jack

Yep, my reply was directed at this comment from Mike, which as I interpret it suggests the possibility of mixing high temp water to a lower temperature for use in UFH: My bog standard Panasonic controller allows different temps to be set for heating and DHW modes. I seem to recall Jeremy's offered that option as well. Worth checking with the manufacturer you're using (or thinking of using), but certainly it doesn't appear to be an uncommon feature.

All hot water is fed via a TMV on the UVC. Can't remember what temp that's set at - it's whatever the standard is for that kind of valve. That's an interesting question actually! We have good static and dynamic water pressure here - something like 6 bar static. Our plumber was concerned about making sure we had good water pressure throughout the house, while still comfortably satisfying the water usage requirements for a new build. In the end, he installed a 1.5 bar pressure restrictor on the way into the house. This means that our showers are fairly low pressure. I thought this would really annoy me, but it isn't that bad, and it does force us to use less water (I'm the only one in the house who would ever turn a shower on less than full bore!) The main problem is the pressure drop when the shower is on and someone else turns on a tap or the water softener goes into a regeneration cycle. There's still a tolerable amount of shower flow when that happens, but the pressure drop is quite noticeable. The plumber will come back and put in a higher pressure valve once the house is signed off. Let me measure the shower water usage tonight and get back to you. Edited to add: are you going for a single immersion? I've got one just above the ASHP coil, and another about a quarter of the way from the top, and I can choose which one to boost. When it's sunny, the diverter does the top portion first, then switches to the bottom immersion. Many days in summer we ended up with a full tank at 80C by lunchtime - for several months the ASHP simply didn't ever turn on!

Yep, I know 55 is plenty hot enough, but as you say, it's a matter of stored usable energy. I need to figure out whether I need the extra energy associated with the top-of-tank boost. Also, having the tank sitting at 55C should reduce standing losses over having some of it at 80C. Complicating matters: - I still haven't insulated all of the pipework yet, as I'm waiting on the final okay from the people doing the RHI stuff for me before fitting it. At the moment, standing losses are a lot higher than I expect them to be once the insulation is done. - We have waste water heat recovery on the two showers that are generally used. That should increase how much usable hot water can be delivered, but by how much I haven't a clue! (edited to add) And yes, in my experience, showering is the massively dominant factor for DHW usage. We use a dishwasher, so only occasionally use hot water at the kitchen sink. The runs to bathrooms are long enough that we don't bother with waiting for hot water to wash hands after using the toilet. Other than washing up things that can't go in the dishwasher, and shaving every couple of days, I'm struggling to think what other DHW we actually use! I get what you're saying, but I don't completely agree. It is a fact that I presently boost the top portion of our 250L tank to a higher temperature than the 55C generated by the ASHP. It is also a fact that we don't ever seem to run out of water despite my particular family's usage of 4-6 showers a day. I speculate that I can reduce the amount of boost while still not running out of hot water, and when I get the chance I'll do so and report back. Unfortunately, our bathing activities can't be as simply characterised as "X litres of water at Y temp", because our day-to-day showering activities are hugely variable. 80 degrees is the stat temp on the immersion element. There's a one hour boost controlled by our immersion diverter after the ASHP is finished its work. I haven't yet got things set up to be any more clever than that!

Mine's set up to do DHW between 5 and 6:30 am every morning. Temp for that is set at 55 deg. It then runs the UFH for several hours during the middle of the day (the most likely time it'll be able to use the PV) as required. This is set for the lowest possible temp of 25 deg - I wish it would go a little lower! There's a bit of weather compensation (max temp of about 28 degrees if it's below zero outside), but frankly I suspect weather compensation in the short-term sense is a bit pointless in a well-insulated house. I suppose you could run the UFH at the same time as the DHW and allow the TMV on the manifold to mix the temp down, but in my case there's no need to have them both going at once. I also don't like the idea of generating high grade heat at lower efficiency, and then mixing it down to a much lower temp.

This isn't quite our experience. We have an ASHP that runs to 55 degrees (5kW Panasonic Aquarea). I haven't experienced (or at least noticed) a lot of defrosting going on, although I only have last year's very mild winter to refer to. We presently top up the upper quarter of our UVC with the immersion to 80 degrees early every morning once the ASHP has the entire tank up to 55 degrees. Based on recent analysis, I'm not sure this is actually required - we always have quite a bit of hot water left at the end of the day. I'm about to start some experiments to see whether I can reduce or even do away with the boost, which would save up to 3kWh per day. We don't have a buffer tank. With in-slab UFH, I doubt there's any need, as the slab is its own buffer. I'm not sure whether this would be the case where a thinner screed is used.

As an aside, I believe Panasonic manufactures more air-conditioning & heat pump compressors than any other company in the world. I don't know how that translates into completed units - I assume they manufacture for others as well. But the general point is spot on: heat pumps are one of the best understood pieces of tech around. It's the same tech that's in every consumer fridge and aircon unit, and they are, in general, incredibly reliable. The important thing is to make sure that it isn't being asked to do more (or too much less) than it's designed for. In general, the bad reports from air source heat pumps installations have been in leaky, poorly insulated buildings where they just weren't the right answer. Build it insulated and airtight, and ASHPs are fine. You also need to think about whether your heating and hot water will be supplied by the same system.

Thanks all. First point, the architect did show a suitable detail, but in the heat of the moment (erm, several months long moment), we overlooked it. Second, there are no physical impediments that would allow me to argue for an alternative solution. There's an almost completely flat 5m wide driveway extending several metres directly away from the door. A bit of additional background for the sake of any other naive fools like myself reading this in the future: I wanted a built-up porch that mirrored the overhang (about 5m wide and 1.2m deep, from memory). I was concerned, however, about how to handle bridging between that and the house, given the porch would be at the finished floor level. I put off thinking about it far too long and the next thing I knew, the people doing the external hard landscaping were onsite and looking for direction. Annoyingly, if I'd given just a bit more thought to this at the time we'd have been able to sort something out fairly easily I'd have thought, but I didn't, so here we are. All part of the risk of not having a main contractor to blame! That would have been the plan if I'd thought about this before having the driveway completely laid and many square metres of large-format basalt concreted in place! If we go with a temporary solution, I have my eye on the side door (still accessible from the drive), which is a less obstructive place to put it. The additional issue with the side access door is that we'd need to widen a 600mm (one slab width) path to 900mm. No an insurmountable issue, but I need to compare the two solutions against each other. How do you think a BCO (private) would react to a clearly temporary structure? I guess they all know the games that are played, and perhaps this isn't an area they'd be interested in long arguments about given how little they have to gain.

Hi all Slowly working my way through our remaining to-do list for sign-off and have hit the access requirements of Part M. To be honest, I've been putting off dealing with this, as I know we're going to at least incur some annoying costs. My preference would be to have a collapsible ramp that we can put in front of our step if anyone in a wheelchair ever comes to our house, but I suspect our (private) building inspector won't go for that! So before I talk to him about this, does anyone have any experience in this area? Quick explanation of what we have at the moment: there's a large, flat paved area that a car can drive up onto, with plenty of space for a wheelchair user to exit the car. I believe that satisfies the approach requirements. The paved area is about 150mm below the highest point of the threshold, which in turn is about 10mm above the finished floor level. There's an 80mm gap filled with gravel between the threshold and the paving that allows any water making it near the door (there's quite a large overhang) to drain away. Here are some very rough not-even-close-to-scale drawings (plan followed by section): I clearly need some sort of ramp to allow a wheelchair user access. Looking at, eg, the NHBC's guidance document, I should be building a 3m long ramp at 1:20, but that would be ridiculous in the circumstances. There are alternatives given for steeper ramps with landings, which would shorten the necessary ramp, although then I'd need to include a landing just outside the threshold which will leave me not much short of a 3m approach anyway! So what options are realistically available? The simplest one would be a temporary ramp made out of, eg, wood. That would strictly satisfy the requirements, although I suppose the inspector could argue that it's clearly a temporary structure and refuse to sign it off. I know someone (Jeremy?) knew of someone who cast a temporary ramp out of weak concrete and demolished it after completion, but that seems a lot of work and waste. Before I talk to the inspector, does anyone have any thoughts or ideas? Many thanks

Cordless Makita multitool with tool-less blade change, as was discussed on another thread by @Ferdinand I think: http://www.ffx.co.uk/tools/product/Makita-Dtm51Z-0088381667418-18V-Lxt-Multi-Tool-Bare-Unit

Surely the title of that article should have been "Pitch Perfect"?

Morning and welcome. I understand that the passive slab approach works very well on soft ground. Indeed, when our (private) building inspector's engineer demanded a statement from us about why we chose this rather than more conventional foundations, MBC's (supplier of slab and timber frame) engineer pointed to the relatively low bearing pressure of the ground we're building on. We have an attached garage. There's a separate EPS upstand between the garage and the house so that the slabs are effectively thermally insulated from each other. The garage slab is still only 100mm thick on 300mm EPS, although there's a full width 100mm deep reinforcing rib every 1200mm or so from memory. One thing you do need to think about is the transition from outside to the slab (See here: http://forum.buildhub.org.uk/ipb/topic/416-handling-transition-into-garage-on-raft-foundation/). Feel free to drop me a pm if you'd like me to email you our passive slab plans.

I just realised that I started scratching the wasp sting on the back of my hand while I was reading this!

There are lots of youtube vids of people doing dumb stuff with wasp nests. Killed a couple of hours...

I walked face-first into a massive spider's web when I was about 11. I freaked out, and in the course of pulling at the spider's web, managed to wake up the wasps in the nest to which the main anchor thread was attached! Thankfully only one of them got me despite the number buzzing around, but I still remember how much it hurt.

Ha, haven't read Viz for years. Every year at the airport when heading off on hols, I used to buy Classic & Sports Car, Viz and Private Eye, and slowly read them over the course of the holiday. I haven't bothered with Viz since the kids came along (particularly since they learned to read!)

I do high intensity training three times a week and can't recall whether it's made a difference, but that might because I'm usually in a coma by the end of each session! Will take notes when I go again tomorrow!

Famous last words!

I was stung by one (a wasp, not a newt) on the back of the hand just over a week ago. No idea where it came from, and I smacked the blighter so hard when it stung me that I'm not sure where it went either! Took a week for the swelling to go down and the wound itself is still inflamed and itchy. Poor me.

I've tended to buy at the cheaper end of the Makita brushless technology, rather than higher up in the brushed range at a similar price. With brushless, you get more battery life, lighter weight for the power, and less heat. As someone said earlier, you're trading brushes as a failure point for electronics, but I haven't heard of any issues with the reliability of the brushless tech.

I was one of a couple who posted I think. I can dig the link out again if you're interested. They were just some well-reviewed 4Ah batteries from Amazon. Still going strong 18 months later. Having come from a very cheap 10 year old cordless drill, I still can't get over how much work I get out of a single battery (which is a good thing given that the second one I bought went walkabout from the site at some point!)

Definitely want to keep your hedge trimmed.

When it comes to battery power, you tend to stick with the first one you buy. Batteries are expensive, so once you have a couple, there's a very strong incentive to stick with that brand for other cordless tools. Most guys involved in building our house who had cordless tools used either Makita or Dewalt.

Makita all the way for me with this sort of thing. Their chargers take 20-odd mins to give you a full recharge - important when you don't want to be standing around waiting. There are also good options available for unbranded batteries.

Is the fencing his or is he renting it? If it's his, then I'd have thought it's his responsibility. Even if it's on hire, as you say, he should have been cracking on with the job. Not surprised you're annoyed, either way.