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Rads are now based on a "50 degree" basis (formerly 60C), this is the mean rad temperature minus a nominal room temperature of 20C, For example if your rad had a flow temperature of 75c & a return of 65C then you would have a "50 deg rad", ((75+65)/2)-20. If you had a flow temp of 75C & a return of 45C ( to get full condensing benefit) then you would have a "40 deg rad, ((75+45/2)-20, you would then have to install a bigger rad(s) to compensate for this and all the rad manufacturers have correction tables, I don't bother looking at them because I figured out (from the trend line on a spreadsheet) sometime that they are using (generally) a correction factor of ^1.3, so the correction factor for your rad is,(50/40)^1.3, 1.34 which means that the rad would have to be 34% "bigger" or if you installed the rad based on 50 degrees then it would output only, (40/50)^1.3, 75%.
The reason I used 41 degrees as the base is because the boiler had its set point at 65C which resulted in my rad(s) being only a "41deg"one so I just compared the output of the BTOE rad based on this. I could have and maybe should have corrected both of them to the 50 deg standard, this would equate to outputs of 77% & 55% respectively to the BOE & the BTOE rads so the BTOE rad would still output (55/77), 71% of the BOE one as stated above.
The reason I used 41 degrees as the base is because the boiler had its set point at 65C which resulted in my rad(s) being only a "41deg"one so I just compared the output of the BTOE rad based on this. I could have and maybe should have corrected both of them to the 50 deg standard, this would equate to outputs of 77% & 55% respectively to the BOE & the BTOE rads so the BTOE rad would still output (55/77), 71% of the BOE one as stated above.
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So what does your symbol of ^ mean. Sorry but maths was never my strong point, I’m but a humble Hoover man lol
"^" is to the power of, you have heard of "squared", 2 squared is 2x2 or 4 but if you were to do this calculation in a spread sheet, you would enter = 2^2, and so on,
Based on your calculations I’m arriving at the same answers, just doing it differently lol. Like I said I’m not an installer, I service, repair and commission oil fired appliances. I’ll leave the plumbing to someone who wants it lol
Im keen to see Johns answer to your question Chris. Like I said I don’t install, just service oil appliances. However I always went by the formula of flow temp is say 70, return is say 50, so average rad temp is halfway between. Then minus room temperature of 21 gives the final figure. Similar to how you guys have said you do it above.
Yes, this is quite correct in the case of a BOE or a TBOE plumbed rad but is not (IMO)) the true mean temp in a BTOE (wrongly??) plumbed rad.
Re Chris's query above, I can,t really get higher than 70C flow temp as I have a oil fired boiler which has a max set point of 75C and a hysteresis of 10/12C so hard to get a steady flow temp for readings but they are quite reasonably correct.
His "39 deg rad" should emit 72.3% of a "50 deg rad" and the "38 one "will emit 69.9%
Re Chris's query above, I can,t really get higher than 70C flow temp as I have a oil fired boiler which has a max set point of 75C and a hysteresis of 10/12C so hard to get a steady flow temp for readings but they are quite reasonably correct.
His "39 deg rad" should emit 72.3% of a "50 deg rad" and the "38 one "will emit 69.9%
Plumb Center are doing a Testo 830-T2 infrared thermometer for £50 + vat currently.
I have a more expensive Testo model
Pleased with mine, they might still have some in your local Lidl it was about 4weeks ago
I agree, I will focus on the fact that the flow temperature is 53 degrees where it should be much higher.
Then they can rectify the fact that they have piped it incorrectly.
They also need to get rid of the air in the system.
When engineer was on-site he showed me the heat exchange unit had temp of 80 degrees but I believe that was the incoming hot water from district plant.
Anyway I will order a thermometer to take readings of all my rads.
Will then see if neighbor will assist to provide theirs.
Then they can rectify the fact that they have piped it incorrectly.
They also need to get rid of the air in the system.
When engineer was on-site he showed me the heat exchange unit had temp of 80 degrees but I believe that was the incoming hot water from district plant.
Anyway I will order a thermometer to take readings of all my rads.
Will then see if neighbor will assist to provide theirs.
One more thing I can recollect in my mind is when the first visited the flat last year, they did mention they moved something to the highest setting. It could have been the pump or it possibly could have been the thermostat for the heating in the heat exchange. The thermither range is between 35 and 75 degrees. Maybe there could be a possibility that the thermostat setting is still stuck on the original setting or maybe it's not functioning correctly. I can't turn it as it seems to be stuck in its current position which is at the highest setting.
I got one of those too, quite impressed for the price.
Ok I have a response.
They contacted the manufacturer stelrad and they told them they need to swap the flow and return.
I have also asked them to resolve the incorrect flow temperature as it should be much higher.
They contacted the manufacturer stelrad and they told them they need to swap the flow and return.
I have also asked them to resolve the incorrect flow temperature as it should be much higher.
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