Central heating header tank

[StephenC]

My house is compact 4 bed. with conventional CH and HW system, tanks in loft. The primary has Fernox inhibitor, 8 litres. What concerns me, is that the primary header tank seems to get brownish coloured scum form in it, bit off an off-odour as well. Anyone know what could cause this? I did reckon the system could be pumping over, as the vent pipe did not appear to run high enough - vent pipe to header water level should be half inch for every foot between header tank water level and boiler base I was told - so I made the vent pipe run to a higher level before dropping to a position over tank. Any info. would be appreciated, thanks.

[BigWallop]

How long has the system had the same water in it ? Have you fully drained and flushed the system in past five years ?

Inhibitor can't just keep getting added to the system unless the system is fully drained, flushed and refilled. An excess of inhibitor will actually cause the water to turn a brown gunky, smelly goo unless it is drained out and cleaned "at least" every five years.

If you're sure that this is not the case, then you can start looking in other place for the cause.

[mike ring]

[e-mail] (StephenC) wrote in news: [e-mail]:

Me, too

(Sorry about that, I can't make Xnews watch this thread unless I post in it!......anyone like to help me out on that?)

mike

[Set Square]

There are several factors which influence whether pumping over occurs. The most important are the relative positions where the fill and vent pipes connect into the system, closely followed by pump speed and flow direction.

If your boiler can stand it, have you considered converting the primary circuit into an unvented system? That way, pumping over *cannot* occur - because there's no header tank on the primary - and you're less likely to get air drawn in, so the inhibitor is more effective.

[Mark]

Group= mark selected as= high score

[mike ring]

"Mark" wrote in news:L06zc.1081$1W6.381@newsfe2-win:

Bodacious - excellent newsreader, shame about the manual

Thanks

mike