Radiator loosing heat

[kellyb]

We have microbore in our house and are converting each room to 15mm as we go along, we have done the bathroom - no problems. We have recently converted the box room and put on a new radiator but we have a problem.

If we bleed that radiator the heat comes flying out and on the max temp the radiator is too hot to touch, but then over the course of a few hours it looses the heat and just isn't producing the correct amount of heat for its setting.

Does anyone know why this could be please? The boiler keeps loosing pressure in conjunction with this.

Many thanks

 

[Burnerman]

A boiler losing pressure means a leak somewhere, unfortunately......!
However, the more the rad is bled, the more water you have to add to your boiler.
John

 

[kellyb]

Hi, thanks for your reply...there is no leak??

 

[Burnerman]

In the words of the christmas panto....'oh yes there is'
Seriously though, when you have installed new pipes and rads, these have to be filled up by using the boiler filling loop, and then the rads bled until all the air has gone.
The boiler is then brought up to pressure again (about 1 bar as a ball park figure) and that pressure needs to be maintained. Expect the pressure to rise a bit when the heating is running.
If pressure drops, check the boiler release vent outside. If thats dry, check the automatic air vent on the boiler top somewhere - as well as your new pipes, of course!
John

 

[TicklyT]

A requirement for frequent bleeding suggests there may be corrosion taking place in the system. Frequent topping up will have diluted any inhibitor in the system.

Small leaks may go undetected if the system is hot. The water from any leaks may be evaporating as fast as it is leaking.

 

[kellyb]

Thank you all for your replies, these are very helpful. I have one other question if you don't mind....

Where might we find the boiler release vent (as it isn't anywhere outside)

Thanks again

 

[mickbrearley]

on top of pump looks lika a car tyre valve. make sure it is loosened 2 turns good luck.

 

[Burnerman]

The pressure release valve overflow is a copper pipe, outside, turned back on itself to face the wall....dunno why you can't see yours?
Automatic air vents usually sit on the top of the boiler casing - often a round brass cylindrical thing.
John