Cold radiators in loft

[ShaunCorbs]

Thanks for the info. This is a little beyond my knowledge level, but I will consider it after I have tried everything else, if the issue persists.

In my case, it is actually easier for me to lay some new 22mm pipe as I'm currently renovating my bathroom, which involves lifting a lot of floor boards. This is the reason why I've decided to attempt to resolve the loft issue now, while I've got access to the bathroom CH pipes that feed the loft.

Our boiler is due a service next month, so I will discuss it with the heating engineer and see what he says, however, I hope to have the loft radiators working before then.



Yes, I have tried this a couple of times and when the "power flushing guy" came round, he also tried it. I think he assumed he would easily be able to clear the blockage, but it made no difference.

I will try this again however but with the pressure raised to 2.5 bar as suggested by Stigster.

Pull one of the rads off

Open the flow into a bucket does much water come out and the pressure drop in the system

Do the same test on the return will tell you which one could be blocked

 

[milleniumaire]

Pull one of the rads off

Open the flow into a bucket does much water come out and the pressure drop in the system

Do the same test on the return will tell you which one could be blocked

Thanks Shaun. You have just reminded me that last year after I had replaced the TRV's on both radiators, I tried this. The water from the piping connected to the lockshield side of the radiator (I would assume the return pipe) was much slower, however, there was water coming out, which did confuse me as this suggested it wasn't blocked.

 

[ShaunCorbs]

Thanks Shaun. You have just reminded me that last year after I had replaced the TRV's on both radiators, I tried this. The water from the piping connected to the lockshield side of the radiator (I would assume the return pipe) was much slower, however, there was water coming out, which did confuse me as this suggested it wasn't blocked.

Might be draining from the other rads etc close them off then test

 

[milleniumaire]

Sorry Stigster I didn't see this original post. I will definitely try this. I assume to increase the system pressure it's simply a case of letting more water into the system and monitoring the pressure gauge. While the boiler is running hot, the pressure is at 1.8 bar, so I guess I could increase this to 2.5 bar and then afterwards let water out through the magnaclean connections.

Tried this tonight but increasing pressure didn't make any difference.

At the weekend I will drain the loft down and disconnect it from the rest of the heating system, then after removing the radiators try forcing mains pressure water through some of the pipes.

 

[milleniumaire]

I had another go at flushing through last night, but the water is still only trickling through, so the pipe run I'm currently working on is still obviously blocked. After I poured out the water from the bucket, I was surprised to see this:

This is from only one pipe run of the 6 I have to flush!

Although I've flushed through one of the radiators outside, I may replace them both as they are around 15 years old. Not sure what to do about the chrome towel rail. I assume these can also corrode on the inside?

Not sure if this sludge in the loft pipes is purely from the loft radiators or if it will be from the whole house, but will have settled in the loft pipes due to the poor flow.

This amount of sludge explains why the radiators in the loft aren't warming!

 

[centralheatking]

I had another go at flushing through last night, but the water is still only trickling through, so the pipe run I'm currently working on is still obviously blocked. After I poured out the water from the bucket, I was surprised to see this:

View attachment 41184

View attachment 41185

This is from only one pipe run of the 6 I have to flush!

Although I've flushed through one of the radiators outside, I may replace them both as they are around 15 years old. Not sure what to do about the chrome towel rail. I assume these can also corrode on the inside?

Not sure if this sludge in the loft pipes is purely from the loft radiators or if it will be from the whole house, but will have settled in the loft pipes due to the poor flow.

This amount of sludge explains why the radiators in the loft aren't warming!

Well done so far, it gets easier with practice, look on the bright side, at least the sludge is black...brown sludge is very naughty. Remember when you think its all done it is not
at least two more passes...but think how much money you are saving and you know its been done. award yourself 4 tins of whatever straight away and a similar portion at the end with a takeaway...centralheatking

 

[milleniumaire]

Well done so far, it gets easier with practice, look on the bright side, at least the sludge is black...brown sludge is very naughty.

I'm intrigued. What is brown sludge?

 

[milleniumaire]

One radiator and associated pipes have now been cleaned out and reconnected to the CH system and it is working perfectly.

Just the towel rail and another radiator to go.....

 

[centralheatking]

I'm intrigued. What is brown sludge?

Oh sorry I missed this, my understanding is thus
1. Black Ferric Sludge occurs with a sealed system inc. an open vented system and needs to be dealt with.
2. Brown Ferric Sludge indicates that the system is continually introducing fresh water with air dissolved into it, maybe eg an open vented system is pumping over.
I tested this towards the end of my last house which I sold for demolition...I had an Eclipse MicroMag industrial filter on it when we deliberately left an mt cock slightly open the ch water turned from black to brown when we took the micromag out of circuit.
To explain my main workshop in that house had the boiler located there so we used to use it as a test vehicle for all sorts of things.
centralheatking

 

[milleniumaire]

2. Brown Ferric Sludge indicates that the system is continually introducing fresh water with air dissolved into it, maybe eg an open vented system is pumping over.

I did Google Brown sludge but only found references to car radiators.

As my system is sealed hopefully brown sludge won't be a problem, but I am alarmed at the amount of black sludge I have come across in the loft pipes and radiators, which is strange as the magnaclean never seems to get very clogged up. I need to check it again now that I've re-introduced one of the loft radiators.

 

[centralheatking]

I did Google Brown sludge but only found references to car radiators.

As my system is sealed hopefully brown sludge won't be a problem, but I am alarmed at the amount of black sludge I have come across in the loft pipes and radiators, which is strange as the magnaclean never seems to get very clogged up. I need to check it again now that I've re-introduced one of the loft radiators.

You are quite correct water cooled motor vehicles do suffer badly, we did look at automotive with Honeywell but there was no commercial traction so we both walked away It is not for me to criticise
any domestic magnetic and strainer type ch filters. Its been at least a decade when I designed some..domestic mag filters .not Magnaclean. You might go along your naughty radiators and visible pipes with a magnet and a soft rubber mallet...thats quite good
there is an adgitator tool which you can put on a domestic electric drill that was origionally my idea I dont know what they call it ...But I got paid for it as usual...nice holiday.
Chemicals will only maintain the status quo not remove the stuff ...a really good reverse pump out first is good...this should take two men all one day.
centralheatking

 

[milleniumaire]

...a really good reverse pump out first is good...this should take two men all one day.
centralheatking

Is this different to a power flush?

 

[centralheatking]

Is this different to a power flush?

Well a proper power flush ought to incorporate reverse flush in my opinion...the trouble is a proper one really does cost hence naughty boys under quote or even quote but do not do it properly. If it was my gaff...I would take the day off and check it all...others on PF will explain what to watch for .....centralheatking

 

[milleniumaire]

I spent the weekend working on the towel rail in the loft. Removed the towel rail and the valves leaving only the copper tails, to which I attached my hosepipes. The other end of the supply/return pipe was connected together using a speedfit flexible hose. So, I have a loop and I pushed in mains pressure water to one radiator tail and the other tail had a hose with the end in a bucket.
No matter what I did, I couldn't get any water through this setup. Actually, there is a very tiny slither of water coming through, but barely anything.

I tried reversing the hose pipe connections and I tried isolating only one of the pipes (to shorten the length being cleaned i.e. hose pipes on both ends of a single pipe) but still no water came through. These pipes are well and truly blocked!

Last night I put some Sentinel X800 into both pipes in the hope this might loosen up the sludge and I will try flushing through again tonight.

I know Sentinel X800 is used for cleaning systems, but I'm not sure it will "dissolve" the hardened sludge in these pipes enough to move it. Can anyone recommend a better chemical? Would Fernox DS40 be better (it's certainly a lot more expensive).

I'm close to the point of giving up and accepting these two pipes will need to be replaced, but that then makes the job a whole lot more complicated due to access!

Any ideas would be welcome.

 

[centralheatking]

I spent the weekend working on the towel rail in the loft. Removed the towel rail and the valves leaving only the copper tails, to which I attached my hosepipes. The other end of the supply/return pipe was connected together using a speedfit flexible hose. So, I have a loop and I pushed in mains pressure water to one radiator tail and the other tail had a hose with the end in a bucket.
No matter what I did, I couldn't get any water through this setup. Actually, there is a very tiny slither of water coming through, but barely anything.

I tried reversing the hose pipe connections and I tried isolating only one of the pipes (to shorten the length being cleaned i.e. hose pipes on both ends of a single pipe) but still no water came through. These pipes are well and truly blocked!

Last night I put some Sentinel X800 into both pipes in the hope this might loosen up the sludge and I will try flushing through again tonight.

I know Sentinel X800 is used for cleaning systems, but I'm not sure it will "dissolve" the hardened sludge in these pipes enough to move it. Can anyone recommend a better chemical? Would Fernox DS40 be better (it's certainly a lot more expensive).

I'm close to the point of giving up and accepting these two pipes will need to be replaced, but that then makes the job a whole lot more complicated due to access!

Any ideas would be welcome.

Try finding a drain off at the lowest point possible in the whole building put a hose on it with a jubilee clip run to the outside. Then re visit your loft connect mains pressure to one tail.....blank off the other....first thing will be the rads will glug glug but dont touch them yet.
Then give it a gentle blast of mains ..to check connections..when sound open it up you really should get plenty from the drain off hose. usually black stuff. are you sure up in the loft you are on mains ..not tank fed low head pressure. ask away we are here to help
centralheatking

 

[milleniumaire]

Hi, thanks for posting.

Just to clarify, the towel rail and its piping in the loft have been isolated from the central heating system, which is operating as normal.

So, I have a couple of hep20 pipes in the loft which connect to the tails of the towel rail and the other end of these pipes do not connect to anything. I am therefore able to so push mains water through these pipes in isolation of the CH system. Despite doing this, I'm unable to get mains pressure water to pass through either pipe due to the extent of blockage.

As I say, I've tried using X800, which may loosen up the blockage, but I won't know until tonight. I'm trying to determine if there is a better chemical to use in case X800 doesn't work.

Thanks.

 

[centralheatking]

Hi, thanks for posting.

Just to clarify, the towel rail and its piping in the loft have been isolated from the central heating system, which is operating as normal.

So, I have a couple of hep20 pipes in the loft which connect to the tails of the towel rail and the other end of these pipes do not connect to anything. I am therefore able to so push mains water through these pipes in isolation of the CH system. Despite doing this, I'm unable to get mains pressure water to pass through either pipe due to the extent of blockage.

As I say, I've tried using X800, which may loosen up the blockage, but I won't know until tonight. I'm trying to determine if there is a better chemical to use in case X800 doesn't work.

Thanks.

Well its obvious then one side of the rad was a feed the other a return no matter what you do there is no circuit..you might have created the blockage yourself...do a diagram we can all look at it later when we get gnome. centralheatking

 

[milleniumaire]

HI, sorry I'm obviously not explaining myself very well.

Here's the original posted diagram of my CH system (the original posted diagram seems to have disappeared). Notice the loft piping:

So, originally, I disconnected all the pipes in the loft from the supply and return (copper pipes from 1st floor to loft). I then flushed through one of the radiators and pipes and successfully cleared them. This radiator is now connected back up, so the current loft setup is shown as follows:

As you can see now, only ONE of the loft radiators is connected to the CH system and this radiator is working perfectly - it gets red hot. I'm now working on the towel rail, shown in the diagram as Loft En-suite, which is currently disconnected from the CH system, allowing me to work on the towel rail and connected pipes in isolation. Here's how I initially connected up the pipes for the towel rail to create a small isolated "circuit":

Note: The towel rail and the valves connecting the towel rail to the Hep20 plastic piping (via copper tails) have been removed, so I'm now working with ONLY the piping. Each pipe run (supply - red and return - blue) is around 4m, so not very long, but they are obviously well and truly blocked.

The above diagram shows I have connected one end of a hose pipe (yellow) to the tail of the supply pipe and the other end is connected to an outside tap, with mains water pressure. Another hose pipe (green) is connected to the tail of the return pipe, with the other end of the hose pipe in a bucket ready to catch the sludge. Between the flow and return pipes I have fitted a flexible hose, so I now have a circuit of piping.

When I turn on the outside tap, the water should end up in the bucket! But I get nothing because the pipes are well and truly blocked. I've tried the following circuits to reduce the length of pipe being cleaned, so I'm doing one pipe at a time:

I've tried the above setup on both the flow and on the return and reversed the hose pipes to flush from both ends, but can't get water through either pipe (apart from the smallest of drizzles).

So, last night I put some X800 into the tails of each pipe until it started (very,very slowly) leaking out of the other end of the pipe, so I knew it had gone through, or at least it was pushing water out. By tonight, this concentrated X800 will have been in for 24 hours and I will attempt to flush the pipes through again.

However, I'm not convinced that X800 is actually the correct chemical to use as I've read it doesn't dissolve sludge, which is what I need it to do, hence the question about other chemicals that may do a better job.

 

[centralheatking]

It would seem you really do have a severe blockage, have you been along with a magnet ? you could also be gently aggressive with a wood mallet or a rubber hammer. I will ask my friends at Sentinel in Runcorn about really naughty chemicals that you might get...not ones you can purchase ...unless others on PF can help chking

 

[milleniumaire]

Unfortunately, I can only access the pipe in the eaves, not the pipe running under the floorboards between the joists, which are full of wool type insulation.

I have had an idea though. I have a long piece of thick, malleable wire that I use for those DIY jobs that require cable to be fed through difficult to access holes etc. I can probably push this in from the eaves end of the pipe although I don't think it is long enough to reach the other end. There will be a 90 degree elbow joining the copper tail to the plastic pipe, so wouldn't be able to access this end with the pipe unfortunately as it wouldn't get around that bend.

If I have no success flushing again tonight (after the X800 has had time to work/not work) I may try using the wire, but as a last resort if the above fail, I would be tempted to nuke the pipes with more chemicals 🙂