Part Twenty Three – Odds And Ends And First Fix

This twenty third entry was published originally by JSHarris on the 6th December 2013 and received 1,388 views on the closed forum

A bit of a mixed week. The roofers are nice enough lads, but frankly having to lend them my tools so they can do their job (like snips, a circular saw and a drill) together with their failure to turn up for days on end and their inability to arrange for suppliers to deliver as required, means they won’t be getting a recommendations from me. I’ll refrain from mentioning their name for now, but when they have finished they will will get a mention for being, like so many others in the building trade, totally disorganised.

This week has been full of doing what I thought would be simple first fix jobs, but which have taken far longer than I thought, and have been interrupted by sorting out problems with sub-contractors. Right now I can positively recommend our ground works contractor, Digging It, Andover, our frame and foundation supplier, MBC Timberframe, our brickie, Chris Coward (CC Brickworks) and our renderer/plasterer (Rafe Gulliver, Vale Plastering). The rest are either in the “insufficient information to form a view” category, or are in the “definitely don’t deal with these people” category. I’ll hold off with the full list of good and bad contractors until the end.

I am finding that, at least locally, the young guys are generally doing the best work and showing the greatest commitment to both customer service and doing a good job. It’s getting to the point where I will take a chance on a younger guy than risk getting dicked about by a long established local firm.

Another change this week has been the switch to me doing a lot more hands-on work, in fitting the MVHR system and all the first fix plumbing. Some of this has been cost driven, some driven by my desire to get a job done that met my (perhaps rather demanding) specifications. I also wanted to be sure that the MVHR ducts were not constrained by wiring put in by the electrician, so wanted to get them in first.

A big cost saving was to buy the active MVHR unit we wanted directly from a supplier in Denmark, rather than through the UK supplier. The cost saving was enormous, even with 25% Danish VAT, and shipping the exact same unit was around £5,000 from Denmark, when the UK supplier wanted £7,933. I would strongly encourage anyone looking at buying any costly item that’s manufactured elsewhere in the EU to shop around, and ignore UK suppliers. Our experience has been that rip-off Britain in still alive and well.

The unit we’ve opted for is the Genvex GE Premium 1L. This unit has an air to air reversible heat pump that can provide around 1kW of cooling in hot weather or maybe 2kW of heating in cold weather, via the MVHR system. We won’t need to run it at this sort of capacity, as the small ASHP that warms the underfloor heating will do the bulk of the the heating, at a sightly better COP, but it will be a useful way of providing quick heat (and cooling) via the air supply.

Plumbing was a bit of a problem. We wanted to run a lot of the pipes under the first floor, where they would be inaccessible later. I wanted to avoid having any joints under the floors, and after a bit of debate on a thread here was steered towards using small bore copper (because I also wanted to reduce warm-up time at the taps. I have to say this turned out to be a nightmare. Try as I might I could not uncoil 10mm copper pipe and feed it neatly through the Posijoists. It snagged on the sharp internal edges of the metal webs and was very difficult to get to run straight and neatly. After a few hours getting a single run of hot water pipe in across to the kitchen sink I called it day, and ripped the lot out.

I switched to the dark side and bought a 100m roll of PEX pipe and a load of fittings and clips. What a revelation! This stuff is so very easy to lay, and I’ve now plumbed in the kitchen, downstairs WC/utility room and both bathrooms with 15mm PEX, all led back to a pair of 15mm manifolds fed from 22mm copper pipe connected to the hot and cold systems. This went in very easily indeed, in fact it was a doddle to fit. I now have radial 15mm PEX runs to these rooms, all fed from a 22m feed right adjacent to the thermal store and cold rising main. Dead legs are al pretty short, so hopefully taps should run hot pretty quickly. The hard part was fitting double clip-fit 15mm pipe clips to the joists, and getting adequate pipe support, I’m hoping that clips every 400mm will be enough to hold the runs place. To make these detectable behind the plasterboard I00mm wide lengths of aluminium tape were stuck to the service duct space wherever the plastic pipes run. Hopefully this may reduce the risk of someone drilling through the pipes in future.

The last event of the week was to take delivery of the Newark custom built, double insulated, 210 litre thermal store and the double insulated 64 litre buffer tank for the heating/DHW pre-heat system.

Next week promises to be hectic. I have two chippies on site doing the larch cladding, the roofers are (supposedly) back on site, a couple of guys are (supposedly) turning up to do the fascias and soffits and the electrician is (definitely) turning up to do the rest of the first fix electrics. With me finishing off plumbing in the thermal store and buffer tank, parking space on site will be tight.

The electrics have changed a wee bit, as when I pulled the three core 25mm2 SWA through the underground duct today I realised that it would make more sense to put the airing cupboard in the utility room, above the buffer tank, and put the CU and incomer in the service space on the first floor. Luckily there’s enough spare 3 core 25mm2 SWA to do this.

The final job this week was to remove the 100A isolator I’d fitted in the meter box, re-jig the old meter tails into the Henley block that feeds the auxiliary CU in the cabinet (the garage, builders supply and sewage treatment plat feeds) and fit a new 100A fused isolator from the Henley block. This will connect to the 25mm2 SWA that feeds the house. The meter has a built in isolator (damned good idea) so makes this sort of work easy and safe (and it will be checked and signed off by a Part P chap).

So. now I will have a “plant room” upstairs that will house the MVHR, the thermal store, the CU and all the ducting. It will also have the controls for the UFH, the over-ride timeswitch for the thermal store and the diverter unit to pass surplus PV to the immersion heater in the thermal store.


joiner 07 Dec 2013 11:15 AM :

 A short sigh of relief then?


 jsharris 07 Dec 2013 12:03 PM :

 Plenty of sighs, Dave, along with groans as I discover yet another aching muscle or bruise!

 I have learned that it is a real pain working on your own. Take one simple job I did yesterday. I needed to put a bit of 25mm duct through the insulated wall right up near the eaves, so that I can run the satellite cables in easily. I made up a long 6mm pilot drill by turning down the shank of a 6mm wood drill to 3mm, drilling a 3mm hole in the end of a bit of 6mm rod and brazing the two together. This gave me a 6mm drill around 400 mm long that I could drill right through the wall with, at a very slight downward angle. The plan was to then drill a 25mm hole either side, using the 6mm holes as pilots. I’d also turned up a bit of 25mm ABS into a cone, with a stepped shoulder that was tight push fit into a bit of 25mm conduit, the idea being that the cone would push the Warmcell insulation out of the way as I pushed the bit of conduit through, and help centre the duct in the hole on the other side.

 A great plan, you may think. So, I drill the pilot from inside, as high as I can get it in the service space, well clear of the internal timbers in the frame. I leave the pilot drill in when it’s right through and climb downstairs and look up to make sure it’s sticking out in the right place outside. I then climb the ladder back upstairs and pull out the pilot drill and open the inner hole out to 25mm, then climb back down, go outside and climb three ladders up to the top scaff level at the eaves. There I drill out the outside hole to 25mm and try to push in the conduit. Will it go in and line up with the hole inside? Will it heck as like. Back down three ladders to ground level and up one ladder to the first floor and up the step ladder to see if I can poke my finger around in the hole and feel which way the conduit has gone. Repeat this process about three times, before deciding it won’t work and pull the conduit out. At this point I have to sit down for ten minutes, because I’m knackered from running up and down bloody ladders for the previous half hour.

 Go back up to the top inside, armed with the long pilot drill and find that I can easily poke that through from inside. Go back down to the pile of surplus reinforcement bar I have and find a 2ft length of 12mm rebar. Climb back inside and manage to get that through to outside OK. I then remove my far too clever ABS cone and thread the bit of conduit over the 12mm rebar and after a bit of wiggling get it through. Go back out, up three ladders and seal up gap around conduit and inside area where it comes through the outside layer of OSB with squirty foam, then apply some sealant around it to be sure nothing can crawl in around it (this will be behind the larch cladding, in the void behind it). Back down all the ladders, inside and up two more ladders to seal the inside and make it airtight with bits of Siga tape.

 One simple job that took me maybe an hour and a half on my own, but which could have been done in may be ten minutes with two people. I have a new found respect for those who self-build single handed – it’s knackering and very frustrating at times.

 BTW, once the four sat cables and one DAB cable are through that conduit it will be filled with low expansion foam to seal it up


 SteamyTea 07 Dec 2013 01:54 PM :

 Just think how you will feel when you watch a self build homes programme.

 I don’t have a telly.


 ProDave 07 Dec 2013 04:13 PM :

 Well I’m an electrician, and I work on my own most of the time.

 I’ve had the same thing this week, rewiring two cottages being knocked into one.

 The process involved drilling two 25mm holes through 2ft 6 stone walls to feed the interconnecting cables through.

There’s no door between the two yet, so the process involved MANY trips down the stairs, out one front door, along the street, in the other front door, up a ladder into the loft (one cottage is a bungalow) and crawl along the loft to where the hole has (hopefully) come through.

 But glad you are making progress, and your difficulty using microbore copper pipe noted.

 Re your plant room and CU in the plant room. Just take note that building regs require a CU to be accessible, and has to meet the silly socket and light switch height requirements, but you should be okay as long as it’s between 400mm and 1200mm from the floor.


 jsharris 07 Dec 2013 05:47 PM :

 You have my sympathy, Dave! All the running around, up and down ladders just seems to waste time and energy when I should be using it to get the job done. I’ve been recommended a couple of local young lads who’ll work as labourers on an ad hoc basis, so may look at hiring one of them for days when I could really do with an extra pair of hands. Has to be less stressful paying someone £70 to £80 a day to just give a helping hand than do all this running about, even if I have to give clear instructions for every little job.

 This is the new layout for the services area.


The door into it leads into bedroom 2. The thermal store, MVHR and MVHR ducting were going in here anyway, all I’ve changed is to decide it’d be easier to put the CU up there as well. All the cable runs are through the Posijoists immediately underneath the floor, so it should make for an easy wiring job, with all cables dropping from the CU to the under floor space then running through the Posijoists and up or down via the 5omm deep service space for either the upper or lower floor.


 ProDave 07 Dec 2013 05:53 PM :


I would have perhaps put it nearer to the right end of the mvhr, closer to the thermal store. Knowing how cupboards fill up, with “stuff” you might find it hard to get to if something trips.


 jsharris 07 Dec 2013 06:08 PM :

 If the length of SWA allows it I may do that, Dave.

 At the moment I’m not sure how much slack I’ve got. 3 core 25mm² (with blue, brown and green/yellow cores) isn’t cheap, so I ordered 15m to allow for a bit of slack when the CU was going to be on the wall on the floor below. At the moment there is perhaps a metre spare at the meter box end; I need to check and see if I can pull another metre through the duct into the house and still leave enough to hook up to the gland on the base of the meter box and up to the new 100A switched fuse I’ve installed near the top of the box. The meter box wiring got changed yesterday, when I removed the 100A unfused isolator that was connected directly to the meter tails and was feeding a Henley block. I’d realised that doing it this way didn’t provide additional fused protection for the house feed cable, it relied on the company fuse, which is a no-no (even though it’s the same rating, 100A, as the new switched fuse I’ve put in………………)..

 I shifted the meter tails down to the Henley block directly (handy having a Siemens meter with a built in isolator!) so now the Henley feeds a 2 way CU in the meter box that feeds the external electrics (a 16A socket, plus the treatment plant and garage supply) and also has a pair of 25mm² tails that feed the new switched fuse, which will then feed the house via the length of 25mm² 3 core SWA.


 ProDave 07 Dec 2013 06:34 PM :

 I would put an 80A fuse in your own switch fuse.

 Yes connect up being as efficient as you can in the meter box, with any slack getting pulled back to the house, and see where it will reach to.

 Relocate your own switch fuse near the bottom of the meter box if that buys you a little extra SWA.


 jsharris 07 Dec 2013 07:19 PM :

 Good plan, the switched fuse came with a spare 80A one, I’ll swap them over.

 I suppose another alternative might be to stick another Henley where the SWA will reach, plus an earth block, then run new tails from there to the CU. That would get the CU a fair way over to the right and closer to the thermal store.


 ProDave 07 Dec 2013 07:53 PM :

 Yes two henleys as close as you can get them to the SWA termination.

 some electricians will argue you should not have the exposed cores of an SWA exposed anyway except inside an enclosure, as (unlike meter tails) they are only single insulated and not sheathed.

 Don’t forget the banjo to earth the armour of the cable at the gland in the bottom of your meter box.


 jsharris 07 Dec 2013 08:29 PM :

 I agree with the exposed SWA cores, and have grey sleeves to go over them and retain the double insulation where they are exposed. The SWA external gland in the meter box is already banjo’d to the earth block. The in-house end of the SWA is being sealed off at the cut reinforcement/outer sleeve with a heat-shrink sleeve, that will not only close the end of the cable off neatly but will ensure that the additional grey sleeves over the L and N cores are bonded tight to the end of the cable.

 I’m hopeful that I can pull enough extra through to get the SWA across a bit further and allow the CU to be shifted right, where there’s more headroom.


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