Finding a blockage in heating pipework

[Last Plumber]

I'm thinking that if those rads are not working and there is some sort of restriction in the flow around the system, it is a good place to start. As good a place as any.

You will confirm whether there is a clear path to each end of each rad.

It will only tell you if that length of pipe to the rad is clear of course. Beyond that is more difficult, it can flow from either side of a tee, for example.

You may be better releasing the pressure from the rad in your case, that way there will still be pressure in the system to allow water to be pushed from the end you have disconnected. You will have to keep it topped up too.

Once you've done that and ruled out a blockage in each section, you can move on with your thinking.

A lot depends on route too and like I said earlier, we haven't seen the job.

If for example, the two downstairs rads are fed together then a blockage in either flow or return would stop them both from working but if they are both tee'd off separately, you are less likely to learn anything because water can flow form either direction.

I am just trying to think of a good place to start !
Hope this is helping and not confusing the issue.

 

[Last Plumber]

Just to refer back to CHUCK's comments earlier.

This blockage ( if it is a blockage ), could just be partial and could cause the Boiler to short cycle.
That would prevent the downstairs from getting hot.
If that's the case, the you would possibly still get a flow from each leg.

What size are the pipes in the downstairs circuit, are they the same as the rest of the circuit or smaller?

 

[jaydebruyne]

I'm thinking that if those rads are not working and there is some sort of restriction in the flow around the system, it is a good place to start. As good a place as any.

You will confirm whether there is a clear path to each end of each rad.

It will only tell you if that length of pipe to the rad is clear of course. Beyond that is more difficult, it can flow from either side of a tee, for example.

You may be better releasing the pressure from the rad in your case, that way there will still be pressure in the system to allow water to be pushed from the end you have disconnected. You will have to keep it topped up too.

Once you've done that and ruled out a blockage in each section, you can move on with your thinking.

A lot depends on route too and like I said earlier, we haven't seen the job.

If for example, the two downstairs rads are fed together then a blockage in either flow or return would stop them both from working but if they are both tee'd off separately, you are less likely to learn anything because water can flow form either direction.

I am just trying to think of a good place to start !
Hope this is helping and not confusing the issue.

No I hear what your saying, and I really appreciate your help.
NEW: if I turn off the very first rad from the boiler

Just to refer back to CHUCK's comments earlier.

This blockage ( if it is a blockage ), could just be partial and could cause the Boiler to short cycle.
That would prevent the downstairs from getting hot.
If that's the case, the you would possibly still get a flow from each leg.

What size are the pipes in the downstairs circuit, are they the same as the rest of the circuit or smaller?

As far as I can see as I've taken up a couple of boards downstairs is in 15mm. I've strangely got flow now. Gone open one rad at a time and see what gives me the weakest flow and return temp to see if I can narrow it down

 

[jaydebruyne]

I'm just uploading some vids to YouTube to post here so you can see the run of the circuit but here's what I've learned:

Boiler feeds
upstairs small bedroom first = good flow/return
Tees off to
Left to office rad = good flow no return rad gets hot via bypass
Right to hallway rad = good flow/return
Continues right and I pick up a square grid of pipework
Tees left to feed downstairs and to feed
upstairs bedroom rad = good flow no return rad gets hot via bypass
Tees right from square to old gravity pipework and just loops and returns = good flow
Downstairs rads all have good flow and no return all rads get hot via bypass

So basically the return path stops after feeding upstairs small bedroom and upstairs hallway and then disappears.

So I'm thinking to start lifting boards there????

Upstairs circuit

Downstairs circuit

UPDATE:
Found the blockage!! Whoop. It's on a tee after the first 2 rads on the return just before it goes downstairs. Well happy. Thanks so much for all your help everyone, couldn't have done it without you ❤️

 

[Chuck]

My reading of the situation is that the return doesn't seem to get back past the 'square grid' but is okay before that. That would point the finger of suspicion at the section of return you are looking at between 15s and 17s in the first video.

If it were my nice wooden floor, I would want to use this a hypothesis and test it by checking that the returns between radiators on the far side of the hypothesised block were all talking to each other but not to anything on the near side of it.

Once you have pinned down the blockage don't let the joy stop you thinking. Whatever you do next needs to get it out of the system not just move it somewhere else. If power flushing failed, as it did in this case, the best strategy might be to replace the blocked length rather than try tricks of the trade to unblock it.

 

[jaydebruyne]

My initial impression is that the return doesn't seem to get back past the 'square grid' but is okay before that. That would point the finger of suspicion at the section of return you are looking at between 15s and 17s in the first video.

If it were my nice wooden floor, I would want to use this guess as a hypothesis and see if it was consistent by checking that the returns between radiators on the far side of it were all talking to each other but not to anything on the near side of the hypothesised block.

Once you have pinned down the blockage don't let the joy stop you thinking. Whatever you do next needs to get it out of the system not just move it somewhere else. If power flushing failed as it did in this case, the best strategy might be to replace the blocked length rather than try to unblock it.

Absolutely! I'm going to cut out the section of blockage and repipe it

 

[jaydebruyne]

The pipework is silver.. what's that about? Def not chrome. I know the pipework is quite old. Just wondering what it's about and if I can solder to it?

 

[ShaunCorbs]

Thin steel (copper shortage in the 70s)

Only compression can't solder

 

[Chuck]

If it looks grey but is fairly soft and silver if you scratch it it's likely to be lead. Lead was still used up until about, say, 1970.

Anyway, the techniques used for jointing lead are not quite the same as for copper tubing and I would recommend you don't make the first time you try it on a customer's system.

There are a couple of people who are active posters (Last Plumber and JustinLead1 come to mind) who have mentioned they have leadwork skills. Probably best to upload a couple of photos and hope they drop in.

 

[jaydebruyne]

Thin steel (copper shortage in the 70s)

Only compression can't solder

Cheers Shaun

 

[jaydebruyne]

If it looks grey but is fairly soft and silver if you scratch it it's likely to be lead. Lead was still used up until about, say, 1970.

Anyway, the techniques used for jointing lead are not quite the same as for copper tubing and I would recommend you don't make the first time you try it on a customer's system.

There are a couple of people who are active posters (Last Plumber and JustinLead1 come to mind) who have mentioned they have leadwork skills. Probably best to upload a couple of photos and hope they drop in.

Def not lead. Exactly like copper but silver. Cheers chuck

 

[Chuck]

Thin steel (copper shortage in the 70s)

If it is steel then, obviously, you can't use a magnet to tell whether it's blocked...

 

[ShaunCorbs]

Would give them a price to re pipe if it is what I'm thinking about

 

[jaydebruyne]

Thin steel (copper shortage in the 70s)

Only compression can't solder

Is it thin/soft enough to cut with a pipe slice? There's no room for a hacksaw lol

 

[jaydebruyne]

If it is steel then, obviously, you can't use a magnet to tell whether it's blocked...

I know where the blockage is.. but no.. glad I found it before I got the magnet out lol

 

[jaydebruyne]

Would give them a price to re pipe if it is what I'm thinking about

As in rip out all thin steel pipe? It's not weird sizesis it? Standard compressions will be ok?

 

[Old Account]

Maybe you could cut the T out to inspect how badly it was blocked. It would interest me

 

[Chuck]

Standard compressions will be ok?

Not if it's what I think it is (galvanised steel). You'll need to use a 'dielectric' coupling and put a thread on the end of the steel pipe. There may be other methods, my only real experience of steel pipe is seeing it in a skip after someone else has ripped it out. But... I'd describe it as looking more 'grey' than 'silver' (think electrical conduit). 'Silver' could describe stainless-steel, but I've never seen that in domestic premises.

Sorry, I think you'll need to post a picture for a postive id.

 

[ShaunCorbs]

Is it thin/soft enough to cut with a pipe slice? There's no room for a hacksaw lol

No hacksaw job sorry to say or grinder

 

[ShaunCorbs]

As in rip out all thin steel pipe? It's not weird sizesis it? Standard compressions will be ok?

Yea stnd 22mm will fit you might need some 3/4 olives tho