Some heating circuits not working well - what to do..?

[gaz1]

The last test is what I describe above. Just that one rad on. I don't understand why I can get a good fast clear flow with a hose yet the pump won't get heat there when that's the only rad available to circulate to.

i dont use a hose pipe as its direct pipe feed theres a difference to full flow and hitting sludge in pipework

hosepipe is known to fly off when your using the water pressure of our area hence the reason to use direct pipe connected

and yes you can still have sludge in your system even when you have full flow of clear water going through your pipes

if you want to test that rad close it off and drain it take it off the wall and swap with another one thats the same size rad with another so then you can test the flow of another rad the same size as the bad flow could be the rad itself

if still the same issue then its ceratinly got issues with the pipes up to the manifold or swap pipes at the manifold and try again and see what happens so your also then checking the manifold itself

its just many ways of testing the rad pipes and manifold to see what the issue is swapping and testing is the way to go if your diy it

 

[gaz1]

you can get clear water through a sludge up copper pipe easily as a hole will still go through the pipe

note the pic the sludge is still there and because your pipes run in a u shape once sludge gets into the pipes it will settle and stay there



a power flush dosnt always remove it due to the u shape of the system but can show clear water going through thats why reversing method can shift a bit more

the only sure way is to remove the lot and fit new pipes

ive got one to do and ive power flushed it the best i can do and thats on a 18 year old system badly maintained has been sludged up to hell and back

 

[reb78]

you can get clear water through a sludge up copper pipe easily as a hole will still go through the pipe

note the pic the sludge is still there and because your pipes run in a u shape once sludge gets into the pipes it will settle and stay there

View attachment 471754

a power flush dosnt always remove it due to the u shape of the system but can show clear water going through thats why reversing method can shift a bit more

the only sure way is to remove the lot and fit new pipes

ive got one to do and ive power flushed it the best i can do and thats on a 18 year old system badly maintained has been sludged up to hell and back

Point taken.

Silly thing is these will be the newest pipes in the house - all plastic of some sort.

 

[JimmyS]

Hmm all a bit odd. Is the circuit sealed or vented?

 

[dobbslc]

the most troublesome rad only - i.e. no others receiving pumped water, it still takes forever to get warm.

Is the lockshield valve fully open? I've had them stick shut before.

unplug the other pump

@gaz1 is it possible that even with that pump turned off it's still letting through and diverting the water?

 

[reb78]

Hmm all a bit odd. Is the circuit sealed or vented?

Vented due to the use of the solid fuel Rayburn in the system

 

[reb78]

Is the lockshield valve fully open? I've had them stick shut before.


@gaz1 is it possible that even with that pump turned off it's still letting through and diverting the water?

Lockshields are all clear on that rad - I checked recently when I was flushing it and it was behaving the same before the flush.

Re the turned off pump - the flow pipe beyond it never got hot when I was only running the manifold pump so I don't think it's bypassing there.

 

[JimmyS]

I'm assuming that the open vent and cold feed will be directly to the thermal store then? If so it's not likely to be an issue with that.

Have you checked the regulating valves on the ufh manifold are fully open? Some ccts have flowmeters and some don't from the photo?

 

[gaz1]

Is the lockshield valve fully open? I've had them stick shut before.


@gaz1 is it possible that even with that pump turned off it's still letting through and diverting the water?

it wont due to the second pump pushing water down the line of tube a rough water flow diagram of rebs system

both lines must be equalised seperatley as well as the flow taken into account with the return flow as well should be run in 28 or 32mm pipe before the split as you are getting 2 flows at the return the pump with a better speed push the water will aim that way more than the other line due to more pressure that side of the line


the only thing i can test with now on rebs line is try another pump down the issue line again and then after swap the rad for another rad if you have the same size rad on the property to swap with alternate way is buy a new rad but you could be wasting your money until that lines is tested with another rad as the issue could be within the pipes or at that new manifold

i suspect pipes or the rad has an issue so to take out the rad swap it for another one and see what you get

for me and kayos its easy enough for us to test the line by using fittings and a bit of pipe between the rad fittings with no rad involved than pipe at the return side will become red hot at first run of it therefore testing the pipe in that line if still remains with no heat at that point you have a pipe blockage or a very low flow through each valve back to the manifold

 

[Nomad]

I've done work in a few places with older CH systems (as a keen DIY'r), some suggestions :

Good advice above about swapping the problem rad with a known good working one if possible

I normally take each rad into the garden (careful not to drip any black "ink" on the carpet), fill half full of water and sloosh it around to loosen sediment inside. Rinse well, repeat until the water is clear.
Have also seen - on here? - to put an SDS hammer drill onto a plank of wood held against the rad - vibrations shake any sediment loose.

When I was working alongside a plumber he used to fit magnetic filters in places that had problems with sediment, MagnaClean or similar, Worth thinking about? https://search.brave.com/search?q=magnaclean+central+heating+filter

Had good results for a couple of "problem" rads by fitting new rads - a quick job if you buy with the same spacing between the inlet / outlet so you don't need to adjust any pipework. Think about replacing your problem rad?

I had problems recently that turned out to be a stuck plunger in a one-way valve, have also seen systems acting up if a motorised 3-way port / valve failed. Could you have anything like that in your system?

An IR camera would be good but I just use a £10 IR thermometer (from Maplins), handy as a quick check. Look into IR imaging apps for your phone, they were starting to become common 5 years ago when I last looked.

 

[reb78]

The most problematic rad is a 600x1400 type 22 (I think type 22). I domt have another one this size in the house. Seem to be around £170 to chance a new replacement.

 

[gaz1]

have you another closer to the size you are wanting as you have found out its dear just to try a test rad when it could be something else

what type of rad valve do you have since you have removed it and refitted it

some are a compression type of fitting one of your pics



as compression and a piece of pipe can be used to connect either rad valve to each other for flow testing between them

seen as your really skinny with pics to show your system

 

[reb78]

Just two basic lockshields on this one. No TRV. No others really close to this length in the house unfortunately. I guess I could join it with a washing machine supply hose just to prove how well/if it flows without the rad in the way?!

 

[gaz1]

its just a flow check but run within 5-15 mins and that heat should be back at the manifold as its a direct connection

this checks that the issue isnt the pipes but the rad itself

 

[reb78]

its just a flow check but run within 5-15 mins and that heat should be back at the manifold as its a direct connection

this checks that the issue isnt the pipes but the rad itself

Exactly what I was thinking. At the moment, the rad is taking an age to get warm but thinking about it, I can feel heat at the inlet so perhaps it is blocked. Very odd though as these troublesome ones will be some of the newest and being upstairs, seems odd that they would be an issue as would expect all the crap to fall lower.

 

[JimmyS]

Take the valves off and just blow through it and see if its blocked, watch for the black crud though