Radiator Cooler at Bottom

I=92ve just drained & refilled my CH system (first time I=92ve done it myself) & it went fine. The water that came out was surprisingly clear, with no signs of black sludge. (It was last drained 2 yrs ago & Fernox was added.)

1 small thing I=92ve noticed is that 1 downstairs rad has more of a difference between top & bottom than other rads (eg when I measured it the radiator was about 44 deg C at the top & about 38 at the bottom). I think the rad was also a couple of degrees cooler than some of the others. The radiator bleeds fine.

From a google it looks like sludge might be the cause ... except the water that came out was pretty clear. Not sure if I just need to give it a bit longer, or if it=92s maybe something to do with the rad valves needing to be adjusted?

Michael

Reply to
Michael D
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What's the radiator temperature at the pipe exit? Is that at 38 deg C?

Reply to
Fredxx

44 vs 38 is fine. Fwiw its probably the one getting the least water flow per rad volume.

NT

Reply to
NT

If the return pipe is hotter than the cold part of the radiator, then it's sludge. If the return pipe is same temperature as the cold part of the radiator, then it's due to low flow through the radiator. Is your system properly balanced?

Reply to
Andrew Gabriel

No it hasn't been balanced for at least the last 4 years. I'll check the return pipe temp this evening.

Michael

Reply to
Michael D

Right I=92ve measured it again (deg C):

Bottom of radiator In: 54 Middle: 36 Return: 38

Top of radiator In: 50 Return: 48

So it=92s fairly constant across the top, but differs markedly across the bottom. For info it=92s an oldish radiator and it=92s long =85 probabl= y about 10 feet long. I=92ve a feeling it=92s one of the last in the circuit and it definitely hasn=92t been balanced for some time.

Not sure if this indicates sludge as the water that came out when I drained it was very clean =85 unless the sludge somehow gathered there & didn=92t travel round to the drain point?

Michael

Reply to
Michael D

The exit temperature is pretty much the lowest temperature of the radiator, that suggest the flow is quite low rather than a problem with the radiator itself. It may well be caused by either being the furthest leg of the system, or perhaps may benefit from from some improved system balancing.

Reply to
Fredxx

What's the flow temperature set to at the boiler?

Reply to
David

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