Should I Powerflush?

[Assimalyst]

Hi,

I have a central heating system that was seriously clogged up when I moved in 2 years ago. I had the old boiler replaced immediately and the storage tank removed, it now uses a combi boiler to heat the 5 rads. Recently one of the heaters developed a leak hole, and I have had them all replaced. Unfortunately 2 are permanently cold (one upstairs, one downstairs, both at the same end of the house).

The 2 heaters in question were just about working before, but were cold at the bottom, but after replacement are stone cold. The plumber thinks the the recent flush through could have dislodged some scale and blocked the manifold (presuming it exists). I have tried locating it, but think it may be under the bathroom tiles, which would be expensive and messy to fix, if that turns out to be the problem.

The plumber tried cold water flushing, but there is virtually no flow though the radiators, however there is still circulation when the boiler pump is on and all heaters are off, which makes it hard to force any flow through the problem radiators.

Is powerflushing likely to work? Or should I bite the bullet and start ripping floors up in an attempt to find the manifold? Note the pipes are 10mm external diameter, which I presume is 8mm microbore (please forgive my ignorance!!)

Any thoughts/suggestions?

Many thanks.

 

[Andygasman2010]

there is still circulation when the boiler pump is on and all heaters are off.

I'm not quite shure what you mean here, how can there be any circulation when the radiators are all turned off?

With 8/10mm pipe you probably won't get the best results from a powerflush. You might want to try adding X800 and leaving it circulate for a few days, doing one rad at a time. Obviously this will only work if you have partial circulation. If you don't, you'll need to cut-out the blockage which will probably be at the manifold.

 

[Assimalyst]

there is still circulation when the boiler pump is on and all heaters are off.

I'm not quite shure what you mean here, how can there be any circulation when the radiators are all turned off?

I'm not either!!

My best guess is that when the storage tank was removed, the loop was just joined rather than blocked. If that is the case then presumably this could be blocked to improve circulation? It seems a waste to have a loop there that essentially does nothing.

 

[Andygasman2010]

It's very difficult to advise on this kind of thing without seeing pipe layout, any chance you could upload some photos? Particularly of where the old pump/cylinder was.

 

[Assimalyst]

Thanks for your response, i really appreciate it.

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I have uploaded 2 images (sorry they are not a bit clearer), it shows the left and right side of the 4 pipes situated below where the storage tank used to be.

Pipe A: comes up, travels along a horizontal pipe and goes straight back down into the floor. It is hot.
Pipe B: comes up, travels along a horizontal pipe and goes straight back down into the floor. It is warm.
Pipe C: comes up, and goes to the hot tap of the bath, situated to the right of the second pic.
Pipe D: comes up, and goes to the cold tap of the bath, situated to the right of the second pic.

Hope that gives some clues. My guess is pipes A and B used to connect to the storage tank, and a bit of pipe has been put there in the tanks place.

I presume removing those bits of pipe and blocking the joints would stop flow when all the rads are off (as mentioned above), and would help force flow to the the trouble rads. if I just opened them individually. Does that seem likely?

Thanks again.

 

[Andygasman2010]

I see it's grey plastic pipe, it's much more likely to be blocked than piped up wrong. When you talk of a storage tank being taken out and a loop put in its place, do you mean between the flow/return connections of a hot water cylinder? Either way this would be wrong. The cylinder and hot water circuit should be removed completley and the heating circuit should be the only thing in the equasion. A closer inspection of the pipework layout is needed here i'm affraid.

How much of the system is on that grey plastic pipe?

 

[Assimalyst]

Thanks again.

Yes, as far as I can tell the pipework is all grey plastic, similar to pipe C.

To me (very much a non professional!) it looks like the hot water cylinder was removed and the flow and return pipes were just connected with a pipe (A & B) instead of being removed from the system completely.

I don't fully understand how the storage tank would have fit into the system, but could it be that the rads were on one loop, for heating, and the storage tank was on another loop, for hot water. Now the tank is not there, there is just a dead loop that allows easy circulation, and essentially steals any flow from the restricted pipes to the problem rads?

Thanks

 

[Andygasman2010]

If that's the case then it is piped up wrong. It also sounds like the plastic pipe is blocked too.

I'm affraid you're going to have to get a pro in to sort this one, unfortunatly!

Don't be suprised if he advises a full system repipe. Good luck!

 

[Assimalyst]

Not what I wanted to hear!! But huge thanks for your time and your thoughts, it saves me paying for a power flush that would most likely be pointless.

Thanks again.