Combi v Gloworm & Electric shower

[utterlydiy]

Want your views on the topic whether a Combi may or not be any better than my present Hot water system.

The current hot water system is a Gas Gloworm boiler of some 20yrs old feeding 11 rads in a 4 bedroom detached, plus tap hotwater, bath is rarely used. The dishwasher and washing machine use cold water supply. An 7.5kw shower in bathroom.

The shower was originally fed from the hotwater system, but with 4 grownups using the shower and domestic uses, one was always moaning the hotwater had been used.

But now I find the fuel bill has increased more so with electric because of the shower, but no change in the gas.

So the question is,

Would I be better off in the long run in fitting a Combi system and changing the shower back to a system fed shower.

thanks

 

[Slugbabydotcom]

Do some sums
When I did some I reckoned that it would be better to stick with my old faithful thorn olympic [65% efficient] + electric shower than to stick in a combi [90% efficient]
In my case I would have zero installation cost for a new combi and zero labour charges although while I am fitting or fixing my own I am not making money elsewhere.
I'll do my calc again and see what happens

Existing boiler cost nothing to leave where it is
New boiler would cost say £800 inc TRV's
Expect to spend say £500 more on parts over the next ten years [expected lifespan]. Theres more to go wrong in a combi. In the last 20 years old faithfull has cost me 3 thermocouples and a gas valve say £100.

So it would cost me 1250 for a new set up for 10 years.
Thats £125 a year.
My gas for last 12 months was about £400 So say with increases £500.
At 65% I am getting £325 of energy and paying £175 for waste gas.
So if I need £325 energy and my boiler was 90% efficient I would pay £361 saving £139 a year
Ok so I am £14 a year worse off! Well for £140 over the next 10 years it can stay the way it is and I wont have to take as much time out to fix it!


Heres how I would expect Joe Average to fair up


New combi £2500 inc Part L compliance, powerflush and registration.
BG scheme £216 per annum

£466 a year


Existing boiler servicing 500, maintenance, parts and labour 500 for 10 years. Non BG scheme ... They wont let you in! The boiler is too old Lets add another £660 to cover a powerflush , pump and diverter valve for your existing system and to make the figures easy!

£166 a year

So you would need to save a massive £300 a year for it to be worthwhile

Take a bigger than my bill £800 as being your yearly cost @ 65%
Thats £520 worth of energy.
If your boiler was 90% efficient you would pay £578 so your saving would be £222 but your new combi would cost £300

I've just saved you £780 over the next ten years! Will that keep your leccy shower running? Remember that if your shower water was heated by gas then your gas bill would be higher and when your combi broke down you wouldn't be able to get a wash.

Whatever ... Bounce a few figures about and see what happens

 

[utterlydiy]

Thanks Slugbaby,

I forgot to mention that the Gas water system ie: Boiler, rads, tank, valves etc are under a Gas board service contract at approx. £150yr servicing and covering parts and labour in the event of a breakdown. Which I've had the thermal couple and motorised valves changed. They say most parts for boiler as old as it is, are available as they are common.

If it was found that the Combi was a better choice, I would also fit the sytem at zero costs apart from parts and Gas re-routing.

 

[utterlydiy]

I see from various posts, that some of the Combi's can be troublesome. As I've not any particular choice of manufacture, before I do sums as suggested, what choices would be made for quality and maintance free.

As I said earlier the Gloworm is some 20yrs old and although the engineers say its in good nick. Theres going tobe a time to replace it.

So as already said would I be any better off with a Combi than my present setup with costs of servicing and use of fuel.

 

[Slugbabydotcom]

My philosophy generally speaking is to take whatever you have now, get your bobs worth out of it and run it into the ground. Others may have a different opinion.

It goes something like this.

If it ain't broke don't fix it
If it is broke fix it
If you cant fix it economically then renew it
If you can afford it then do what you like

Its your decision at the end of the day and I don't want to make that decision for you.
If you have the money and want more readily available hot water at the risk of what is likely to be a less reliable combi then go for it.

Maybe a conventional system with unvented hot water could be an answer that you are looking for. These have a better recovery time for hot water so you wont have to wait as long to heat a cylinder full of water plus the benefit of mains pressure hot water + You could use an immersion heater for hot water if the boiler packs up.

Sorry I cant help you with boiler choice. Everyone has their own favourite.
Its a bit like buying a car. They are all made from more or less the same parts just put together in different tins with different price tags.

The only thing apart from the tin that differs significantly from one boiler to the next is the electronics.

Maybe looking up a 'Which™' report could be of some help?

 

[kevplumb]

crawled out of yer coffin again