Sealed CH Radiator problem

Hello !

I have a sealed (ie pressurised) gas central system. Majority o radiators are fed through 8mm ?micro-pore? copper pipes which ar orginal to the house build of 1992.

The boiler is < 1 year old and running at 1.5 BAR and really kicks ou some heat

I have read the FAQ wrt radiator balancing and understand the concept.

A couple of the radiators do not get as hot as others despite havin balanced the system. So if I feel the 8mm pipe (to what I think is feeding the radiator it is too hot to touch for too long but the retur valve pipe at the opposite end is considerably cooler. I have opene both the return and flow valves to their maximum flow but this tem differential still remains and the radiator does get hot but not as ho as some others.

Any help would be much appreciated. The only thing that spring to min is that perhaps the return valve is stuck in one position despit rotating (doubtful) ? or the radiator is bunged up with sludge ?

One other quick question ? surely when trying to determine which is th inlet and return end of a radiator - if one of the radiator feed pipe is very much hotter than the other this would indicate that it is th inflow. The reason I ask is that all the downstairs rads have a integrated bleed valve on one side (which I took as being the retur side). But I have found that this side produces consistently hotte feed pipes which to my small brain indicates that they are the inflow

Hope this makes sense

Many thanks

-- Tim Kedwards

Blimey, I hope not!! Micro-BORE more like. (You don't really want them to

*breathe*, do you?!)

What sized radiators (in terms of their rated heat output) are they? Does each radiator have an individual 8mm feed and return pipe, connected back into something bigger - or is a single 8mm feed shared by more than one rad? [There's a finite limit to how much heat you can reasonably carry through

8mm pipe. I forget exactly what it is, but it's in the region of 1.5 - 2 kW]

What happens if you turn all the other rads off - do the 2 cool ones get hot then? If so, you still have a balancing problem. Is your pump running on its maximum setting? If not, turn it up a notch and rebalance. It it's already at max, or if these rads are too big for 8mm pipe anyway, you may need to increase the pipe size.

It doesn't matter which side the bleed valve is. Integrated ones are often on the right - but which side is feed and which is return is usually determined by which is more convenient from a plumbing point of view. The bleed valve simply lets air at at the highest point, regardless of water flow direction. Your assumption is right about the feed pipe being hotter than the return pipe.