 40
• 2104: 5
• 2105: 20

It surprised me to see the middle three values being set to so much higher than the defaults. So I then looked at what the return and flow temperatures were showing as, and I'm getting readings in the region of 30 for return temp and between 30 and 35 for flow temperature. I've checked a few times now in the last 24 hours and haven't seen a flow temp higher than 35. It seems this is where the issue lies? And also suggests that the A1 error code is actually indicating that something is wrong, rather than something to be ignored. 

If you have got this far, thank you for reading. I am a bit stuck as to what to do next, so would love to hear your advice/suggestions. 

Thanks!