Example Of Poor Central Heating Pipe Insulation And The Fix
This example comes from our second house and the pictures show the before and after for the main heating and hot water pipes which run through the unheated garage. The boiler is on the other side of the wall which means these are very nearly the hottest pipes in the heating system and any loss from these pipes will affect the heating for the whole house. The normal approach is just to fit pipe insulation but I decided to go further to try and reduce the heat loss to a very small amount. This picture shows the original state of the pipes which are situated adjacent to the door into the house. Notice the electric cable running behind the pipes in a metal sheath. This was in contact with the pipes and before doing any modifications small plastic insulators were fitted to keep the metal sheath off the pipes to lower it's temperature. The pipes are from left to right: Extension central heating flow, Extension central heating return, Hot water flow, Hot water return, Main central heating flow and Main central heating return. The 2 pipes on the left are 22mm diameter copper and the other 4 are 35mm diameter pipes. Notice the gaps around some of the pipes where they enter the ceiling. The temperature drop across each pipe was approximately 2 degrees Fahrenheit with the system stabilised at temperature and the boiler and pump running. A 2 degree drop with the water flowing at pump pressure over such a small distance indicates a significant heat loss. The air temperature in the garage when the measurements were made was 38 degrees Fahrenheit. The wall behind the pipes is relatively warm due to the boiler and pipes on the other side.The door into the house can be seen on the right of the picture. The room above the pipes is the main bathroom which is draughty due to the holes in the ceiling around the pipes..
The picture on the right shows what the pipes look like with the pipe insulation nearly completed. The only tasks remaining are to cut small pieces of insulation to fill the gaps and tape all the insulation joints with gaffa tape. Insulation was the tube foam type (not the very cheap stuff) that can be purchased from most DIY stores. The foam insulation had to be carefully cut around the earthing wires joining the pipes which can be seen at the top of the picture above.. To improve the fit around the joints which are thicker than the pipes the insulation was carefully hollowed out wit a sharp knife. The gaps around the pipes where they enter the ceiling were sealed with a flexible filler. In the corner of the wall the wooden batten to fix one side of the enclosure can be seen fitted around the door lintel.
The picture on the left shows the final result with the pipes fully boxed in. Rather than build a massive box to cope with the pipes sticking out I decided on a box with a power bulge, this was to minimise the effect of the box on the adjacent door into the house. The strip of wood along the top of enclosure is to prevent the front bowing with time because the ceiling is not suitable for fixing to in this area. The excess space within the box was filled with loft insulation. Measurements with temperature sensors on the pipes inside the box showed that the temperature drop from end to end of each pipe was less than 0.1F. The air temperature in the garage when the measurements were made was 41 degrees Fahrenheit. The surface temperature of the enclosure with the heating running and stabilised is only about 3 degrees Fahrenheit above the ambient air temperature. The gap where the wire enters the enclosure was sealed to prevent any air flow. Subjectively the garage now feels noticeably colder indicating a significant heat loss has been removed. From the measurements and subjectively this change looks like it has achieved the desired result. The final proof will come over time by comparing heating oil use taking account of the ambient outside temperature before and after the change. Another noticeable effect is the boiler is cycling less indicating the heating system is holding it's heat better. Finally the main bathroom is now free of draughts reducing slightly the heat required to maintain a reasonable temperature.