Can someone please explain how an unvented cylinder is better than a combi boiler? Both heat the DHW direct from the mains. So the limitations due to flow rate, pressure, number of simultaneous outlets in use apply in both cases.
Unvented Cylinders v Combi
- Thread starter D_Hailsham
- Start date
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Personally i prefer unvented cylinders, but thats me, you have to choose to best suit your own needs
It's possible to have a far higher flow rate out of a UV cylinder than it is from a combi, provided of course the mains can provide that flow rate. For example, a combi will give you 14l/min hot water regardless of whether the main can supply 14l/min or 40l/min. If the main can supply 40l/min then the UV cylinder will also provide that (roughly, granted there are pipework losses and valve to consider, but the point still stands)
N
namsag
Having used all 3 systems in my properties i can say without a doubt unvented cylinder is by far the best the water delivery is second to none and no fluctuation at all if another tap hot or cold is turned on.
If the watermains and budget would stretch to it i would install it everytime/but it is far more expensive to buy and install than a big combi
If the watermains and budget would stretch to it i would install it everytime/but it is far more expensive to buy and install than a big combi
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M
mysteryman
Look at the storage combi if your mains pressure AND flowrate are good. The storage combi combines the advantages of both with simplicity of installation.
Surely that depends on the output of the boiler. A 14l/min flow will require a 35kW boiler, while a 40l/min flow will require a 100kW boiler.
Until the temperature of the water leaving the cylinder had dropped too much.
The only advantage I can see is when you have a very high flow rate. Instead of needing a 100kW boiler to heat a 40l/min flow, you can use a much smaller system or OV boiler of, say, 15kW. This is because you are only having to replace the heat lost as the hot water in the cylinder mixes with the cold water coming in. In that sense, it is no different from a standard cylinder with a CW tank in the roof.
yes it is basically a power vs time argument.
if you have the time then you can use stored water and reduced the size of the boiler. on average a domestic home will use hot water 40 minutes a day meaning we can use a smaller boiler that better meets the heating needs.
if you don't have the time then 100kw boiler maybe needed
but most domestic homes only have a u6 sized gas meter
if you have the time then you can use stored water and reduced the size of the boiler. on average a domestic home will use hot water 40 minutes a day meaning we can use a smaller boiler that better meets the heating needs.
if you don't have the time then 100kw boiler maybe needed
but most domestic homes only have a u6 sized gas meter And cost!
On recent visits to two new housing developments nearby, I have noticed that the three and four bed houses with one or more baths and showers all have fairly small boilers (12-15kW) coupled to large Range Tribune cylinders. Presumably this is the cheapest solution.
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