Should I replace my conventional boiler?

[FrugalShaun]

I'm sure this is an old question but here goes. I'm looking for some advice regarding switching from a conventional boiler to a combi.

I moved into my current house about a year ago. It has a conventional boiler with a hot water tank. The boiler is Vitodens 100-W, which is a condenser boiler, but isn't a combi. I suspect the boiler has been in around 10 years, but can't be sure. So far it's been reliable. TBH - I was surprised that the house had a hot water tank as I thought those systems were a thing of the past!

We have our hot water configured to come on for just half an hour a day, and this seems enough. Our shower is electric, and we don't use the bath, so other than occasionally washing up, we don't use much gas-heated hot water at all! There are 4 of us in the house, with one bathroom and a downstairs toilet.

By switching to a combi, I'm expecting a few benefits:

• Reduced gas bills due to only heating water on demand, and generally a more modern, efficient boiler.
• Will allow us to have a thermostatically-controlled mixer shower fitted, and get rid of the electric shower (the pressure isn't great and it's expensive to run).

-Removal of hot water tank and the header tanks from the loft, so more space.

The first two are the main benefits.

My question is, regarding the energy savings, am I likely to actually see much difference between my current boiler and a new combi boiler? My instinct is no, because we're only currently heating that water for half an hour a day. I'm not sure what cost this equates to but it feels like it would take the life of the boiler to recoup the outlay. Is that fair?

If we also get rid of the electric shower then that could make a sizable difference, but again, I assume there's quite a significant upfront cost to replace the shower (or maybe not?).

I was given a price a few months ago of £2,500 to replace my existing boiler and system with a Ideal Logic Max 30. This seemed pretty reasonable to me.

Finally, the water pressure in our area is great. If the pressure isn't good enough for the new shower, is there something I can do? I've heard there are pressure tanks you can have fitted?

Any advice would be appreciated.

Thanks

Shaun

 

[gmartine]

Correct, it would probably take the lifetime of your new boiler to recoup your outlay on a new system if at all.

It's a decent enough boiler so if it's working well get it serviced, make sure the water quality/cleanliness is up to scratch and leave well alone and you "should" be able to get another ten years out of it.

It depends on your usage but you wouldn't necessarily see any if any HW efficiency gains by swapping to a combi. Improve your shower water pressure with a pump and use the hot water in your store where you can still use a thermostatically controlled shower.

 

[FrugalShaun]

Correct, it would probably take the lifetime of your new boiler to recoup your outlay on a new system if at all.

It's a decent enough boiler so if it's working well get it serviced, make sure the water quality/cleanliness is up to scratch and leave well alone and you "should" be able to get another ten years out of it.

It depends on your usage but you wouldn't necessarily see any if any HW efficiency gains by swapping to a combi. Improve your shower water pressure with a pump and use the hot water in your store where you can still use a thermostatically controlled shower.

Thanks very much for your advice. Just to clarify - the electric shower pressure is currently OK, as the cold water pressure in the bathroom is generally OK, but not great. However, the hot water tap pressure in the bathroom is terrible. I've been told this is because the system is based on gravity, and since the hot water tank is basically at the same level as the bathroom, the gravitational pressure is very poor. Makes sense to me! If I put in a thermostatically controlled mixer shower, and therefore the water comes from the hot water tank, the pressure would be terrible. I would need a pump as you say. Is this something that can be easily fitted to my existing system? I'm pretty sure there is already a pump of some sort, but I'm pretty ignorant to these things as you can probably tell!

 

[Last Plumber]

The head of water is provided by the tanks above, not the hot water cylinder but you're on the right track.

It is hard to say how much you would save in heating hot water as it depends on your cylinder size and type.
Swings and roundabouts really.

You save space with a combi but although you are only heating water whilst you use it, they use a high input as it is instant heating of water to provide a decent flow.

Shower would be off the mains and work well if the main is as good as you say. There are downsides to a combi, e.g. if you are in the shower and someone opens a tap, you will probably notice. Most people work around it or get used to it without much trouble to be honest but they aren't the same as stored water.

I wouldn't change it just on the grounds of efficiency. If it was at the end of its life, then is the time to decide what you want and change it to suit you.

 

[SimonG]

If pressures and flows allow then swap vented cylinder for unvented then swap your shower.

 

[DJKent]

I wouldn't change it just on the grounds of efficiency. If it was at the end of its life, then is the time to decide what you want and change it to suit you.

LastPlumber's view makes sense.

Anyway this is no longer true "I was surprised that the house had a hot water tank as I thought those systems were a thing of the past!"
As if ever you move to a Heat Pump in the years ahead, you'll need a HW tank. So keep it.
To save energy - maybe just get obsessive with more insulation for the tank, and all the pipes that come from it, and any caps for immersion heaters etc. And draught excluders round the cupboard door to keep the warmed air inside.