MikeSharp01

They must have a sprinkler system and perhaps a ladder out the back, or a secret door through into next door - good point!

I have a smaller one, plus a few 'skill' saws (Dewalt, Bosch and Festool plunger) but it (they) won't do the 300 x 90 I-joists which are the main components of the build. I watched a video of it and appreciate its big but my plan is to ensconce it in the site 'shop' and leave it there when I am on site. I want repeatability and accuracy which no matter how I try with the one I have I cannot get to the level I want it.

Today we got an email from the council saying that they, and the valuation officer, had accepted that we not longer need to pay council tax on the property we are building in Seasalter as there is no longer a habitable dwelling on the site. The roof has been long gone and I am just salvaging the main timbers, those that are not rotted, for general purposes around the site. The small win is that although they only checked on the site in October, after we requested the council tax to stop, they have back dated the non payment to the date of the demolition order (August), some here might remember that asking for a demolition order triggered an automatic commencement of the build. So we are due for a small windfall in council tax repayment which I am looking forward to putting towards on one of these if anybody has experience of the beast please let me know good / bad!

That's amazingly compact! Answers from my research - have not actually installed one yet. 1. The most you can manage but the general feeling looks like being at least a meter. One, exhaust, could be above the other but some horizontal distance will help, you want to avoid exhaust air returning via the inlet. 2. In theory but you would need plenty of gaps at the bottom / top of the door to ensure circulation but this may interfere with Q3. 3. Higher the better but somewhat depends on whether you are putting heat in via the MVHR with an air battery in the feed duct because hot air rises and you may want to induce gentle, very gentle, mixing of the air in the space using this flow in sympathy with that generated by the airflow. Extracts IMO want to be as high as possible because they go in 'warm' / 'wet' spaces. In your Living room / Kitchen you will need both inlet and extract and this in itself will cause useful circulation in the room to help handle the cooking vapours. The extract(s) will be above the kitchen and inlet(s) at the other side of the room. If this has a vaulted ceiling you will want to think hard about where the cooking smells will be going, assuming you are using a recirculating cooker hood. 4. Oversize has the advantage of having loads in reserve so should do your job very quietly in normal mode because it will be at a low setting. It can then boost loads of air in the summer if you need it. (see below) 5. Depends on what other cooling you have in the house - windows, induced circulation etc and can then turn off the MVHR. In air tight buildings I would be concerned about turning it off if I could not leave secure openings elsewhere in the house. In the case of loo you will need another extractor if you do intend turning off the MVHR. If it is running without summer bypass it will return exhaust heat. So, again IMO, you probably do need summer by pass. Hope that helps.

Sorry Nick - Typo. Yes this is a concern but I will do the sums on the heat loss, its not a huge mass but its hot - kept hot and not that brilliantly insulated. I think I was working on the basis that we would switch them off in the summer when showers can be a bit less sizzling and we don't want the heat loss warming the building. My only worry with the system as it stands is getting it to tick over at a low enough level to run the UFH and / or Air battery in the MVHR. We have VG mains pressure and flow, I will do a full test with a direct connection to the meter, when we dig it up, later in the build but a single hose delivers 24L/min from an outside tap and throws it 12 meters so I suspect full bore will be fine for our needs.

Hopefully around £1200 + VAT (New build so will get that back) the unit is THIS one suggested by @Nickfromwales. It does have some standing losses because it has a very small heat buffer in it but I think, if I read the blurb correctly, you can configure it not to use the buffer tank if you are not going to experience high demand.

Not always that directly - the old DHW / space heating question again. We, most of us, have been around the dwellings on this, our passive house design model shows we will need around 2Kw of heat, worst case - peak in a typical winter and max of 3Kw once every 10 years. BUT following a conversation elsewhere with @Nickfromwales we are going, as things stand, for a 35Kw Combi because we want to run two simultaneous showers at 10+ L/min and don't want the standing losses from a tank which @JSHarris has shown, and is discussed above, can be a problem in the well insulated home. The conversations above make the same point in that heating a well insulated home consumes a lot less energy than the DHW demand if we are all showering frequently as has become the norm or at the very least demands the ability to expend energy at a hi rate to recover hot water in standing volumes quickly in readiness for the next hose down! This is a classic 'no one right answer' problem - just an optimal one for each according to their circumstances....

Our experience was that an internal process in the council triggered the start of the development. We are not subject to CIL, at least the council have not mentioned it and we are a redevelopment that does not add more than 100SqM so should not be. However if we were seeking exemption then our experience tells us that if you go for a demolition order even if you do not intend to demolish immediately the act of getting a demolition order puts your project onto the commenced list. We them got an immediate stop order from enforcement because we had not closed our finish materials condition. We fought the stop and they agreed we had not started all the work we had done was classed as preparation so the order was lifted. Suspect that there are a number of such triggers.

Unless you want a large number if holes to seal try and get the plenums in the air tight zone that way you only have two pipes to seal.

Just so organic.....sensual even! Don't you just want to get naked, roll around on that and become one with it? Well are several reasons why not. 1. Working at height. Not sure how you can be harnessed and rolling at the same time. 2. Performing lude acts in public. I suppose you could put a scaffolding screen round it and carry on all weather's. 3. Somebody might think you had a mental health problem and section you thus slowing up the day job -assuming you are not already banged up under 2 above, leading to loss of income, divorce and penury. Not to mention having to give the other half 50% of you power tools. My advice - get over it!

Just enough time not to crack the slab by heating it too much in one go. This is a worry I have been mulling over. Our polished concrete floor needs to heat and cool very slowly if cracking it to be avoided. So in some ways its good that the time constant is sooooo loooong but if I recall my control theory its all about the sample resolution (digital systems) so you can spot the smallest changes that are above the noise or filter out the noise and get even closer. Sampling the slab depends on the coil pattern a bit I guess as well. Until a couple of weeks back we were not having UFH, didn't need an ASHP but its great to hear that the ASHP can feed the slab direct, that makes perfect sense in a number of scenarios and I am going away to model that and see how close to the optimum COP you can get & stay without cracking the concrete and / or overheating the house.

Looks like a classic self tuning PID controller would tackle this Terry, there are many implementations for raspberry PI - such as this one. It would need time to learn, some upper and lower limits carefully set and servos (or digital equivalent) on all the controls but then it should just read the stat and go from there.

Size not but technique yes.

My point entirely, why abstract the ideas on there why not instead have your own. Ah.. good point on one level BUT (won't use the consultants AND here) it is not possible for humans to have spontaneous ideas. The ideas we have are in fact new combinations of things we already know. This is how progress happens. So to have your own ideas you need a feed of ideas to combine in new ways and it is this feed stock that I think house of the year does for me. Once upon a time... someother time.

Just watched first of house of the year, blown away by some of the ideas and the two best got on the shortlist IMO although the other three had a lot about them. Building the house around the street - inspired.

I think MBC now have a UK facility so they may not be affected as much by exchange rates which might help a bit.

Hedge and buy everything now. You will have the cost of the money for the extra few months but that won't be much even if borrowed at 5-6%. I am discussing this with the other half to see if we should do it.

Hi just back from Jewson the site singe pack is £135 decided I can do better elsewhere on this one. Will be off to eBay shortly.

Yep trick is to source as much in UK as possible and that's not easy. I think I have found the timber frame components here the cladding and about 50% of the insulation. Was warned by insulation supplier that price rise of PU is coming in January. Other Big ticket items however are very difficult like passive house windows. They all seem to be EU based as are the MVHR units. Still we are keeping the local professionals busy Architect / SE and Jewson. Must get timber ordered.

Ok so two flow meters one in the waste water and one in the heat exchanger, four temp probes one in each input and output and a data logger! Then a bit of integration should lead you to how much you are getting back. The question is from / via where is it coming back! Easier to use a pair of range assumptions. Assume 10% efficiency (worst case) so for every hundred litres of hot water you get back 10L and 64% as quoted in the Recoup literature (which is IMO more than you can expect and perhaps therefore a bit missleading) and get back 64L I think not!!!! The answer will be in that range somewhere, probably nearer the the middle than the top. You could look at it another way. 1. You only shower in hot water so you don't really care about the inflight cold water at the start of your shower but you need to know how long it runs cold for, call it ifh. 2. You shower for 4 minutes and use 40L (10L/min) @ 40degC @Nickfromwales would approve. 3. Plus (and this is where the time derived form 1 above is important) you have left ifh seconds of hot water inflight to the shower head and it is now cooling down and it won't go through the Recoup device. Lets say ifh is 15sec (I would hope a lot less!) you have actually used 42L of water @ 40 degC. 4. So you loose almost 7% that you cannot recover, so even if perfect only 93% is available to recover. 5. Some heat will be lost as the water cools, flowing over you - a somewhat cool 37 degC, the shower tray, down the plughole and along the pipes to the Recoupe device. Lets say it drops by 5 degrees. (You could measure this with an IR device at the top of the recoupe device I guess) 6. So once the HW hits the Recoupe its down to 35 degC so its given up another 17.25% (assuming your incoming CW is at 6 degrees) of its heat 7. You now have just 40L of water at 35 degC now only carrying 76% of the heat you lovingly put in at the generator end. 8. Now multiply that 76% by the 64% efficient (assuming system A and the recoupe figures) and you get 49,25% 9. I think that means you might get back about 49% of the usable shower from the Recoupe device itself! BUT because you have a neat little MVHR most of the heat coming from the inflight hot water now standing in the pipe, the heat given off by the shower tray and pipes as they cool and that generated by your good self giving yourself a good rub down with a towel (you may of course be lucky enough to have somebody else doing the rubbing down in which case you can double the output) will be kept in the house anyway so in a very real sense you get much of that back also. Not unreasonable to expect the MVHR to be 90% efficient. Extending this idea a little further we find that its not so much how much you get back but rather only how much actually goes to waste having run through the Recoupe device. It looks like a good proportion of rest is kept about the place via the MVHR. Hmmmm... I think I will go and have a snooze after that and contemplate not bothering with traditional waste water heat recovery but just slow the output flow down enough to let the MVHR pick up heat from the pipes as they cool... and just let it go in the summer!

1. Cos they could not predict the future - of insulation. 2. The client didn't want to pay for copper they didn't need although the cable supplier would be very happy. 3. They worked out that across all their jobs the resulting voltage drop would be wasteful, requiring more power stations then heretofore even if it made little difference in this one job. (Green before their time so perhaps they could have predicted the future!) 4. Nailing cables onto sky hooks not taught on their ONC / NVQ. 5. The boss worked out that across his lifetime the resulting increase in costs associated with the cable clips would mean he / she would not be able to: get new car / retire early / take up with a toy boy / girl - dump the wife / husband and still have something in the bank.... I could go on - perhaps somebody will. HOWEVER this does not mean I don't feel your pain - empathy is everything you know.

What system are you using for this, should be possible to get an idea shouldn't it, amount of water x temp delta x efficiency of the system or have I missed something, only looked at such systems in the first stage, have kept the waste water separate from the 'number 1s & 2s' to the plant room in case it looks like a worthwhile proposition. (Must add that to my post above about things to remember.)

Yes that is what I meant but its only mixing down with the return flow from the UFH and the other high grade losses will only be in the pipework between the heat source and the UFH mixer valve. However your point about high grade heat, what is your definition of high grade I wonder, and mixing is a good one and perhaps we (I) need to think about it in energy terms more directly. My thinking was that the boiler would only deliver what was required, modulate down and stay within its efficiency range, once the hot tank was filled. Trouble is, when you expect that, the efficient modulation range of the boiler (or other heat source) I think the smallest boiler goes down to about 3Kw which I suspect is much more than you would need to put into an already warm slab which is surrounded by an airtight and well insulated structure. Your other point about getting the floor temp down is a very good one that needs thinking about, as you say I also seem to recall JSH struggling with that one as well but I have not followed it up. Is the limit set by the mixer valve I wonder. Off I go to read the JSH stuff again.

This is possible because the UFH will (can) mix return water from the UFH with hot water from boiler to control slab temperature the full hot water can go off round the hot water tank.

Yes Jack you can get by with 55 deg in the UVC but how many showers can you have and you still have the standing losses? Not sure but I get the impression that showers are at the core of all the DHW challenges.