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BigBurner
It is quite common to use combis as multi-points by loop the CH flow & return pipes together.
To get a decent flow rate a high flow combi is needed and these tend to cost. An Andrews WHX42 NG External Water Heater, giving 17 litres/min, costs £575.75 Including VAT, the internal model is more expensive. A 42kW W-B approaches this flowrate but costs far, far more. But some budget combis like Heatline can do lower flowrates and still be very cost effective.
When used as a multi-point water heater do most modern combis leave the 3-way valve alone? That is, if the valve fails it doesn't matter as it doesn't not move and always in the DHW position. The CH controls don't matter either. This makes them more reliable when used as DHW only water heaters.
The problem with the competitive Andrews multi-point, is that it is not condensing, so will use more gas to run. Although being fitted outside is a great bonus. They do have inside models.
To get a decent flow rate a high flow combi is needed and these tend to cost. An Andrews WHX42 NG External Water Heater, giving 17 litres/min, costs £575.75 Including VAT, the internal model is more expensive. A 42kW W-B approaches this flowrate but costs far, far more. But some budget combis like Heatline can do lower flowrates and still be very cost effective.
When used as a multi-point water heater do most modern combis leave the 3-way valve alone? That is, if the valve fails it doesn't matter as it doesn't not move and always in the DHW position. The CH controls don't matter either. This makes them more reliable when used as DHW only water heaters.
The problem with the competitive Andrews multi-point, is that it is not condensing, so will use more gas to run. Although being fitted outside is a great bonus. They do have inside models.