Heating Problem

[bathroomboy]

Been round to look at brother in laws heating, problem poor flow to rads taking a long time to heat up esspecially last ones on the circuit, a couple of new rads were added a few years ago, but even turning these off it's still poor, system is initially 22m/m primaries wich tapers down to 15m/m, all rads are fed from 10m/m branches, Had a look at the pump which has been changed in the past and it is allready set on maximum which indicates to me that flow was poor when the pump was put in, I am wondering will a more powerful pump cure the problems, the only drawback I can see it may pump over the f&e with a greater head pump but vent could also be raised to compensate. If I swop the pump for a 6mtr head will this make an improvement?

 

[helpsy]

Balance system maybe????
F&E vent should be 450mm above water level.

 

[bathroomboy]

Changed pump but still not good, 2 port valve suspect after pump,drained down and fitted valve, now this is where it gets wierd, I have drained and refilled many a system, anyway system refuses to fill, i suspect blockage in the f&e pipe, tried to blow out to no avail, spilt pipe prior to primaries and really filthy water came out not what you would expect from a system thats just been drained down,rodded out remaining, boxed it all up and managed to get downstairs rad (site of drain down) to fill, but still having problems filling upstairs rads, no movement of air when attempting to bleed.
Left it for today, will try and force fill it tomorrow, I have worked on stuborn systems before but this is strange, system is approx 30yrs old with many original rads, could it possibly be sludge related?

 

[REDSAW]

how hot is the hot water?.
too much flow to the h/w and not heating.
is there a valve near the pump / cylinder?. close it down to 20%.
it could be diverting too much to the h/w circuit thats causing the problem.

 

[bathroomboy]

Return pipe to boiler is blocked solid with sludge, probably need cutting out, might be an idea to replace the whole system.

 

[WHPES]

The blockage is usually by the tee for the F&E. Cut it and have a good poke about with a chisel or old screwdriver. You may have to hit the chisel with a hammer - it will be set like concrete.

 

[bathroomboy]

Yes thats where it is but it seems to be a fair way down the pipe.

 

[WHPES]

unroll some solder wire and poke down the pipe to find out exactly where it is.