06-01-2012, 12:05 AM
Quote 'Yorkie':
The main drawback with combi boilers is the poor delivery rate of hot water. Not too noticeable if you only use showers, but very noticeable if you want to fill a bath. This is even worse in winter when the cold water from the mains is so much cooler, because to provide a constant output temperature with a fixed heat input to the boiler, the only way to maintain the temperature is for the boiler to slow down the water flow rate.
Unquote.
Very recently, I replaced my ageing 'Glow-Worm' gravity-fed boiler with a Vaillant combi. The house here is a typical 1930's 3-bed semi. None of the problems reported by Yorkie above are manifest, although I must add that I have experienced those problems with other makes in other places where I have lived.
I can adjust the temperature of the hot water from the taps to the sinks in the lavatories and kitchen with the control on the boiler. I can adjust the temperature of the radiators by another separate control on the boiler. All the radiators have their own thermostatic control valves.
As a consequence of that replacement, I now no longer have a cold water tank nor a header tank for the boiler in the attic: more room to store vintage radio stuff!
And the hot water cylinder in the airing cupboard has gone too, so bigger cupboard (but I am forbidden to put 'radio junk' in there! 
).
Overall, I am happy with my new system, especially as I know it will be cheaper to run. I have no pecuniary interest in Vaillant nor their products.
Al.
The main drawback with combi boilers is the poor delivery rate of hot water. Not too noticeable if you only use showers, but very noticeable if you want to fill a bath. This is even worse in winter when the cold water from the mains is so much cooler, because to provide a constant output temperature with a fixed heat input to the boiler, the only way to maintain the temperature is for the boiler to slow down the water flow rate.
Unquote.
Very recently, I replaced my ageing 'Glow-Worm' gravity-fed boiler with a Vaillant combi. The house here is a typical 1930's 3-bed semi. None of the problems reported by Yorkie above are manifest, although I must add that I have experienced those problems with other makes in other places where I have lived.
I can adjust the temperature of the hot water from the taps to the sinks in the lavatories and kitchen with the control on the boiler. I can adjust the temperature of the radiators by another separate control on the boiler. All the radiators have their own thermostatic control valves.
As a consequence of that replacement, I now no longer have a cold water tank nor a header tank for the boiler in the attic: more room to store vintage radio stuff!
And the hot water cylinder in the airing cupboard has gone too, so bigger cupboard (but I am forbidden to put 'radio junk' in there! ).Overall, I am happy with my new system, especially as I know it will be cheaper to run. I have no pecuniary interest in Vaillant nor their products.
Al.
