chemical flush

thebullsback

New Combi boiler been fitted next week to replace non working boiler we have now. 
Part of new installation is a chemical flush before new boiler fitted. 
my understanding is that the flush uses the boiler pump to circulate the chemicals .Problem is boiler is non working.
Is there a way to chemically flush without use of boiler pump?

FreeBear

thebullsback said:

New Combi boiler been fitted next week to replace non working boiler we have now. 
Part of new installation is a chemical flush before new boiler fitted. 
my understanding is that the flush uses the boiler pump to circulate the chemicals .Problem is boiler is non working.
Is there a way to chemically flush without use of boiler pump?

When I had my new boiler installed last year, there was no "old" boiler connected to the system - Had replumbed the CH & DHW system prior to the new boiler being installed (also a combi).
The engineer plumbed in the new boiler, bunged in the chemicals, and cranked up the heat to max via a service menu setting. With a hose connected to a drain down point, he kept the system running and opened up the filling loop to flush the system through. Seemed to be a bit of a slapdash approach to my mind as he didn't bother checking that all radiators had water flow through them... But most of the radiators & pipework were brand new, so not likely there was any sludge in the system to start with. Paperwork got ticked to say a flush had been done, and the magnetic filter should trap any ferrous particles before they get to the boiler.

Browntoa

The flush I had done was a standalone machine the flushed the chemical the reverse way round the system 

Eldi_Dos

As above:

It would pay you to check all your TRV's are operational and have them fully open when installer's arrive.

thebullsback

Thanks for you replies .Looks like my situation is not so unusual so i will just put my faith and £2850 in the hands of the heating engineer.
Mercifully I have all the work schedule in writing and also paid via Credit Card \  

thegasmon

You can flush 3 ways normally. 
Gravity
Mains powerd
Machine

Gravity is normally only done on new systems that are known to be clean

Mains powered is using the water main to flow water through and push debris out of the system. This is normally done on moderately soiled systems with a little corrosion.

Machine is using a pump attached which runs at a high flow rate. The High flow rate being the important part as it helps dislodge and remove more solids.

All can be and are best done with a large magnetic filter attached and obviously with cleaner chemicals. Chemical types depend on system metals. Acid based being the best if metals are suitable.  

Time is very important. All take time, cleaners need hours even days to work. Flushing takes multiple hours to complete correctly. 

A flush on a clean system should take around 2 hours with the cleaner circulating for 1 to 2 hours 

A flush on a dirty system should take 3 to 8 hours with the cleaner circulating 3hrs to 2 weeks. 

Results should be based on tds readings or turbidity tube testing to prove the contaminates have been removed and maybe thermal image before and after shots, although you will never get a very dirty system very clean. 

Obviously this is labour intensive to fo correctly. So if you are getting a boiler changed on a dirty old system in 1 day you are probably not getting the flush the system needs. An incorrect flush will void the boiler warranty and lessen the lifespan of the new boiler. 

thebullsback

Boiler now installed and 90%certain no flush carried out at all ,Boiler situated in out building and cctv allowed me to see what went in and what came out and I saw NO sign of Flush or Inhibitor bottles .
Boiler was removed from building in 25mins and replacement fitted and up and running  1hr 20 mins later so take from that what you may.
I have tested my central heating system water using fernox test strip and it indicates over 150ppm of inhibitor present but my guess is that's from the original system water that was left in.
I used an online Boiler installation company as I had difficulty getting a local company to fit one quickly 
Boiler is running fine at moment and I would use company again BUT only because I paid via Credit Card for extra protection  and Boiler has a 10 year warranty 
 

FreeBear

In all fairness, the bottles may have been delivered in a plastic bag alongside assorted fittings. Then when the guy was done, chucked in a box along with other small bits of rubbish. That said, 1hr 20min is not enough time to fit a boiler AND do a flush. Did he tick the box on the commissioning paperwork to say a flush had been done ?

Hopefully, the magnetic filter will trap any sludge circulating within the system, so it may pay to see how much is in there after the boiler has been in use for a month or two. It would also be worth checking the boiler parameters to see if it has been set up correctly, bleed the radiators, and tweak the balance - I've been adjusting some of my boiler settings that the installer had left at factory defaults. Pump speed being the main one (now turned right down to get the proper temperature drop across each radiator).