Rad sizes and regs

[darkart]

Hi all,
In new builds do radiators need to be designed to meet the requirements of the room size and kw output needs?

Reason being, in a friends new build the radiators are tiny and blatantly undersized; probably half the size need and rooms do not get warm due to this issue.

The builder is proving to be a constant nightmare and refusing to answer concerns with this and many more issues with the new build. It seems builders can do as they please with no governing body in place to help sort out complaints.

Basically, does the installer need to comply with any regulations I could use to get them come back and alter the system.

It seems plumbers worked to a plan and installed the rads then a gas fitter later came and installed the gas boiler and commisioned the system.

Many thanks in advance

 

[kidgreen61]

Interesting question.

I am a plumber/ gas engineer who doesn't do site work, or work for national housebuilders.

Both my daughters bought new builds last year, and when I went to inspect, I was amazed at how small the rads were.

BUT, the houses are so well insulated, they just don't lose heat, so the fag packet size rads are more than adequate to heat the house.

I'm sitting here in my barn conversion watching all the heat from a huge rad disappear through the walls with this easterly breeze

 

[ScottishGasMan]

They need to know the heatloss of each room and size the radiators accordingly.

The heatloss should be very low if it's a new new build,

What temperature is the boiler set to?

 

[Madrab]

The architects will have designed the system for the house design as a whole and would need to comply with the current energy efficiency regs and Part L 2013 (2016) of the BR, to have it signed off. New builds are usually pretty well insulated as previously mentioned and small rads are more the norm.

I'd be looking at the NHBC website, loads of new build/building regs info there.

 

[JohnD]

rooms do not get warm

The heat output of radiators, in the manufacturers specs, are calculated using unrealistically optimistic assumptions

The heat loss calculations are also unrealistic

So using the official documentation ends up with little radiators that are cheap for the housebuilder.

Are the radiators fully hot all over?

 

[darkart]

Apologies for the late reply, the rads are tiny all over the house apart from one fitted in a bedroom that is smaller than other rooms ?

The rads do get hot but due to being small do not get the rooms hot. The rad in the hall where the room stat is located again is tiny and does not heat up the hall.

It seems they have fitted the smallest rads they could find.

Building say its not his problem

 

[Madrab]

Building say its not his problem

Who's problem is it then? Builders cannot 'do what they please' any more, they have regs to stick to and if they don't then they can be hauled over the coals for it.

If it isn't him that is responsible for specc'ing the system then he needs to tell you who it was, as someone is responsible. It should all be in a new build pack that he should have been given - was it an individual build or was it a developer?

All new builds should all be highly insulated and typically will have really small rads as a consequence, seen it loads of times recently, so I'm not surprised they are small but they should be properly sized for the house they're in.

If the architect/designer hasn't specified a suitably sized heating system though then it's really down to them and that all depends on the information flow,
- Who gave who the plans and who told who to do what.

Either that or your pal isn't using the system properly. Time for more info methinks.

 

[D_Hailsham]

The heat output of radiators, in the manufacturers specs, are calculated using unrealistically optimistic assumptions

Radiator output is measured in a controlled environment as laid down in BS EN442. What gave you the idea that it is calculated?

 

[JohnD]

It's a long time since I looked at the assumptions, perhaps you can correct me, but when I did I thought they were unreasonably optimistic.

My recollections may be at fault.

If I have it right:

the assumption is that the Flow temperature will be 80C and the return 60C
and that flow will be TBOE
and that desired room temperature is 20C
and that outdoor temperature is 0C

Is that correct?

My objections are:
modern condensing boilers usually run below 80C (so the assumption is incorrect and optimistic)
UK radiators are most BBOE (so the assumption is incorrect and optimistic)
UK winter temperatures are often below 0C (therefore a radiator calculated for 0C will be unable to cope on a cold winters day or night)
the energy required to raise a cold room to 20C is greater than the energy required to maintain a room, already at 20C, at that temperature (therefore a radiator calculated to maintain will not be enough to heat a cold room in a finite time).

Are my objections wrong?

I formed my opinions after using a heat-loss calculator and finding that although meeting the calculations, my house was constantly chilly in cold spells, especially on frosty nights, and took a long time to become comfortable when I returned after working away during the week. I took steps to reduce the heat loss and to increase radiator size, and have been an advocate of oversized radiators ever since.

 

[dilalio]

Amongst all of this, one has to also consider that sensitivity to temperature differs hugely between individuals.

Minimum standards exist (and likely constantly change due to trends and research) and house builders will decide whether to meet or exceed these standards, according to their business model and target audience.

Building a house to put on the market depends on that market. Building a house for a specific customer is entirely different.

I've ripped out and replaced a kitchen and bathroom on a new build that were only installed 2 weeks prior.
Customer bought off plans and despite requesting the developer to leave these rooms bare AND NOT seeking a reduction in the sale price, he was told that contractual obligations meant they had to be fully installed at handover.
Crazy huh!

 

[bernardgreen]

Are my objections wrong?

Not wrong but seem to avoid any mention of flow rate ot water through the radiator.

Energy supplied from water to radiator in a period of time = drop in temperature of the water times the volume of water that passed through the water in that period of time

 

[motorbiking]

You should be able to run some calculations on the set-up and determine if they are under sized. If the central heating system is not capable of getting the room to 21 degrees with an outside temperature of zero, then you might have an argument that the system is not fit for purpose. Legally its going to be cheaper to upgrade the radiators in place, perhaps using double convectors or taller units. It might also be possible to increase the flow temperature or simply adjust the timing to come on earlier. A new build will have very low heat loss assuming its been built to spec. Unfortunately, Property law doesn't give you any major recourse, unlike consumer law. So had you got the builder to design and install it on an existing property, you'd have more rights than buying it as part of the package.

Personally I'd start by turning the rad flow temp up and check that each rad is getting a hot supply and getting hot all over.

 

[D_Hailsham]

If I have it right:

the assumption is that the Flow temperature will be 80C and the return 60C
and that flow will be TBOE
and that desired room temperature is 20C
and that outdoor temperature is 0C

Unfortunately, you are incorrect.

The current standard (since 1997) specifies:flow of 75C, return of 65C, room temperature 20C. The rad is connected TBSE (same end). There is no specified outside temperature as it is irrelevant; the test is measuring the output when the air temperature is 20C, not how much heat is required to raise the temperature from 0C to 20C. I assume the room temperature is maintained at 20C by other means.

As for your objections:

The standard was designed to provide consistency in measuring radiator outputs throughout the EU.

Although the standard does not take into account the lower temperatures required for maximizing the eficiency of a condensing boiler, most rad manufacturers' provide correction factors which enables the system designer to size the radiators correctly.

TBSE is the standard on the continent (I have seen rads connected that way in every European hotels I have visited. The British use BBOE because it looks "nicer", with about 2% loss in output. The 10% to 20% "allowance" provided by most rad calculators takes care of that.

The outdoor temperature is only relevant when calculating the size radiator required. Heating from -10C will require a larger rad than from 0C. (The same goes for room temperature. If you want to heat the room to 23C, you will need a larger radiator)

The standard is not concerned with how much energy is required or how long it takes but with measuring the output of the radiator under specified conditions. A nominal one kW radiator actually gives of 1.5 kW if the room temperature is maintained at 0C. A radiator is not like an electric fire, which gives off a constant amount of heat.

 

[motorbiking]

The standard is not concerned with how much energy is required or how long it takes but with measuring the output of the radiator under specified conditions. A nominal one kW radiator actually gives of 1.5 kW if the room temperature is maintained at 0C. A radiator is not like an electric fire, which gives off a constant amount of heat.

Can you explain how? That would seem to be 0.5kw of free energy. Or are you saying its able to radiate 1.5kw of energy against a rating of 1kw, rather than turn 1kw in to 1.5kw.

I believe the argument being made is that the OP should be able to run output calcs based on room size and materials using any number of on-line tools, or the old fashioned way and then compare the output capability of his rads to see if the rad is capable of meeting the output required.

Given humans like to live at temperatures of 18-23 degrees C. A central heating system is not fit for purpose if its unable to heat a room to that temp, given a design baseline of Outside temp at 0 degrees. Whether he can make a claim for damages, is unfortunately complicated by the somewhat "sold as seen" nature of property law.

If he can show the system is deficient he might have a claim against his surveyor if it wasn't flagged.

 

[dilalio]

If he can show the system is deficient he might have a claim against his surveyor if it wasn't flagged

I get the impression it's not "that type" of new build... ie its been bought off plans or after build.