I have a system boiler abot 10 years old (non condensing). It is a Glowworm complheat. I am getting condensation from the flue dripping down the wall and staining the brickwork. Any comments? Is it serious? How do I stop it? How do I clean the bricks?
Check the return water temperature to the boiler when the heating is running (and up to temperature). It ought to be about 70 on a conventional boiler. If it is too low (i.e. less than 56 deg C) then that will promote condensation of the flue gasses.
Condensation in a non condencing boiler? Yup, can be. The condesate is wet (obviously!) and mildly acidic. A combination that can rot the inside of a boiler or heat exchanger in short order if left unchecked.
Re-balance the system (see FAQ), you may need to increase the pump speed to prevent the water cooling too much per circuit. In particularly tricky cases you may need a blending valve to mix a little hotter water from the flow side of the boiler into the return to keep it above the dew point.
Are they just wet or actually stained?
Also check that the flow temperature control isn't too low.
Christian.
I suspect that may be the case. I'll check temperatures shortly (could be a week or 2) and report back. The radiator load is quite low, but there is a bypass so I suspect the temperature difference is normally quite low.
How to get the staining off the brickwork is another matter. It is up the side of the house where we never go, so it could have been staining for years. I've tried hosing it off but no-go. brick cleaner perhaps?
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