Adding second circulating pump?

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Morning All,
We have a 4-year old Viessmanm Vitodens 100 system boiler, and our CH is under performing.
It seems to be a problem of water circulation, return pipe is cold.

System has been flushed few times
Has been treated with X400 in for 4 weeks.
Water Flow/Return to each rad is ok, so no obvious blockage.

We have add 2 plumbers in, but no improvement.

Circulating pump is integrated in boiler.
Is it possible to add a second circulating pump external ?
Thanks
 
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Yes, but it's not as simple as just bunging a second one onto the pipe. You'll need a low-loss header / closely space tee arrangement to provide hydraulic separation between the boiler & the system
 
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Thanks for your prompt reply.

Is there any example/drawing you could point out to me please?
Is it DIY level ?
 
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I would expect your problem to be that a motor valve is not opening fully ( or at all ).

It does not seem your two "plumbers" were very capable or motivated if they could not find such a simple problem.

Were you actually calling them in on a paid basis? Or just from the pub with no expectation of getting paid?
 
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The plumbers were from local companies, all legit with invoice.

The plumber disconnected/checked the flow/return flex hoses within the boiler. They were ok. He spent 2 hours my system.
I ran him up again, and now quoted €850 to power flush heat exchanger only and fit mag filter.
 
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The question about the rads was more to do with pump sizing than powerflushing although I agree the price is ridiculous.
 
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Morning,
I would appreciate your view on this one.
Over the week-end, i connected a shower pump to the fill pipe of my central heating (Salamander CT FORCE2.0Bar), pump feed from the attic water tank.

The idea was to run a higher flow through out the system than would normally do with just mains. Sort of mini power flush

I flushed one rad at a time, all good, and also flush through boiler heat exchanger/pump. Water was flowing very well and very little sludge came out since the system has been drained/refill 4 or 5 times on the past 8 weeks. At some stage, i had X400 for 3 weeks in the system.

I am running out of idea......CH is still under performing, and can't see any blockage anywhere.

How can i go about testing the boiler pump (Viessmann Vitodens 100 system boiler))? install a flow meter on flow or return pipes?
 
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