JohnnyB
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Everything posted by JohnnyB
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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.
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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!
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Can the flow temperature be too low?
JohnnyB replied to JohnnyB's topic in Air Source Heat Pumps (ASHP)
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. -
Can the flow temperature be too low?
JohnnyB replied to JohnnyB's topic in Air Source Heat Pumps (ASHP)
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. -
Can the flow temperature be too low?
JohnnyB replied to JohnnyB's topic in Air Source Heat Pumps (ASHP)
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 -
Can the flow temperature be too low?
JohnnyB replied to JohnnyB's topic in Air Source Heat Pumps (ASHP)
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 -
Can the flow temperature be too low?
JohnnyB replied to JohnnyB's topic in Air Source Heat Pumps (ASHP)
@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. -
Can the flow temperature be too low?
JohnnyB replied to JohnnyB's topic in Air Source Heat Pumps (ASHP)
@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?
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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.
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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.
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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.
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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.
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Thank you Nick, that is very kind. cuold you send me your address please and I'll head round at some point very soon
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I'm looking for advice on sealing around the windows and doors in our hempcrete house. I was thinking I would use compriband tape and then airtight tape on the inside between window frame and studwork but the hempcrete doesn't have a smooth even finish and there are gaps under the timber spacers fixed to the timber frame. Does compriband expand into small gaps and holes to seal tight againest the weather or would I be better to use FM330 foam and then us something else in the gap between the frame and wall to insulate the gap? If I used the foam any ideas on options to insulate the gap if it doesn't have compriband tape in there? Compriband would seem a little expensive/overkill if I use FM330 to seal the outside. The outside is timber clad so I will have timber around the outside reveal and the inside will have woodwool board and then plastered. Also any thoughts on fixing plates? I was thinking of simple metal strips but are there other options? Thanks, Johnny
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New water connection. Expected costs?
JohnnyB replied to flanagaj's topic in New House & Self Build Design
My new connections was in January this year and I had to have at least a the standpipe as Nod's picture with pipe going to the edge of the road for them to fit a meter to before they would fit the meter. They sent someone out to check it was all to their spec a few days/weeks before they came to make the connection. If you contact whichever compnay supplies your water they will give you a quote and a list of their requirements, what you have to pay them for and what you can get other contractors to do. I dug the trench, fitted the stand pipe with a pipe going to a point they specified My cost was about £3k with about half of that being the cost to close the road. -
@ReedRichards You are right that a heating system is more comfortable to live with and discussing it over the weekend we are coming to the conclusion that we should be fitting a heat pump, but when we were planning the build the intention was to put this building up cheaply and fit it out to a basic level to start with. We planned to use this as extra space for a games room/yoga studio/additional space when family and friends come to stay. We were then planning to fit it out as a full house as we had time and funds to do so. I have several years worth of free logs stored already and more drying so it is free heat. Most of the year it won't need any heat so lightling a fire when we want to use it seemed fairly simple. As it happens timings haven't worked out as planned, we started building a lot later than expected and ended up building this buildng first. It's turned out to be a slightly quirky building and a space I really love that I can imagine living in once we want a smaller house, although my wife isn't so sure she wants to do that. We will probably spend a year living in it while we build the main house that we are now planning to start next year. We have been discussing fitting an air source heat pump over the last few days and the plumbers are going to give us a price for that. We've already had UFH pipes fitted in the screed ready for future use so it would make sense to use those. From their initial estimates it will probably be about the same cost as fitting a woodburner as a reasonable stove and flue isn't a cheap option, especially as it needs to go through the airtight membrane. The main issue is that several things have been designed around the woodburner being where it is including the staircase going round it and the walls of the 'chimney' surround supporting the 1st floor landing so the space for it can't be removed at this stage.
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We did discuss electric heating but he said that would be hard to make work as direct electric heating needs offsetting with solar, which we're not putting on the annexe only on the main house. If I combine @Dave Jones and @ReedRichards suggestions, specifiy a hear pump but never get round to fitting it, maybe we can get around it.
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We didn't have SAP calculations done at planning stage, or before we started to build. so wasn't aware of the need for heating controls until now.
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We are in the middle of our self build and I have just been told that I can't just have a wood burning stove in our annexe as the heat source. The sap guy has said the heat needs to be controllable otherwise the software will show a fail It is a separate building so is being assessed separately to the main house. It is a 130sq mtr 2 storey building that we are insulating to a good leave and as it isn't intended to be our main residence we thought a wood burner would be a cheap and simple way to heat it when it is being used. If the building wasn't already up with the blockwork in place that creates the space for the stove we would probably say forget the wood burner and fit an ASHP but we seem to have gone slightly too far for that. Does anyone understand what the SAP calculations need, or even better have ideas of ways around fitting a full heating system at this stage. In the future we may want central heating but at this stage it isn't really need as well as the having a wood burner.
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It's a very late reply but I had this on a stove I installed myself many years ago. After much investigation and trying different ways to seal the joint, I put it down to condensation as once the chimney was really warm it stopped dripping. There definitely wasn't rain getting in. We had a 12" clay liner and I fitted the flue from the top of the stove straight into that, and I think that was the issue. If I'd fitted a metal liner and back filled so it was insulated then I don't think there would have been a problem but that would have stopped the chimney heating our bedroom. As we ran the stove nearly all the time it wasn't an issue to us and I found that leaving the door open while the chimney warmed up stopped it dripping. Not a great solution but it might shed some light if yours is a similar situation and you haven't sorted it yet
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Where is best to by an electric mains kiosk?
JohnnyB replied to saveasteading's topic in Barn Conversions
I built a brick one for ours. My electrician wanted enough space for a board inside the box as well and it was getting large and ugly. It wasn't the easy option as there's quite a lot of spec that should be followed but it was still cheaper than buying a box -
We coment just recently that we wouldn't want to do it if the kids were small, but that is self build in general not just the static! We have two still living with us but they are 18 and 22. We re pushing hard at the moment to get into a building before it gets too cold again. Stories of people in statics with frozen pipes and heaters on timers to try to take the chill off in the morning isn't really for us. We had water and electric on site and the sewage treatment plant plumbed in before we moved to site. The footings weren't in but that wasn't really a consideration for us and could have been either way. Make sure you have a bit of time to set it up, it took longer than I expected to get it to the right position, level and the plumbing sorted. The pros are being on site all the time and being easy to get on and work whenever there's a free moment. If we weren't living on site I would rarely see the family. It's also much cheaper than renting and it's a big incentive to get on with the build and move out quickly. At the moment the downsides are few, there's less space and the temprature follows outside quite quickly, but my wife loves camping and being outdoors so as long as the weather is good then all is OK. We have additional space in a shed for washing, drying, fridge etc. Make sure there is hard standing or a good path between any buildings. It gets very mucky when it rains and that easily carries inside. Personally we wouldn't do it with young kids or over winter, but were getting a bit older and not so hardy as we were 20 years ago when we first looked at selfbuilding. For us it is working well at the moment and we are quite happy most of the time.
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Double or triple glazing options, what is the difference?
JohnnyB replied to JohnnyB's topic in Windows & Glazing
I don't want to block out the outside. We have moved to the countryside and love the sound of the wildlife around. Living in a static caravan on site helps us to hear what is going on around us!