Pipework changes needed to replace a conventional boiler to a combi ?

[hat]

What pipework changes are needed to replace a conventional open vented gravity boiler to a combi boiler ? Would toilet flush/cisterns need replacing ?

 

[gmartine]

Cold water storage, boiler feed and return tanks in the attic will be made redundant.

As long as they're not too ancient the cisterns should cope with being presurised.

 

[Rojroj]

Thanks gmartine.

Cold water storage, boiler feed and return tanks in the attic will be made redundant.

Wouldn't the cold water storage tank still be needed for feeding the cold water taps upstairs (1st floor). The boiler will need a pair of pipes (can the existing pipes be used?) for the sealed heating system and a new pair of pipes for hot water (cold water feed and hot water out to the taps).

As long as they're not too ancient the cisterns should cope with being presurised.

I got two modern button press type cistern/flush (dual button, one for water saving) which was installed when I changed the toilets in 2015 or so. However, one in the ensuite is still the old handle flush type. Would the cold water pipes feeding the cistern have to change too? I thought it's just the cold water pipes feeding the boiler that would be new, not the output from the boiler (heating or hot water). If not, then the whole pipework for the hot water taps need to be changed?

 

[hat]

Cold water storage, boiler feed and return tanks in the attic will be made redundant.

Thanks gmartine.

Wouldn't the cold water storage tank still be needed for feeding the cold water taps upstairs (1st floor). The boiler will need a pair of pipes for the sealed heating system (can't the existing pipes be used?) and a new pair of pipes for hot water system (cold water feed and hot water out to the taps).

As long as they're not too ancient the cisterns should cope with being presurised.

I have two modern button press type cistern/flush (dual button, one for water saving) which was installed when I changed the toilets in 2015 or so. However, one in the ensuite is still the old handle flush type. Would the cold water pipes feeding the cistern have to change too? I thought it's just the cold water pipes feeding the boiler that would be new, not the output from the boiler (heating or hot water). If not, then the whole pipework for the hot water taps need to be changed?
Regards

 

[gmartine]

RE: Cold water

You can keep the CWST if you wish, I wouldn't for the sake of upgrading a cistern/flush or two if that's even necessary. Supply pipes to them or outlets don't need to be changed.

 

[hat]

RE: Cold water

You can keep the CWST if you wish, I wouldn't for the sake of upgrading a cistern/flush or two if that's even necessary. Supply pipes to them or outlets don't need to be changed.

So, would the cistern/flush still work or would they stop getting filled until they are changed ?
Also, if I decide to get rid of the CWST, wouldn't all the feeds to the upstairs cold water taps need changing as they are currently being fed from the CWST (I assume) ?
Thanks again.

 

[gmartine]

Everything upstairs fed by CWST can be fed by a mains supply, you can basically replace one feed with the other without having to replace any actual pipework.

 

[hat]

Everything upstairs fed by CWST can be fed by a mains supply, you can basically replace one feed with the other without having to replace any actual pipework.

Ah, great. Re the old cisterns/flush, would they carry on working (albeit slowly/partially) or would they stop completely forcing me to change them immediately ?

 

[gmartine]

Consult your installer, they might want to fit a pressure reducing valve depending on your incoming pressure and replace any inadequate fill valves.