Numerous issues can be fixed by power flushing your heating system and
we have discussed these in previous blogs. However, there are some things a flush won’t fix and there are heating systems that can’t be flushed. Systems that cannot be flushed or are more challenging than others include a one-pipe system and those that contain a Primatic cylinder.
One pipe system:
With this type of system, the water flows differently and there is no way to control the flow going through each radiator, making it difficult to remove the sludge from the water. As much as it is not recommended to flush such a system, if you are determined to do so I would recommend using two packs of chemicals and while attempting to flush an individual radiator operate the flow reverser more often than not. You could also add isolation valves below each radiator to help circulate the water around that particular radiator.
Primatic cylinders:
This system can be identified by the presence of a cold-water storage cistern, but you will not have a feed and expansion cistern in the loft. This is because the cylinder supplies the feed and expansion for the heating system. They work in such a way that the cold water can be fed into the heating system but not vice versa. If you were to flush the cylinder it would dislodge the air bubble from within leading to the mixing of radiator and tap water. The only way to flush such a system is by disconnecting the cylinder and creating a temporary loop on the pipework and flushing from the heating circulating pump.
It's also worth noting that flushes will not rectify mechanical issues within the boiler or system, of course, keeping the system clean reduces the likelihood of things going wrong.
So as good as flushes are they aren’t always the solution. A good gas engineer will be able to advise on the best way to maintain your heating system. If in doubt arrange a visit.
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