flushing new system

[johnad]

can anyone tell me the best way to flush a new combi system.
do i flush the whole system boiler connected, ?
do i use the fill loop to flush, ?
when flushing do i bleed the rads or just pump the water around the system, ?
whats the benefit of a power flush and is it worth it, ?
thanks.....

 

[bengasman]

If there is sludge in the system, the only way to get rid of it properly is with a power flush machine with instant reverse and done by someone who knows the job so the answer is: yes it is worth the money. From all the breakdowns I get that are not down to just a cheap, low quality boiler, at least half are down to the flushing not done properly after insttallation.
If the whole system is new, including pipes and rads you can just use chemicals without the pump, provided the installer has taken care that no foreign matter has entered the system. Due care is essential as too little or too weak chemicals might not do the job properly whereas certain boilers will be ruined by certain chemicals.

 

[ollski]

You do the powerflush with the old chb still connected as there is a fair chance a powerflush will destroy a low water content heat exchanger. Fit the new system, fill it up then drain it off for your cold flush. Fill it up run the boiler to heat it all up then drain off for your hot flush, then one more cold flush.

 

[ChrisR]

a fair chance a powerflush will destroy a low water content heat exchanger

.


Never seen that!

What boiler/chemical combinations?

 

[oilman]

a fair chance a powerflush will destroy a low water content heat exchanger

.

Never seen that!

What boiler/chemical combinations?

Aluminium heat exchanger and 3 molar hydrochloric acid gets through them no probs.

 

[johnad]

the whole system is new so if i was to just use chemicals i can shut the service valves under the boiler and just flush the pipes and rads i assume i can use the fill loop to fill, ?
how do i get the chemicals in the system, ?
thanks

 

[blahblah]

I put a small leg on both the F and R just below the new boiler then powerflush with the boiler isolated. Cap the lags off afterwards obviously! Works for me but can't claim the idea though.

 

[johnad]

i intend to put drain valves on the flow and return below the boiler so i was going to use this for flushing.
thanks for the info everyone.

 

[ChrisR]

Don't use drain cocks they're all useless! I suggest a compression Tee with a 15mm branch, you can put a pipe in or a cap on.
Or use these:

 

[johnad]

thanks chrisR excellent advice
so whats the best way to get the chemical in the system
and the inhibitor come to that
???

 

[ollski]

thanks chrisR excellent advice
so whats the best way to get the chemical in the system
and the inhibitor come to that
???

Isolate 1 radiator, drain a couple of litres of water out of it remove the radiator plug and use a skeleton gun and inject a tube of chemical in.