I am in exactly your position but already have a good water main. The other
thing that I noticed is on the 837 model you have to have a 28 mm gas main
all the way to the boiler (I have 22mm). Even if you do it won't help if the
gas supply in your area is not good enough. I know a lot of places Transco
have fitted small bore plastic inside the old metal mains to save time and
money but results in a supply that can't cope with the demands of such a
boiler. In many areas the gas supply is not as good as it should be due to
big expansions in housing tagging on to the old system. Transco cheat by
increasing the pressure but that cant help if the pipes are to narrow. It is
like using a hundred tones of pressure to force sand through an egg timer.
It will only go so fast through a small hole
Anyway the boiler will still work but won't reach full potential. Also if
Valliant see you don't have the 28 mm gas supply they won't support you if
there is a problem
Both systems will be at the mercy of your mains water supply. Both rely on
mains pressure for their flow rates. The Megaflo instructions are just being
a bit more realistic about it than the combi's, as they know that a 15mm
main won't get the full benefit of the system.
However, if the 15mm pipework gives you sufficient flow rate at the mains
fed taps now, then it won't be a problem. You may find it better to run the
main feed to the cylinder in 22mm from the stop cock, though. Then you can
upgrade the water main in the future.
Installing a second electric shower will still run into problems if the
limiting factor is water main flow rate, rather than water heating rate.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.