Easy Guide: How To Flush A Pressurised Central Heating System
At Grand Union, we specialise in helping our customers with central heating repair in Milton Keynes and the surrounding areas. We are specialists in radiator replacement in Newport Pagnell and we are recognised heating specialists in Buckinghamshire and surrounding counties.
We know though, that there are a lot of you out there who will have a go yourselves and for you we have put together this handy step-by-step guide to help you carry out a problem free pressurised central heating system flush. If you need us, however, we are the go to heating specialists in Northamptonshire and all surrounding areas and we will always be happy to carry out the work for you.
Before you start, identify which system you have. A sealed system will feature a pressure gauge, situated on the boiler.
You will need to understand how the boiler and your heating system work. You will also need to be able to connect and disconnect a radiator from your system. Once those boxes are ticked this is our 16-step guide.
First you will have to take a machine rental and purchase two chemicals: (One central heating inhibitor and one sludge remover)
- Drain a radiator: One in the bathroom is good as you will have water there and can drain the dirty water into the toilet. You may also have a bath to put the radiator in when it’s disconnected.
- Close the right and left radiator taps with some towels at the ready. Loosen but don’t disconnect one of the nuts that connects the radiator tap and the radiator. Have a flatish container ready for the water as it drains from the radiator (2-15min), the water may look very dark if the system is dirty.
- When all the water has been drained then you should disconnect the radiator taps, (right and left) from the radiator, carefully lifting it out. Connect the hoses from the machine directly to the 2 radiator taps (with supplied adaptors). Next open both valves on the radiator. Now you are in the system. The level of water may rise and might even overflow. Be ready. Now put the dump hose into the toilet, and tape it down.
- To fill the rental machine: put it in the shower tray or the bath, connecting the flow and put the dump hoses back according to instructions. Use the shower feed pipe, without the head, to fill the machine. Be careful not to overfill.
- Open the radiators right and left valves to the max, turned fully to the left.
- Start up the machine.
- Now start up the boiler – set the temperature at thirty degrees and programme on ‘constant’. The system should then heat up and the machine water will also heat up. (Some boilers won’t work when there is low pressure, so you may not be able to run your boiler while flushing.)
- Next add the chemical “sludge remover” while the machine runs according to the instruction – usually this will take around 2 hours. Do not leave the machine unattended.
- Isolate all but one radiator in the house. On all radiators, except the one to be cleaned first, turn off one valve – flow will be through this radiator. You can hammer the radiator gently with a rubber hammer to help sludge dislodge and then wait for five minutes before reversing the flow.
- Draining and filling: Ensure the dump hose is securely anchored in the toilet. Next you can discharge the dirty water from the radiator through the dump valve so that the dirty water flows into the toilet. The machine’s water level will drop so refill it every time water is dumped. Repeat these steps until the water is clear.
- Go to the next radiator and open the tap that is closed then close the one on the radiator that has just been flushed.
- To clean the radiator magnets, after each of the radiators has been cleaned, stop the machine then remove magnet or magnets and then wipe them clean.
- Move through the system one after another reversing the flow and then dumping the water till it’s clean, cleaning the magnets as you go.
- Next the “inhibitor” chemical should be added to the machine and allowed to run for ten minutes.
- Now you can turn the machine off and close radiator taps in the bathroom disconnecting both the hoses and the machine.
- Wash the inside of the bathroom radiator (in the bath or shower cubicle) by filling it and then draining using the flexible shower hose utilised when you filled the machine. Once it is clean reconnect the radiator, open both of the taps and then bleed the air out.
At Grand Union Plumbing & Heating we are very proud of the high quality plumbing, heating and gas services that we offer. We are based in Milton Keynes, with many clients in the surrounding areas. Regardless of how complex or simple the job you need doing, you can rely on us, because we pride our selves on our customer service. We are affordable and dependable, and we are ready to work with you on any project, large or small.
Are you a landlord looking for a plumber?
If you’re a landlord and you need experienced and swift action taken to replace an old cranky boiler, please don’t hesitate to give us a ring on 01908 034194. We’ll work quickly to get the problem resolved and keep your tenants happy.
What Our Customers Say
I’ve used Grand Union 3 times and every time the service is excellent and the price very reasonable. Engineers are very good at letting you know what they are doing and there are no hidden charges. They even managed to do a job at short notice. They work tidily and even followed up with a message to check my heating was still ok the following day. Highly recommend
Excellent service from Mitch!
Responsive, courteous and informative.
Work swiftly done too, with clear explanations throughout.
Thanks again, Mitch.
100% will be used again in the future
It’s not very often that you find a quality tradesperson who is reliable, honest, and competitive on his pricing. Mitch has done a number of jobs in our house, including installing a new boiler, water tank and radiators. All to a brilliant standard. I will happily recommend Mitch and Grand Union Plumbing!
I have called Mitch out twice since moving into our new house a month ago. Both times he has managed to fit in an appointment fairly quickly to resolve our issues. He has been professional and friendly, offering advice on other issues that I have seen. I would definitely recommend his services.
We have used Grand Union Plumbing several times as we had a really tricky fault. We found Mitch to be really excellent. Very happy to recommend, 10/10
Called Mitch out on very short notice, extremely reliable and great rates, would highly recommend Grand Union Plumbing and Heating. Also provided advice with other queries aside from the job at hand- with no reluctance. Great service, thank you for your hard work and honesty Mitch.
Definitely recommend these guys. Had a job done by them and they wasted no time to get it done and made sure I was completely happy before any payments. Nowadays companies just want to rush and take your money. Big thumps up
Have used Grand Union twice now. They are very quick to respond to enquiries, reasonably priced, tidy workers and very friendly. I can’t fault them. Definitely my go to guys now for any plumbing needs.
I found Grand Union Plumbing through the Gas Safe Register. I had a boiler service and gas safety certificate. Mitchell was very professional and the prices were very reasonable. I would definitely recommend and use again.
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