JohnMo

That is exactly the way mine is wired up. I am using a Computherm thermostat it has an adjustable hysterisis which is good, I am using 0.1 for the UFH great for limiting temperature over/under shoot.

That's ok for your rads, but not the UFH. To get a set-back you just need a simple thermostat with a timer. Basically reduce the target temp a couple of degrees at say a hour before you normally go to bed and set it back to the higher setting an hour or so before you get up. Depending on how long your house takes to cool will determine how long your heat pump stays off. Only thing to concider is your heating curve needs to take account of having to play catch-up to get the rooms back up to temp. So small set-backs are good. Or use your night setting which in effect do the same thing, but will leave the heat pump ticking over If you run WC, the moving a thermostat temp up will have zero effect on the heating, moving it down will.

No

Loads of threads on here - herex is one https://forum.buildhub.org.uk/topic/26090-underfloor-heating-and-radiators-mix/

There is an exposed length of silver pipe at the bottom of the photo (looks like it may be a different in reality) I think the velocity across the short section of pipe should help, the water being in a exposed section for a second or so.

HVO in a domestic situation where other options exist, should be a no go. Not mentioned above is shelf life. Bio biesel has a short shelf life due to the methanol added. HVO has an unlimited shelf life However I can see the viability for diesel driven fire pumps and emergency generator, where batteries would not be a viable option. Your options are quite limited, you could burn hydrocarbon diesel or veg based alternative. On a global scale, overall CO2 released is on a different magnitude. But the whole CO2 profile needs to be taken into account, pre used oil should be the feedstock not virgin oils. Question - anyone know what happens to used veggie oils at the end of their normal life? If it's incineration, which is worse incinerator with little or no useful function or using to put out possible fires or providing electric to keep the lights on in an offshore environment?

The chemical process for HVO is different from bio diesel. Sorry long read below - cut and paste. HVO is produced by hydrogenation and hydrocracking of vegetable oils and animal fats using hydrogen and catalysts at high temperatures and pressures. In this hydrotreating process, oxygen is removed from the feedstocks consisting of triglycerides and/or fatty acids. The resulting products consist of straight-chained hydrocarbons (paraffins) with varying properties and molecular size depending on the feedstock characteristics and the process conditions. The conversion usually takes place in two stages: hydrotreatment followed by hydrocracking/isomerization. The hydrotreatment typically takes place between 300 – 390°C. For treatment of triglycerides, propane is a typical by-product. Hydrotreatment reaction for fatty acids RCOOH + 2H2 -> R-H + 2H2O Hydrotreatment reaction for triglycerides (typically vegetable oils) C3H5(RCOO)3 + 12H2 -> C3H8 + 3RCH3 + 6H2O Firstly, hydrogen is added to double bonds in the renewable feedstock. Thereafter, more hydrogen is added to remove propane by cleaving the triglycerides to fatty acids. Lastly, the fatty acids are converted to hydrocarbons by hydrodeoxygenation (removing oxygen as water) and/or decarboxylation (removing oxygen as carbon dioxide). Thereafter, the hydrocarbons are converted to a quality that meets the end-user criteria, for example conventional petroleum fuel criteria by isomerization and cracking treatment. The production of HVO is well-developed at industrial scale. The investment cost for HVO facilities are generally higher than for biodiesel production plants (FAME production from vegetable oils). The hydrogen used in the HVO production today mainly comes from fossil sources. HVO can be produced from any kind of vegetable oil and fats consisting of triglycerides and fatty acids. Some examples of feedstocks are rapeseed oil, sunflower oil, soybean oil, corn oil, palm oil, waste cooking oil, tall oil, and animal fats. Thereby, the process is flexible to convert a wide range of low- quality waste and residue materials to hydrocarbon based drop-in fuels. All HVO must fulfil the sustainability criteria stated by the EU Renewable Energy Directive (RED). The vegetable oils used (i.e. triglycerides) are also used as feedstocks for producing FAME (fatty acid methyl esters) biodiesel. Compared to FAME, combustion of HVO in engines generally gives lower NOx emissions and reduced issues of poor cold properties (e.g. flow properties), storage instability and aging of the fuel. HVO is a renewable paraffin with similar combustion properties as other renewable paraffins such as Fischer- Tropsch liquids, which are produced via biomass gasification and chemical synthesis. HVO can be produced in dedicated facilities which produce 100% HVO, or it can be co-processed with fossil oil in refineries. In co-processing, biobased feeds of typically 5-10 % are blended with fossil feeds. Higher blends of biobased material are also used, for example by Preem in Sweden. In co-processing, the biobased components are fractionated in different refinery lines and end up as multiple products. The HVO process can also be modified to produce renewable kerosene, for example for the jet fuel applications.

I have tried this a few times - it made no difference to our house, so really wouldn't bother. In fact I was so unimpressed, I took the facility off the heating system. Keep as simple as possible. Don't see why you buffer/volumiser config wouldn't work.

I have got to write a specification of requirements for an offshore oil rig looking at this very thing. HVO, or hydrotreated vegetable oil to give it the full title. Basically you take any oil vegetable, fish or animal derived, it is basically treated to get rid of debris and treated in a similar manner to crude oil to break down the molecular structure. Then as it's a substance that absorbs CO2 (before being cropped) it's treated as low CO2 fuel source, so green wash. Particulates and other nasties are just the same as diesel. You can use anywhere, you use diesel. Lot of downsides Not enough used material available, so raw oil gets used, the HVO prime ingredients are palm oil derived, mostly shipped from Malaysia, palm oil plant isn't that great at soaking up CO2 apparently either. Crops get diverted to making fuel instead of feeding people. Food price increases Just as much CO2 gets dumped to atmosphere. Move the co2 from Malaysia to the UK. Just more green wash, kicking the can down the road.

Yes that's the issue. You need more system engaged to get away from short cycling. If it's not easy to get say the towel rads on, the only option is a small buffer. There are no real disadvantages having a buffer in this situation, as long as it's used in a two port configuration. The water from the heating circuit at or close to boiler goes into the top port, the water from the buffer to boiler out the bottom port. The buffer is basically acting as a volumiser add water volume to the system, so when a small volume circuit like your UFH is only on the boiler has a meaningful volume of water to heat up. An analogy- Just like a kettle, you put a small amount of water in, it heats up very quickly, you get one cup out, but not enough for the wife, so you put a bit more water and boiler again, get another cup and so on. Fill the kettle up it takes a while to boil, you, your wife and a couple of others get a hot drink. The boiler is just the same, the hot water in the buffer/volumiser, gets heated with central heating or UFH, it carries on being circulated after the boiler has stopped heating, the heat gets used in the system, when it's cool enough the boiler starts again..

Not really related to this thread, but Ideal brand Gledhill cylinders to Ideal, sell them at cheaper prices to Gledhill branded ones. I bought an Ideal 210 slimline heat pump cylinder at £805 +vat, the same model Gledhill one was £987 +vat, from the same supplier.

No boiler would be able to support the UFH without a high risk of short cycling. So you have to options. 1. Leave everything as it is add a buffer, so if your UFH has 160m of pipe that's about 25l of water, so you need a 25l buffer. 2. Don't install a buffer, but have a rationalisation of the TRV's and zoning. So you always have a decent circuit volume open. You would need to do some balancing of the radiators to keep the room from overheating. Having the towel rads as a buffer my be the easiest solution. Have them so they are always on if anywhere else calls for heat why If you are going new boiler I would suggest the minimum. Have it set up to run weather compensation, to do this, it will need to be a boiler that will do one temperature for cylinder heating and a different temperature for CH. Don't go low loss header. Get rid of most of your TRV's so the system runs open circuit, but on weather compensation, with a temperature setback overnight. Get the whole system flushed.

Our summer house is almost air tight, until it came to the windows supplied, they are a leaky pile of x"xx. But I decided a dMEV fan was good enough. Part time use building, set it to min flow rate, which means it silent. Also in a small well insulated building, any noise from fans is ever present, so care is needed

If it the white plastic duct you are thinking about you can use plastic pipe solvent cement also.

Wouldn't the time switch be an circuit during the day and act as a breaker preventing a flow to grid?

Use this calculation method As it says if reasonably airtight use the figure suggested, if old and drafty possibly double the figure. If has MVHR, you need to take heat recovery efficiency into account also. https://www.open.edu/openlearn/nature-environment/energy-buildings/content-section-2.4.1

I have bought bits from them

All depends on the flow rate though the system, length and bends. Is your manifold with mixer and pump or direct from heat pump?

The boiler isn't the issue really, to a short cycling issue it's how you split the system up. A boiler can only deliver a set min load. If the system isn't big enough to absorb the heat the boiler manages this by shutdown. You may have 3 zones, but how many loops on the UFH have room thermostats and actuators and radiator TRV's? All make a system smaller. For every 6kW of heat delivered from a boiler or heat pump you need approx 50L of water engaged to stop short cycling. If you want to operate on small circuits you need a buffer cylinder in the return of the CH circuit

Have a look at Beam also, they are the same units rebranded (much lower price when I last looked) and the accessories are the exact same.

Does it matter really to anyone, if someone with a leaky house wants to make it sound better than it really is, the only one person their kidding - is themselves. Let them live in a make believe world, and pay the heating bills. An air test actually measures m3 leaked per m2 of all internal surfaces at 50 Pa. It not even the same as ACH as building geometry also plays a part in that calculation. Move on, look after your own house, and don't worry if someone you don't know, is telling porkies or not, to make themselves feel good. No one cares. My house leaks x m3 of whatever units? You don't care and why should you.

I am not voting, it's a waste of time.

Let's do some assumptions. If inside is at atmospheric pressure and outside is the same. There is zero motive force to move air, so the ACH must zero. This will be true in all cases. As an example on a still day (no wind) you open your front door, the air doesn't move after the door is opened. Now pressurise the house, so the air pressure is higher inside compared to outside. Now you have a motive force so air leaks through the building structure. Same example as before, you open your front door in a gale, you leave your door open, you gets lots of wind blowing in the house. So the figure must be at 50Pa.

Those rates may apply to a commercial kitchen, but why you would need them in a domestic house is questionable. The further the extractor is away from the hob the less effective it is at taking away the smells and grease, so manufacturer quote stupid flow rates to get around it. 10x kitchen volume is the whole house volume or more every hour. Passivhaus did a test on extract hood flow rates and effectiveness, basically the conclusion was min allowed distance from source to fan was best and required least flow.

Do you or are you having MVHR?