new pump

[dicky]

hi anybody.i have sealed system, conventional boiler(60,000btus),4 large double rads(high output),3 single,standard cylinder.i currently have a 5 metre head pump.2 downstairs rads only warm a little when the water is on as well.water also takes quite a bit longer to heat.will fitting a 6m head pump solve this or is there a danger of system being over pumped?system has been balanced and also has valve on return from cylinder.any help will be greatly appreciated thanks,richard

 

[JPC]

i would say u'll over pump.

could it be sludge in downstairs rads ?

 

[dicky]

i would say u'll over pump.

could it be sludge in downstairs rads ?

hi jpc thanks for your input,no sludge in rads they have been off and flushed.what happens if you over pump,cheers,richard

 

[brumylad]

close down the lock shields on the upstairs rads and water cylinder (count the turns so you can put everything back as it was) and see if the downstairs rads will heat even in this condition.

Is the system microbore from manifolds?
Is the problem getting worse?
Is the existing pump knackered?
How far does the 22mm pipe travel from the boiler before changing to 15mm?
Does the boiler cut out from overheating or fire for shorter periods than it used to?

 

[dicky]

hi brumylad,cheers for that mate.tried your theory regarding closing valves to no avail.the problem has always exisited,not got worse.22mm at least 3m away from boiler.boiler working normally no cutting out too early as pipe thermometer shows,cheers rich

 

[brumylad]

I guess you are able to bleed air from the rads ok ?

If the valves are thermostatic check that with the thermo head removed the pin is free to move down (push with the flat of a spanner etc), they can get stuck.

if it is micro-bore pipe it might be blocked if the rads are not heating even when everything else is closed.

The pump might be suspect, if your pump has an end cap, they say you shouldn't be able to stop a pump from turning when using finger pressure on the spindle when the motor is running (end cap off for this obviously)