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Stage 1 was to work out how to just set the thing on all the time. That was the easiest. Stage 2 was to work out how to set the timer. Setting the timer is better but more complicated. Edit: Short term, as a trial just turning it on can be tried. Long term you likely want to adjust the timer.

Yes, on is on at a fixed set point. The timer mode allows you to vary the setpoint over time. The next point on my list was to find out how to adjust the timer. Did you do that? If not, then maybe theres a video on youtube on how to do it, or someone here who knows Valliant can help you through it. Did you have a conversation about the thermostat? What was the answer there? It's not something you would want to be fiddling regularly. In the ideal world you would set this up once and then not touch it again. A lot of people will set it up at when things start turning cold and then turn it off when it's warm (but with the right set temperature, even this is not really necessary). This is a common understanding but it's not exactly correct. In houses with thick stone walls like yours to be comfortable you need to warm up the structure. I know this seems wrong to you, all we can ask is for you to give it a try and see if it works. In my case, I was originally only heating the space I was in, I was warmish, but had very cold feet. Then I switched to trying to heat the whole place up in the morning and letting it cool overnight. It would take hours to get up to temperature and then lose all the heat overnight and have to start again in the morning. This was very expensive. Now I have switched to keeping the place at a relatively constant temperature (with a setback) it's much more comfortable and burns less gas than heating from cold every morning.

In a normal house maybe. But not so sure in this particular one, especially during the warm up phase. The 2ft thick walls downstairs will still be emitting coolth, long after the modern upstairs bedroom has warmed up.

@Nickfromwales's suggestion of just wiring in an external wireless one is the easy solution to that. TBH I think that's likely the better option in anycase. But doesn't seem like something that will be ready for Monday.

The important thing is the thermostat is moved into the cold, old, part of the building, not close a raditor or other heat source. It doesn't strictly have to be the coldest room as long as its generally cold in the area. Putting it in the hallway or the bottom of the stairs is common. If you moved it into your warm bedroom/warm workshop that would be bad and might make things worse.

@zoothorn I think I was the one who saw you saying you were still cold and suggested you try again at making changes to things so you could get warm. I know you didn't come back here asking for that, but since you have a new system it does seem worth trying. I agree with @Nickfromwales that this thread could do with a timeout until after the engineer visit. We are all trying to help. I know some of the suggestions seem wrong to you. The go against your experience. All I can say is that people aren't making these things up, they are the result of real-life experience in their own and friends homes. We are passing on what has worked for us and many others. Once the engineer has visited then you have a choice, you can come back here and work with us to try new things (even things that seem wrong to you) to see if it works, or you can not. As a group I think we all think its possible for you to be much more comfortable than you are now (not perfect, but better). To be clear though, it will cost you more in bills. If you can't stand any higher bills (at least double what you pay now) then that puts a blocker on things.

Setback is the minimum temp you want the house to be kept at, ie, overnight if you are running a timer schedule. Rad temperature. 46C is lower than I was guessing based on your description of the rads being hot. Your system should be relatively efficient with rad temp of 46C. So a COP of >4 rather than the 2.5-3 I'd previously guessed. This is good. Though rad temperature and setback temperature are two different things so maybe he was talking about multiple things and the two got jumbled? Different to HW temp. Ideally HW temp should be a bit hotter. 55C maybe 46C is a fine temperature for your situation, I wouldn't worry about changing it but if you want to then ask the engineer on Monday.

The £700 is an approximate maximum amount of energy your heatpump could use in 1 month if running flat out 24x7. It is not what you need to spend to warm your house. That your bills are so low is a sign that your heatpump has been working much below it's maximum capacity and with some changes could provide much more heat. @Big Jimbo's question is a good one. Would appreciate your thoughts on that.

Couple of things to add: 1. The only time a 9kw heatpump would need to work flat out continuously in zoots property is during the few super cold days of the year, if that. The rest of the time it would work a lot less. 2. The electricity bill is averaged over the year, so even if you spend £600 in the worst month, the amount you pay monthly will be a lot less than that. 3. @S2D2's calcs assume a COP of 3. That's the measure of efficiency of the install. A COP of 3 is a good guess for zoot's current setup (maybe less) but with some changes the COP of 4.5 or even higher is possible. If that was done the amount of electricity used to produce the heat goes down a lot. Instead of needing 3kw of electricity it needs 2kw. So £446 running flat out vs £669.

As you said yourself the rads were coming on and off. They weren't on continuously. We have talked about how the thermostat is in the wrong place. The system may have been set to run, but the thermostat was stopping it running most of the time. Your bill would have been very much higher had it been actually producing heat constantly. Both @Dillsue and I have done some rough calcs for your place. The results are that your heatpump is likely not able to maintain 20C internally during the coldest days of the year. No company would want to install something that can't maintain 20C during the coldest days. In fact I suspect that most companies would want to make sure the heatpump could maintain 23C. That doesn't mean that the heatpump flat out wont work. Just that for 2-3weeks a year it will be colder than 20C inside. Given right now you are much colder than that I'm suggesting changes that could allow you to be warmer than you are now. @Big Jimbo is right though, if you want to be warm in your house you will have to be able to afford bigger bills. How much bigger is unclear, but his estimate of £250 is a good starting point. Some things are not as obvious as they seem. Because the old rooms have very thick walls, once they are cold they are difficult to warm up. So if you really want to prove your theory you need to run the house for at least a week, probably more with the heating on and rads warm continuously. If after 2 weeks of doing that, it's still cold then you will have proved your point (at as the house is now). If it's warmer but not toasty then we can have a conversation about making it better. Edit to add: if after two weeks of constant heating it's still deathly cold then its still not game over, just that improvements need to be made to the place and I'm not talking insulation. It's more likely plasterboard tent type issues or drafts (despite your best efforts).

The physics is the same, to get a comfortable house you will undoubtably have to spend more on bills than I do but the same principles apply. My mums house does not and she is able to heat that perfectly fine. Yes it costs her approx £2000 a year but its not cold (so long as the heating is on) Medium warm rads on 24x7 will output much more heat than hot rads on for short periods of time. 12 rads designed for heatpump temps should be able to output the full capacity of your heatpump without issue. The fact your energy bill is only £70 shows that this hasn't been tried yet. For you to get a warm house it will cost substantially more than £70 per month. If my mums leaky, mostly uninsulated house can be kept warm then so can yours. Take @Nickfromwales up on his offer. TRY to run your house in a different way. Physics and experience from people on this forum says it's possible. Unfortunately you've had a bad experience with previous installers putting a system in that wasn't set up right and gave the impression that your house is unfixable. Try to set that experience aside and start with a blank sheet of paper.

I'm saying the rads should be hot whenever the room is colder than your set temperature, including overnight. This is how I run my system, how @Nickfromwales runs his, ditto @JohnMo@marshian and many many more. With a TRV you can set the temperature in your bedroom lower, but the heat is required in the rest of the house to prevent the stone walls getting cold. Once they are cold then warming them up again is super difficult. Once your house is warm, the radiators will only be on as needed to maintain the warmth, but to get the house warm they need to be on continously, likely for many many days because your house is so cold right now. As I said many posts ago, I've found running my system 24x7 seems to be using less energy than running my system on a timer. The reason is that it takes a lot more energy to heat a cold space up than it does to maintain a constant temperature.

Maybe this helps: The Thermostat/controller is there to put heat into the system whenever the coldest room needs heat (to do this it needs to be located in the coldest room) The TRVs are there to set the hottest temperature you want the individual rooms to reach. There are ways to make systems work without TRVs but your house is a long way away from that. So you need TRVs in rooms that would otherwise get too hot as the system is heating up the cold rooms. You don't really need TRVs in the cold rooms. In my flat I have removed the TRVs from everywhere but the bedrooms and it works fine, but if I remove the TRVs from the bedrooms then the bedrooms overheat as the system is trying to warm up the cold other rooms. (My bedrooms have much better thermal properties - like your new bedroom in the old house)

Yes always on, the radiators should be hot/warm until the house is warm. Once the house is warm then you would expect the system to automatically turn on and off to maintain that temperature. You need to keep the system on to maintain a relatively steady temperature in your house. With thick walls like you have, once the heat is lost it takes an enormous amount of time and energy to heat up again so the key is to stop them getting cold in the first place. I've suggested you get a TRV fitted to your bedroom radiator. This way you can set your bedroom temperature independently from the rest of the house and set it a couple of degrees lower. But the system will still be on, pushing heat into the rest of the property.

I can't explain past decisions. What's important is to solve the problems now. Not at all. Traditional Gas systems usually have a controller (that might be near the cylinder) but a seperate thermostat somewhere central in the house. Heat pumps often by default have the thermostat inside the control screen. This should be installed in a place that is exposed to the coldest indoor temperatures (so it doesn't switch the heating off until the coldest place is warm). From what you've said your thermostat is near your cylinder, which explains your problem. The cylinder is mostly likely the hottest part of the house, so the thermostat is sitting there thinking it's 18C when you are sitting in the sitting room freezing. So either you need an engineer to attach a remote thermostat to your existing system or to move the existing thermostat.

That's pretty much what I came to as well. Glad to see it verified.

Just echoing the others £70 is way too low to cover the cost of energy to heat the house. That's just proof your old system wasn't set up right and wasn't outputting much heat. My bills in a large 2 bed modern flat are higher. My mums bills in a 1940s 3 bed semi, uninsulated solid walls, no floor insulation, 250mm in the loft are about £2000 a year. In winter she spends £10 a day heating the place (bills average it over the year). I said earlier that I didn't think your new system on for four hours a day would cost more than the old one on 24/7, now I'm not so sure, I don't think the old one was doing much at all. @zoothorn you mentioned your regret for persuading your parents to upgrade their storage heaters as it didn't make any difference. I'm afraid you will feel the same regret if you proceed with your concrete floor. It's the wrong place to spend money. Spend your money moving the thermostat (if needed), installing TRVs in the warm rooms and running the heating 24/7. Once the house is warm there are things that can be done to lower bills but first step is getting the house warm.

Firstly, not blaming you at all. You've relied on others to set them up (both times) and I'm not convinced either was done in a way that will fully work for you. There is plenty of evidence from other people with similar houses that these houses can be heated, physics says they can be heated. The only question is whether it's economical, which is why I'm trying to help you have another run at addressing this long standing issue. I know you've been around and around this issue and I know you are getting frustrated but the goal of being warm is worth some persistence. From what you've said it wasn't running as I propose at all. If the room is below the desired temperature then the rads should be on pretty much continuously (except when the hot water is being heated). The fact you noticed them regularly going on and off suggests things weren't working correctly. I've asked a couple of times where the thermostat is. I suspect the most likely reason for them going on / off is that the thermostat is located in the warmest part of the house so the system is stopping because it thinks things are warm enough. If not that, then there are other possibiilties. I doubt as it's currently set up (4 hours a day) it will be costing you more than the other system on 24 hours a day. If you set the current system to run 24 hours a day then it will likely cost more than the previous system because the water temperature is set higher but this is all adjustable and can be looked at so no need to panic. I do think you are not getting value for money out of the system as you are still cold and do think it's possible to do better. Earlier, I did a quick calc based on some Scottish government research for buildings with thick solid walls like yours. That calc suggests your heatpump is likely just enough to keep things warm in your place except during the coldest few days of the year. It was only very approximate because I don't know that much about your place, but the house is not huge and has a modern extension which helps limit energy needs. I don't share your confidence in this, there is some evidence supporting your view but it's not conclusive. There is also evidence that maybe you've never had a system that was set up to maximise the chances of success and there is also evidence that there are some relatively easy to fix issues that could be limiting things (walls upstairs causing the loft insulation to be bypassed). One of the big issues in your house is that the really thick walls means that once it is cold (and damp) it's really really difficult to then warm things back up again. As in it might take many days (even weeks) of continously hot radiators. The heatpump really isn't big enough to do that, but it is likely big enough to stop things getting cold in the first place, so long as it's given a fighting chance to do so. This is why I've been pushing for you to be ready for end of summer. How to be ready: 1. Get the engineer on Monday to show you how to: a. turn heating to - "always on" - "always off" - "timer" b. adjust the set temperature c. adjust the timer 2. Deal with the bedroom external walls as discussed. 3. If needed, arrange for the thermostat/heatpump controller to be moved to a cold part of the house 4. Possibly, get TRVs installed on the radiators in the warm part of the house (this is something that could be done if needed at a later date).

It has other uses than just insulation. Modellers might well want small quantities.

I was thinking CoP 2/2.5 rather than 1 but no doubt the system is not being used optimally and will cost a lot for very little when with a relatively small amount of effort it could likely work quite well. However, zoot is currently living in conditions that would displease a Victorian and it's a major physical and mental health hazard so in my book it's worth trying to make progress.

Think about going back to the AT and paying for construction drawings. You are only at the very start and have hit multiple roadblocks/issues with drawings already. You'll probably save any upfront cost with less delays/mistakes later if you have proper drawings to go off.

Ok thats great to hear (not sure you said that before) and thanks for highlighting this. It's revealed to me my sloppy language, I'm sorry for that. When I said 'it's wrong' I was mainly referring to the system only being on 4 hours a day. I think it needs to be on longer so you have more warmth. I'm not proposing lowering the radiator temp in the short term. In the long term (after you've made some more improvements to your property and you've been able to maintain a better temperature) it would be good to look again at the temperature of the radiators. Once the room is warm, you won't need to feel the heat from the radiators any more to feel comfortable and then you can start tuning for efficiency. Modern heatpumps can support a property like yours. It's a myth they can't. It's possible the one you have is a bit too small and it seems likely that you need to make a few more improvements to get it working in your situation but it's very much doable with a little thought and care. @Dillsue has highlighted similar examples. If it's colder inside than it is outside, are you opening the windows to try and get some warmer air from the outside? (not during your bath but before and definitely after to clear the moisture) The problem you have is that your building has a lot of heavy solid materials in the structure. These take a long time to heat up and cool down. The key to living comfortably with them is to stop them cooling down in the first place as trying to warm them up quickly will lead nowhere. Clearly your bathroom has got cold and once cold a towel rail isn't going to be able to compete with the raditors emitting cold that are the walls. As a temporary measure while you explore the improvements already discussed, it might be worth considering abandoning trying to heat the space and focus on just heating you. A good way to do this is radiative (infrared) heating panels. One of those pointed directly at you while sitting in the sitting room will likely make you feel a lot warmer and use less energy than running the heatpump. Not so good for making you feel a bit warm when you get up in the morning, but maybe an idea for evenings. https://www.toolstation.com/tristar-smart-infrared-panel-heater/p78401 (not a recommendation just an example) Still, I think you can do better than just heating yourself if you can prepare well this summer.

Seconded

Houses that can't be heated exist but the reason they are like that is that they have problems and these problems can be fixed. As we've discussed already, houses that are relatively well sealed from outside air blowing the heat away can be heated. The only question is whether the cost of heating them is economical. So far you haven't got to the point where you can make that decision and I think you need to get to that point before giving up. I doubt that's a good description. The hotter the heatpump runs the radiators the less efficient it will be. I'm sure he set the temperature high because your house seemed cold and he thought it was what was required. It certainly would be required if only running the heating for a few hours a day but running the heatpump for longer at a lower temperature can be less costly than running one at high temperatures for shorter. No thats wrong. You need to get that changed, you can change those setting to run the heatpump as much as your want and I very much doubt that running it as above will result in anything other than wasting money and no real feeling of warmth. In a house like yours, it's likely you need to keep the internal temperature of the building fairly stable because of the amount of energy it takes to change the temperature is immense. It's why I suggested being ready at the end of summer with the heating set to never let the internal temperature drop below a certain point. At least for a while so you can work out how much it costs to do so.* The exact opposite in many ways. You are asking the HP to work at maximum output for those 2 hours then turn off. Heatpumps ideally like to run continuously and a relatively low output. Basically you are asking a marathon runner to compete in 100m sprints. Do you have a copy of those calculations? Would be good to see them. I tend to agree that it's a big ask for a 9kw heatpump in your space especially if you want warm (>20C) rooms. However, given the work you've already done plus a bit more this summer I do think the heatpump should be able to keep your space warmer than it has been. Maybe it's only capable of maintaining 17C or even 16C when it's really cold outside but thats still much better than what you have now if you can see your breath inside. But the key to making this happen is to make the heatpumps job as easy as possible and that means not letting the building go cold in the first place. This is something you really need to confront not run away from. At minimum you need to know how to turn the heating on / off manually and adjust the temperature. I had a quick look and it's only a few button presses. Ideally you'd also know how to adjust the timer. Best advice for how to get this from the engineer is to say something along the lines of 'I really struggle with technical stuff like this can you show me how to turn the heating on and off', then when they try and press the buttons say 'no, can you let me drive, just tell me what to press'. Then you build up the muscle memory and can go at your speed rather than let them do that. If dealing with the timer is too difficult I would at least want to know how to switch between timer and 'always on' (or 'always off'). This is concerning, you don't have the best of luck. Hopefully, things improve from here. That's very defeatist and I do understand the feeling, it's been a long journey for you. If you have the conversation with the engineer as described above you should come away able to switch just the heating off while leaving hot water on. In anycase, if the temperature is set to something like 17/18C then theres no real need to turn it off at all. During the summer the heating just wont come on because the temperature won't drop enough to trigger it. Plus, if something else is wrong best to find out about it during the summer when it's warm, not when you are wanting the heat when it's cold. Edit to add: * I know the old system was set to be always on at 17C and you also had no luck with the stove on for long stretches. So I definitely see the need to make some improvements (and also make sure the thermostat is located correctly), but with the work you've done already I think you are not far away from where you need to be.