Working on a combi central heating system

[fsmozz69]

Hi all,
I have just had a new combi boiler installed in the upstairs loft, and it is a whole new ball game to me, with the 22mm flow and return from the new boiler linking up with the old 15mm copper pipe.The two radiators upstairs are getting really hot, but the radiators downstairs are struggling to get hot, presumably because the flow to and from the boiler is being restricted up to the point where the 15mm flow and return pipes previously started.The installer has recommended that the flow and return pipes be changed to 22mm to increase the flow, which is very straight forward.......My question is, if I start to change over the pipes, and don't get it finished the same day, whilst the heating side of the system is empty, providing that no heating is called for, can hot water still be drawn from the boiler.
Your thoughts would be appreciated........[/quote]

 

[jackthom]

Scrubbed. Much better advice below from leytonjc.

 

[ianblue]

I would doubt very much if you would need to increase up to 22mm.
Sounds more a case of balancing.
Also your pump will probably have different speed settings. Moving upwards will help you to get that flow but first try to reduce flow to hot radiators.
I wish I could see a diagram of the system.

 

[jackthom]

Unless I've misunderstood the original post the entire heating system is being supplied via a single 15mm pipe. That's really pushing your luck for all but the smallest of houses.

 

[ianblue]

I think we need a clearer picture of the system.
Sounds as if its just a new boiler with an existng system when the down stair rads were fed through a 15mm F&R and presumably worked ok.
I have envisaged the 22mm splitting two ways and reducing to 15mm up and 15mm down.
Maybe the OP will claify things for us. Does not sound a large house with two rads upstairs. How many downstairs?

 

[leytonjc]

hi, if your combi is an INTERGAS boiler you can use it as a multipoint (dhw only) with the heating system drained, if not you would have to loop the flow and return together a minimum of 1m from the boiler as a temp fix.

 

[Agile]

Since Intergas boilers probably represent less than 0.1% of those being installed currently thats unlikely!

So a one in a THOUSAND chance that its an Intergas boiler! Even if it was then it would still have the old flue arrangement!

Many combi boilers CAN be set up to give DHW while the heating system is drained.

However, in this case I am at a loss to understand how any professional can have fitted a new boiler and then wants to charge more to make it work with the heating system!

Its no wonder when I give quotations for doing a job properly they are put aside in favour of someone else who is going to do half the job for half the money!

Tony