MVHR

Gas!

For some, the choice of a passiv-standard house and a gas boiler for hot water and UFH provision  would appear to be an odd one. Why not fit a ground or air-source heat pump (GSHP/ASHP)? Well, a number of reasons actually. GSHP aren’t cheap (could easily be £15k+ by the time it’s finished) and they require a fair bit of land into which the pipes are buried. Although our garden is a reasonable size, not all of it would be suitable for laying the pipework. ASHP aren’t particularly efficient and still quite expensive, although they are a chunk cheaper than GSHP. Gas on the other hand is pretty cheap to install and run – and we have a gas main running right across the front of the plot. On top of that our heating demand will be extremely low so paying out more than a couple of thousand for hot water just doesn’t stack up. Being efficient is far more important to us than fitting ‘stuff’.

I’d been warned many times that getting the utilities organised and connected was probably the hardest, or least most frustrating, part of the build. Not wanting to be caught out, I made initial contact with each supplier very early on in the process – I knew the gas connection wasn’t a priority but I still wanted to be on top of it all so I made the initial call to get it kicked off even before we’d broken ground.

That call amounted to Good News – the connection was relatively cheap (£400-ish); we had the option of digging the trench on our land for the pipe ourselves or letting them do it; and they only needed 4 weeks from start to finish. Easy! So I parked it.

Fast forward to the end of March and talk of needing to get the UFH up and running started. Obviously, we wanted to get it working in case there were issues that would need resolving but we also needed to get the floor fully dried and the system ‘run in’ before we laid the wood flooring and tiled the utility room floor. No problem, I’ll just get the connection sorted – it’ll be about 4 weeks.

One phone call later and 4 weeks became a stated 6-8 weeks! Major panic ensued, in me at least. I got the groundworks guys to dig the trench at the side of the house and National Grid came out to survey the site. All good except they weren’t happy with the duct I’d had installed in the wall of the plant room through which the gas pipe would route and instead they insisted that they drilled the hole themselves. Not in my house you’re not – you’ll use the duct! We had a discussion and everyone agreed that I was getting my way, which was nice 🙂

While the trench was open we had the BT duct, water pipe and a duct carrying the mains electric to the house laid at the appropriate spacing and depths. National Grid actually laid the gas pipe at the end of April – almost 4 weeks to the day after my initial order! Naturally I then proceeded to forget that I needed a gas meter. School boy error.

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Yellow is gas, blue is water, grey is BT

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Grey BT duct laid and pegged by ourselves. Gas by National Grid. Water and electric below

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Gas and others enter the plant room

You’re generally given a few options by National Grid as to where the meter is to be located. I think these days they like to fit them in a cabinet set into the external wall. Now, not only do they look ugly but in a highly insulated and air-tight house they are a Very Bad Idea. Another option is to have one installed externally at about ground level. I don’t like these either but if that’s what we have to have then so be it. In fact we didn’t need either of those two options and were able to put it inside the plant room right by the boiler, exactly where I’d planned for it almost a year earlier!

Meter installed (despite a load of par-for-the-course whinging by the installer) and we were up and running. Boiler fired up, UFH running, no leaks. We were in business. Of course, we were now into June and the weather was warming up. Good insulation, an air-tight structure, large amounts of glazing, high external temperatures and a UFH system that was being slowly ramped up to maximum isn’t a good mix. It was HOT inside the house. Really hot. Too hot to work comfortably, that’s for sure. No surprise then that the electricians switched it off a couple of times! One saving grace is that we’ve built on top of a hill (the slab is 79.00m above sea level) and with the windows and doors open we get a lovely breeze through the house, which did help to cool things down somewhat. It was still warm though.

 

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Gas meter installed

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Neat plumbing

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Plant room getting busier

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UFH pipes – thermostat heads ready to go on

Anyway, it’s off now. The next job is to try and work out which pipe belongs to which room/loop so we can fit the thermostats. I ‘think’ I know which is which but I’m sure we’ll find out sooner or later.

MVHR

Just one last job before I forget. The plant room was looking pretty untidy as I hadn’t bothered to connect the red MVHR ducts to the distribution boxes. I decided it was time to fix that. I’ve got a couple that I’d like to tidy a bit better, but it’s looking pretty neat now I think.

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A (Quick?) Update

There’s quite a bit to report on and as there have been so many different things going on it’s difficult to know where to start, so there might be a bit of jumping around and I apologise for that.

MVHR Jobs

The main job that’s been taking up our own time over the past few weekends is to progress the installation of the ducting for the ventilation system. All the pipes are in place with the exception of one which is a few metres short as we ran out, but it’s not really a problem as we have plenty of slack on other runs. Until we fix everything in place though  it will stay ‘pending’.

We’ve also now fitted the plenums for the ventilation system. These  are simply a plastic tube with a couple of small openings and one large one – the red ducting fits inside the small openings and the larger opening leads into the room and is fitted with a valve that allows us to adjust how much air is allowed to flow through the plenum (either as an inlet or outlet). At the moment the plenums have been fitted so that the large opening sticks out quite a bit through the wall or ceiling but this will be trimmed flush when the plasterboard has been fitted. The valves just push in and will be done after decorating. All the plenums are the same so where there is only a single red duct to it then the redundant opening is sealed with a bung.

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Plenum with 2 duct and plenum with single duct

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Plenums serving the two main bedrooms

Theoretically I could get the ducts fixed into place now but I’m going to leave it for a couple of weeks or so, at least until the acoustic insulation has been fitted.

Acoustic Insulation

As part of building regulations, the house has to be ‘insulated’ acoustically. Aside from it being something that we have to do, it’s something that we would do anyway to improve how the house feels and sounds – there would be nothing worse that it sounding like a wooden drum! I think the regulations call for something like 50mm thick insulation in the walls and 100mm in the ceilings but I was happy to pay the extra for 100mm all over for, hopefully, better sound insulation and a more solid feel. I’ll have no idea whether the additional outlay was actually worth it or not though!

We initially took delivery of 30 bales of 100mm thick Rockwool – each bale contains 5 or 6 slabs and covers just under 3m2. We know we’ll need a lot more than this but it does take up a lot of space so only got what we could use for now.

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Rockwool Bales

Rockwool is made from volcanic rock and unlike some of the fibreglass-based products isn’t that bad to work with. It cuts easily with a large knife and isn’t anywhere-near as itchy when it’s on your skin. You still need gloves (and ideally a mask too, especially when working overhead) but it’s fine really.

We knew it would take a while to do the whole house so we made a start while we could, focusing upstairs in areas away from where the electrician and plumber would likely need access. I think we got through about half the bales before my dad took over and finished the lot off! Thanks dad 🙂 Unfortunately for him I’ve just order another 40 bales and I think we will probably need another 40 more.

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Acoustic insulation on landing almost finished

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Acoustic insulation in bedroom 2

So far we’ve done most of the landing area and odd bits in the bathrooms and it’s noticeable how different the house now feels in those areas. It’s almost starting to feel like a house now rather than just a shell.

Cat’s Paw

As an aside, I needed to remove a few of the boards that were installed to help keep the stud walls solid – these are just 11mm OSB fastened to the studs with nails from a gun. The first one I removed by punching the nails in (with a punch) and it took aaaaages. Just after I finished, Darren from MBC suggested I get a Cat’s Paw tool to do the rest. I thought he was joking but a quick Google threw up what I was looking for.

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Japanese Cat’s Paw Tool

Essentially it’s a small hand-tool about 200mm long of Japanese origin and is really good at removing nails without destroying the timber. Obviously it does leave marks but nowhere near as much as you might think and it’s really quick. If I had a top 10 list of hand-tools this would be my number 1! (I might well have a top 10 list, but if I did it would be a secret, although a pair of oil-filter pliers might also find their way onto the list too. At number 7)

First Fix Electrics

First fix has officially started in earnest.

Work on the electrics started upstairs with all the cabling for lights, sockets and switches being routed and back-boxes fitted where needed. By and large we’ve opted for double sockets everywhere (most room corners) and supported by additional 5A sockets. The 5A sockets are a useful addition as they allow you to have floor and table lamps switched from the wall just like a normal light. This is great for us as most of our lighting, in the bedrooms at least, is quite subtle and in contrast to the approach taken by many. I’m not sure why people see the need to flood-light bedrooms, bathrooms and the like.

Lighting

On the subject of lighting, I’ve been working with Guy at EcoLED to come up with a lighting design for the interior, with a focus on the ground floor. EcoLED produce some stunning luminaires and we’ve gone for what I believe to be a one-of-a-kind design – we’re using their Zep6 Eyeconic  Trimless range which are very small and have a directional ‘eye-ball’. Each item is anodised with an mid-bronze colour and then hand finished to give an antique look which should look stunning next to the rest of the modern interior. I’ll do more of a feature on the lighting when it’s time to fit it.

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Memories of an aeroplane safety briefing

First Fix Plumbing

This has also started but is lagging the electrics by a couple of weeks but despite this I’m hoping that it will be finished in 2-3 weeks. Part of first fix is to fit the Geberit frames for the wall-hung WCs. These, plus the Hansgrohe iBoxes that are used to control the showers were bought direct from Germany through www.reuter.de Their prices and service is superb and we’ll be getting the majority of the bathroom kit from there as needed.

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I’ve also had a little bit of stud-walling and boxing-in fabricated. We don’t yet have a joiner (yes, I know it’s a timber-framed house!) so I took a bit of a leap of faith to find someone off MyBuilder. It’s not a difficult, nor critical job, but to be fair he did what I wanted at a price I was happy to pay so all good. I did offer him the chance to fit the timber cladding but his quote of 20 man days for 50m2 was a little on the high side as I reckon on it taking about 5 man days. He had the chance of lots of work on-site, which he openly admitted he wanted, but he blew it by being greedy. There are some idiots around.

Media Distribution

As part of the first-fix wiring, I’m going to be routing  network cables to the locations where we will have, or may have, a TV point. At each point there will be 3 Cat6 cables and 2 co-ax and they will all be routed to a central location from where the different sources will be located. What this will mean is that each satellite receiver, DVD player etc. will be able to serve all locations and won’t need to be sat under the TV. This will be achieved through the use of an HDMI matrix and in our case we will use a 4×4 matrix, which means 4 sources can be distributed to 4 locations.

So what are all the cables for, I hear you ask? One Cat6 will be used to carry the signal to the TV. The way it works s that the source (DVD for example) is linked to the matrix by an HDMI cable. A Cat6 cable then carries the signal to a ‘balun’ behind the TV and the balun is connected to the TV by another HDMI cable. In this way an HDMI signal can be carried over Cat6. The second Cat6 is a standard network cable for the smart TV and the third is a spare. The co-ax cable allows us to send a standard satellite or terrestrial signal direct to the TV if we wanted to – we’re unlikely to do this but it’s easy and cheap to do it now so it would be foolish not to.

Some might call all this ‘future-proofing’. Others might suggest that more cables or the use of Cat6a or even Cat7 would tick that box. The reality is that they’d all be wrong. Future proofing would allow us to change the technology easily, say to fibre or magic fairy dust, but all we are doing is allowing for better capacity.  Which is fine for me, as I’d rather be out driving or playing the guitar. Just thought I’d make the observation 🙂

Aluminium Pressings

Finally, these will be fitted next  week! Getting this done will allow us to get the rendering and timber cladding finished and then we can get the scaffold down and off hire.

These pressings will be fitted to the parapets and as copings and also as decorative trims above the large first floor windows. They will coated with the same finish as the windows and should look superb when done. I’ll create a new blog entry for these in a week or so.

We are still waiting for the ridge end caps and a rainwater hopper but these should be with us next week.

Letter Box

We’ve started to get mail! This is a Bad Thing as it’s usually bills or junk but it prompted me to buy a new letter box which I mounted on the gatepost…

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Ventilation first fix

This is a job I’ve been putting off for a few weeks. I had intended to fit the ducting over the Christmas holiday period but the reality was it was cold and I didn’t fancy it! It would have been different if it was holding anything else up but it wasn’t 🙂

As the house is so air-tight (did I mention we achieved 0.21 air-changes per hour in a recent test?) we need to find another way of supplying fresh air. The solution is a Mechanical Ventilation and Heat Recovery (MVHR) system, which will be housed in the plant room. Fresh air from outside is drawn in and passed through a heat-exchanger before being ducted throughout the house. Stale air is extracted and again passed through the heat-exchanger before being ducted outside. This is normal practice for houses such as these! The MVHR is not a complicated pieice of kit and is probably even easier to install.

Routing the ducting

First fix requires that the ducting is routed throughout the house according to the design that was put together for us by BPC Ventilation, the suppliers of our system. Essentially, fresh air is pumped into the habitable rooms (lounges, bedrooms etc.) and stale air extracted from the wet areas (bathrooms, kitchens etc.).

The upfront design of the route the ducts take is largely ignored by most, but lack of planning before construction of the building can be problematic. I spent an age on the design (with both MBC Timberframe and BPC Ventilation) and even then there were challenges to overcome. One area that the design did highlight was that we needed a number of penetrations through the steels and each of these was cut to 85mm in diameter. We also had additional holes cut for the electrics and plumbing, just in case.

The ducting

For this first fix we have used 400m of 75mm Vent Axia Quiet-vent radial ducting – the red pipe in the photos. It’s not a difficult job so we did this ourselves over the course of a weekend. At the moment we have left plenty of slack on each duct in case we need to re-route anything but as a consequence we are slightly short for the final run. Not an issue though as, hopefully, we can join together any spare lengths we end up with.

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Penetrations in the main steel

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Posi-joists make routing a lot easier

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Duct ready to receive the plenum

It’s going to be ‘busy’ in the plant room so once first-fix plumbing and electrics have finished, I’ll get it all tidied up as best as I can. That should be a fun couple of days!

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Plant room getting busy!