Cold radiators in loft

[milleniumaire]

Hi, I've have a problem with my CH system for around 18 months now and it's time to get it sorted. Here's a diagram showing our current heating system:

The house is 21 years old and the loft extension was performed around 15 years ago. As you can see they simply extended the existing 15mm pipes up into the loft and then split them. The Vaillant equipment is 8 years old and still going well. We had the UFH installed 5 years ago as part of a kitchen extension.

Only one of the radiators in the loft gets a little warm, never hot and the other radiator and towel rail are always cold, so there's clearly a blockage or two. I have accessed the 15mm flow and return pipes to the loft at the point they are connected under the bathroom floor and the flow pipe gets very hot, the return pipe is barely warm. I have tried closing all valves to force the water into the loft pipes but it makes no difference.

I have been considering replacing the existing 15mm pipes into the loft with 22m pipes and connect them up earlier as is shown in the following diagram:

Obviously I'll have to resolve the existing blockages in the loft pipework.

My diagram may not be accurate for the Ground floor radiators. It currently shows the flow going into the final toilet radiator and then back out into the return. Is this how you would expect the pipes to be connected at the end of a run or would the flow become the return? The 1st Floor to loft connections shown in the first diagram are exactly as they are plumbed. So, if all the loft radiators were turned off, there's no way for the flow to return to the boiler (I think!). In fact, in my diagram the only way for the flow to become the return is through a radiator. Not sure how accurate this is.

A couple of concerns:
1. Will the boiler pump be able to handle the additional 22mm pipes running into the loft?
2. Should I consider re-routing (new) pipes around the loft as the "star" connection currently used looks to be a limitation to my untrained eye.

Thanks in advance for your thoughts.

 

[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

 

[centralheatking]

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:

View attachment 41439

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:

View attachment 41440

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":

View attachment 41441

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:

View attachment 41442

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.

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

There is sentinel ..deposit remover.. which is supposed to be really naughty hot or cold....Its a bit off the wall but we used to use my 140amp arc welder to heat up frozen pipes years ago...this would certainly get to the parts you cannot reach.
Attatch the earth clamp to bare copper pipe and run big fat cable 10m 20m away to another earth clamp switch on bingo after a while. Do not do short lengths of pipe as you might vapourise the copper...fun in my workshop it was when we had had a few tins. centralheatking