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central heating micro bore system,
All the radiators in the house are hot except the bathroom (which is downstairs) this is luke warm,have removed the radiator flushed out and refitted, whilst the radiator was removed opened the thermostat and lockshield valves and water was coming out of both valves,but dont know,how much the flow should be,
after refitting, the pipe to the lockshield valve is warm but the pipe to the
thermostat valve is cold, and it sounds like water is flowing through the radiator,
any ideas please

Turn all the other rads off and see if it warms up..

Thanks for reply
Have tried turning all other radiators off, but doesnt improve the temp, on the bathroom radiator,this radiator temp is approx 20c lower than all other radiators,the pump speed is set on no2 would increasing this to no 3 have any effect, or could it be a faulty valve not allowing full flow to the radiator
any help please

Hi baz1,

This is a difficult one. Initially I would have said the system needed balancing, but as you've tried turning off all other rads and the bathroom rad still remains lukewarm, that is unlikely to be the reason.

Can you give more info. Where is the bathroom rad on the pipework? Is it at the end of a long run? Are there any rises or falls in the pipe feeds?
Has the bathroom radiator ever worked at full temperature?

The reason could be obvious if I knew more about the pipework.
Incidentally, a microbore system is more sensitive to airlocks and balancing of the system than a standard pumped system.

Hi there Alien,
thanks for your reply,
This is a 2 bed terrace house, the boiler is in the kitchen downstairs and the pump upstairs back bedroom,the bathroom is an extension to the kitchen downstairs,as far as i know the microbore pipe run to the bathroom rad rises and falls from the back bedroom from the manifold which will possibly feed the back bedroom radiator as well, so the distance is probably about 15 ft to the bathroom rad,
This radiator has been hot in the past,but last year we had a new boiler and pump fitted as far as i can remember i dont think it has been 100% since.
all other rads are red hot (Total number of rads on system 5)the back bedroom rad i just have the L.S. valve 1/4 turn open,ive also had inibitor in the system from day one,
hope you understand all this and is of help
await your reply
thanks baz

Hi Baz

Thanks for details of pipe scheme. It sounds ok. The bedroom rad would vent the manifold and you say that rad is working ok.

It seems a silly question, but when you refitted the rad in the bathroom did you vent it until water came out? Sometimes the airvent can get blocked.

Assuming you did, the only other suggestion I have is that the TRV (Thermoststic Rad Valve) is an old pattern that only works on the flow, and somehow the TRV and LSV (Lockshield Valve) have got refitted onto the wrong pipes. Is that possible?

Alien

Hi Alien,
thanks for your reply,yes i did vent the rad until all the water came out, you maybe right about the trv valve being the old type as the system has been in a long time,
i have removed the thermostat bit of the valve (top Bit) and left it fully open also the lockshield valve fully open as well, i seem to think same as you that the lockshield valve is the inlet to the radiator as this inlet pipe is hotter than the other one,over the last couple of days the radiator has got slightly warmer,but dont know if this is with the ambient temerature getting warmer,but it is still 20deg c lower temp than the other rads but do you think if the valves were the wrong way round this rad would have never got up to full temp before
hope you follow this,
thanks Baz

[b]Hi baz

Sorry about delay in coming back, been busy!

It was when you said in your previous post that the return was hot but the temperature of the flow tail was cool that I realised the valves were almost certainly reversed to normal practice. This doesn't matter with current products that are a better design, but most older TRVs would only work properly the right way round. Lifting the thermostatic head wouldn't help because the valve was usually a loose jumper, driven open by water pressure up to the restricting piston of the thermostatic cartridge. Obviously if water was going in the opposite direction it just forced the valve shut.

Did you say that this rad had worked ok at one time or not?
If you've never had it working correctly, I would suggest you change the valves over. It should work ok then.

Alien[/b]

Hi there Alien.
thanks for your reply and patience trying to solve my problem,
yes the radiator worked fine up until this year, i can hear water flowing through the radiator,but wonderd if it wasnt getting enough flow through to get it up to full temperature, do you think it could be sludge in the system causing this problem
thanks Baz

[b]Hi Baz
It could be that the pressure washout was not completely successful, and has pushed sludge into the rad.

You need to take down the rad. If it is full of sludge you will find it.

A word of caution. Do not expect the TRV to hold closed at low temperature. Most are designed to open as the temperature approaches freezing even when turned down tight. This is a safety feature to prevent water freezing in the pipes. Special caps to replace the thermostatic head and hold the valve closed are available, alternatively make sure the room is nowhere near freezing while the rad is down.

Regards, Alien[/b]