Replacing old boiler for new to save money in the long run

Golden_Holden

Bendy_House said:

The quote you've received, is that for a combi?

Yes, a Worcester Greenstar 2000 30kw

BUFF

bear in mind that the replacement cycle after this one is most likely to involve a heat pump & therefore require hot water storage (a tank) ...

Golden_Holden

BUFF said:

bear in mind that the replacement cycle after this one is most likely to involve a heat pump & therefore require hot water storage (a tank) ...

Good point. We have plenty of space in the loft eaves. I was tempted by a heat pump now but I'm not convinced it's worth the outlay at the moment. I'd welcome your thoughts

Bendy_House

Heat pumps will almost certainly drop significantly in cost. Best done when the house insulation is improved too! (What's it like?!)

The CHEAPEST swap would be for another heat-only boiler, and if the rest of your system was working well (highly insulated hot tank, good water flow, etc) that's what I'd be recommending. But, if you need to factor in a new hot cylinder as well, and some way of improving the flow that doesn't rely on pumps, that will add to the cost.

However, I WOULD also get quotes for an 'unvented' hot cylinder coupled with a new heat-only boiler. Generally more reliable than a combi, and will also accept other heat sources such as solar or PV.

BUFF

Golden_Holden said:

Bendy_House said:

The quote you've received, is that for a combi?

Yes, a Worcester Greenstar 2000 30kw

It should be cheaper to replace with another conventional boiler than with a combi.

As for heat pumps, my opinion (& I make no claims about experience) is that whilst they are certainly greener to run than a gas-fired boiler they are not currently cheaper to run & are more expensive to install even with the grant. Of course, that can all change in the future as volume ramps up.
Also, how well insulated is your house (& indeed your hot water tank)?

FreeBear

BUFF said:

Golden_Holden said:

Bendy_House said:

The quote you've received, is that for a combi?

Yes, a Worcester Greenstar 2000 30kw

It shoud be cheaper to replace with another conventional boiler than with a combi.

As for heat pumps, my opinion (& I make no claims about experience) is that whilst they are certainly greener to run than a gas-fired boiler they are not currently cheaper to run & are more expensive to install even with the grant. Of course, that can all change in the future as volume ramps up.
Also, how well insulated is your house (& indeed your hot water tank)?

Some are claiming a COP of 3 with heat pumps - Yes, you'd get that with ground source, but with air in the depths of winter, I doubt you'd get much better than 2. Up north in the cold windswept moors, quite possible the COP would drop to 1.

It is not just insulation that would need to be improved. Heat pumps would (generally) require larger radiators and/or UFH - It all pushes the cost up.

Apodemus

FreeBear said:

BUFF said:

Golden_Holden said:

Bendy_House said:

The quote you've received, is that for a combi?

Yes, a Worcester Greenstar 2000 30kw

It shoud be cheaper to replace with another conventional boiler than with a combi.

As for heat pumps, my opinion (& I make no claims about experience) is that whilst they are certainly greener to run than a gas-fired boiler they are not currently cheaper to run & are more expensive to install even with the grant. Of course, that can all change in the future as volume ramps up.
Also, how well insulated is your house (& indeed your hot water tank)?

 Up north in the cold windswept moors, quite possible the COP would drop to 1.

And up here (further north than the cold windswept moors!), quite a number of new houses are being built with an oil boiler to supplement the ASHP, for use during the depths of winter - and that's despite being well insulated!  

Golden_Holden

Bendy_House said:

Heat pumps will almost certainly drop significantly in cost. Best done when the house insulation is improved too! (What's it like?!)

The CHEAPEST swap would be for another heat-only boiler, and if the rest of your system was working well (highly insulated hot tank, good water flow, etc) that's what I'd be recommending. But, if you need to factor in a new hot cylinder as well, and some way of improving the flow that doesn't rely on pumps, that will add to the cost.

However, I WOULD also get quotes for an unvented' hot cylinder coupled with a new heat-only boiler. Generally more reliable that a combi, and will also accept other heat sources such as solar or PV.

On this and BUFF's point - my thinking was that a heat-only boiler which heats a full tank of water each time is an inefficient way of providing hot water for two people plus heating so whilst the initial outlay is cheaper the ongoing costs would be great. Is this the wrong way to think about it? I'm very ignorant when it comes to this stuff. 

BUFF

It depends upon how much hot water you actually use & the capacity & insulation of your DHW tank. You don't have to heat a full tank each day or indeed every day.
Combis also are not as efficient at DHW production as conventional/system boilers.

Bendy_House

Golden_Holden said:

Bendy_House said:

Heat pumps will almost certainly drop significantly in cost. Best done when the house insulation is improved too! (What's it like?!)

The CHEAPEST swap would be for another heat-only boiler, and if the rest of your system was working well (highly insulated hot tank, good water flow, etc) that's what I'd be recommending. But, if you need to factor in a new hot cylinder as well, and some way of improving the flow that doesn't rely on pumps, that will add to the cost.

However, I WOULD also get quotes for an unvented' hot cylinder coupled with a new heat-only boiler. Generally more reliable that a combi, and will also accept other heat sources such as solar or PV.

On this and BUFF's point - my thinking was that a heat-only boiler which heats a full tank of water each time is an inefficient way of providing hot water for two people plus heating so whilst the initial outlay is cheaper the ongoing costs would be great. Is this the wrong way to think about it? I'm very ignorant when it comes to this stuff. 

That is a valid point, but provided your hot tank is well insulated, it'll retain its water temp really well - for days. So, in practice, you'll only be using the hot water you actually require; the rest will remain in the tank, and just need 'topping up'.

Combis are also more complex, with more moving parts. You can probably anticipate parts wearing out after, or before, a decade. Heat only boilers have much less to go wrong, and usually keep on chugging.

As I understand it, there isn't a world to choose between them from an 'energy efficiency' pov. Usually the choice will come down to points such as a combi only being able to supply one tap at a time.