Power Flushing

Reasons for needing a power flush.

Normally on central heating systems, over time you get a build up of sediment inside the radiators and pipe work commonly known as “sludge” this is caused by the internal side of the radiators starting to decay. Leaving a sludge like substance in the system.

Typical "Sludge" from a central heating system

Typical “Sludge” from a central heating system

Now if there is enough sediment build up in the heating system then this will start to cause problems, the most common problems due to sediment build up in a central heating system are, radiators completely not getting hot at all, or if you find that your radiator is getting partially hot mainly at the top but cold at the bottom, this is because the sediment is made up of small metal filings which are heavier than water which sit  in the bottom of the radiator  causing the bottom half of the radiator to block the flow of water stopping the bottom from getting any heat. Another very common problem that is found is that your central heating circulator pump, will over time block up with sediment causing it either to not work to its true potential or stop completely, in this case none of the radiators will get any heat. Unfortunately your boiler is a great place for sludge to build up due to its delicate internal parts, when a boiler does start to catch the sediment, normally means that it will start to kettle, “kettling” this is where the flow of water is restricted going through the boiler, but because the boiler thinks that there is the correct flow, is continues heating the water as it normally would, causing a lesser flow of water going through, which in this case will start to “boil” in this circumstance you will hear knocking, banging and whistling sounds coming from your boiler.

What’s involved in a power flush?

We like to do power flushing properly, so here is a detailed description of what happens when a power flush on a system is carried out,

Power flushing is carried out on EVERY boiler change.

A power flush will take up to 60-70% of sediment out of the system if done properly. Which can take up to a day or even two if needs be.


Power Flushing Machine

First of all we will enter the property laying out the appropriate dust sheets throughout the house, then we will drain the system down into a drain outside the property, so that the power flushing machine can be connected without any water being in the system, the power flush machine its self is a three horse power pump which with a chemical which gets connected to the system. Once it is connected it can be filled back up and the drain hose disconnected.

We use two types of chemical when doing a power flush. We use a product made by “Wessex chemicals” called “silt free” and “sludge and flux remover” these get flushed through the system to help remove the sediment from within the system. we have our own magnetic filter which will be put onto the power flush machine to catch any sediment as it comes through the machine, which gets cleaned out after every two radiators or if needs be every radiator. Combined with the chemicals we use a soft non marking rubber mallet to help aggravate the sediment by knocking each radiator one by one,

Once the machine is on and running, we open all of the lock shields on the radiators so that there is no restriction going into the radiator, once this is done we then zone down each radiator individually using the thermostatic radiator valve, isolating all of the radiators bar one, this gives that one radiator that is on the full force of the power flush machine. We then set a timer and let each radiator have a certain amount of time being flushed depending on the state that the system is in. Meaning it will be continued until it is running clear. Once every individual radiator on the system has been flushed through thoroughly we leave the machine running on all of the radiators to make sure that as much as possible can be removed from the system. once we are happy that the system is clean we run clean fresh water through at the same time as dumping the dirty old water out and will carry on this process until the water comes out of the dumping hose completely clean. Then the system can be drained back down.

 Now that the system is clean the machine can be disconnected, if on an existing system or new boiler then the original or new parts will be fitted or put back to its original state. Including a new magnet filter which gets placed on the return on the system, before it goes back into the boiler, Preventing any further damage or future damage to the new or old boiler.

The system can now be filled back up with clean fresh water with added “system inhibitor” to help protect against sediment build up again, the amount of inhibitor put into the system is defined by the size of the central heating system. We use one tub for every ten radiators. Now that the system has been bled and is completely full. The system will need to be balanced correctly to get an equal heat around the property. This is done by adjusting the flow into the radiator using the lock shield side. This is taken place whilst the heating system has been fired up and it getting hot. Using a temperature gun we can tell the heat difference between each radiator. Now that this has been completed you are left with a cleaner and more efficient heating system.