the bottom line is that combis are great in certain situations, and wholly inappropriate in others. having the ability to recognise those situations is what its all about as far as making customers happy goes.
I agree, they have their place - but too many plumbers seem to have some sort of implant that makes them immune from consideration of other options. We've seen in this thread, yet again, how some people are proud to state that they won't consider all options when designing a system
I see two old wives tales come up yet again about thermal storage.
The stat on the thermal store in my flat is set at 60˚C - not 70˚, not 80˚, but 60˚. It gives quite adequate hot water which is limited only by the supply. Don't think I've measured flow rate, we do have a static pressure of around 6bar - but it's a 1/2" service and all 15mm copper internally. Still, does an impressive blast when directing the hot tap for the washing machine into a bucket (only a matter of seconds to fill a 2g bucket).
When I fitted the thermal store, I took the trouble of actually measuring standing losses. Not guessing, not listening to old wives tales, but measured it. I shut down the boiler and left the store on the immersion heater, after a couple of days (to allow everything to stabilise) I read the lecky meter, and a few days later I read the meter again. The difference worked out to 80W average - somewhat less than the naysayers keep claiming.
I did the same with the combi in the house - but working from the gas meter. Just keeping itself warm to as to provide hot water "quickly" rather than in up to a minute*, it used the equivalent of about 160W. Yet it has an eco mode, but what's the point of a hot water system that only delivers hot water when you've finished using it !
* Yes I timed it, from cold it can take a whole minute to deliver hot water to the tap at the end of about 6foot of pipe.
True, the store and it's insulated box does take about 1m2 of floor space in the garage (which is under the flat), but the benefits far outweigh that. The tenant seems very happy with it - and the old boiler hasn't broken down once since I stopped using the combi function on it.
