Plumbing help!!! Rads not heating after draining - SORTED!

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TrimTheKing

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Evening all

I'm hoping there are some plumbing experts on here that can help me as my main contact (cousing who's a British gas fitter) has been talking me though it but is offline for the next few hours.

Long story short, I turned on the guest bedroom rad yesterday morning as it was feeling a bit chilly in there (it hadn't been on since Christmas) and within minutes had water pouring out from around one of my ceiling mounted speakers in the lounge :shock:

Managed to get a view of the problem today and it was a dodgy solder joint behind the wall on the return leg from the rad. The joint was heavily oxidised so must have been weeping for a good while but I guess going from cold to hot must have sprung the joint open.

I drained the system down and removed the rad, sweated the dodgy joint off, cleaned up and sweated a new elbow on. Job's a guddun ;)

Took my cousins advice on filling the system (opened bleed valve on replaced rad and opened filling loop until water came forth, the repeated around the other 2 rads on the loop). SWMBO managed filling loop while I bled rads (we kept in contact by walkie talkie :D) and pressure is currently at its normal operating pressure of 1.5Bar.

Heating is now fired up and the downstairs underfloor heating is toasty again, the bathroom towel rails are boiling but the 3 rads are stone cold!!!

All 3 heating methods are off the same boiler/pump so can't understand how the u/f and towel rails can be hot but none of my rads. I have checked and quadruple checked all isolation/stop taps to make sure they are all open, and the flow/return pipes from boiler to rads and boiling but it's just not getting into the rads.

System is pressurised (no tank) oil fired boiler with single flow from boiler branching to 3 different systems/zones (ground floor underfloor-working fine, 2 guest bedroom ensuite towel rails-working fine, 2 guest bed and one landing rad-all colder than a penguins tatties).

Can anyone tell me what I've done wrong? :oops:
 

matt

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Turn the stat up to make sure the boiler is constantly on and then shut down some (or all) of the rads nearer to the boiler (or all of the ones that do work). Be patient - good half hour or so.
 

jasonB

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Is the motorised valve for that part of the system working OK and are those 3 rads controled by a wall mounted stat anywhere?

As you say "three heating methods" I'm assuming they are separatly controlled.

Jason
 

TrimTheKing

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matt":2jihiuyx said:
Turn the stat up to make sure the boiler is constantly on and then shut down some (or all) of the rads nearer to the boiler (or all of the ones that do work). Be patient - good half hour or so.
Thanks matt

Done this. Isolated the underfloor and towel rails so the it is only heating the upstairs rads, been at it since you posted this but still no warmer. It must be airlocked somewhere but I can't understand how/why?

The upstairs towelrails and megaflow are taken by flow/return straight from the boiler flow pipe (there are pumps upstairs by the megaflow so I assume that the water is being pulled up rather than pushed???) and both how water and towelrails are too hot to touch.

Next inline after these, from the boiler flow, is a pump which feeds both the upstairs rads and the underfloor heating (which has now also died by the way :roll: :cry: , so I must have moved some air somewhere.)

The pump is too hot to touch for long but both the flow pipes to the rads and underfloor are only lukewarm, and almost cold by the time it (pipe for rads) gets to ceiling height. Boiler is floorstanding if that matters.

Not sure where to go with this now. Am trawling google but it's not much help.
 

TrimTheKing

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Thanks for the reply Jason

jasonB":vilymnfz said:
Is the motorised valve for that part of the system working OK and are those 3 rads controled by a wall mounted stat anywhere?
Everything was working absolutely perfectly this morning before I turned off the stats before removing rad. It was hot water that was coming through the ceiling :shock: No local stat for rads, see below.

jasonB":vilymnfz said:
As you say "three heating methods" I'm assuming they are separatly controlled.

Jason
The underfloor downstairs is controlled by a 'Robbens' installed system and each room has its own wall mounted temp sensor and 'microtemp' thermostat so you can have each room at a different temp. The hot water is controlled by time set on the boiler, and upstairs rads are simply heated when the boiler fires to recharge the underfloor and controlled locally by thermostatic valves.

Hope that makes sense.
 

CHJ

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I suspect you have an airlock in either the feed or return pipe to the radiator loop. The radiators will fill from one end and appear to bleed correctly..
If you can, close off the feeds to the other circuits to put more flow pressure on the defective circuit to see if it will move it.

The above scenario can often be proved by shutting both rad vales on all affected rads and slackening connection to each side of a rad in turn. The working feed or return line will show water flow, the line with the airlock will not show continuous flow.

I had one property where I had to use suction from a wet and dry vac. to the slackened joint to suck the water passed the airlock point. On another occasion blowing by mouth caused enough disturbance to move it. (in the latter instance it's best to do it from the radiator side of the (diconnected) valve so that you have a quick way of shutting off water feed)
 

TrimTheKing

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Cheers for the reply Chas

Sorry for being a dumbass but I'm struggling to get a grip on what you have explained. I have closed off both the towelrail and underfloor circuits as you say but it hasn't improved any as yet.

When you say 'slacken connection to each side of a rad in turn' what connection are you talking about? :oops:

I'm assuming you mean either the flow or return on the first rad in the chain? Also, do I have the system running while doing this?

Cheers
 

CHJ

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Turn pump off in the first instance (system off) Close the rad valves on affected rads.

Crack compression connection to a rad valve on one side of a rad. does significant water flow?

If so tighten joint and try other connection to rad. If there is an airlock preventing water flow then one side is most likely to have no significant water flow.

I'm afraid it's basins and plenty of old towels time doing this or a good wet and dry vac. to gather any flowing water.
 

RogerS

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Keep your pump running. Turn off all the Ok rads, UFH etc, towel rail. Turn off the duff rads including the lockshields.

Then on duff rad 1 open the bleed valve and the lockshield. It should vent. Make sure that you let it flow freely. Shut the bleed valve. Shut the lockshield. Open the TRV on the rad and then the bleed valve. Make sure that you let it flow freely. Basically you are trying to encourage flow in both legs of the rad pipework. Trouble is that the pressure might not be enough to flush the airlock.

Repeat for the other two. Hopefully that will fix it. Failing that askthetrades is a pretty good forum if you draw a blank here.

Roger
 

matt

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I hesitate to suggest it cos it's not my plumbing; however... Connecting a hosepipe to the drain tap and pushing a bit of water in that way may push the air enough. I've used mains pressure to clear airlocks in gravity fed hot tap water systems (but you have to be careful because hot water cylinders are not designed to handle too much pressure).
 

RogerS

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matt":exo4g5xy said:
I hesitate to suggest it cos it's not my plumbing; however... Connecting a hosepipe to the drain tap and pushing a bit of water in that way may push the air enough. I've used mains pressure to clear airlocks in gravity fed hot tap water systems (but you have to be careful because hot water cylinders are not designed to handle too much pressure).

That works ! Trouble is not all installs have drain puffins per rad!
 

RogerS

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Mark

Did you get these fixed in the end?

On another forum they said that you should not have the pump running when you're bleeding the rads. So some of the above may be duff info.

Roger
 

jasonB

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I've always been tought not to have the pump unning when bleeding as there is a chance the pump can suck air into the system

Jason
 

CHJ

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jasonB":3p2te52e said:
I've always been tought not to have the pump unning when bleeding as there is a chance the pump can suck air into the system

Jason

Exactly: this is why I said switch system "off" in the first instance, like all "fixes" such as 'power flushing' with mains water it's best to lead someone who has no experience of heating plumbing problems through the less risky processes first.

Bleeding with pump running can sometimes be beneficial but the person doing the bleeding needs to know how to detect if the 'bleed air' is coming out or going into the rad.

I have seen a bedroom ceiling wrecked from someone using mains flushing, they had managed to fill and overflow the roof expansion tank via the pressure relief overflow, like all work arounds a knowledge of the particular system construction and consequences of various actions is desirable.
 

TrimTheKing

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Nope, still not got it sorted. I have completely drained down the system again (isolated the underfloor and towelrails/hot water legs of the system first) and refilled (with pump turned off) but still the same problem.

My cousin works for British Gas and has been talking me through it and I have done exactly what he told me (I'm no expert but I'm no numpty either) but the upstairs rads are still not getting hot so it's definitely airlocked somewhere.

My next step, as advised by cousin, is to isolate the pump (has isolation stops either side of it) and turn it round so it pumps round the other way which should hopefully push the air round into a rad...

If that doesn't work I'm totally stumped!

Luckily the air is only in the upstairs part of the system so the downstairs underfloor still works fine when I un-isolate that so at least we are warm.
 

CHJ

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Do you have a wet and dry Vac? have you managed to determine if it's the supply or return leg that is not feeding?

One thing to try when refilling is to close ether all the feed valves or all the return valves on the rads concerned, this may create sufficient pressure on the 'locked' line to move the air.
 

TrimTheKing

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CHJ":16ho1s5d said:
Do you have a wet and dry Vac? have you managed to determine if it's the supply or return leg that is not feeding?

One thing to try when refilling is to close ether all the feed valves or all the return valves on the rads concerned, this may create sufficient pressure on the 'locked' line to move the air.
I am away tonight with work but will try that idea of locking up one leg when I get home, cheers.
 
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