@chandykris Also, it may be a little too late in the process now but, if they have designed room temperatures that may be some 2 or 3 degrees C higher than you require, it is possible they will be fitting radiators larger than you actually NEED in some rooms - or worse still, designing the system’s operating temperature somewhat higher than needs be and this may be of some import to you! I’ll admit, it is a good idea that someone or some organisation is there to offer helpful advice when a possible user lacks the knowledge to ensure that a heating system they propose to have will be able to maintain the comfort level they require - but when the potential user has engaged with the requirements and has stated their needs, the likes of MCS should respect this too! Regards, Toodles.

@toodles That's a good point. Thankfully, the flow temperature is 46 degrees, and WC will be set. Hopefully won't impede the efficiency.Also, we are reusing some of the slightly larger K11 radiators from downstairs for the bedrooms and not install new big K22s upstairs. So, they are not massively oversized. Glad I asked them to reuse the radiators, albeit for preventing perfectly good items going to landfill.

Another follow-up from me, this time on the Aira app. I have sent my requests, which all pretty much focus on the Insights page. This is in the app where you can see how much energy the Aira system has consumed in kWh over a Day, Week, Month.  My requests are:

@chandykris habitual rooms should be designed for a temperature of 21° and bedrooms 18° You can of course turn your thermostat up or down but once you have your ideal temperature set then don’t be tempted to touch the thermostat again

@bromide I think it is time the term ‘Thermostat’ was consigned to the plumber’s waste pile; modern system ought to be using intelligent controls to maintain desired comfort levels rather than very dumb, brutal on/off switches. These thermostats really don’t do us any service at all with Heat Pumps - they are outdated and should only ever be in circuit as a failsafe limiter should all other means of control fail! Outspokingly yours, Toodles.

@toodles I agree. I’m not against room temperature monitors but we shouldn’t be changing the target temperature. A friend of mine had a heat pump installed and was turning the thermostat up and down just like a gas boiler. Once I explained how HP’s work fortunately he left it alone and now has a constant temperature of 20° (which is their desired temperature)

@bromide Yes, that's the plan. Find the sweet spot and leave it as-is.

Hearing from you all, I wonder whether I could have pushed back on the 21 degrees temperature in the bedrooms. Especially, as heat flows up and currently with the gas boiler, by the time upstairs bedrooms zone turns on, the bedrooms are already at the required 18 degrees. But, with the heat pump there will just be one zone and it will be on always, so need to find the ideal nighttime cool down temperature to suit us. If not for us, at least for our dog. If it's too hot, she won't sleep properly and keep us awake too!

We will hopefully know in a couple of days when the system has been commissioned and is up and running.

The higher design temp in the bedroom isn't necessarily bad eg spare bedroom used as an office or hobby room where maybe 18 would be not as comfortable.

Will you have TRVs on the bedroom rads to use as limiters? My master bedroom has a oversized rad and without either turning down the lock shield valve or using the trv as a limiter I'd overheat. 

@gunboatdiplomat Yes, the lead installer did say that all the rooms would have TRVs. I have already installed two Tado thermostats and five Tado TRVs on.our gas central heating system. I think we will still keep them for monitoring temperatures and humidity, but not use them for zoning or for scheduling.

A question for others who have had Aira installed. How long did it approximately take for your installations?

We are well into day four, and generally only one lead installer is here on site. Electrician turned up for a couple of days. The second plumber hasn't even been here once. Generally, videos of other installations I have seen on YT suggest a small army of installers turn up. In our case, the primary and return pipes aren't even in place. None of the radiators have been changed. Electricity wires aren't connected to the heat pump. The cylinder is just going in today. I wonder whether they would even get it finished and commission it tomorrow. And apparently this is not even a complex installation. No floorboards to lift, straight connection from the heat pump to the hydro box.

Don't get me wrong, the installers who have turned up are really good. But, it doesn't feel like they have put enough resources needed to get it done this week. For the past two nights, it has been very cold, and we have been surviving on the infrared panels I had installed last year in the open plan area, and a couple of oil filled radiators we had already. They didn't even offer any electric heaters temporarily. Thought it was by default offered by other companies such as Octopus. I am having to move a kind of hot oil filled radiator from lounge to the bedroom upstairs towards end of the day. Don't think we can go on like this over the weekend.

As only installer is on site, if they need any material, he has to travel to their preferred supplier forty odd minutes away, to and from. That takes 1/3 of their day. Had they sent additional people on site, things should be far ahead of where we are and can expect this to be done by tomorrow. I wonder whether other customers here have faced similar issues with their Aira installation.

@chandykris I had 2 plumbers full time for 4.5 days. They were both actually lead installers so really knew what they were doing. I had 5 rad changes which took them about half a day. Had electricians sporadically popping in and out but at most had 2 electricians for a day and a half. Didn’t really feel like an army to me but the two plumbers did a bucketload of work so I imagine with only 1 it will go a lot slower. I asked for fan heaters and they provided some but I was also slightly miffed they didn’t just offer them.