JohnnyB

I'm not going to be able to make it, when I mentioned it yesterday I was reminded that we are away that week. The bar at the crown isn't too large, you find each other easily enough.

Looking forward to meeting lots of you. The Crown is easy to get to from the A14, and fairly close to me so a good choice!

I'm interested, IP14

Where do I find the minimum turn down my unit will go to? My heat load is about 3kW on paper but being a self build I've tried to be careful and do some extras so the actual load should be a bit lower. Also it isn't as cold as the temperature used in the calculations so actual heat load at the moment might only be 1kW. Switching the oven on for half an hour or so increases the temperature downstairs, mostly one open plan area. With a small heat load would it be better to use the thermostat more and just have it off lots of the time? I changed it to 1 hour, the DHW has a max run time of 40 minutes. I've just had a thought that the max run time may only be when there is a call for heat at the same time so maybe I should set it longer. I don't think there was an option for off. There are 4 in our house and I had been getting complaints of cool showers buy the third shower if I have it switched off morning or evening. 2 boys, 19 and 22 who like their sports and gym and my wife is also at the gym regularly so 3 showers close together isn't unusual. It is set to heat overnight to 48 deg, then eco during the day which lets the temp drop by 10 degs, and turned off between the Agile peak of 4-7pm. It does seem to heat up quite quickly but noit in 20 minutes, possibly not in 40 minutes, I'll have to try setting it to a longer time and see if that helps as well. The house should easily go without heat for an hour once the floor is warm.

Thanks all, I think I'm starting to understand it a little. A volumiser doesn't effect the efficiency like a buffer does? My HP has a minimum of 30ltrs and I have 42ltrs in the UFH pipes plus 10ltrs in my F&R pipework so more than the minimum amount before manifolds, HP, other pipework etc, although I have read somewhere that 15 ltrs per kWh output of the HP is good for efficiency. I have increased the flow temperature to about 33 and measured the return temperature which is between 2.5 and 4 deg lower than the floe temperature. I haven't tried measuring the return when the temperature as around 25 and on all the time but I wonder if the difference between flow and return was very close. My pumps are fixed speed, and on the highest setting so the flow rate is about 27ltr/minute. The spec sheet for the 5kW unit says nominal flow rate is 14.5ltr/min. Would this be better running slower? @JohnMo From what you say it doesn't matter which is the slower flow rate, if they are different either way the result is the same. I could have the buffer changed to a volumiser, remove the pump and motorised valve, and run everything from one pump. I think from the video notes in IGP's post it should have been a PWM pump. I did discover last night that the DHW cycle was set so the immersion heater comes on if the cycle goes on longer than 20 minutes. As I have been running it so the water temperature drops by 10 deg before starting to heat I think it is taking longer than 20 minutes most of the time so that wouldn't have been helping the COP.

I don't think I need a volumiser either, there is more than 30 ltrs of water in my UFH pipes and another 10 ltrs in my F&R pipes, plus everything else. Would changing it for a volumiser make much difference to the efficiency? I'm starting to understand there's probably a lot of things in my system that's not needed and it could have been a lot simpler

Thanks for all the input. I'm going to have to make time to see is the HP is cycling, watching it for 10-15 minutes it seems to be fine, I assume the fan would stop if it is shutting down. I'm also trying to read up on heat pumps and heating, exactly what I didn't want to do and why I used plumbers who are supposed to know what they are doing but there are so many things you are saying that I don't really understand. I'm trying to build 2 houses and thought this was one thing I could leave to others to sort easily, didn't realise HPs need to know so much just to run them efficiently! I had a message yesterday from the plumber and they have another unit like mine that is getting a similar COP which the client has full monitoring on. They have emailed Samsung for advice and he is going to try to get out to me before Christmas to take a look and see if he can see anything obvious. I have been looking for more info and it seems that the video linked to above, and ringi, aren't the only people saying really low flow temperatures don't equal a good cop. If I set the flow temperature so it's leaving the HP at 30-35deg I would probably have the heating on 2 or 3 times per day to warm the floor up, but that isn't as comfortable as having the flow temperature at 23-25 deg and the floor at 20-22, which kept downstairs at a fairly constant 20deg. The higher temp has helped the COP, it was 2.8 yesterday, but it was off all night and has taken a long time to get the floor back up to temperature this morning. The problem of a well insulated house and floor, it doesn't need much heat. Maybe I can set the system so it uses the floor temperature as the set point instead of the room temperature, put water in at 35deg but switch off when the floor gets to 25deg and come back on when it cools down to 22 or something like that. Should be slow heat and cool down times for the floor. I have 60mm screed with 2 layers of 100mm PIR insulation beneath and it seems to hold it's heat for several hours. By LLH are you referring to my buffer tank and pump? What you are saying is the opposite of what I thought I was understanding when reading on the renewable heating hub forum, that the main pump should be running faster than the secondary pump. I have noticed this valve is set to a low pressure and the water seems to be passing along the shortest distance. I was told this is to allow water through if the valve doesn't open and the pump starts, but I can't see why I even need the valve there as the pump only starts if it is open and it doesn't divert the water, just stops it flowing. I do have a diverter valve on the main F&R the switches the flow between DHW and heating. As mentioned before I didn't want the buffer in there but was told I had to have it. If they can't sort this sufficiently I will insist it is removed. I really can't see the need for it when I can't close the loops, there is no zoning and I have a lot more than 50 ltrs in my pipework without the buffer, they have fitted 32mm flow and return to the HP and the buffer, my DHW cylinder and buffer are 3-4 mtrs apart because of space issue with 32mm pipe between them, must be about 15mtrs of 32mm pipe

@JohnMo If only I had time to sit for an hour and see what the pump is doing, I'm trying to finish off the house! I don't have a smart meter indoor display, but the Samsung controller will show the power being it used by the HP. I'll have to watch that and see if it shows anything interesting. It's a real shame they don't give access to proper data. My pumps are identical and both set on the same setting, plumbers said that was necessary. They are mostly both on at the same time, apart from when the DHW cycle is on or occasionally one to the HP will be on without the other for a few minutes, the HP pump will occasionally start up without the thermostat calling for heat. I've turned the flow temperature up and will turn it off when it gets to 4pm and see what happens to the indoor temperature. (I'm on Octopus Agile which isn't a great tariff for a cop of 2 at the moment!) The plumbers told me the internal thermostat isn't great and that I needed an external one, but in the video @IGP linked to Glyn is using the internal thermostat and it sounds like it is working well for him so that could be an option. Glyn had the flow temperatures basically the same in the WC settings as the COP dropped if the flow temperature dropped below 33 deg.

@IGP Thanks for the link, I watched the video then read he has updated to firmware so it works with a PWM pump and he can drop the flow temperature lower without effecting the efficiency. I don't have a PWM pump but maybe my pump would be better on a lower speed? Something to discuss with the plumber. @JohnMo I only have the Samsung controIs and can't see details of what is running when and how long it is running for etc., is there an easy way to find out cycle times without an energy monitor like you have on your system? We don't have zoning, there are no actuators on the UFH manifold. I've read lots of your comments on here so have been trying to keep it simple, although the plumbers have insisted we have to have a buffer for the warranty and one pump for the HP and another for the UFH pipework so it isn't as simple as you would recommend. I think if I set mine to 35 deg we will be rather warm and our feet will cook, I haven't been above 30 at the water outlet yet and that was already quite warm, although if it only heated the slab to a lower temperature and then switched off we could probably control it that way.

I have recently had a 5kW Samsung gen 6 heat pump fitted, been running about 10 days, and I had a look at the energy used and the energy generated on Friday and I'm getting a COP of about 2 so something isn't right. I've contacted the plumbers who are going to take a look but I wanted to get a few thoughts from here on how I am running it. The plumbers are known locally as being good and only fit heat pumps so they should be able to sort it but always good to have some knowledge before they try to explain things away. It's a new self build with UFH and I have been running it 24/7 with the water outlet at the pump between 23 and 30 deg, regulated by the WC. The temperature on the floor is about 20-22 deg which keeps the house around 20 deg. Is there a point where the flow temperature can be too low so the heat pump is cycling and not running efficiently? Should I be using the thermostat in the house to switch the heating on and off with a higher flow temperature instead of running it low and constant? Anything else I should be asking about?

Sorry for the slow reply, I've been rather busy trying to get enough finished in the house to be able to move in and haven't been on here for a while. I didn't use the compriband in the end as it needs a reasonably smooth/flat surface to work, and hempcrete isn't smooth. I ended up using the Illbruck FM330 expanding foam and that has worked well for my situation. I used it under the windows as well. I have done it but still have the main house to do next year so I will look at that for next time. As mentioned above I used airtight foam which has worked well but doesn't feel quite the right thing to be using with hempcrete but at this stage there have been a lot of compromises that's very few things I regret yet. It varies depending on the exterior finish and the wall build up needed to make the cladding longer up with the brickwork as we want it, but the thinnest sections are 380mm of hempcrete and 440 at the thickest.

Thanks, I hadn't seen that, although I do remember reading the thread you linked to a while back but I couldn't find it again this morning - I quess because I wasn't looking in the ASHP section. My quote isn't as high as that one, although I do have quite a bit less going into mine. My space limit is in diameter but have standard height ceilings. I can get a 600mm diameter tank in there but there's not much room for lots of pipework around it. I know they have said a pre plumbed tank wouldn't fit. @Dave Jones I do wonder if i am paying over the odds, hence the post. This isn't being done with the grant so I don't have to go MCS registered. The problem I have is I don't have the knowledge to sort it myself and don't have a local plumber I know and trust to do it well. I've done most small jobs myself and haven't needed a plumber for years. This company have a good reputation and have installed a lot of ASHP locally and seem to know what they are doing. It depends on how much over the odds I'm paying and if there are cheaper ways of doing it. I have read a few of your posts this evening and it seems your advice is to keep it very simple. Speaking to Nick earlier today I'm going to look into a Sunamp, or even a standard hot water tank heated with an immersion heater, with the ASHP just connected to the UFH. That may help.

How much are people being quoted to get a 5kW ASHP installed in a new build? I have just been quoted £8k as below. It seems rather expensive to me but after reading a few other threads on here it may not be too bad? This is for the 'annexe' and the grant will be used againest the main house. I was given an estimate of £13k after the grant for the heating and second fix plumbing in the house, which was the cheapest quote I received. It was hard to even get quotes on that about a year ago. Any suggestions for sensible quotes in Suffolk if this isn't sensible? Thanks.

Yes, that would work but I'm not sure I have the time. I would need to wait for the plasterer to come and put a thin coat on and then let it dry before I could fit the windows. The windows are arrive about the same time the plasterer is coming to start on the internal walls. My previous attempts at plastering have been terrible so I'm not going to try doing it myself.

Thank you Nick, that is very kind. cuold you send me your address please and I'll head round at some point very soon