• Content Count

  • Joined

  • Last visited

  • Days Won


JSHarris last won the day on January 9

JSHarris had the most liked content!

Community Reputation

2,795 Excellent


About JSHarris

Personal Information

  • About Me
    Retired scientist, made the decision to build our own home a few years before retirement, then had the good fortune to be able to retire early and start the self-build journey. Started our build in late 2013, took far longer than anticipated to finish, but have now moved in and we are enjoying having a house with no bills at all (except for the blasted Council Tax...). The house pays us a modest income from the excess energy we generate, over and above the energy we use for heating, cooling, cooking, hot water etc, so we now have a healthy retirement holiday fund.
  • Location
    Wiltshire/Dorset Border

Recent Profile Visitors

6,428 profile views
  1. I did pretty much the whole design, plans, planning permission, building control submission etc myself, having had no previous experience of it at all, other than a bit of DIY over the years. I found it a steep learning curve, but as I was time rich and cash poor I didn't mind spending a lot of time getting to grips with everything, although this was helped by there being a year of enforced delay between having our offer for our plot accepted and actually exchanging contracts, because of some legal issues that the vendor needed to resolve. The one advantage I had was being reasonably competent at producing drawings, and being familiar with using CAD (which itself is a steep learning curve if you've not used it before). The one professional service I had was a topographical survey, which provided me with the base model from which I could produce pretty much every drawing. This cost around £400, IIRC, and the survey company provided me with an electronic copy of the file that I could just load into AutoCAD and work with straight away. The hardest bit of the whole process I found was getting the design to look right. Drawing up houses in CAD is easy, but not being an architect, or having any experience of architectural design, meant I struggled a lot to get a design that actually looked OK, as well as having all the functionality we wanted.
  2. I've never seen the learning behaviour, but according to the manual it must have done it when I originally wired it up for the very first time. It doesn't do this every time it's powered up, though, as it seems to have a supercapacitor inside to allow the calibration to be remembered for a fair time. There is a procedure for getting it to recalibrate, which involves powering it on for 20 seconds, then powering it off again within one minute, then powering it on again, when it will go into the calibration mode. Mine's powered off except when there's a call for heat, and it opens up and starts to regulate within about 30 seconds at the most, until it has settled to its initial opening point. I've not seen the 2 minute turn on time that is given in the manual, and suspect that may be for the worst case condition As the manifold starts to heat up it will occasionally motor the valve for a few seconds as it readjusts, but that's all. When powered off the internal spring just winds the valve back to being closed again. Mine is screwed tight down on to the head, and isn't at all loose. The manual for them is here: https://www.salus-controls.eu/media/product/docs/thb23030-qb-we-v003-compressed.pdf
  3. The simple answer is that they don't have any learning period as such, they just work to maintain a set temperature differential between the two sensors (they don't care which way around the sensors are fitted, either). The flashing LED means the motor is operating to open or close the valve a bit, so they will periodically do this as they motor the valve in order to maintain the temperature differential. The actual temperature differential they try to achieve depends on the flow temperature, so if it's below about 30 deg C (IIRC) it tries to maintain a 4 deg C differential, above 30 deg C and I believe it tries to maintain a 7 deg C differential.
  4. JSHarris

    Roof sarking boards. Treated, untreated.

    Yes, that's what we have. OSB3 sarking boards, then 50 x 25 counterbattens nailed through along the line of the rafters, then non-tenting membrane laid over the counterbattens, then 50 x 25 slate battens nailed to the counterbattens over the membrane. It makes for a very solid roof, and because we have very deep (400mm) rafters, hung from a ridge beam, with no purlins, it also adds a lot of cross bracing and stiffness to the whole roof structure.
  5. JSHarris

    Roof sarking boards. Treated, untreated.

    It's very much a regional thing. Sarking boards were always used with slate in Scotland, and it's become standard practice there to use sarking on any roof now. Our new-build bungalow in Scotland had a tiled roof, bit still had plywood sarking. I really like the idea of sarking boards, for a few reasons. They stiffen up the roof structure a fair bit, help to prevent wind-wash through the membrane and also reduce rain noise a bit. In addition they make life easier for the roofers, as there is a solid roof under their feet and they aren't reliant on just the strength of the battens when working up there.
  6. JSHarris

    Air Test Passed

    Just the one. IIRC the result was 0.43 ACH @ 50 Pa, so massively under the Part L1A maximum allowable. This included some known air leaks at the door locks (easily fixed with the injection of some very thick, aerosol-applied, motorcycle chain lube) and leaks at two doors where the hinges and catches needed some adjustment (again, easily fixed, although a bit fiddly to do in the case of our French windows). I'm certain our airtightness is now better than when the house was air tested, but whether this makes any measurable difference to performance is debatable. I'm inclined to think that once you get down to below 0.6 ACH variations from changes in the wind speed outside impacting on the MVHR are probably a greater influence. I found that when balancing the MVHR there was a pretty wide degree of variability in flow rate as the wind gusted outside, presumably due to local small dynamic pressure differences between the external intake and exhaust. Not worth worrying about, but it was clear that this variation probably swamped any variation from air leakage.
  7. JSHarris

    Kitchen tap flow restrictor

    The problem with that is that it tends to result in a greater variation of flow from one outlet when another is turned on. I had a pressure reducing valve fitted when we had the original thermal store, and found things were much more even when I took that out, when I fitted the first Sunamp (which didn't need the pressure reducer). Fitting restrictors in the tap fittings also has the advantage of lessening the interaction between outlets even more, not that this effect is very noticeable with a manifold distribution system, but every little helps. We've found that the ceramic insert taps, in particular, are a lot easier to control than before I fitted the flow restrictors, but it's perhaps worth noting that our water pressure is reasonably good; it's always between 2.5 bar and 3.5 bar.
  8. JSHarris

    Positive placement nailer

    Yes, or missing the strap altogether!
  9. JSHarris

    Staple gun - recommendations wanted

    I've probably had three or four hand staple guns and all have had their problems, from being very fussy about the type of staples used to just randomly jamming and being awkward to clear out. A while ago I bought a cheap (around £40) air stapler and it's never once misfired or jammed, so I'd say go for one of those if you have access to compressed air. By the same token I have an air nail gun, and that has never jammed either, unlike the Paslode guns the guys who put our cladding up were using, which seemed to need pretty regularly cleaning in order to keep them working reliably. Mind you, I'm a big fan of air tools anyway, so may be biased.
  10. JSHarris

    Positive placement nailer

    If you need to drive a nail precisely into a hole, say in a strap or joist hangar, then you need a positive placement nailer, as they they do what their name suggests, put the nail exactly where it's needed. An ordinary first fix nailer isn't very accurate; it will put the nail in more or less where you want it, but can be a few mm out as there is no guide as to where the nail is actually going to go.
  11. JSHarris

    Kitchen tap flow restrictor

    Spot on. I just fitted restrictor washers in the tap connectors, dead easy to do as they just replace the rubber or fibre washer that's in them as standard. Cheap too, and makes some taps a lot more comfortable to use, with less splashing. We had a building inspector who insisted on them being fitted, which I thought was a pain, but the only ones I've since removed are those on the shower and bath, as all the others reduced splashing and made the taps easier to use.
  12. Both the same thing. All lithium chemistry cells are lithium ion, and all use a polymer electrolyte/separator, so the terms are interchangeable. The difference is all to do with the electrode chemistry, with LiCoO2 being lithium cobalt oxide, LiFePO4 being lithium iron phosphate and LiCoNiAl02 being lithium cobalt nickel aluminium oxide. There are other variations, too, like LiNiMnCoO2, lithium nickel manganese cobalt oxide, LiMn2O4 and LiMn2O3, both lithium manganese oxide and a few others.
  13. JSHarris

    Air Test Passed

    This is the first part of the reply from our Building control Area Manager after I sent in the Air Test Certificate and EPC: This was followed by a request asking me if I'd provide a couple of hours on site to chat to some building inspectors, planning officers etc about how we'd gone about building a house that was so much better than the requirements in Part L1A...
  14. I believe that the "throughput" is measured as equivalent charge/discharge cycle capacity, in kWh/day. Batteries are still, to a large extent, cycle life limited, with even the very best dropping capacity after a few thousand charge/discharge cycles. It's quite possible with a home battery system to have several charge/discharge cycles per day, if the house has a big PV system, and uses off-peak charging as well, so 1000 cycles per year seems possible under a fairly extreme use pattern. That's a fair bit more than most electric cars, that probably rarely go over around 300 cycles per year (judging from a month of ownership I'd say my electric car usage will be well under 100 charge/discharge cycles per year). i can understand Tesla being concerned about this, as the battery chemistry they use is inherently less capable of tolerating a large number of charge/discharge cycles than some other battery chemistries. For example, the Pylontech home batteries use LiFePO4 cells, that have more than double the cycle life of the LiCoNiAlO2 cells used by Tesla, but have a lower energy density and so are less well suited to high power electric vehicle use (FWIW my electric motor cycle originally used LiFe PO4 cells, I changed to using LiCoO2 cells and got more than 5 times the max discharge current and double the range from a pack 2/3rds the size, albeit with increased fire risk). For home storage I'm in no doubt at all that LiFePO4 cells offer far and away the best long term prospect out of all the lithium chemistries currently available. They are bigger and heavier for a given capacity and maximum discharge rate, but that doesn't really matter too much in a home storage application, where weight isn't really a critical issue.
  15. Sod all to do with making one, just about knowing how they work so that one that does heating and cooling can be chosen. Not rocket science, just a matter of reading the specs and understanding that the manufacturers of ASHPs often hide the fact that they will cool just as well as they heat, perhaps because to be eligible for the RHI the cooling functionality has to be hidden, even though it's always there for a heating ASHP.