I really don't think it makes much of a difference as after all its a pumped circulation system, its probably no worse than the conventional bottom to bottom almost universally used system which works pretty well to my mild surprise.
Welcome to the forum. Although you can post in any forum, the USA forum is here in case of local regs or laws
When designing a heating system using rads a heatloss calculation is completed to determine how much heat is going to be required to keep the room at the required temperature (say 21C) when it is, say -3C outside. This is used to select a suitably radiator to do the job. As others have said the outputs the rad manufacturers state is based on being tested in a standard way (MW-air temp = 50) Here is the important thing in your case - they also connect up the rad in a certain way, typically Top & Bottom Same End (TBSE) if you change the way it is connected then you change the radiator ability to heat the room (stated output).
This is fine if you know how the rads are going to be piped up for instants in this country we mainly use Bottom Oppersite Ends (BOC) which is less efficient at proving heat from it, still that is not a problem we just make them bigger to allow for this.
TBOE connections like yours mean that the rads can be around 15% smaller than if they had been piped BOE, why?? because when they are piped with the flow (hotter lighter) water to the top connection & the return (cooler heaver) water out of the bottom you are working with gravity & not against it. God knows what effect on its output piping it up the wrong way is having on the outputs but effectively you have very much undersized rads which will not do the job they were put there to do. Very simply they are not fit for purpose as they are currently installed.
Don't take any more old crap about this from them, ask for the heatloss calculations for your property so you can see what is require & ask them once again to install them as per the designs.
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OK then I ran a 1400 x 400 mm double rad BTOE for approx 40 minutes and I can confirm that the performance is certainly affected, unfortunately I didn't have my temperature scanner but the last ~ 1/4 of the rad was much more noticeably cooler than the remainder apart from the top. I would estimate that the performance loss at ~ 20/30%, this would possibly reduce over a longer time period but to quote Chris Watkins..."they are not fit for purpose as they are currently installed."
Thanks. You guys are brilliant offering great advice. Also you have common sense unlike the cowboys I am dealing with. As we are in our defects period I will fight to get this resolved. I will keep you guys updated but this could take some time.
I asked them how long would it take to swap the pipes and they said 2 hours. So do not understand why they simply won't just swap the feeds around.
I asked them how long would it take to swap the pipes and they said 2 hours. So do not understand why they simply won't just swap the feeds around.
Don't assume things that are central to the diagnosis of a problem.
The fact that the flow temperature was 'set to 75 degrees' does not mean the flow temperature *is* 75 degrees, particularly if your measurements say it's 53 degrees.
If you don't trust the temperature measurement, get another one made using a proper pipe thermometer. Alternatively, press your thumb onto the pipe and count in seconds how long before it's painful enough to make you pull it off. If you only get to one it's 75°C but if you get to more than ten it's 50°C.
Got a few temperatures last night with "old" temp scanner but good enough I think for comparison purposes.
Anything in the interest of science.
All temps taken after 40/45 mins, the BOE gave the fastest warm up from cold.
View attachment 37621
All temps taken after 40/45 mins, the BOE gave the fastest warm up from cold.
View attachment 37621
I don't supposed you took the flow & return water temps of each one do you John? only what would have told us the heat out put. Interesting to see the heat distribution across them & the mean water temp 51.53 top, 60.93 middle & 59.2 bottom
They were pretty close to the sketch, ie, BTOE 65/56, BOE 65/58 & TBOE 64/54.
So pretty conclusive without it being carried out in a climate chamber.
BOE = 7, BTOE = 9 & TBOE = 10 & flow was only 64 so would have had the smaller differential between the water to air.
Yes, Probably not thermodynamically very accurate but I just averaged all the temps and the BTOE was 51.5C="31.5 deg rad" or 55% output of a 50 deg rad, the TBOE was 59.C="39.1deg" rad or 73% & the best (marginally, apart from the quickest heat up) was the the BOE, 60.9C="40.9deg" rad or 77%.
If the flow rate was the same in each case, it would more accurate to infer the emitted power from the fact it's proportional to deltaT. If this is correct, there is only a 10% advantage for TBOE over BTOE at deltaT = 9 °C. The heating engineers the OP is arguing with are claiming TBOE vs BTOE makes an insignificant difference and this result supports them; if the OP's radiators are running at deltaT = 3 °C rather than 10 °C the difference will be even smaller.
I wouldn't mind betting the 3 °C was not as per the design. With these communal systems the heating pant is invariable N.gas powered & capable of condensing so the design should be very much that of the domestic gas boilers system.
It must be remembered that normally the mean rad temperature is conveniently taken as (flowtemp+returntemp)/2, this in turn infers that there is a gradual fall in temperature between the flow and return which can be seen quite clearly in the sketch in both the BOE & the TBOE cases but not in the BTOE case where several temperatures are only in the 40s. To put it another way, when I average the 15 readings in both the BOE & the TBOE and compare them with their mean temps based on (flow+return)/2, one gets (BOE) 60.9 vs 61 & (TBOE) 59.1 vs 59, very close in both cases.
If one compares these numbers in (BTOE) one gets 51.5 vs 60.5, a huge difference (obviously because of the non linear fall in the actual rad temps).
If one accepts this reasoning, then the BOE is the best performing rad and is a (61-20) "41 deg rad"(partly because of the low flow temp of 65C), the next best is the TBOE, a (59-20) 39 deg rad, almost identical (apart from slower warm up) than the BOE.
The BTOE rad is only a (51.5-20) 31.5 deg rad so its performance using the BOE as the bench mark is only outputting (31.5/41)^1.3, ~ 71% of the BOE output?.
If one compares these numbers in (BTOE) one gets 51.5 vs 60.5, a huge difference (obviously because of the non linear fall in the actual rad temps).
If one accepts this reasoning, then the BOE is the best performing rad and is a (61-20) "41 deg rad"(partly because of the low flow temp of 65C), the next best is the TBOE, a (59-20) 39 deg rad, almost identical (apart from slower warm up) than the BOE.
The BTOE rad is only a (51.5-20) 31.5 deg rad so its performance using the BOE as the bench mark is only outputting (31.5/41)^1.3, ~ 71% of the BOE output?.
I agree. The deltaT = 3, which I inferred from post #20 seems far too low. The flow temperature, if it is 53 not 75 is also too low and is where I'd look. Anyway, I'm repeating myself so I'll shut up now.
I have just cleaned up the sketch, it seems pretty clear that convection just won't work properly in any system with the return on the top. In the BTOE there are 8 readings between 45C and 38C, the flow just seems to flow upwards to the top of the rad and then partially short circuits out the other end whereas in the other two it flows along the top of the rad and then drops down in parallel flow paths and out the return, (makes sense I suppose).
John.g how did you arrive at the figure of 71% output in comparison with the BOE? I understand everything but your calculation of (31.5/41)^1.3 ~71%. I’m not an installer, I work with oil fired appliances but I’m keen to fully understand this.
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