Advice on building over underground central heating pipes

Hamish10

Just looking for some advice on building small extension at rear of house. Have oil central heating which is supplied from burner located in brick boiler shed located at bottom of garden.
Pipes run underground (not sure how deep) from there to house. Will have to locate pipes when wall and floor foundations being dug.
My questions are,
Can I build extension over these pipes.?
Do they need protection from weight of walls and floor.?
No option to re-route pipes as this would mean taking up existing tiled floor in kitchen.
Any advice greatly appreciated

BryanF

Take up the pipe and re route.

Hamish10

BryanF wrote: »

Take up the pipe and re route.

Thank you, can I re-route them from where they enter house and run them over ground with plenty of insulation along Garden partition wall back into boiler house. They have run under kitchen floor for past 20 years with no problems but am just worried about covering them with extension floor and encasing them in foundations . Currently they run under back garden lawn into house thanks

sydthebeat

Hamish10 wrote: »

Thank you, can I re-route them from where they enter house and run them over ground with plenty of insulation along Garden partition wall back into boiler house.

you could but that would be a disaster for efficiency

Hamish10 wrote: »

They have run under kitchen floor for past 20 years with no problems but am just worried about covering them with extension floor and encasing them in foundations

unlikely they are deep enough to be affected by foundations..... so if theyve run under kitchen floor with no problems, then expect them to run under new extension with no problems.

if anything, your efficiency will improve as the run though exposed ground will be lessened.

Calahonda52

Time to move the boiler.
All very fine and dandy to talk about different levels of insulation, the elephant in the room is the heat loss from the pipework due to the long pipe runs.

So how long is the pipe run from boiler house to hot water cylinder/rads?

Lets crunch some numbers here:
say 25mm pipe, by 2, which gives you about a litre , or 1 kg per meter of water that needs to be heated from say 10 to 70 degrees.

The specific heat capacity of water is approx 4.2 J / g.K

The increase in temperature is 60 Kelvin (70-10)

So the energy needed is 1000 g x 60 x 4.2 = 0.252MJ

1kWh = 1000W x 3600s = 3.6MJ

Hence, the energy needed is .252/3.6 = 0.07 kWh per litre
Assume 70% efficiency in the boiler, so its 0.1kWh per meter of twin pipe each time you fire up the boiler and let it cool down.

Assume a run of 10 meters and a 180 day heating cycle, twice a day, assuming you use elec for summer
then thats about 40 quid per annum at a minimum of heat loss.
This math ignores heat loss from the pipes into the ground.
[ I think the math is right ]