Paul Barker said:
Bigburn said:
Because you would have a true dual system like the dual ignition on a Rolls Royce, all functions would remain available to the user if one combi broke down. This is the main benefit of the two boiler option. Simpler because In your method you would need a hell of an array of diverter gear to switch the duties of one or the other combi to perfrom the role of the other while it was on shutdown.
I didn't really think this needed any thought.
Paul, you got it wrong. It was one combi doing downstairs CH only one doing upstairs CH.
Two separate systems. Easy to do. Both can be side by side or split. No diverter valve, etc.
The DHW is split, one combi doing one bathroom, one the other, The outlets only combine for baths using check valves.
If one goes down then there will be DHW and heat somewhere in the house.
No diverter valves or complex control wiring at all. Just two white boxes on the wall and a clock programmer for each. Make sure the two combis do not exceed the gas meter rating. A gas meter can take approx 62 kW. Two 24 kW combi will do fine.
This a is highly cost effective route to get a cheap to run zoned CH system, mains power showers and quick bath fills. And backup too. Price up two boilers, cylinder and all the zone valves - no contest. I have seen a number of these installations and they work very well and no tanks or cylinders either. One had the combis on top of each other under the stairs. Another had them in the garage, another in the loft. Another had them split, one in the loft and one in the kitchen. The one in the loft did upstairs CH.
The same with washing machine, Have two £300 jobs in the garage (can be stacked) rather than one £1,000 Meile - people only buy a Meile because it is reliable and attempt to reduce down time. With two the washing is done all in one day and the load is spead between the two so they last longer. If one is down one works. Easy, cheaper and no down time.