Time to replace gas boiler!

reloaded25

I currently have a 12 year old combo boiler that is being problematic and is undersized for the house. My question is what would be more cost effective, a properly sized combo boiler (30kWh) or a system boiler and 180l unvented hot water cylinder. The other thing to factor in is that I have a solar PV install so could use a solar emersion product to use excess solar power to heat the water in the tank.

Any advice greatly received.

Cardew

The consensus of opinion on these boards, on economic grounds, is you do not replace a boiler until it dies completely.


That said some boilers, particularly combis, are on their last legs after 12 years.


The combi v system boiler debate has been discussed on these boards for years - I am firmly in the system boiler camp!


When you say your boiler is undersized for the house, that presumably is for hot water demand? Most boilers can cope with the CH demand.


Obviously your PV panels in conjunction with an immersun type device diverting surplus electricity to a HW tank is a bonus - but any savings are only at gas prices. It is also pertinent that 'smart meters' are likely to be compulsory for houses collecting FIT/export. Thus you are unlikely to get the 50% assumed export of PV electricity, and there may not be much differential between lost export income per kWh and gas savings per kWh - and an immersum fitted costs £500??

reloaded25

As you say, I won't be replacing until it's dead but with a baby in the house I want to be ready when the time comes, so I thought I would get my research in now. Yes it is hot water supply that is really a problem, it's a 4 bed house with a 24kwh combo boiler (non-condensing) and it struggles to fill a bath in a reasonable time or supply a shower along with a hot tap etc. Heatings not too bad but it could do with a bit more capacity as we have cast iron rads.

matelodave

Don't forget that if you opt for a system boiler you'll have to find space for the hot water tank and the place will need some re-plumbing which could be quite disruptive. You'll also need a cold tank in the loft unless you opt for a pressurised (non-vented) system which are quite expensive so a bit of research is required.

Our 200l pressurised H/W tank is quite a big beast (46" high by 22" in dia) with lots of bits around it - pressure regulating & safety valves, overflows and a pressure vessel so it needs a decent sized airing cupboard or utility room to accommodate it and access to the drains or outside for the safety valve overflows. Controls will also be a bit more complex than a combi as you'll need a thermostat on the tank and motorised valves to control the water flows between the boiler and the heating & tank.

If your existing boiler is a non condensing unit then the new one (whether it's a combi or system boiler) will have to have to be a condensing boiler (regulations) and will need a condensate drain which might also complicate the installation depending on the location of the boiler and drains.

reloaded25

Are you saying that Smart meters will be forced upon us and that once fitted our agreements will be changed so that we will be paid for what we actually export rather than the 50% rule that we signed up for?

Cardew wrote: »

It is also pertinent that 'smart meters' are likely to be compulsory for houses collecting FIT/export. Thus you are unlikely to get the 50% assumed export of PV electricity, and there may not be much differential between lost export income per kWh and gas savings per kWh - and an immersum fitted costs £500??

Cardew

reloaded25 wrote: »

Are you saying that Smart meters will be forced upon us and that once fitted our agreements will be changed so that we will be paid for what we actually export rather than the 50% rule that we signed up for?

Well compulsory smart meters for FIT claimants are conjecture, discussed in forums and it obviously makes sense.


You have 'signed up' for your FIT rate, but I doubt if there is anything binding about the 50% assumed export. The terms of the PV subsidies are generous enough without paying you for 50% of generated electricity when it can be shown that you are exporting less than 50% - in theory exporting nothing.


Don't forget many with PV will gain from smart meters as they will export more than 50%.

supermiffy

Im in the same or similar position. I have a Worcester combi boiler which is almost dead.. we get heat but no hot water.

Our house was subdivided into bedsits before we moved here so we actually have 2 complete boiler systems. The one upstairs where al the bedrooms are is fine. The one down stairs as I said will only give heat and that is the one we need to replace. It has 3 public rooms a hallway and a kitchen where the current boiler is.

The house is terraced, high ceilings, single glazed and built in 1852. We have fireplaces in 3 rooms which we use when it is REALLY cold but to be honest, our house is always freezing. Oh... we live in Scotland.

Obviously getting one boiler system is probably cheaper in the long run but for nor we are going to struggle to pay for one that will do for just down stairs.

No idea where to start but we do have British Gas coming out to see us and expect they will try to rip us off ...

What do we need to look out for and ask???

reloaded25

British Gas quote £5k to replace a combo boiler on their website, so yes they will try to rip you off.

Cardew

supermiffy wrote: »

Im in the same or similar position. I have a Worcester combi boiler which is almost dead.. we get heat but no hot water.

Our house was subdivided into bedsits before we moved here so we actually have 2 complete boiler systems. The one upstairs where al the bedrooms are is fine. The one down stairs as I said will only give heat and that is the one we need to replace. It has 3 public rooms a hallway and a kitchen where the current boiler is.

The house is terraced, high ceilings, single glazed and built in 1852. We have fireplaces in 3 rooms which we use when it is REALLY cold but to be honest, our house is always freezing. Oh... we live in Scotland.

Obviously getting one boiler system is probably cheaper in the long run but for nor we are going to struggle to pay for one that will do for just down stairs.

No idea where to start but we do have British Gas coming out to see us and expect they will try to rip us off ...

What do we need to look out for and ask???

Is the upstairs boiler a combi or conventional boiler with hot water tank.


Do both boilers have the same gas supply?


I suspect most of the larger combi boilers will cope easily with the heating load of both floors. The 'Achilles heel' of combis is coping with hot water demand, especially to two bathrooms.


Would it be possible for a plumber to modify the plumbing so the upstairs(working) boiler ran the whole house?

macman

BG will typically quote you 40% more than an independent local RGI for an install.