Heating System Design for New House Builds

[thescullster]

Hi all

Just a point of interest really....

Does anyone know whether heating system "design" is regulated for new builds in any way?

Most contributors here I'm sure will know that, to run efficiently in condensing mode, the system temperature for condensing installations needs to be rather lower than older systems. This means larger radiators are needed to supply satisfactory heat input to a room with a given heat loss.

It is in the installer's interest to fit smaller radiators at a lower overall cost. But this would lead to a higher less efficient system temperature being necessary to sufficiently heat the property.

Does anyone know if checks are done for heating system efficiency, particularly on major builders' sites?

If not, then the claimed boiler manufacturer efficiencies will be meaningless.

Thanks

Phil

[Alan]

Through Gassafe and the Boilers Manufacturers Warranty.

The Housebuilders will have very little input on what the Heating people put in.It will be a sub contractor who does the heating work, and they will have that Contract through being the cheapest Tender. All the Housebuilder will demand is a radiator in each room and a boiler to give the correct heating characteristics for the house. They will not check the designs. The Builder will deny all responsibility for heating faults and design failures, and point you to the Heating Engineers if there is a fault.

[Chris Hogg]

I understand that the heating engineer does a calculation taking into account the room sizes, outside wall areas etc, to work out the number and sizes of the radiators needed and hence the boiler capacity. There are probably formulae on boiler or radiator mfrs web sites for doing it. From what the OP was asking, that formula ought to include the temperature that the boiler is set to, or do the formulae just assume a value, such as 65C or whatever?

[Brian Gaff (Sofa]

Also of course a lot, and I mean a lot of people seem to be getting their boilers replaced at the moment for condensing ones using the old radiator runs, what effect does that have on the assumed better economy of the new boiler? Brian

[Robin]

The builder may well do so. But that doesn't mean they can get away with it. As usual, it all depends on the contract. Builders don't /have/ to provide any heating. But most new builds will have heating; and I've not heard of buyers being told they need to enter into a separate contract with the heating engineer. Heating systems are also covered by the standard insurance polices and they do have things to say about heating systems if they are provided. E.g.

[Andrew]

Don't Building Regs make you adhere to something like the SAP rating of the proposed construction ?.

A farming friend built a new bungalow on his land and the BCO made him fit a particular type of fire-behind-glass which he had every intention of removing so he could have a blazing open fire instead. Not sure what the outcome was.

[RJH]

Related piece in the Guardian today:

Householders buying brand new homes in the next four years are likely to find an unpleasant surprise awaiting them in the future: homes built today will have to be retrofitted with energy efficiency measures and low-carbon technology, at an average cost of more than £20,000.

[Alan]

Yes, but the Builder will just say it is not our problem, we'll ring the plumbers and get them to look at it, then they'll ring the plumbers, and tell them to sort it. So there is a guarantee, but, the builders have sub'd the work out, hence the plumbers are liable.

[Alan]

I very much doubt that there are any calculations done regarding boiler feed and return temperatures compared to the room sizes and a standard temperature for that room. They'll just see a 3 metre square room, think 'we'll need a 600btu radiator for that room' and that is as far as the calculations will go.

[Robin]

I repeat, it all depends on the contract: if your contract is with the builder for a house with a heating system then then it's the builder who is liable if the heating system is faulty.

[Andrew]

More project fear from the Labour party. Building regs are never retrospective, apart from updating gas and electrical installations.

And no-one knows where that mythical £20K figure comes from. The Grundian article avoided any elaboration too.

Houses being built today are far more energy efficient than the millions+ built in the 1970's and 80's.

Remember, it was NuLabs 'warm house' project that resulted in Grenfell Tower being clad the way it was.

[The Natural Philosopher]

and mostly they wont be *wrong*

[ARW]

Or the architect?

This post is about design flaws not failures.

OK so this is a refurb and not a newbuild I am working on.

It is massively over specced but seems to give little consideration to anything to do with assisting the boiler to modulate.

It also probably has the worst UFH setup I have ever seen - I had a regular poster pop in and have a look at it so that he knows how not to do it when he fits his own UFH.

It's going to end up with overheated rooms and cold rooms.

All fitted to the architects specs and drawings.

[Andy Burns]

For UFH all the manufacturers will take a floor plan and return a pipework plan that splits it up into different zones with one or more loops per zone ... I doubt the architect does much more that cut and paste that.

The design of that system would probably benefit from having more than one manifold location to have run the loops from.

[Robin]

Good point. If your contract with the builder is "work to these specs from the architect" then architect's tender bits are on the block for design faults.

[Andy Burns]

Is the whole thing anywhere near done yet?

[Tim Lamb]

One difficulty we discovered with a refurb and planned underfloor heating throughout is adequate insulation over solid floor slab.

The original arrangement with wall hung radiators had 25mm polystyrene under 22mm chipboard. The new system uses slotted polystyrene slabs with about... 25mm of insulation below the pipes!

We could have put more under but only by losing ceiling/door height.

[Owain Lastname]

Sounds about right.

Owain

[Nikki Smith]

But how many building contracts stipulate that the builder *must* follow the design information? I've never seen it. A client would be mad to agree to that.

A designer works to a "reasonable skill and care" duty - so only liable if he or she drops below that. An architect copying and pasting a bespoke design from a UFH supplier would probably meet that duty of care, assuming the UFH designer was supplied with all necessary info.

Building contracts put a higher duty of care on the builder - a fitness for purpose. Any client who reduces the builder's liability by insisting on "work to these specs" deserves what they get...

[Andy Burns]

UFH for a refurb is obviously more difficult than a new build, from what I can remember it's mostly(?) the new bits of Adam's site have UFH and hopefully decent insulation under, the old bits have radiators, but it looked like a rat's nest in the corridors.