Combi or regular boiler ????

paulsully

What i meant was we need a combi which has a shower flow the same as our current power shower because it would be replacing the power shower.

Our plumber is a RGI and lives a few doors up, our pressure here is very high.

What about this idea. we replace the old back boiler with a worcester 24KW heat only boiler, leaving everything else as it is. I think this is a good plan.

What about this : later on in the year i plan to swap the cylinder for a non vented mains pressure one, so that we can have hot water at mains pressure with no pump at all. I'm not a plumber but that seems like a good shower solution.

What do you think?

Seanymph

We went from an old boiler with a tank to a combi boiler and have saved one tank of oil this year (£600).

We have a shower - and it works fine.

Cardew

Seanymph wrote: »

We went from an old boiler with a tank to a combi boiler and have saved one tank of oil this year (£600).

We have a shower - and it works fine.

But moving from an old - and thus inefficient - boiler to any new boiler will make savings. It is simply not possible to quantify how much of the £600 is due to having a combi. As stated above:

A modern Hot water tank, at 65C, in 24 hours will lose heat taking around 2kWh to replace - they are tested to a British Standard. So around £30 a year(with gas) if kept at 65C all the time; in practice the loss will be less than £30 a year.


However that heat is not wasted for much of the year as it 'escapes' and warms the fabric of the house - and many HW tanks are in an airing cupboard.

A shower from a combi will of course work. However the OP wants a flow like they get from a pumped power shower.

malc_b

Cardew wrote: »

But moving from an old - and thus inefficient - boiler to any new boiler will make savings. It is simply not possible to quantify how much of the £600 is due to having a combi. As stated above:

And even if the 2 boilers were the same efficiency a cheaper solution would have been to heat with electric, ideally E7 which is cheaper than oil. It's hard to heat water with an oil boiler efficiently. If you just heat water with no heating then you will probably go into short cycling as the you can't dump all the output into the hot water tank quick enough. When I heated with oil (now I use E7) I had my time clock set to give 3 bursts of 10min on, 10min off, as that way the boiler ran for 10min solid rather than cutting in and out every 2min. Of course in the winter you can run rads and tank in parallel so there isn't the problem of short cycling but then it takes longer to warm up the house.

matelodave

I've had both conventional (boiler & tank) and combi and I much prefer the combi - I'd have one now if we had gas.
They are fine with showers providing your inlet pressure is adequate. Both my daughters have had combis installed to replace their old conventional systems and both of them are saving a lot of money on their gas bills and more than happy with the shower performance.
The only slight disadvantage with a combi is that it takes a bit longer to fill a bath, however you can fill it continuously or have multiple baths one after the other - you never run out of hot water like you do with a tank system.
They cost a bit more to install because the pipework needs modifying, but you do get rid of the hotwater tank & all the tanks in the loft, so the possibility of freezing is significantly reduced.

Cardew

matelodave wrote: »

Both my daughters have had combis installed to replace their old conventional systems and both of them are saving a lot of money on their gas bills and more than happy with the shower performance.
.

As stated above, replacing an old(and thus low efficiency) conventional system with any type of efficient new boiler(conventional or Combi) will account for the majority of savings.


The savings of a combi over a conventional system are not large:

A modern Hot water tank, at 65C, in 24 hours will lose heat taking around 2kWh to replace - they are tested to a British Standard. So around £30 a year(with gas) if kept at 65C all the time; in practice the loss will be less than £30 a year.


However that heat is not wasted for much of the year as it 'escapes' and warms the fabric of the house - and many HW tanks are in an airing cupboard.

I have both systems and IMO a conventional system wins every time.

Lgas

Conventional system, definately. Don't forget combi's were invented for flats where there is no room for a hot water cylinder - and there are less taps! Combi's suffer more in hard water areas, the plate heat exchangers get blocked with sludge, more components to fail inside the boiler...not a fan, I don't like fixing the things when they go wrong, which is often!

*If money were no object I would personally have a condensing system boiler with an unvented cylinder*