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Many heatloss calculators make an allowance of about 5% for the heat lost from uninsulated pipes. So, in my case with 13kW of rads there would be 650W lost from the pipes.
If you search for "heat lost from uninsulated copper pipes" you will come across a lot of info on the subject. But they all give a result similar to this:
Flow Temp 75C, Room Temp 20C = 45.31W/m (15mm); 60.41W/m (22mm)
Return Temp 65C, Room Temp 20C =34.85W/m (15mm); 46.46W/m (22m)
Assuming the hidden pipes in my house follow the shortest route, I estimate that there are 54m of 15mm and 68m of 22mm. (That's total - flow plus return). A quick calculation gives the following heat loss from the pipes:
15mm = 2164W; 22mm = 3634W. Total = 5798W!!!
That's nearly 10 times more than heat loss calculators suggest.
Can anyone explain the discrepancy?
(Yes, I know that the heat isn't really lost as most of it is within the insulated envelope of the house so only the heat from pipes under the floor or in the loft is 'lost', but that's irrelevant to my question.)
If you search for "heat lost from uninsulated copper pipes" you will come across a lot of info on the subject. But they all give a result similar to this:
Flow Temp 75C, Room Temp 20C = 45.31W/m (15mm); 60.41W/m (22mm)
Return Temp 65C, Room Temp 20C =34.85W/m (15mm); 46.46W/m (22m)
Assuming the hidden pipes in my house follow the shortest route, I estimate that there are 54m of 15mm and 68m of 22mm. (That's total - flow plus return). A quick calculation gives the following heat loss from the pipes:
15mm = 2164W; 22mm = 3634W. Total = 5798W!!!
That's nearly 10 times more than heat loss calculators suggest.
Can anyone explain the discrepancy?
(Yes, I know that the heat isn't really lost as most of it is within the insulated envelope of the house so only the heat from pipes under the floor or in the loft is 'lost', but that's irrelevant to my question.)