One of the options that attracted us to the Ground Sourced Heat Pump was that you could also use the return feed of cold water to cool the house in the summer. Although 2007 and 2008 have hardly been blistering summers, only three years ago everyone was talking of summers getting hotter and hotter. So two comfort cooling units were added to the heat pump order to cool bedrooms and the lounge.

But having decided to fit a heat recovery system since we bought the comfort cooling units we have to think about how we duct the whole system. After considerable discussion with those in the know, we have decided to duct the comfort cooling system separately. The Heat Recovery system has a “summer bypass” that is a thermostatic switch which cuts out the heat recover element if the ambient temperature goes over a certain level and we will set the comfort coolers to cut in at that same point – hopefully!

Of course all this means our super tilt and turn windows and trickle vents will be unnecessary and the idea of living in a house where you do not need to open windows is not going down well at present. Only by living with it will we see how it performs. 

 You can run the pipework in a variety of sizes. Main ducts are 150mm in diameter close to the unit, branching off to 125mm and then sometimes down to 100mm if you wish. In some tricky places you can use the rectangular equivalent of these round sizes to get round corners or reduce the size of pipwork that you are boxing in.

We finally gave in and decided to include two fitted cupboards which will hide pipe runs between the first and second floors and here the rectangular section is a neat space saver. 

 Here’s some 125mm diameter heat recovery pipework over the kitchen. It’s one thing working out what you need on paper, but working in 3D with the really thing is very different, and you find you are ordering more and more pipes, bends, connectors etc.

Initially we thought the best place for the heat recovery unit would be over the kitchen and bathrooms, but after working on it in that position for a day there was a sudden eureka moment when we realised that putting it on the other side of the house would shorten 2 of the 4 pipe systems (fresh air inlet and “wet” air exhaust) substantially so we remounted the unit and started our three dimensional puzzle afresh. 

 We have been convinced that putting heat recovery in the house will improve the energy efficiency and air quality in the house. So here is the unit, which will take warm and smelly air from “wet rooms” such as the kitchen, bathroom, WC etc, take the heat out of it using a heat exchanger and transfer that heat into fresh air from outside that is then fed into the “dry” rooms, lounge, bedrooms etc.

 The ground workers are back and we can start putting the rain water pipes in to get rid of water from the roof. However, again after much reluctance we are going to add a little something else. Watch this space

 Here is our last close up for now. We will try to get up with a ladder to keep you updated later in the summer.

 From our close up collection of the sedum roof before the scaffold came down, more Yellow ones

 As we have two ground source loops in 32mm pipe coming into the house, they will have to be joined up, or “manifolded” as a plumber would say into 38mm pipe. Here is the neat manifold that comes in the kit from the heat pump suppliers with shut off taps. There is one manifold for the incoming “warm” water/glycol mix at about 12 degrees C and one for the returning cold water which will typically be around -5 degrees C.

 So now the scaffold is down we have unfettered access to the outside of the house and can bring the ground source heat pump loops inside. The 32mm groud loop pipe has to be sleeved with closed cell foam for the last few metres as it approaches the house because it will be running at well below zero on the return side and could freeze the ground or any water pipes near it. Each 2 metre length of “Armaflex” is glued to the next with contact adhesive applied with a brush. You must use Armaflex because other plumbing products are not closed cell and will allow water into their structure which will freeze. Armaflex is available as a tube or a tube with a slit down the side. It is better to use the version without the slit and slide it on before you pass the pipes into the house if you can organise this.

We also  decided to give some mechanical protection to the Armaflex by sliding 85mm land drain pipe over it. Not the easiest of jobs due to the natural curve in the pipe and in the end we cut the 3 metres of pipe we needed into three bits to slide each one over.

 The outside of the house is leveled up and a perforated pipe is put in at the house boundary, backfilled with 20mm rejects and then covered with Teram (geotextile membrane) to create a land drain or “French Drain” to help keep the lawn dry in heavy rains. This will be hooked up to the rain water drain and then fed into our next bit of fun, a rainwater recovery system for toilet and washing machine use.