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Rads need constant bleeding

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Discuss Rads need constant bleeding in the Central Heating Forum area at Plumbers Forums

MaksimsK

MaksimsK

Gas Engineer
Messages
32
Hi.
After the boiler swap in mid december (Ideal logic Max combi c30), we started having this problem with rads.
Usual symptoms: colder top rad, I can hear water flowing in pipes and rads. Usually need bleeding every 1-2 weeks since then. Pressure was on same level even after bleeding, but not today. After rad bleed, pressure has gone to 0.

Guy who installed this boiler dodging to come and solve the problem, he says that the boiler works fine, he is not trading anymore (but its just the reason not to come and solve that problem)

So his thoughts was:
  • residual air from install
  • air sucked from rad connection
  • lock shields restricting the flow causing turbulence ( water flowing sound in rads)
  • erp pump create vortex down the pump

I can fit Spirovent or self bleeding valves, but its not solving the root problem.

Any thoughts?
 
EvilDrPorkChop said:
Did the old boiler hold pressure OK? Has it only since you've had the new one fitted you've got the pressure issues?
Click to expand...
the old boiler has no problem with pressure as far as I know. we bought this house in November 1st, but in mid-december, pump died to sludge and PCB as well. so it was like for like change
 
Well you've got a leak on the system somewhere. Without knowing what it was like over a longer period of time on the old boiler it's hard to say whether it's part of the new boiler installation or a leak on the existing system.

Have you been round and felt all the joints on the radiators, top and bottom to see if you can find anything? If you are only loosing pressure ever week the leak isn't going to be major.
 
Sealed systems with air ingress often happens on the vacuum side of the circulating pump. It's well worth giving both pump valve nuts a bit of a tighten and see how you go after that.
 
EvilDrPorkChop said:
Well you've got a leak on the system somewhere. Without knowing what it was like over a longer period of time on the old boiler it's hard to say whether it's part of the new boiler installation or a leak on the existing system.

Have you been round and felt all the joints on the radiators, top and bottom to see if you can find anything? If you are only loosing pressure ever week the leak isn't going to be major.
Click to expand...
its not losing pressure, the system is filled with ar after a week or so. But only towel rail, master bedroom rad, ad one of the kitchen rads.
All floorboard are lifted, no leaks at all.
[automerge]1583700643[/automerge]
moonlight said:
Do you have a faulty pressure relief valve?
Click to expand...
pressure stable on 1.2, on full heat up to 1.8-2. no leaks on prv pipe
 
MaksimsK said:
the old boiler has no problem with pressure as far as I know. we bought this house in November 1st, but in mid-december, pump died to sludge and PCB as well. so it was like for like change
Click to expand...
If the heating was sealed before why sludge?
[automerge]1583700720[/automerge]
Have you checked the filling loop is not letting by? on the new install.
 
moonlight said:
If the heating was sealed before why sludge?
Click to expand...
no one bothered to service it for ages (since Ariston was installed 8-10y), no filter, no chemicals. when we moved in, the bottom of all rads was cold, pump noicy as hell

filling loop
 

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  • 2020-03-08 20.54.28.jpg
    2020-03-08 20.54.28.jpg
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Are you 100% sure its air and not hydrogen? Hydrogen can form by a number of ways ie. The oxygen content of dissolved air reacting with the iron content of radiators causing hydrogen and rust to form. Hydrogen can also gather when water splits due to galvanic corrosion between two dissimilar metals. It can also form if the PH value of system water is acidic, speeding up the corrosion process.
If you're sure its air then I would check all joints on the negative side of pump, this can draw air in if not installed correctly.
 
SJB060685 said:
Are you 100% sure its air and not hydrogen? Hydrogen can form by a number of ways ie. The oxygen content of dissolved air reacting with the iron content of radiators causing hydrogen and rust to form. Hydrogen can also gather when water splits due to galvanic corrosion between two dissimilar metals. It can also form if the PH value of system water is acidic, speeding up the corrosion process.
If you're sure its air then I would check all joints on the negative side of pump, this can draw air in if not installed correctly.
Click to expand...
I'm really lacking experience on this and can't be 100% it's not hydrogen. like previously mentioned - light up to check?
can't see the reason why it should be hydrogen if the system was power flushed and protected with Fernox F1 Express + New boiler. Shouldn be all old problems cured with that?

PH problem? how do i solve that?

i will do check all joints on rads and pump tomorrow.

also, my main concern is: do the installer should solve this mystery or it goes beyond his work?
 
You could purge the gas into an upside down cup and try igniting it yes. Yes usually when the right dosages of correct inhibitor is used you protect the system. PH test kit will allow you to test acidity of the system water, they're relatively cheap and are often used in diagnosing problems like this, although with the inhibitor I suspect it will be ok, was just pointing out any acidity from excess flux etc can speed up galvanic corrosion.
Purge as I said and try igniting, if its hydrogen then you know where to look. If its air then look for any leaks on the suction side of system
 
Everything tightened. So far so good.
But the sound in rads still there (

Just realized, air gathering only on one branch.
One branch for kid's bedroom is ok.
The second branch for second kids bedroom and hall - ok
But third with Master, tower rail and kitchen rads - always gathering air.
 

Attachments

  • 2020-01-30 19.48.34.mp4
    4.6 MB

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