Lukewarm radiators - New boiler needed?

[JayPee]

Hello,

My CH system (inc boiler) is about 20 years old. It's a conventional vented system and the radiator circuit uses 10mm microbore pipe.

Although I get hot water, the rads are barely lukewarm. The problem is getting worse. I need to turn off some radiators to help others heat up; when I try bleeding the rads, it's obvious there's hardly any pressure.
I've replaced the pump and motorised valve but to no avail. The boiler appears to be working but could it be at fault? Can an old boiler corrode internally and restrict the flow? How do I check this for certain?

I hope someone out there can help... Thanks

 

[gas4you]

Sounds like a build up of sludeg in the system that is restricting the flow to the rads. If you have a manifold system it could be this that is blocked.

I would suggest adding a good cleanser to your system or employing somebody to carry out a powerflush, although this is not always totally successful with microbore systems

 

[JayPee]

Thanks, I try that first.
Do you recommend any particular cleansing products? It might make sense for me to use a cleanser first, then get a power flush a week or so later.... Any thoughts on that?

 

[gas4you]

Personal choice really. I always use Sentinel X400. Fernox do equivalent. Leave in system for up to 4 weeks if badly blocked

 

[Bamber gaspipe]

Rip out the pipework & have it done in 15mm. No cleanser in the world will descale 10mm pipework thats been in for yonks. It might work in the short term. You have to remember that 10mm pipework was thrown in for speed & it`s flexibility,it`s not worth a carrot,rip it out now.

 

[2face]

i would rip it all out and renew the money it costs will soon be recuperated with the more efficient combi and correctly sized radiators .. y throw money into a empty pit m8. we have guys up here doing a combi and 7 rads for under 2000 ..

 

[Timmyturtle]

I would try to add a chemical first .
Most people cant afford to just renew everything
Personally i use Kamco Hyperflush and leave it in for a couple of weeks.
Its non acidic so wont harm anything but seems to work ok.
Powerflushing is not as effective (as already said) on microbore but does help,though it is costly

 

[JayPee]

Thanks guys. Replacing the pipework is not an option! Most of it is buried in walls and under floors, some of which are tiled and covered in hardwood flooring...

I've just bought some X400, so I'll try that at the weekend and hope that helps. If it's still not better in a few weeks, I'll have to resort to power-flushing... If that doesnt work, I'll just have to sell the house!!!

 

[gas4you]

Maybe you will need to look out for an Eskimo asylum seeker

 

[Timmyturtle]

If its adjustable put the pump on full (you probably already done this)
You can get 2 types of X400..in a bottle or in a tube that goes in a "silicone" gun.
The gun one can be put in a rad bleed
The bottle can also be put in same area if newish style rad if you isolate the rad and drain some off
If you put the X400 in the loft expansion tank you need to drain a bit off from the heating to get it in the system properly