SteamyTea

I was thinking outside, not in the house.

Yes, and moisture permeable on the cold side. It is how it works. The detail is in choosing all the right materials. Long time since I was using them. Used to be a company in the NE making the chemicals. But think of it this way, if oil is turned to foam, it is not being burnt. The trick is to get the overall CO2 emissions lower, not all components at the lowest.

Only if the house varies in temperature because of externalities i.e. wind and sun, night and day. If the losses are just high, then delivering more energy i.e. at a higher temperature or a larger emitter area, will work just the same. But I know what you mean.

Thanks

Many PUs are, as they now say, plant based. Many Welsh sheep farmers drive inefficient vehicles. Many people will tell you to use 'lime' on old buildings. That is fine, as long as you are happy that your grandchildren are one ones to see it properly dry. I am not sure about old buildings, renovation is a tricky thing. But when they were built, one open fireplace was the norm, not central heating. In a modern building, the moisture comes from the inside and condenses at the first place that the dew point temperature is conducive. This is why vapour barriers are used. The internal air is then mechanically vented out the building and the energy is recovered. So a different solution to air bricks, which I think were to stop wooden joists rotting (and they failed anyway). You can easily work out the heat losses though a material, thickness in m/W.m-1.K-1 you will soon see that you need a lot. I would not bother with a thermal camera, just a candle will do to find the holes.

Except they transfer mostly by convection. What is probably happening is she used to find a draft free area to sit, either by design or accident. I have not been convinced that low temperature radiant heating makes any noticeable difference, other disagree and use example of the sun though a window. The sun is at millions of degrees, not 50 above ambient like a radiator is, and only 22 above body temperature, and then they are often small in area. The attenuation is quite great over a short distance (I think attenuation increases with distance, but not sure, entropy increases with time).

Can you explain more, with some pictures please.

I think that traditional radiator heating systems are hampering out understanding of thermodynamic. When they started to become popular in the 50s, 60.s and 70's, people used them like fireplaces. They got home and turned the heating on. Then turned it off at night. We don't have to live like that anymore.

And a buffer tank. Could this be a case of a traditional plumber treating a heat pump system wrongly and turning up the temperature as high as they dare because 'heat pumps are not hot enough'

Welcome Why bother with solar thermal? It is a one trick pony, and once it has heated your domestic hot water, it will just sit there doing nothing, until it is time for a costly service. PV is much better, and supplies energy in a more useful form. How much can you get on your roof and is the roof at the correct angles to get full advantage of it? Insulation is only part of the thermal losses, but as a rule, the more the better. This is especially important if fitting any under floor heating, energy will leach away to the ground (so not that important on first floor, vital on ground floor. Not talking about 50 or 70mm here , 200mm at a minimum. The other big element of heat loss is ventilation. Old houses are full of holes, so large, some small. They all need to be fixed. That is your hardest task by far. Regarding wood burning stoves and sustainability. They are just not, they churn out more CO2/kWh that a gas boiler, and the particulates have no safe level, regardless of where you live. Best avoided, and it makes blocking up the large holes that are chimneys easy. As you currently have gas, you can calculate your current usage fairly easily. This is useful as you can start to block up some holes and see what the improvements are. Around windows and doors is a good place to start. Just reread and noticed this. Internal wall insulation is probably your only option, but you still need to make sure that there are no drafts behind it. You may want to rethink using wool.

Using that mean temperature, and a standard deviation for the whole month of 4°C, -5°C will happen for 3 percent of the time. 22 Hours. A 1m by 1m by 0.1m concrete block, heated at 25W/m2 will take 2.39 hours to raise up 1°C. If it looses 5W/m2 to the ground, then 3 hours. If another 12W/m2 goes to heating the air (which is what you are after) then 7.5 hours. (only had 1 mug of tea so far so may be wrong)

Have you thermally modelled the different options. You can possibly 'claw back' some of the losses with a different choice of insulation. I see you have an corner (Kitchen/Diner) on the outside. My Mother's house has something similar that is always in the dark (she keeps all 3 wheely bins and the 4 recycling box there). It is always damp and mouldy. Is the roof a warm or cold one, is the roof light needed?

You are not building a block of flats, the fire issue was caused by a number of failings, not just one.

Not necessarily. It really comes down to how variable the weather is. It could work out cheaper if you do not have to 'overheat' to get the temperature you want later. An ASHP works best when it is doing the least work.

I did not include MVHR in my calcs. Just trying a basic model out and I tend to see how close it gets to my actual data collection.

Can you reduce that. Try it at 32°C.

I think the trick is to get both right at the start of the design stage. Then it is relatively easy to do the rest. The one thing that is hard to model is the effect of windwashing. A stiff SW wind is generally warm, but even a relatively slow NE is anything but. I may try and incorporate some solar gain and wind effects later. The trouble with even a basic model is verifying it against real data. I can make just about any model fit existing data, not so easy the other way around.

Using min OAT and adding a bit to allow the temperature to change is probably good enough. I was, just because I was up early and bored, knocked up a very basic calculator. The thermal losses via ventilation dominated.

A slightly left field look at this, and in no way am I suggesting this can be done safely, but: As the boiler usually has water circulating around it, which limits the temperature (until it boils and can release hundreds of times the energy), would it not be possible to pump air though it instead. It may need a relatively high pressure pump to give a decent mass flow rate, which needs to be at least 4 times the usual water mass flow rate, and probably 12 to 15 times in reality as you don't need air coming out at 80°C. Then that warm air can be piped to where it is needed. This dose run a risk of filling the house with smoke, or worse, carbon monoxide, if the boiler jacket leaks. So I would not try it. Probably much better to get a Honda Generator and run an Air to Air heat pump from it.

No, you need to use the minimum OAT that the Met Office supply, and preferably the daily data not the monthly data. https://catalogue.ceda.ac.uk/uuid/b37382e8c1e74b849831a5fa13afdcae I think soil temperatures are buried in there as well. To give you an example, my Feb (coldest month) temperatures have a mean of 4.3°C, but a minimum of -0.8°C (the whole month, in 1986) Is this just the footprint of your house, or the total floor area, or even the total liveable area? Just thinking that @joe90's place is about 200m2 and his HP is 4 kW, and that does his DHW as well (I know that we are in the very mild SW, but you are not so different being on the west side of Scotland (Isle of Sky climate is very similar to Cornwall, within a degree).

Assuming ground floor, UFH can loose more energy to the ground, which generally has a lower temperature for longer parts of the year. On a second floor, it should realistically make no difference. If by you mean mechanical ventilation and heat recovery, then no practical difference as that is to do with air changes and not the losses though the walls, floors, roof, windows, doors etc. Depends on the view and if you are an artist. If the thermal losses are manageable, then no problem. Near me is a small cove, if a house has a south view, it would be of industrially scarred land, but the north view is of the Atlantic.

What happens if the cylinder is not up to the desired temperature after 30 minutes, does it totally isolate from the rest of the system. And was the system working correctly before the Nest was fitted?

It may make the numbers worse as the surface area to volume ratio is 6/a. Basically large houses have a better kWh/(y.m2) number than smaller ones. But then I think using the mean air temperature is wrong. There will be no excess heating for a large proportion of the year. I think this has to be modelled on a weekly basis, the MET Office probably has better data. I use a daily mean air temperature of 10°C as the point where I need to turn on or off my heating, using your number of 9.4°C would mean I have the heating on all the time.

From my understanding, condensing boilers are more like turbocharged cars. They reclaim some of the energy that usually goes to waste. If you run a turbocharged car at too low an engine speed, it is basically 'running rich' as there is not enough air to burn all the fuel. A similar thing can happen at the top end as the fuel injection system tries to put in more fuel, but the turbo has 'run out of puff'. So there is a sweet spot where all the fuel gets burnt, and maximum torque is produced. Now a boiler is obviously not the same as a TDi. Rather than having a 'rev range' is has a thermal range. This is just a range of temperature differences where the boiler can transfer the most energy for the least fuel. This is easier as a formula: Q = U×A×ΔT where, U is the overall heat transfer coefficient A is the overall heat transfer surface area and ΔT is the mean temperature difference between hot and cold side The trouble is that the cold side i.e. the water is not a constant, it varies, and as it varies in temperature i.e. gets hotter, the coefficient U would have to changes to keep the efficiency the same. As a rule, the flame temperature will be constant (within 10°C or so), A, the area of the heat exchanger within the boiler will stay constant, so all that can be changed is the temperature difference ΔT. As heating is not a linear process but follows an exponential curve: T(t) =1- t- exp(-k * t) Where T is temperature, t is time and k is a constant. This produces a chart that shows that when there is a large temperature difference i.e. cold store, the energy transfer is large, but as the store warms up, the energy transfer decreases, even though the fuel burnt per unit time, is the same. Or in simpler language, the hotter you get, the more fuel you burn. The trick there is to find a lower bound temperature that satisfies your hot water needs i.e. 40°C and an upper bound for safety i.e 60°C Using the made up chart below you can find out the amount of time the boiler needs to run at (bare in mind this is showing % change, not absolute temperature). So what you need to find is the range where the boiler is condensing, the water never goes below an acceptable temperature, and never goes above a safe temperature. And runs for the least amount of time, as I think oil boilers do not modulate (I may be wrong here, but the physics is basically the same, just another variable in the mix). I have highlighted this with coloured lines. So for the same temperature change between the blue lines is 7 times units, and between the yellow lines is 22 time units.

It will be in the wording if the deal somewhere I am sure. Their compliance lawyer will have checked. So just change. There are plenty of others that are about to go pop. Or, phone 0161 836 1346 You and yours likes this sort of thing. I think Tuesdays are 'energy day'.