Have an ancient gas boiler, currently configured as a gravity fed system.
Generally, how easy is it to replace the boiler with a combi one? Any major gotchas?
As there'll be a problem with getting a mains water supply to the boiler, is it acceptable to 'bridge out' the headre tank?
sPoNiX
Not usually, provided the existing radiators are on a modern two pipe system. Any controls have to be brought up to modern standards, including thermostats when appropriate and TRVs, when appropriate. Any part of a gravity system on its last legs may leak when pressurised. This should be taken as a sign that the component needed replacing anyway, and at least the plumber is on site when it happens.
What do you mean by this? Most boilers can accept the filling loop being remote from the boiler. However, a combi boiler needs a mains supply to the hot water section so it can provide hot mains water out. If you can't supply a cold mains supply to the boiler, then you can't use a combi (unless you have a cold tank gravity system through the combi section).
Christian.
Good. As expected. The exisiting system is 70's vintage so is it reasonable to expect a twin pipe system?
What I mean is that there's currently a cold feed going to a header tank in the loft. The output of this tank goes to the existing boiler.
I'm unable to provide a cold feed directly (Due to layout of the building) but could connect the header tank feed to the header tank output somewhere in the airing cupboard.
This'd mean the cold feed to the combi would take a bit of a convoluted route.
sPoNiX
Be careful in that case because the flow rate could be poor, especially if most of the existing pipework is 15mm.
I'm unable to provide a cold feed directly (Due to layout of the
building) but could connect the header tank feed to the header tank output somewhere in the airing cupboard.
This'd mean the cold feed to the combi would take a bit of a convoluted route.
sPoNiX
Got yer. Not a problem, but sounds odd someone competent to fit a ga appliance can't route a cold pipe to anywhere in the house
-- Paul Barker
It's the shortest practical route without doing major structural work to the house.
Concrete floor in the kitchen so its got to go over the ceiling. The cold feed would only be about 3' longer if we make a connection in the airing cupboard thatn if we surface mounted a new cold feed.
There is insufficient space under the upstairs floor to route a new pipe without taking an even longer route.
sPoNiX
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