Heating System Requirements
The heating system comprises the following seven aspects
- underfloor heating to the ground floor rooms
- radiator heating to the bedrooms and snug
- heating to the swimming pool and pool-hall
- heating to the games room air handling unit
- heating to the TV room air handling unit
- heating to the bathroom towel rails
- heating to the domestic hot-water calorifiers
The entrance hall, kitchen and orangery will all be finished with a stone floor while the drawing room, library and dining room will be finished with an engineered wood floor. In all these cases there will be no fitted carpets although in certain areas the floors to these rooms will be partially covered with rugs. Therefore in all these areas we consider that the most appropriate form of heating is “wet” underfloor heating. This form of heating uses a series of polythene pipe loops buried in the floor screed through which hot water from the domestic heating boilers is passed. The photographs below illustrate the installation of underfloor heating pipework prior to the floor being screeded
In areas where the floors are finished with fitted carpets we consider that a better form of heating is to use “wet” radiators that are heated by hot water from the heating system boilers. The reason for the difference in approach is that in my view fitted carpets act as a thermal insulator to the floor which significantly degrades the performance of any underfloor heating system. I have never been warm in a house that has underfloor heating with fitted carpets! As we intend to have fitted carpets in the snug and all the bedrooms we are therefore installing radiators in all these rooms.
Heating System Hot Water Delivery from the Boilers
To accommodate the seven different heating requirements defined above the heating system employs three separate heating circuits which are illustrated by the photograph below and shown diagrammatically in the Plumbing Schematic drawing accessed at:
In common with all the other aspects of the heating system the boilers are also in a dual redundant configuration. The chosen boilers are a pair of Worcester Bosch GB162 wall hung condensing gas boilers that deliver 100kW of heat each. A data sheet for these boilers is available for download from the blog library:
Our original intention was that the boilers would be mounted in the plant room along with all the other apparatus associated with the domestic hot and cold water and heating system. However during the build process of the house it became apparent that the flues to take away the exhaust gases to the roof would inevitably be in sections because of the length of the flues extending from the basement to the roof level. It is a requirement that the joints of such flues are inspected on an annual basis to ensure their gas-tight integrity. A failure of a flue joint could result in leakage of flue gases and there is an associated risk of carbon monoxide poisoning to the inhabitants of the house. The space in the vertical void that was put in place to take the flues along with the other basement ventilation ducting was extremely limited. To allow safe access for inspection of the flues an access ladder would have had to have been permanently installed in the void also. Whilst not impossible, access would have been extremely tight and claustrophobic and without harnesses when using the ladder that would have restricted access even further it would have been potentially dangerous. Accordingly we decided to install the boilers in the bay of the new garage that had already been designated for use by a standby generator. Pipes with substantial thermal insulation buried in the ground conduct the flow and return hot water between the low loss header discussed above in the basement and the boilers. The heat loss from these extended delivery pipes is negligible. The advantage of installing the boilers in the garage apart from a vastly simplified flue arrangement is that the annual service can be carried out without having to enter the house. moreover there is ample room for access to make servicing as easy as possible.
The drawings that define the heating system are as follows and can be viewed by down loading them from the blog library: