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Brian, Plumber
Category: Plumbing
Satisfied Customers: 862
Experience:  16 yrs. experience as plumber, including full bathroom and kitchen installations.
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Recently replaced 2 rads with double radiators had to change

Customer Question

recently replaced 2 rads with double radiators had to change pipe to 10mm pipe to allow for different locations of pipework as inbeded in concrete top of rads get hot but bottom doesn't drained system down and bled rads no sign of sludge in new rads old 1 was a bit crappy any ideas why whole rad isn't getting hot
Submitted: 4 months ago.
Category: Plumbing
Expert:  Brian replied 4 months ago.

This indicates poor circulation unfortunately. So either it's blocked or the pump is set to low or the system may benefit from balancing. So make sure the radiators are capable of getting hot by turning off all the others. If they get hot you will need to open them all back up fully and use the balancing valve to adjust each radiator down until you get an even heat across the whole system.

Customer: replied 4 months ago.
potentially could the older single rads be blocked and cause this issues? 1of the old rads was quite sludgy but when I rechecked new they were OK since adding second new rad first new raf seems cooler
Customer: replied 4 months ago.
Worth mentioning worcester Bosch greenstar 4 Yeats old and serviced annually
Expert:  Brian replied 4 months ago.

Yes old rads could be sludged up. If you remember water will take the path of least resistance. So if you have dirt and 10 mm pipe it will not flow to that area when it can divert down 15 or 22mm pipe.

Turn all other rads off to see if you can get them hot then it will be clearer as to what needs doing

Customer: replied 4 months ago.
Definitely hotter turned all older rads off with locksheilds was going to put TRV on 2 of the old ones so can remove and flush, have been cleaning Magna filter each time I changed the 2 rads and put fernox cleaner in before adding last one
Expert:  Brian replied 4 months ago.

If it's still not getting hot with all the other rads turned off I would suggest they are really blocked try tapping them on the cold spots really fast with a rubber mallet or heal of a shoe to dislodge the rubbish it will get picked up in the magna clean or Maybe hire a power flusher

Customer: replied 4 months ago.
With others turned off they were too hot to keep hand on and when I put others back on it went back to hit top warm bottom
Expert:  Brian replied 4 months ago.

You need to try balancing the system then turn all rads of via the back valve and crack open the working ones quarter or half a turn hopefully you will end up with a good balance