Following on from Mark's (the bear) post, got me thinking about this and rather than hijack Mike's build thread thought I'd jot down my own musings on this.
We were in a similar position to Mark. Our oil boiler was starting to corrode a little and I decided to replace it but before I did so got its efficiency measured and was surprised to find it was as high as 80%. This meant that for us, had we not had the corrosion issue, then the payback period would have been measured in decades - even at the high oil prices pertaining at the time.
I toyed with the idea of a combi but our water flow and pressure is so poor that it would not have worked properly. Other factors to consider was the 3 litres worth of dead-leg in the HW feed to the kitchen tap from our how water cylinder. A combi for localised heating of that would have worked but I'd still have needed some form of bulk hot water storage for showers etc. The house is old, timbered, a bugger to route pipes plus no sensible route/option/place/way for Bob's elegant thermal storage system and so that was out of the question.
In the end I opted for an external oil boiler sited by the side of the house. Yes, there is some heat loss and I've lagged it as much as I can. The plus side has been the freeing up of space downstairs enabling us to site the downstairs loo where the old boiler used to be thus enlarging the utility room. The added bonus of no oil smell inside the house a bonus.
I put in a secondary feed for the HW to the kitchen (lagged as best I can). The running costs are tolerable and at least we are no longer throwing away 3 litres of water before it runs hot plus three litres of how water being left in the pipe wasting away after thee tap is turned off. If I was starting from scratch then I'd adopt Bob's proposal of spot hot-water heating where it is needed (although not sure how that would work with a power shower).
With biomass boilers I've heard that they are really designed for a constant full-on high heat output and thus not as controllable as other heat sources such as oil or gas. Think like an over-sized Aga.
Heat pump, Mark?
We were in a similar position to Mark. Our oil boiler was starting to corrode a little and I decided to replace it but before I did so got its efficiency measured and was surprised to find it was as high as 80%. This meant that for us, had we not had the corrosion issue, then the payback period would have been measured in decades - even at the high oil prices pertaining at the time.
I toyed with the idea of a combi but our water flow and pressure is so poor that it would not have worked properly. Other factors to consider was the 3 litres worth of dead-leg in the HW feed to the kitchen tap from our how water cylinder. A combi for localised heating of that would have worked but I'd still have needed some form of bulk hot water storage for showers etc. The house is old, timbered, a bugger to route pipes plus no sensible route/option/place/way for Bob's elegant thermal storage system and so that was out of the question.
In the end I opted for an external oil boiler sited by the side of the house. Yes, there is some heat loss and I've lagged it as much as I can. The plus side has been the freeing up of space downstairs enabling us to site the downstairs loo where the old boiler used to be thus enlarging the utility room. The added bonus of no oil smell inside the house a bonus.
I put in a secondary feed for the HW to the kitchen (lagged as best I can). The running costs are tolerable and at least we are no longer throwing away 3 litres of water before it runs hot plus three litres of how water being left in the pipe wasting away after thee tap is turned off. If I was starting from scratch then I'd adopt Bob's proposal of spot hot-water heating where it is needed (although not sure how that would work with a power shower).
With biomass boilers I've heard that they are really designed for a constant full-on high heat output and thus not as controllable as other heat sources such as oil or gas. Think like an over-sized Aga.
Heat pump, Mark?
