CalvinHobbes Posted September 17, 2021 Share Posted September 17, 2021 Hi there, we will need MVHR for our new build but since the house should be at passive house standard concerned about it getting too hot in summer. Seeen people on here saying they had wished they had put in air conditioning pipes during the build. Saw this Nilan Compact P and was told it can lower the temp in sumer by 10 degrees. I mentioned this claim to someone in belfast self build who said that was nonsense. Have any of you experience with Compact P? https://en.nilan.dk/en-gb/frontpage/solutions/domestic-solutions/compact-solutions/compact-p Link to comment Share on other sites More sharing options...
Donegalsd Posted September 17, 2021 Share Posted September 17, 2021 I think it has quite a low cooling capacity. I had looked at it but I had 3kW cooling load and it was too small. It seems pretty good on paper - there's no reason it wouldn't perform OK- so long as you have a low cooling load. It's not Air-conditioning though - I can't see it reducing room temperature by 10°c - more like 2 or 3 °c reduction. 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted September 17, 2021 Share Posted September 17, 2021 (edited) I can't find any CoP/SCoP figures on the technical data. That would worry me. Dropping a temperature by 10°C means very little in itself. You have to know at what temperature it is dropping from, and the volume of air that is cooled (technically the mass flow rate of the air). Edited September 17, 2021 by SteamyTea 1 Link to comment Share on other sites More sharing options...
CalvinHobbes Posted September 17, 2021 Author Share Posted September 17, 2021 Thank you, really appreciate your replies. Link to comment Share on other sites More sharing options...
Bitpipe Posted September 18, 2021 Share Posted September 18, 2021 The challenge with most MVHR systems delivering meaningful heating/cooling is the relatively low airflow. This is ideal for discrete background ventilation but usually not sufficient to quickly cool an overheated house for example. If your house is of passive standard and you minimise overheating due to solar gain and maintain airtightness then MVHR could be enough, however in the real world it probably wont. Link to comment Share on other sites More sharing options...
jack Posted September 18, 2021 Share Posted September 18, 2021 Are you going for an air source heat pump and underfloor heating? Many here have had success with underfloor heating using an air source heat pump in cooling mode? 1 Link to comment Share on other sites More sharing options...
pdf27 Posted September 18, 2021 Share Posted September 18, 2021 11 hours ago, SteamyTea said: I can't find any CoP/SCoP figures on the technical data. That would worry me. Dropping a temperature by 10°C means very little in itself. You have to know at what temperature it is dropping from, and the volume of air that is cooled (technically the mass flow rate of the air). There is normal SCOP data out there for versions of it (AIR and GEO) - the other versions are an exhaust air heat pump only, which is essentially what @Gone West has done as I understand it with a similar system from a different brand. Since they use some of the waste heat for hot water, SCOP will vary depending on how much solar gain you have, etc. so I don't know if they can really calculate it sensibly. They have some under "Technical Data --> Planning Data" which nicely illustrates the problem - you get very high SCOPs because it isn't using the outside air as the only heat source, which is only achievable if you have significant internal gains. The cooling is linked to the MVHR system - as I understand it then it can cool the supply air to 10°C below the temperature of the return air. As it's a reversible system then it'll be broadly similar to the heating graph shown - without very high air change rates you're going to have less than 1kW of cooling. That might work in your situation (our PHPP says 600W of cooling is required for no overheating and never opening a window for ventilation), but will be heavily dependent on house design. Eventually decided against it because the hot water size is quite limiting (180 litres) and the extension tank makes for a very bulky system which doesn't fit well with our house design. Cooling is certainly possible in other ways - lots of people on here have used slab cooling very successfully (running cooled water through the underfloor heating pipes), and it's also possible to put a water-to-air heat exchanger in the MVHR supply duct to provide additional cooling. 1 Link to comment Share on other sites More sharing options...
CalvinHobbes Posted October 21, 2021 Author Share Posted October 21, 2021 On 18/09/2021 at 08:35, jack said: Are you going for an air source heat pump and underfloor heating? Many here have had success with underfloor heating using an air source heat pump in cooling mode? Brilliant. Yes, hope to. Link to comment Share on other sites More sharing options...
Conor Posted October 21, 2021 Share Posted October 21, 2021 The compact P with the ASHP comes in at close to £12k. I dismissed it at the time as thought it too expensive. My chosen install of mvhr and ashp has come in at £11k and a whole load more hassle ?♂️ Link to comment Share on other sites More sharing options...
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