Half downstairs radiators not working

[RedTiger]

Hi all. After some expert opinions/advice please.

We moved into our house 6 months ago. Now winter is coming, we've realised that 4 of our 8 downstairs radiators aren't heating up at all. All 8 upstairs work fine.

My first suspicion is blockages in the microbore pipes, as we had this in our previous house which was also built in 2000. Have tried Sentinel x800 but no use. Have used a footpump on the pipes and cleared out some sludge, but not enough apparently.

I can see the previous owner (now deceased) obviously had some work done as there have been holes cut out of the walls by the blocked rads, and badly filled back in. We wondered if we maybe had a blocked manifold, but hard to tell as we have chipboard.

Any thoughts/suggestions would be appreciated. I'm more than happy to pay for an engineer, but the couple we've had out to date just looked a bit confused and didn't fancy the job.

 

[jeff the gasman]

System may need balancing.
Turn off the ones that work and see if they start to work.
Report back

 

[JohnD]

Turn off ALL the hot ones. Do any of the cold ones warm up? Even a bit? Even just one pipe?

 

[terryplumb]

Do the cold rads have TRV's ? If so remove the actuator heads and see if the pin in the body is moving freely up and down a few millimetres.

 

[RedTiger]

Thanks for quick replies guys.

We have tried previously closing all 12 working rads, but no effect on the others. Still stone cold. 1 or 2 had a warm pipe leading to them, but not for long.

We are going to experiment with replacing the valves, but I think it's a long shot. If it was just one radiator then maybe. I think it's unlikely to have happened on 4. I hope I'm wrong though...

I think the system could be very blocked. Signs suggest it was an issue 2+ years ago for the previous owner, and then the house was empty for 18 months. I need to get a magnaclean, once this is fixed...

 

[terryplumb]

Do the cold rads have TRV's ? If so remove the actuator heads and see if the pin in the body is moving freely up and down a few millimetres.

If the cold rads have TRV's ,and they have all been turned off for some reason ,for a long period, they may well all be seized closed.
There is a simple way to determine if both valves ,and the pipes they connect to ,are running free of blockages.

 

[jeff the gasman]

Remove the heads and tap the pin with a hammer.
May take a few minutes.
Or tap it with a spanner or a piano. Be firm but gentle.

 

[JohnD]

I find an easy way to work pins up and down is with a soupspoon in the palm of the hand. The pin will not bend or slip sideways.

You can use a toothbrush with WD40 to scrub dirt off the pin, more may come up as you work it.

If the pipe is getting warm, there is a bit of flow, so X400 can get through and hopefully loosen some more. A Magnaclean will catch anything loosened that flows round. No need to wait until after it is fixed. X400 can be left circulating for several weeks and is not aggressive. You can rattle the pipes and rads with a rubber mallet to help loosen some, but fit the Magnaclean first to reduce the risk that it will settle somewhere else.

 

[RedTiger]

Thanks all. Slow reply here as I've been working on the radiators. Checked if the valves were jammed/blocked, even changed a few. But no luck sadly.

I fear it's something way behind the floors/walls, possibly in the manifold. Will try and find a good local plumber I think as I'm fairly stumped.

 

[Harry Bloomfield]

You need to find the location of, and access the manifold(s). Have you tried tracing the underfloor pipe runs with a metal detector? The pipes should lead you to the manifold(s).

 

[adamb4321]

This sounds a lot like my heating system, 10mm plastic microbore pipes and an open vented system with an Ideal Classic boiler with a cast iron heat exchanger. House built in 1999 I moved in around 2003. The heating system never worked properly, random radiators produced no heat or very low output.

Various BG engineers tried balancing the system which made a bit of difference whilst they were here, but generally just moved the problem to another radiator. 4 years ago had the system flushed and a Magnaclean filter installed. The plumber that did the work reckoned there was no inhibitor in the system.

Seemed great when the work was done (July) but same old problem of some rads not working was back in the in October when the heating went back on.

Over the last 4 years it got worse and worse, most downstairs and a few upstairs rads had no output at all. I found some TRV heads were not opening, these were replaced.

I did a bucket test on the rads with no flow. most had no output from the valve end. I used various things to unblock: a 5m length of curtain wire was pretty effective but for one rad that took the entire length of wire and still wouldn't produce a flow I gave a short burst from a CO2 bike pump. This cleared the blockage. I had dosed the system with X400 and had it circulating for about a month. Even though I'd now got a decent flow out of all the radiators a lot still wouldn't produce heat.

I found that while poking bits of wire up the pipe did get rid of the blockage, doing on my own wasn't much fun. The sudden gout of black water that erupted from the pipe took me by surprise a couple of times and I could've used another pair of hands to get the valve back on and shut. All I can say is I'm amazed that my carpet vac got the black sludge out.

In the end I powerflushed the system myself using an acid based cleaner to break down the rust. The system was chock full of sludge, it took me about 10 hours to get to the point where the system was running clear. It's been dosed up with X100. I'm sure If I flushed it again I'd get more crap out, there did seem to be an endless amount of it.

The system has never worked so well, that said it's still a crap system. I'm planning to have some work done in the future so it will be replaced.

 

[JohnD]

How often did you empty the Magnaclean?

 

[adamb4321]

I empty the magnaclean a couple of times a year. The Magnaclean didn’t collect that much debris. I initially thought it was because the system was clean. It collects really fine particles well. But the amount of rust that was at least the size of coarse sand or bigger (some much bigger) that came out during the flush was surprising. The big bits of rust and scale probably aren’t very mobile and don’t make it to the filter. I’ll check the magnaclean tonight or tomorrow and see what’s it’s caught since flushing a month ago.

 

[NewhouseOldhouse]

where do I pour X400 into a pressurised system, I have a Magnaclean installed as well?

 

[Harry Bloomfield]

where do I pour X400 into a pressurised system, I have a Magnaclean installed as well?

Basically by what ever method you can use to get it into the system. Depending on how the Magnaclean is installed, you might be able to isolate that, drain and refill with X400. Or isolate a radiator from both flow and its return, drain some water out and add the X400 by removing an upper bung, finally reopen both valves.