How good are Storage Combi's ?

[jazz-uk]

Hi

I'm in the process of updating my heating and boiler system. One of the options open to me is a Storage Combi. I've been told that this should be able to feed more than one tap, due to the built in tank.

I was pretty impressed with the write up of the Alpha boiler. Does anyone have experience of this type of boiler? And how do these compare to an unvented system such as a Megaflow.

Jazz

 

[Agile]

There is no comparisom, they are different.

A storage combi has a small built in tank of about 20 litres but wide variations in size. They increase the flow rate to about 18 li/min for a few minutes until the store is empty and then they give the standard combi flow rate of about 10 li/min. They are good for filling a bath quickly!

Dont be fooled! They are better than a standard combi but many people are fooled into thinging they will give 18 li/m for ever!

Go for an unvented!

Tony

 

[simond]

According to Worcester's own specification the Highflow 440 can deliver 40 gallons of 45 degree water over a continuous 8 minutes, assuming a 35 deg temp rise.

Having used these units myself I can well believe it.

We only actively recommend an unvented if the customer's water main incomer has the capability of delivering in excess of 20l/m, (or less, if they agree to an accumulator).

The storage combi is a convenient one box solution and has a valuable role, although it is fair to say some are better than others. The heatbank principle works well when you have a high flow rate combi and your are augmenting it.

I do not know of a 10litre combi with a heatbank. This would equate to about 25kW input. The worcester has 30kW, which should deliver 13-14litres without the heatbank. I assume the heatbank is kept at a higher temp than the water draw off so the energy stored within is greater than would be the case if you were just mixing in some 50 degree water - thus the longer duration higher equivalent flow rate.

Haven't checked the detail of the heatbank operation but that's my guess.