Do i need a powerflush?

armyguy

Hi there, i was hoping someone could advise me on a tricky situation, i'l explain..

Some details first:
Worcester 24CDi Boiler (sealed system)
Bosch pump (set on 3 (max))
6 rads, 3 up 3 down
Boiler was serviced in November by Brit Gas.
10mm microbore piping throughout

I bought a house in December, after i moved in and the snow hit i realised the central heating wasn't giving enough heat to the house. Its a terraced house with high ceilings so i know its never going to be nice and cosy, but I've had to wear a hat and dressing gown lol. Anyway, I have an open plan living room and dining room with a small kitchen extension and there was only a small radiator in the living room. I noticed that the radiators upstairs were very hot however the radiators downstairs were very hot at the top but about 1/3 of the way down they start getting luke warm to slightly warm at the bottom.
I decided that it was air in the pipes and i got quite a bit out of the system with no massive change, I then decided to take the very large radiator from upstairs (which was hot all the way through) and swap it with the small one in the living room(which was hot at the top). This all went smoothly with quickfit valves and PTFE tape. When i was draining the system i noticed the water coming out was very black and after a second drain (because of a leak) it was still quite black (but not as much). Now with the large radiator in the living room and the small one upstairs i still have the same problem, the small one now upstairs heats up nicely(it didn't downstairs) and the large one now downstairs (which did heat up nicely upstairs) now only gets hot at the top.

This leads me to thinking I've got sludge in my system and i need a power flush, however its strange that its only the downstairs effected. Any idea's??

1984ReturnsForReal_2

Its not air in the rads.

Is the pump working properly?

armyguy

I think so, the boiler was serviced in November and the problem has been the same since i moved in in December. I can feel the pump (or motor) moving but i can't see inside because its sealed. On one side of the pump there is a small screw which holds a plastic covering which has the pump speed selector on. I've just opened that screw and it contains the electrics for the motor i assume. So I can't see the pump working to verify.

1984ReturnsForReal_2

Its a flow problem anyway.

Either there is a problem with the pump or debris is blocking valve/valves.

It could be debris in the radiator valves.

If all of the rads downstairs are the same the blockage maybe around the last rad valve upstairs before the feed drops to downstairs or around the first rad valve downstairs.

armyguy

I've attached a diagram of the layout downstairs, i can't see upstairs layout as its under floor boards.

Also of note is (see pic for details) that the kitchen and living room rad have been added at a later time due to plastic piping T-Junctioning off original copper piping.

plumb1_2

What size are the pipes feeding the rad?

armyguy

All pipes in the whole system are 10mm

keystone

Sounds like sludge all right. Hate microbore TBH. Powerflushing microbore without pretreating is really not that successful. Is it an open vented system? Your plumber might like to look in the usual place (where the cold feed joins) in the primary to see if there isn't a magnetite blockage there as well.

Cheers

plumb1_2

armyguy wrote: »

All pipes in the whole system are 10mm

Have you tried to balance the system? 10mm will tend to get blocked and reduce the flow to rads.I would say a powerflush would help the system, and you have alraedy noticed you have a build up of sludge.
You could take the rads off and flush them with a hose, but this wont remove the sludge in the pipes or boiler.
You should be able to get this done for £275- £325.

armyguy

keystone wrote: »

Sounds like sludge all right. Hate microbore TBH. Powerflushing microbore without pretreating is really not that successful. Is it an open vented system? Your plumber might like to look in the usual place (where the cold feed joins) in the primary to see if there isn't a magnetite blockage there as well.

Cheers

Thanks for the reply.
The pipe coming down from upstairs is really hot so does that eliminate a problem with blockage upstairs?
Also should the hottest pipe go into the LSV or the Thermostat valve?
Since the downstairs rads are really hot at the top do you think i should just flush them out because sludge might be in the bottom 2/3rds?

plumb1_2

keystone wrote: »

Sounds like sludge all right. Hate microbore TBH. Powerflushing microbore without pretreating is really not that successful. Is it an open vented system? Your plumber might like to look in the usual place (where the cold feed joins) in the primary to see if there isn't a magnetite blockage there as well.

Cheers

Its a sealed system, 10mm is a pain the clear, but i always double dose, and would connect to the pump to flush. Thats why i repeat it is not possible to flush a system in 2hrs.