Category Archives: underfloor heating
We have found the leak under the floor in one of the downstairs bathrooms. This has entailed digging up some of the newly laid screed, but it is better to find it now than after the floor has been tiled.
The ground source heat pump was delivered on Monday and we have spent the last couple of days getting it installed. Most of the pipework is now installed, however, there is probably another day’s worth of pipework to go. The electrician is due in tomorrow to start wiring it up.
We hope that the system will be up and running (although in a limited capacity) by the end of the week. This will mean that we should have heat in the building over the festive period. Because we have laid new concrete floors these need to be dried out – and slowly otherwise we risk them cracking. We also want to dry out all the wood (particularly the oak) very slowly – otherwise there is a risk that this will crack too.
As you can see from the photograph below, this kit takes up a lot of space. We have done the best job we can of reducing the amount of space it occupies (including installing a couple of steel beams to hold the tanks), but even so the utility room does look more like a plant room at the moment!
If you are planning on installing this kind of kit, it would be wise to ensure that you have enough space for it. Our house isn’t small and we are struggling to provide enough space. It needs significant planning well ahead of installation time. This isn’t an issue that the providers make particularly clear when selling the kit (surprise, surprise!).
The utility room is fairly big – 2.3m x 3.8m – but there is a lot of kit to go in here. Two cylinders for the ground source heat pump, under floor heating manifold, pump module and the ground source heat pump. The layout suggested by the ground source heat pump installer would have effectively converted the utility room into a plant room.
We realised early on that there was significant height in this part of the extension and therefore decided to raised the two cylinders up onto a platform so that the underfloor heating manifold and pump could be installed underneath them. This reduces the amount of space required in the utility room to install this kit.
The steels that will support the platform for the cylinders were installed this week.
With the underfloor heating installed, it is time to lay the floor screed. This is a semi-dry mix. There were two deliveries during the day. The photo below shows the first delivery of 10 tons, the second delivery was for a further 6.5 tons.
The screed was intended to be 70mm thick, but the existing floor was not level so it varied for 70mm to 100mm in places. The end result was a perfect level floor. The downside is that it used more screed that expected, but we still had a enough. The floor was laid in one day – admittedly, a long day.
It takes 48 hours for the screed to go off, so we won’t be able to walk downstairs until Friday. So we have had to reorganise work for the next couple of days.
The underfloor heating is now installed upstairs together with the first fix plumbing for the bathrooms. The insulation has been installed downstairs. The insulation consists of large slabs of expanded high density polystyrene that is foil backed. It is 50mm thick and is cut to size using a wood saw. Once it is down, it can be walked on.
A strip of expanded plastic is put all around the edge of the room. This forms a gap between the edge of the screed and the wall. This allows the screed floor to expand and contract as it heats up and cools down. Without this, there is a possibility that the screed would expand with the heat, push against the walls and crack.
The screeders are booked for Tuesday morning. By then all of the pipework needs to be clipped to the insulation, so that 70mm of screed can be laid on the floor. It will take a day or so for the screed to go hard. During this time, no one will be allowed inside the house.
While the house is out of bounds, we will install the ground loops for the ground source heat pump in the field.
The pipework has been installed in the underfloor plates that were installed. It seems strange to think that this is going to heat the upstairs of the house. It hardly seems enough, but when you think about it, these plates are really just a massive radiator – albeit installed under the carpet.
The first floor bedrooms will have carpet and it is possible to install “low tog” underlay and carpet that will help transmit the heat through the floor. Often underfloor heating is associated with solid floors, however, I am assured that it works well with both timber and carpet. We will just have to see how it works.
We made a start today on installing the underfloor heating. We are installing this throughout the building – both upstairs and downstairs.
The upstairs heating works via a system of metal plates that are fixed to the underside of the floorboards and heated by a set of water pipes. We left a 25mm gap between the large oak beams and the floor joists to make installing the plates a little easier. We have also cut out notches in the joists before the floors went down to make it easier to run the pipework.
All in all, it only took a day to install all of the underfloor metal plates.
This is due to be installed next week, but the kit has arrived today. We are going to be spending the next few days sorting out the existing floor so that the underfloor heating can be installed directly on top of it.