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Discuss Chemical and/or Power Flush? in the Plumbing Forum | Plumbing Advice area at PlumbersForums.net

thomasar

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24
Some more plumbing advice, please.
I am getting a new boiler installed and this includes a Hot and Cold Chemical Flush of the system. Do I also need a Power Flush or is the Chemical Flush sufficient?
 

thomasar

Messages
24
Normal manufacturers minimal requirements. You getting a filter as well?
Quote is £1970 for a Worcester Greenstar 24RI boiler to be installed plus a Magnaclean filter and a hot and cold chemical flush and carbon monoxide alarm. Also includes removal and disposal of old boiler and a 1 year warranty on whole/existing system except boiler which has a 10 year guarantee from Worcester. Seems a very reasonable price as far as I can see. I have the option of a powerflush which would be an extra £450 and we are getting a new boiler because the old boiler is kettling which means the heat exchanger is on the way out according to a couple of plumbers who have listened to it. No filter was put on the old boiler which is 10 years old and I suspect there is a lot of gung around the system.
 

thomasar

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24
It would depend on the condition of the system.
See my reply above to SimonG. We've never had a powerflush although we have had chemicals put in previously and I want to make sure that the Worcester guarantee is not wasted as I've read that it can be invalidated if the system is not cleaned before a new boiler is installed and I don't know if the hot and cold chemical flush is sufficient.
 

Last Plumber

Esteemed
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Your Engineer who is changing the boiler should be able to advise you on what is required. They will have seen the condition of the system water surely? Did they not take a system water sample?
 

thomasar

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24
Your Engineer who is changing the boiler should be able to advise you on what is required. They will have seen the condition of the system water surely? Did they not take a system water sample?
Since we started getting the kettling noise, I've had 4 different plumbers to look at it and none have taken a water sample. The first did an annual service and told us that we needed a new Heat Exchanger but it would be more sensible to get a new boiler because of the expense of replacing the Heat Exchanger, the second said the problem could be the pump and put in a more powerful pump which did quieten things down for a while but then the kettling started again so we got another plumber recommended by a friend who confirmed it was a heat exchanger problem and said he would send us quotes for replacing the heat exchanger or for a new boiler. He never got back to us even after being contacted a couple of times. We ended up going to a well recommended local plumbing firm but I merely asked the chap who came to quote for a new boiler. He looked around the pipework and I told him that we wanted to replace the boiler because the alternative was a new heat exchanger and that it had probably been ruined by sludge from the system and he then said that as well as a new boiler we should have a powerflush. I don't believe any of the 4 plumbers we've had has ever taken a water sample but we have an odd job man who put some Sentinel X200 a few months ago in the hope it would help and when he was taking water out of a radiator before putting Sentinel in the cold tank the water that came out was very black.
 

scott_d

Plumber
Gas Engineer
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5,963
A chemical flush can be very effective but it’s not a 30 minute job.
Ideally the magnaclean filter would be removed and a magnacleanse fitted in its place for the flush.
Chemicals circulated through each radiator individually and then flushed out with clean water.
Repeat the process if needed.
 

Last Plumber

Esteemed
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Since we started getting the kettling noise, I've had 4 different plumbers to look at it and none have taken a water sample. The first did an annual service and told us that we needed a new Heat Exchanger but it would be more sensible to get a new boiler because of the expense of replacing the Heat Exchanger, the second said the problem could be the pump and put in a more powerful pump which did quieten things down for a while but then the kettling started again so we got another plumber recommended by a friend who confirmed it was a heat exchanger problem and said he would send us quotes for replacing the heat exchanger or for a new boiler. He never got back to us even after being contacted a couple of times. We ended up going to a well recommended local plumbing firm but I merely asked the chap who came to quote for a new boiler. He looked around the pipework and I told him that we wanted to replace the boiler because the alternative was a new heat exchanger and that it had probably been ruined by sludge from the system and he then said that as well as a new boiler we should have a powerflush. I don't believe any of the 4 plumbers we've had has ever taken a water sample but we have an odd job man who put some Sentinel X200 a few months ago in the hope it would help and when he was taking water out of a radiator before putting Sentinel in the cold tank the water that came out was very black.
If the water was black (ink like) then there will most likely be magnetite build up in the system which is a by product of the corrosion process. I would say (without having seen it) it is probably better to have it powerflushed and treated with inhibitor. It should take a full day to do a powerflush properly, hence the cost.

You can put a chemical in the system, such as Fernox F3 and leave it to work round for a couple of weeks, empty it, fill it and hot flush it out again but it may not remove as much of the deposited material as a powerflush will.

Magnaclean filters are very good for magnetite but a filter with both magnet and strainer will work better in my opinion as they will collect materials other than just ferrous.

Hope that helps?
 

Timmy D

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Gas Engineer
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528
If the water was black (ink like) then there will most likely be magnetite build up in the system which is a by product of the corrosion process. I would say (without having seen it) it is probably better to have it powerflushed and treated with inhibitor. It should take a full day to do a powerflush properly, hence the cost.

You can put a chemical in the system, such as Fernox F3 and leave it to work round for a couple of weeks, empty it, fill it and hot flush it out again but it may not remove as much of the deposited material as a powerflush will.

Magnaclean filters are very good for magnetite but a filter with both magnet and strainer will work better in my opinion as they will collect materials other than just ferrous.

Hope that helps?
Agree with strainers.

Here’s some Rubbish that I recently emptied out of a strainer on a system with a magnet.

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thomasar

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24
Agree with strainers.

Here’s some Rubbish that I recently emptied out of a strainer on a system with a magnet.

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Thanks for all the replies. Apparently the filter I will be getting is a Worcester Greenstar System Filter attached to the main return pipe which is described as Magnetic and non-magnetic filtration to collect a wide range of system debris. I'm told this one has to used for me to get the Worcester 10 year warranty.
 

king of pipes

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Thats a reasonable price as Scott advised ideally get it jet flushed or magna cleansed then throughly flushed out with mains cold water. Kop
 

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