New build - is the system the builders are proposing any good???

[stevejw]

Hi everyone, newbie and complete novice here so hoping for advice to help stop us making a costly error!

I'm in the process of buying a new build house and the builder has informed us of a change of specification, away from an unvented (I think that's what it's called; pressurised cylinder in the airing cupboard) system to combination. The house is 4 bedroom with 2 en-suites (showers only) and a bath in the bathroom that we want a shower installed over.

The builders have told us they are installing a Valliant ecotec plus boiler (I'm unsure of output so have asked them to confirm which), with a thermo shower in the en-suite to bedroom 1 only and electric showers to the second en-suite and as the option for over the bath.

I'm hoping for some advice:
Is this going to provide acceptable performance for a house of this size?
Will the performance be notably poorer than a vented system?
Could they plumb for both combi and vented so I can get it changed later if I wanted (the thought of going back to 1st fix to install a different system fills me with dread!)?
Is it true that a combi provides either heating or hot water concurrently, but not both? Is that the same with a vented system?
Could we get one of the showers (say in the main bathroom) changed to a thermostatic and use both thermo showers concurrently?
I'm not that against having the white plastic box on the wall in the second en-suite as it's a useful backup in case of any heating issues, but am less keen in the main bathroom and am concerned about concurrent usage from any of the outlets (kitchen tap or whatever) in a house of that size with a combi.

Sorry for so many questions, but having had this dropped on us I'm concerned they're just cutting corners and cost-saving and as a result will leave us with a system that provides very poor performance; am hoping the experts out there can either confirm or ease my fears

Thanks!
Steve

 

[ShaunCorbs]

no get rid of the combi boiler and stick with the unvented cylinder and heat only boiler

combi are only for a single bathroom and maybe an en-suite

 

[Ch4 plumbing]

I wouldn't want a combi boiler in that situation! And TBH I'd have to question why they have changed their minds and move away from an unvented cylinder set up, which as long as their is the correct pressure and flow rates would be the best option! I can only think it comes down to cost or incorrect initial installation.

 

[ShaunCorbs]

I wouldn't want a combi boiler in that situation! And TBH I'd have to question why they have changed their minds and move away from an unvented cylinder set up, which as long as their is the correct pressure and flow rates would be the best option! I can only think it comes down to cost or incorrect initial installation.

less money for the builder and slightly harder install (combi everything goes to one point)

 

[jonnyswamp]

You can still have an unvented cylinder with a combi if you wanted one at a later date, its just another zone
However, if I were you, I would be negotiating hard with the builder to insist on the cylinder now, or a few grand off the agreed price for what he has suggested and speak to the plumbers on site to run some extra primaries from boiler postion to expected cylinder position

 

[ShaunCorbs]

You can still have an unvented cylinder with a combi if you wanted one at a later date, its just another zone
However, if I were you, I would be negotiating hard with the builder to insist on the cylinder now, or a few grand off the agreed price for what he has suggested and speak to the plumbers on site to run some extra primaries from boiler postion to expected cylinder position

if there are plumbers on site that is

 

[Dotty]

if there are plumbers on site that is

Thought hadn't crossed my mind at all!

 

[ShaunCorbs]

Thought hadn't crossed my mind at all!

esp if its in plastic i would be asking to talk to the plumber

 

[stevejw]

yeah - pushfit all over the place; another thing that worries me a bit!

Thanks for all the replies to date - hand't even thought about a separate zone with a cylinder in it; might be worth proposing to them as a potential "solution"; worth a go do you reckon? could I get a smaller cylinder if I put all the showers off a cylinder and everything else off the Combi?

 

[ShaunCorbs]

yeah - pushfit all over the place; another thing that worries me a bit!

Thanks for all the replies to date - hand't even thought about a separate zone with a cylinder in it; might be worth proposing to them as a potential "solution"; worth a go do you reckon? could I get a smaller cylinder if I put all the showers off a cylinder and everything else off the Combi?

for a house that size i would go with a decent size unvented cylinder 250L +

 

[Ch4 plumbing]

I'd want full unvented, don't settle for an ad hoc system! You will never be happy with a combi.

If they ar'nt putting a cylinder in now they ar'nt gonna put a small one in now!

 

[Ray Stafford]

I'm concerned they're just cutting corners and cost-saving

Your fears are well grounded.

Go back to them, and say that you agreed to buy the property based on the specification supplied, and that you are not happy with the change in specification, but will accept it for a £5,000 reduction in sale price.

They will refuse, and at that point, just tell them to stick to the original spec.

 

[SimonG]

In this situation.....

Unvented good

Combi bad

Somebody is trying to do you over. Stick with the spec.

 

[julesverne]

Unvented cylinder all day long for your house spec. Dont take no rubbish from your builder he doesn't know what he is talking about and ask for the details of the gas engineer who will be doing the work as you want to talk to him personally and put him on the spot. I wouldnt be surprised if the builder would try and get away with fitting it himself as he's prob been quoted more than expected.

Do not let the builder pull the wool over your eyes. He's trying to con you with an inferior system to save his profit margin

 

[julesverne]

Where you live steveJw?