What is the 2020 consensus on boilers?

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Moving in to 1980s 4 bed detached house. Has the original heating system - vented, cylinder, tanks in loft, separate pump for shower. Planning to modernise system this year.

It's a fairly typical house, 2 showers upstairs, one w/c downstairs. Utility etc.

I want to make sure that any choice is future proof (think teenagers and not having to worry about "turning off the washing machine" to have a shower).

I've tried reading on the subject but I cannot find consensus.

  • Is a top end combi (with water reserve?) going to be enough?
  • If not, its vented vs unvented ...no other options?
  • I don't mind spending another £2-3k now to get megaflo if that is the right thing to do
  • Does anyone even put vented systems in with tanks anymore?

Has anyone made a similar decision recently?

Thanks
 
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Personally we kept the tank, we have solar panels and any excess electricity generated is diverted to the immersion, thus reducing our gas bill slightly.

Tank is a good thing IMO, if you have the space for it.
If the boiler packs up you can use the immersion to have hot water.
 
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  • Is a top end combi (with water reserve?) going to be enough? You'll get ones sufficient for a 2 bath, 4 bed house assuming you have sufficient mains pressure.
  • If not, its vented vs unvented ...no other options? There are some hybrids like the Harlequin HeatStream system which is vented tank & uses a heat exchanging coil. I've been recommended this system for my extension. Again, it relies on mains pressure but has the benefit of no pressure vessel that needs regular servicing.
  • I don't mind spending another £2-3k now to get megaflo if that is the right thing to do
  • Does anyone even put vented systems in with tanks anymore? Yes they do, particularly in areas of poor mains pressure.
 
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Thanks, I'll checkout the mains pressure when we move in and go from there!

Also just noticed that the Green Homes Grant will include only Heat pump related systems, so might take a look at those if the incentives make it financially viable.
 
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Personally we kept the tank, we have solar panels and any excess electricity generated is diverted to the immersion, thus reducing our gas bill slightly.

Tank is a good thing IMO, if you have the space for it.
If the boiler packs up you can use the immersion to have hot water.

How does that work then? What kit do you have that decides your excess solar energy is available and thus can be diverted to the immersion?
 
Soldato
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I have the same set up. 5 people in the house. 4 bed, 2 bathrooms, 1 cloakroom. Decided to keep the vented system due to space constraints and mains pressure being on the limit of acceptable but switched to a system boiler. We have a Stuart Turner 3 Bar shower pump for the second bathroom as it was an extension, and the main bathroom had a power shower but it's being upgraded to a digital shower with its own pump.
 
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I've had most types of boiler systems,
Vented, Unvented, Combi and Storage Combi..

I liked the vented/unvented for the overall instantaneous capacity, but the efficiency and immediacy when it's empty are reasons I moved away from these, as well as the vented systems Tank / Hot water cylinder taking up so much room!

I currently have a Combi (Worcester Bosch 38CDI) which is easily good for two showers, or a good large shower and people using hot water taps in other rooms at the same time, and whilst not mains pressure you can fill a bath quickly (16+L/min).

The best boiler system I have had was a Storage Combi Boiler, this has a high pressure thermal store internally (it was a larger unit but did fit OK in an airing cupboard) so you get very high hot water flow rates whilst it's using that store, easily good for 2 showers + washing machine and would fall back to just normal combi performance if the store depletes... Filling a bath was the same as my unvented mains pressure system and the thermal store was enough for a bath.. Plus for our busy house it seemed to give me the lowest bills (roughly equivalent energy efficient houses).
 
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Bumping this back up for any more opinions. We are now in the house and had a few people round to quote and advise on heating system replacement. Flow rate on mains pressure is good. In excess of 20 lpm. 20mm pipe from main.

Current thinking, either....

High power Combi. E.g. wb 8000 45kw. Flow rate 17 Lpm ish in hot water. But also goes low output for the heating efficiency.

or...

unvented and system combo.


Both of the above will be located in the garage and achieve decent flow rates, enough for most scenarios. Actually quite hard to choose. Currently leaning towards paying the extra 1500 quit to go unvented to future proof it, solar etc. What would you do ? Will be here for 20 yrs so want it right.
 
Soldato
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Having been in properties with both types of system, I'd go unvented given the choice.

Having mains pressure hot water and a good flow rate is not something to be underestimated, especially with the big modern showerheads you can get these days. You also have the option to plug in solar and if the thing breaks down you can at least have a hot shower using the immersion. The main negatives are price and space.
 
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Having been in properties with both types of system, I'd go unvented given the choice.

Having mains pressure hot water and a good flow rate is not something to be underestimated, especially with the big modern showerheads you can get these days. You also have the option to plug in solar and if the thing breaks down you can at least have a hot shower using the immersion. The main negatives are price and space.
Does a modern Combi with high flow rate not also give mains pressure hot water ? Would the experience for showers etc be much different with unvented?
 
Soldato
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Having been in properties with both types of system, I'd go unvented given the choice.

Having mains pressure hot water and a good flow rate is not something to be underestimated, especially with the big modern showerheads you can get these days. You also have the option to plug in solar and if the thing breaks down you can at least have a hot shower using the immersion. The main negatives are price and space.

We have a big thermal store and it's great, mains pressure hot water, heated exclusively with solar for 8 months a year. Wood burner picks up the winter months.
 
Soldato
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Does a modern Combi with high flow rate not also give mains pressure hot water ? Would the experience for showers etc be much different with unvented?

It will be ‘fine’, but not as good as a cylinder. Thermostatic showers will help mitigate the shortcomings but you also have to remember that as soon as a second outlet is turned on that figure is effectively halved. A modern shower head can Chuck out a lot of water. The pressure and flow rate will be impacted by things like incoming water temperature, you’ll get less out of it in winter.

They obviously have a lower upfront cost and take up less space as their main advantage. Have you compared the ongoing costs? I’d expect a well set up system boiler to be more efficient as it will be able to operate in its most efficient mode all the time.

We have a big thermal store and it's great, mains pressure hot water, heated exclusively with solar for 8 months a year. Wood burner picks up the winter months.

I’d consider a system with a thermal store to be more akin to an unvented cylinder compared to a combi. The advantage is that they can be very flexible because many can be heated from a wide range of sources as you’ll no doubt be aware. They can also be used for space heating as well as hot water which can be a big advantage if you have a lot of solar.
 
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We have a big thermal store and it's great, mains pressure hot water, heated exclusively with solar for 8 months a year. Wood burner picks up the winter months.

Exactly what I've just fitted, except we have an electric boiler as well, more as a backup and hopefully won't be used that often once I've got the stove in.
 
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