Blocked Microbore to Loft Conversion Radiator

[uktricky]

Hi,

Another case of I didn't install it but 8mm microbore pipe being blocked.

Combi boiler setup - little or zero maintenance in the last 8 years+ I suspect not even a inhibitor in the system. 9 Rads including a towel radiator - Converted bungalow - Boiler in garage and house on top of garage - So boiler is lowest point.

The highest radiator in the system doesn't get warm hardly. I've had the TRV off (it is checked and working) - at the feed pipe, there is barely a trickle when pump on so assuming that pipe is blocked somewhere - Probably best side of 20mtrs back to the manifold under the main floor in the house and certainly not accessible for the main - Buried in eves, under floors, behind plasterboards etc.

With the TRV off - I've tried draining the system a little then reapplying the pressure a couple of times, also tried a bike pump on the 8mm pipe (again with some pressure removed from the feed side) and still I get a trickle when the system is on. So I know not completely blocked.

I really don't want to have to replace the microbore as much as I'd like too as this would be a huge task given the building works, pipes and location of radiator to the boiler etc.

So looking for recommendations from this forum of excellent members
I am not a plumber by any means ... Give me a Computer Network and I am your man!

My initial thoughts are:
1) Close of the other 8 radiator valves (both sides) leaving the "problematic rad" (PR) open
2) Drain the system fully - assume I need to open the bleed value on PR to allow air in?
3) Install some Sentinel X800 from Screwfix via the PR (see point 1)
4) Repressure the system via the filler loop to 1.5bar
5) Run the heating for 1 hour or so
6) Pray that this works!!!!
7) Let the system cool then drain
8) Install some Sentinel X100 from Screwfix via the PR (see point 1)
9) Repressure system
10) Open the other rads

In other words HELP!!! - The Mrs is complaining that the bedroom is cold

 

[terryplumb]

The chemicals will do nowt unless the water can circulate.
If you close the TrV on all rads except the problem one ,turn on central heating , both valves open on problem rad, does it now heat up ?
Is the rad in question a standard panel ,or a vertical " designer" type ?

 

[uktricky]

The chemicals will do nowt unless the water can circulate.
If you close the TrV on all rads except the problem one ,turn on central heating , both valves open on problem rad, does it now heat up ?
Is the rad in question a standard panel ,or a vertical " designer" type ?

Standard Panel ... I can try that later today got to get ready to take my lad to footie!

The Problem one eventually warms a little if I leave the valve open but by comparison after heating has been on a couple of hours it is probably at 30deg versus working ones at 70+ deg using a temp gun!

 

[JohnD]

Needs balancing.

When you have done as Terry says it will become clearer.

 

[terryplumb]

Could just need the system balancing.
Is the lockshield on the rad fully open ?

 

[uktricky]

Lock shield is fully open.

So if balancing problem, I’ll be able to test this by shutting off all the others as I assume then this would flow (in theory)?

doh that’s what terry said

 

[uktricky]

I've presently got all rads other than the Problematic one isolated with the left and right valves.
I've turned the heating on and nothing...
Assume this means a definite blockage rather than imbalance

 

[terryplumb]

That's very odd. If the rad was heating ,albeit to a lower temp, with all other rads connected ,and now nothing ?
Can you do the following ...
Close the lockshield on problem rad ,trv fully open ,,and open its air bleed ( have towels / receptacle to hand) and let it run for two mins.you should get a constant stream until the boiler pressure drops away. This will prove that water is indeed getting past the trv.
Top boiler pressure up to 1.5 bar ,close trv and open lockshield ,open bleed valve. Again you should get constant stream until boiler pressure drops away. That will prove lockshield is allowing water through. Advise results.
By the way you can leave all other rads off whilst doing above and boiler off ( central heating not on ).

 

[uktricky]

Thanks Terry - will try this tomorrow.

when I had a plumber here earlier in the week for a brief look (mate of a mate who was driving past) there was very little water flowing out of the TRV when he had it disconnected from the rad - hence the trickle view in original post.

With the valve open and boiler on I can get to the feed pipe on the ground floor of the property (boiler below this in garage) before it continues upstairs - this pipe is cold into Luke warm for ages so again guessing no flow given the speed the other rads warm up! I’ve not been under the house as yet where the manifolds are to see how warm they get but I am thinking if no flow then it’ll only be residual heat warming the pipe/water ?

 

[terryplumb]

The trv itself may be the problem. It may be in " open" position ,but internally virtually closed. Don't bother with what I said above earlier ,its gonna be inconclusive ,as you have already established that some water is passing the trv. You can buy a cheap trv complete for around six quid. Go buy one ,drain the pressure out from a downstairs drain point ,and put a new trv on.
Has this rad ever heated properly ?
When was loft conversion done and this rad installed ?

 

[uktricky]

The trv itself may be the problem. It may be in " open" position ,but internally virtually closed. Don't bother with what I said above earlier ,its gonna be inconclusive ,as you have already established that some water is passing the trv. You can buy a cheap trv complete for around six quid. Go buy one ,drain the pressure out from a downstairs drain point ,and put a new trv on.
Has this rad ever heated properly ?
When was loft conversion done and this rad installed ?

The plumber who did the test tried the boiler running without the TRV connected and you could blow through it as the water would pass without a problem.

yes the rad used to heat very well and certainly did earlier in he year winter/spring. Conversation was probably done mid 90’s to mid 00’s I’d guess - would need to dig out the building inspection sign off to confirm - would guess rad installed as part of this work.

 

[terryplumb]

Do you mean he removed the trv from the pipe completely ? And had the boiler running at the same time ? If so what was the result at the pipe with no trv on it ?

 

[uktricky]

Do you mean he removed the trv from the pipe completely ? And had the boiler running at the same time ? If so what was the result at the pipe with no trv on it ?

I was in the garage with the filling loop adding pressure - he told me just a trickle of water was getting through with 1.5bar pressure behind it! All the other rads at this point bar a couple we open.

 

[terryplumb]

Then the trv was on the pipe ,but not connected to rad ,and only a trickle came out the trv ?
Then the trv is suspect ,as is a blocked pipe. More likely the trv ,in my opinion .

 

[uktricky]

Then the trv was on the pipe ,but not connected to rad ,and only a trickle came out the trv ?
Then the trv is suspect ,as is a blocked pipe. More likely the trv ,in my opinion .

no the TRV was off the pipe completely

We did the bike pump after this to try clear it - the pressure released a little bit from the pump side we thought this was because it is not 100% blocked although very close!