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

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Discuss New build - is the system the builders are proposing any good??? in the Plumbing Jobs | The Job-board area at PlumbersForums.net

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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
 
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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
 
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.
 
Ch4 plumbing said:
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.
Click to expand...

less money for the builder and slightly harder install (combi everything goes to one point)
 
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
 
jonnyswamp said:
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
Click to expand...

if there are plumbers on site that is :)
 
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?
 
stevejw said:
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?
Click to expand...

for a house that size i would go with a decent size unvented cylinder 250L +
 
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!
 
stevejw said:
I'm concerned they're just cutting corners and cost-saving
Click to expand...

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.
 
In this situation.....

Unvented good

Combi bad

Somebody is trying to do you over. Stick with the spec.
 
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
 
Unvented twin coil cylinder, it's future proofed for some solar panels then :)
 
Your builder is a moron who sticks bricks together. Do not allow home to install a combo.

If he continues with this utter nonsense , grab him by his empty head and plough it in to a combo boiler repeatedly.

Unvented system with a balanced cold.

No variation no compromises.
 
It's not as simple as another zone if you wanted to add an unvented cylinder at a later date. The hot and cold pipe work would all have to be changed to another size and position, discharge pipe work, loads of extra wiring etc.....

On a new build that should not need any modernisation for 20 years get it right first time. A combi is being suggested because of cost and prob room.

Is your builder giving you a huge discount for the change? Speak to the plumber, ask for a copy of the plumbing design specification.
 
Hi julesverne; I live in Warwickshire. It's a Charles Church house and apparently all homes in the Persimmon group are now being fitted with Combis, regardless of size.
 
Thanks! They have the room, the a/c is their but will just be empty... has to be just for cost reasons.
 
Persimmon have a bad name for quality, most house builders do tho.

I have worked on and off new build housing for 20 plus years, the standards are at the lowest they have ever been. The biggest problem is lack of quality control and poor labour prices.

If i was to buy a new build house i would consider hiring a independant professional to snagg the property throughout the build process.
 
Persimmon are cheap skates. Insist on them sticking to the original spec.
 
Like buying a top of the range car & being told when you to come to collect it that they changed the heated leather seats to cloth, they do the same job & you won't notice the difference ;)
 
Where in Warwickshire? House builders are not the example to follow. They use plastic and design on 80c flow temps still
 
Have i read the original OP correct that you will have two leaky showers??

If so pulling a lot of amps that be more worried about those cables overheating
 
It can be done but a pair of contactors would need to be used and wired in correctly so that only one shower can be used at a time.
 
croppie said:
It can be done but a pair of contactors would need to be used and wired in correctly so that only one shower can be used at a time.
Click to expand...

Thought it maybe something like that was under impression you could only draw in X amount of kilowatts in domestic house
 
croppie said:
100 amps but you need to take surge currents into consideration
Click to expand...

+1 and a typical house with the normal lights and tv on draws about 17-20 amps
 
croppie said:
It can be done but a pair of contactors would need to be used and wired in correctly so that only one shower can be used at a time.
Click to expand...

close you can get shower priority boards, so say if no 1 shower is on no 2 doesn't come on until shower 1 is finished and so on

you done your part p refresh yet?
 
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