TW9

Because renewables result in less carbon dioxide going into the atmosphere and less reliance on fossil fuels from other countries, such as Russia. There's no "one size fits all" when it comes to renewables and it is more difficult than building gas power stations but it has to happen if we're to avoid catastrophic climate change.

I'd also educate your tenants, or prevent them changing the controls. Example, they go away for a long weekend in January and decide to save money by switching the heating off. Over the 3 days the house temperature drops quite low. When they're heading home they use their app to switch the heating back on. Firstly the house won't be warm when they get home because the system can't raise the temperature as quickly as a gas boiler. Secondly, to try to heat the house the heat pump will run at a higher temperature than normal (depending on how the controls are set up) which reduces the efficiency and uses lots of electricity. We did this early on with our heat pump, before we learned how to use it efficiently.

If you want to do it for environmental reasons then I'd read up on the best way to set up and control heat pumps. As you won't be there to play around with the settings you want to get it right first time. There are good arguments for not using an internal thermostat so you want to make an informed decision. You should also find a reliable company to do your system design. It isn't as simple as removing the boiler and putting in a heat pump. The company should do heat loss calculations to work out radiator sizes and heat pump size. They will also tell you if any of your pipework will need changing. As I said, I like our heat pump but it isn't a simple task to replace a gas boiler with one.

I really like our ashp but I wouldn't pick one for your house. The don't provide heat in the same way as a gas boiler so unless your tenants are prepared to learn how to get the best out of it they will be moaning to you about being cold or having large electricity bills.

If you want to minimise the stuff you have inside the house you could choose a monobloc heat pump. This has everything except the control box outside. What bits and pieces you have inside will depend on your system designer. You're going to need pipework, pumps etc but if space is critical you could go for a pre-plumbed cylinder then it's all in the airing cupboard.

What does the warranty say? I think it's on their website.

I've dusted off my Ecodan manuals. Your pic shows Auxiliary settings. If you go up one level you should see Operation Settings. Under this there should be Freeze Stat Function with two options. Flow temp and ambient. My manual doesn't say what each option does.

I'm not an expert, just someone with a heat pump, but I'm happy to give my 2p worth. Creating multiple zones can adversely affect the efficiency of your heat pump. There are some people, such as Heat Geek on YouTube, who can explain better than me but in summary... when you switch off heat in a room, the rooms next to it will start losing heat into that room. That changes the heat loss characteristics of the heated rooms which can result in your heat pump working harder to heat those rooms. That can affect the efficiency of the heat pump so you could end up paying more to heat less of your house. But there are lots of variables and it depends how your system was designed, how it is set up and how it's controlled.

Many people with heat pumps are disappointed because the system has been designed or installed badly. There's no reason you couldn't read up on system design and do a great install yourself as there's lots of information available but it isn't a straight swap from a gas boiler.

Yes, we have one. We actually have four Sunamps. One powered from electricity via a heating element and the others from an ASHP. Two of them feed the heating and two are for hot water.

It's not £600. It's 25,000 kWh of gas (actually more because gas boilers aren't 100% efficient) which is well over £2,000 at current prices.

Or fit a monobloc heat pump. It seems bizarre to fit a split unit in that way, unless there's something about the house that we can't see on the video. Credit to the plumber for insisting on tidy pipework and cabling, even in the loft. It's good to see someone taking pride in doing a job well.

Not insulating a house as well as you can afford to avoid it over heating is simply insane. You're effectively saying I want to waste money every day because I think wood burners look pretty (ignoring the environmental impact of wasting fuel). Hundreds of people are heading into fuel poverty and you're trying to waste fuel ?

You can get fan assisted rads that work with lower temperature water. We have them. They work well but are expensive and having the fan come on in the bedroom in the night, if it gets cold, isn't ideal. I would probably go for big conventional rads.

I think our heat pump is sized about right. It certainly doesn't have much extra capacity when it's very cold. Our house is smaller than yours (about 130sqm).

Heat pumps don't perform at their best when you make them work hard. They like producing a low level of heat for hours. If yours is undersized it will either fail to get the house warm enough on cold days or will get less efficient as you try and get it to produce hotter water. It will end up being disappointing or very expensive (or both). Good system design will avoid most of the things you're worried about (short cycling, modulation etc). As for noise, a 14 kW Ecodan will be a little louder than an 11.2kW one but mainly because they don't make the ultra quiet version in that size. But they aren't very noisy so I wouldn't worry about it. Obviously your house will be insulated differently to ours but for comparison, we have a 1990s 4 bed detached with 12 radiators being fed from an 11.2kW heat pump. The only additional insulation we have, over what was fitted when it was built, is an extra 100mm of lift insulation.

Check the COP on the Hitachi if you're asking it to produce hot water. I think the COP over 4 is only if it's running at 30/35 degrees. When you get to 55 degrees the COP is about 2.1.

They mention time of use tariffs as the key to this working, by charging the battery when electricity is cheap. But the only company who have ever offered one is Octopus and that's currently closed due to instability and rising prices in the electricity market. OVO have a platform called Kaluza that can be used to manage devices like this. It's operational but still being trialled in a domestic environment. I can't see how this company are going to compete with OVO on something this complex.

I didn't pay for mine so I can't tell you if there's a price difference for the lower temperature PCM. I don't think a heat battery is suitable as a replacement for a buffer tank. It's better used as a thermal store. We have a small buffer then the two heat batteries are used as thermal stores. The system pulls heat from them for the central heating and only uses the heat pump when the batteries have been drained. We have separate heat batteries for hot water.

Sunamp now sell heat batteries with PCM that works at different temperatures. One of ours charges at 45 degrees.

I do ✋ I have a meter connected to just the heat pump and a second meter connected to the entire system. Take one from the other and you get the electricity used by the circulation pumps, valves, Sunamp heat batteries and the heater in one of the batteries (effectively an immersion heater). As the pumps etc don't use much electricity it gives a fairly good estimate of how much the heater uses.

They're noisier than a conventional radiator ? Ours have two fans speeds. The fast speed is quite noisy. Not enough to stop you hearing the TV or having a conversation, even a quiet one, but very noticeable in a quiet room. It's been many years since I lived in a house with warm air heating but the noise level is similar to that.

We have Sunamp heat batteries running from a heat pump. They work well and are quite small (small enough to fit in a kitchen cupboard) but, as @SteamyTea said, they're expensive.

They are simply radiators with a fan. Nothing more exciting than that. If you want them to cool you need to run cold water into them (yes, they have a condensate drain but ours aren't connected as we only use them to heat).

I assume they're talking about radiators with fans? If so then yes, we have them. We have Mitsubishi i-Life2 rads which were installed when we had the heat pump. They work, although I don't have anything to compare them with.