Blockage in 8mm microbore CH system

[langers]

I have one cold radiator situated in the bathroom when all other rad's are hot.

Through the various steps i have narrowed it down to either a blockage in the pipe (8mm microbore) or a faulty Yorkshire Maxitwin Rad Valve.

Having taken the rad off i have established the inlet valve trickles water (even when fully open and CH is on) where as the outlet flows quite happily. So i am guessing that the problem either lies in the inlet valve or a blockage in the pipe. I have tried closing all other rad's and switching heating on but no luck.

I am considering back flushing the system but am concerned that this may damage the pump.

Any advice/help gratefully recieved.

PS does anyone know where i can get a replacement valve? Most comapnies the valve is obsolete...

 

[kevplumb]

give it a dose of DS 40 and close all the other rads off



http://www.yorkshirefittings.co.uk/...antee?Id=172fb456-e30c-4053-ba0a-f828287640f0

 

[Ihavenojob]

The twin entry valves have a tube which goes into the rad & often falls off over the years.Cut off the old valve.use addapter to increase pipe size to 15mm &fit 2 new rad valves,also flush rad while its off.

 

[kevplumb]

The twin entry valves have a tube which goes into the rad & often falls off over the years.Cut off the old valve.use addapter to increase pipe size to 15mm &fit 2 new rad valves,also flush rad while its off.

Having taken the rad off i have established the inlet valve trickles water (even when fully open and CH is on) where as the outlet flows quite happily.

theres a clue there somewhere

and it ain't the spreader tube

 

[Agile]

You have only done the bucket test at the OUTLET of the rad valve.

Why not do it by opening the inlet pipe connection to that valve?

A blockage often occurs at the inlet to a rad valve.

Tony

 

[namsag]

Microbore blockage is usually at the manifold. Back flushing can clear it if its not too bad ,but cut it out and clean it or try Kevs suggestion

 

[kevplumb]

Having taken the rad off i have established the inlet valve trickles water (even when fully open and CH is on) where as the outlet flows quite happily.

You have only done the bucket test at the OUTLET of the rad valve.

Why not do it by opening the inlet pipe connection to that valve? ]

another pearl of wisdom

 

[tryitandsee]

Trying not to confuse this thread, I am having the exact same problem as you with these twin valves. My thread today under grundfos pump.

Radiator off and letting the valve open into a bucket, the flow is a trickle and the return is good, as expected with a head of water.

Turn on heating (pump) still a trickle from flow. Is it normal for this type of valve? I was expecting a lot more flow especially with the pump running.

Was thinking the valve needed balancing with the screw head return valve when rad reconnected, nothing. So end up thinking valve blocked at flow. But logic says that as it's flowing, albeit slowly, it would still flow enough to get the rad some way hot. It's like the return is stronger than the flow and therefore cancelling each other out. Hence no flow through rad.

This has baffled me for a couple of days and I can only think the pump is not circulating the water when it meets with any resistance. Others say the pipes are blocked, but they can't be as both pipes flow.

John D recommends a good dose of sentinel 400, may sort out the valves and the pump?

Let us know if you manage to work this one out

 

[Agile]

If its a pressurised system then its at about 1.5 Bar whereas the pump pressure is only 0.1 - 0.2 Bar so irrelevant compared with the system pressure.

If its a open vent system in a two story then its still 0.7 Bar head to downstairs.

My advice is the same as I gave the OP above to disconnect the inlet pipes at the bvalve and do the bucket test on them there.

But if thats still poor it might be at the manifold. If its a soldered one that more difficult but if a compression type can be opened there too.

If at the manifold the back pressurising with mains water will often clear it. Othertimes it has to be treated with a cleanser. Acid types are better but risk causing valves to leak.

X800 operates in four hours. John's X400 in four WEEKS!

Tony

 

[kevplumb]

But if thats still poor it might be at the manifold. If its a soldered one that more difficult but if a compression type can be opened there too.

yeah it can shear the connections there as well if its that bad

 

[tryitandsee]

Sorry to original poster but these are one of the same problem.

Agile, I now understand what you are suggesting. You mean that where the micro bore pipe has been cut originally (pipe cutter tend to curve the pipe inwards, restricting diameter) and inserted into the nut and olive in the rad valve. You think the partial blockage would be there.

Just a bit difficult to test with full system as no way to shut off.

 

[langers]

Thanks yo all the suggestions.

I am pretty limited with plumbing knowledge so i have kept to what i can do. I tried to drain the whole system but cannot get any of the radiators downstairs to empty. Not sure if this would suggest anything else.

I have had Fernox F3 in the system for a week now (couldn't get hold of any DS-40) and have not had any change, radiator is still freezig cold.

Any other thoughts or is it time to get a plumber in?

In regards to the manifolds where are the most likely place i will find this?

 

[tryitandsee]

They are normally on two circuits, in the hallway downstairs and on the landing upstairs.

 

[Agile]

You will probably have a problem finding any genuine plumber who will agree to try to sort your blockage.

This is because they can be very time consuming. In many cases cutting and rejoining the pipe in many places.

Chemical treatment with DS40 is likely to cause many leaks to rad valves although it might solve the leak problem but it does have to be used so that its action is concentrated at the source of the problem.

This is not something a lot of professionals are going to want to do. Its easier to walk away. There are nicer and more satisfying jobs to be done.

Tony