Hi All.my dad in law had blocked pipes in his gas central heating leading from the cold water feed to the pump.British Gas came and replaced the pipe,and they told philip(my dad in law) that he would still need a complete system clean and flush for which thet quoted him £528 plus 5% VAT.can anyone tell me if they feel the extra work is justified as all the radiators still get hot.is this the case of British Gas trying to get more money?appreciate any and all of your comments.Thanks John

Hi John -- If you have had a blocked pipe it is very likely that the system still has the debris pumping around it, and could probably benefit from a power flush to clean it out, to stop it re-blocking and to improve efficiency

However that price quoted is well over the top, you can get an independant Corgi engineer to do a power flush a lot cheaper than what he has been quoted. This firm in the article below charge only £250 for a standard power flush and I would bet money, that you can get it done even cheaper using a local reputable engineer.

http://www.taps-uk.co.uk/

Shop around ....

I have 26 years experince in the heating world and was trained by british gas,the system should be cleaned but this does not have to be with a power flush. The radiators can be cleaned with cold water from a hose pipe by taking the radiators outside or it can be chemically treated without a powerflush, but the important issue that they are missing would be pointed out by any plumber/heating engineer worth his reputation. The reason that the pipe became blocked in the first place is from the amount of sludge in the system. This sludge is caused by corrosion in the radiators. The corrosion is caused by oxygen in the water. In a properly designed and installed system this will not occur. The oxygen is entering the system either through a wrongly positioned cold feed pipe or the open vent pipe or from pumping over into the cold feed tank. This can be caused by the distance between the top of the swan neck ( the bend on the top of the open vent) and the water level being less than 18 inches or again by wrongly positioned pipes.There is also the probability of micro leaks sucking in air if the pump is wrongly positioned putting the system under a negative pressure.  Unless this problem is sorted out you will always have corrosion problems within your system. do your radiators need bleeding often? if yes then my theory is correct. this air in the rads could be hydrogen produced by the chemical reaction caused by the corrosion. this can be tested by a decent engineer.

i am not looking to sell my services to you. i saw your page through google while looking for something unconnected and thought i would give my advice.

Hi jpheat,

I have spent a small fortune on having my system reconfigured, power flushing etc by a supposedly qualified engineer to no avail. I still get sludge in the header tank (black sludge in the bottom with a rusty tide mark) which periodically buggers up my sensitive condensing boiler. Presumably this is due see-sawing as there no evidence of pumping over. Any idea on the correct configuration.

I currently have

boiler - vent pipe - (<15cm) - feed pipe - pump

This is the correct config according to the likes of the londonplumb and fernox websites but wrong according to the pumptool website.

cheers

Hi,

I am currently renting out a ex council 2 bed flat in London on the 4th floor. It has a central heating but only 2 of the 6 rads are working, the system is 15/20 years old but has had regular services from BGas. I have been quoted 700 quid for a power flush and 400 quid to get TRV's fitted both with drain down. Is this 1. nessaary ??? 2. usual cost ???

any help advice greatly apprieciated

Mindy Mo

Question 1 difficult to say without seeing the job, but as we all know British Gas will tell you any thing to get your money.

question 2 i could do both jobs for around £800 and that includes travelling from south wales!

hope this helps

Hi John.

I also happened to find this article of yours via a google search on "power flushing".

I wondered if i could ask for your expert opinion as for the last 2 weeks i have had 3 different gas engineers in and still I have the problem not resolved.

Basically I have an IDEAL icos system boiler m3080. I think it's a heat only condensing boiler. It is 5 and 1/2 yrs old.

2 weeks ago the boiler packed up.there was no staus symbol on the display unit even though there was the power light on.I called IDEAL as I had a maintenance contract with them and the first engineer fixed it saying there was a leak that damaged the PCB board. This was rectified but on testing a rattling noise would be heard when the bolier was trying to shut down after it has been on for say 10 mins. It sounded like it came from the boiler's pump. The engineer said to give it a few days to see if it wound settle.

Off course it didn't so a second engineer came out. His diagnosis was that a new pump would be needed as well as a new expension vessel but this wouldn't be done until our system would be flushed out clean which we had to do ourself as the contract did not cover for this. The reason was that the pump that he looked at was covered with black muck and he said this black muck would be circulating round the system so it would damage the new pump and expansion vessel unless we have it flused.We never have to bleed our rads as it is always hot top and bottom left and right and in the middle so i don't know if we do really have sludge. The rads are also 5 1/2 yrs old and is a new build house. I did bleed the rads to check for the colour and it came out light watery grey. Hopefully that's ok???

3 days later the noise got worst and only happens when the boiler is shutting down from when it has been on for a while (and also i notice the pressure gauge does go upto 3)and again the boiler packed up.This time it had a LF code which means Flame Detection Error. A 3rd egineer was called out and the fault was a blocked condesate tube whom so happened to say that our system DOESN'T need to be flushed.

However the rattling noise is still there. can you help?

Much appreciated

David