New Combi or Unvented Cylinder?

[PullerGas]

Evening all,

We've currently got a 15 year old Worcester Oil Heatslave 18/25 Combi, it's working fine but we're about to replace the kitchen and in order to make the kitchen work properly we either need to move the boiler by about 12" or fit a smaller one.
So I'm thinking that if we're moving it we might as well replace it at the same time as it must be towards the end of its life now.

But then I was thinking, we have an airing cupboard very close to the location of the existing boiler, so would it be worth considering to put in a system/regular boiler and an unvented cylinder instead?

The mains water pressure here is really good, too much intact as I had to fit a pressure reducing valve.

Showers off the current combo are fine, there's only two of us in a 5 bed house currently so no issue with showers running at the same time but in the future when kids are about it could be more likely.
At my last house I fitted a Valiant 837 and that managed to cope with two showers just about so am wondering if we stick with a combi and put a big one in then two showers might be OK?

The house has one bath, and three showers.

There's no way we can have solar as the house is listed so no benefit to having a solar loop in the cylinder. The electric might be useful if we ever run out of oil though.


Any thoughts or advice?


Thanks

The hot water flow rate can be very poor on most oil combis Eddy & with no immersion heater backup for hot water they're not the best. Oh fine for you & the wife, but if you ever have house guests & a high hot water demand. I won't recommend an oil system boiler either, generally the expansion vessel is too small & you pay top dollar for very few advantages over a standard boiler.

The performance from a unvented cylinder is second to none & in 2015 you'd be bonkers fitting a vented hot water system.

So my recommendation; normal floor standing oil boiler, unvented hot water cylinder & central heating sealed system expansion vessel & kit.
HTH

 

[EddyP]

Very interesting replies. Thanks all!

I must say I've been impressed with the hot water flow so far from the combi, but as Mr Puller has said, it's only two of us, if we're replacing the boiler we need to account for 15 years which means kids, which means more showers etc.
Think I'll try one of the other showers tomorrow when the mrs is in the shower and see what the consequences are

What sort of size UC do people normally go for ? 210L? and roughly how many average showers can that do?
I know I could work it out but I'm thinking that if the hot water in the cylinder is at say 55 degrees, and the boiler is running, it'll blend the water as it fills and heat it, so surely you'll get more than your 210L but the temperature will be on a gradual decline?

I seem to read very mixed reviews on Worcester Bosch oil burners, obviously they've done very well with Which, and the local Grahams chap recommends them, but what are the views of people on here who actually work on them? are there any others you'd recommend?

Green box outside isn't an option as we're G2 listed, they wouldn't approve it, plus it would ruin the garden.

Finally to make things more tricky, currently the house is split into 3 zones, we may add another with some UFH, so potentially 4 zones + DHW, will need to work out how to plumb that up and control it. I'm hoping the smart control routes get even better soon so that may be an option, current control can't be too efficient, simply a timer for each zone, TRVs and no thermostat!

 

[Dan Robinson]

Having a combi doesn't preclude you from having a cylinder (vented or otherwise) as well.

Evohome is the perfect control system for what you describe too.

 

[Dan Robinson]

Ignore which? Magazine and the opinions of counter monkeys.

Trusted local installers are the best source of information.

 

[Dan Robinson]

Where are you located?

 

[PullerGas]

Having a combi doesn't preclude you from having a cylinder (vented or otherwise) as well.

Evohome is the perfect control system for what you describe too.

Very true Dan & I'd be the last Plumber on the planet to condemn a hybrid installation.
Recommendation for oil boiler;
http://www.hounsfieldboilers.co.uk

 

[Happyplumber]

My god the voice of reason is Puller!

That would be my choice to and most system boilers are actually combination boilers with the diverter Valve removed and the setting changed on the PCB
Expansion Vessel will be far too small.for house that size so Heat only With external pump,correctly sized expansion vessel is definetly the prefered choice .
I would never recommend a Combi where there is more then one bathroom and high demand for hot water
Flow and pressure allowing then an unvented cylinder,especially now as they are very affordable and cost effective every time

 

[PullerGas]

My god the voice of reason is Puller!

That would be my choice to and most system boilers are actually combination boilers with the diverter Valve removed and the setting changed on the PCB
Expansion Vessel will be far too small.for house that size so Heat only With external pump,correctly sized expansion vessel is definetly the prefered choice .
I would never recommend a Combi where there is more then one bathroom and high demand for hot water
Flow and pressure allowing then an unvented cylinder,especially now as they are very affordable and cost effective every time

I'm not as big a tosspot as people make out mate.....

 

[Happyplumber]

Mate I know ,remember I know you from the Screwfix days .In a politically correct world unfortunately people can't handle your hagging sometimes .personally it.don't bother me .....

 

[EddyP]

Very useful, thanks!

We're near Banbury.

Puller - I've never even heard of Hounsfield, how well known are they? I wouldn't like to fit a boiler from a company that might not be going in 5 years as I could imagine spares could be a nightmare.
How do they compare price wise with the likes of Grant or Worcester which seem to be the more common oil burners.

I think we're 90% sold now with changing to an UV, just to weight up the price etc.
Is there any particular make of cylinder that would be best to go for?

I understand I can't legally put the cylinder up, but I'd prefer to do most of the leg work to keep the price down, need to find a plumber that'll be happy to have me work with him.

 

[PullerGas]

Very useful, thanks!

We're near Banbury.

Puller - I've never even heard of Hounsfield, how well known are they? I wouldn't like to fit a boiler from a company that might not be going in 5 years as I could imagine spares could be a nightmare.
How do they compare price wise with the likes of Grant or Worcester which seem to be the more common oil burners.

I think we're 90% sold now with changing to an UV, just to weight up the price etc.
Is there any particular make of cylinder that would be best to go for?

I understand I can't legally put the cylinder up, but I'd prefer to do most of the leg work to keep the price down, need to find a plumber that'll be happy to have me work with him.

I've honestly not fitted one yet Eddy but they've had some very favourable reviews from people in the trade that I'd trust implicitly. Plus, I'm not a fan of either Grant or Worcester.

The boiler burner for the most part is the major component on the appliance & spares for these are readly available.

Regarding unvented cylinders; Megaflo have several redeeming features, but are expensive. Most of the other stainless steel units are much of a muchness, with Range Tribune being a good choice. Another one that's a good unit but more expensive is OSO.

Hope that's some help.